handbook engineer
DESCRIPTION
book engineerTRANSCRIPT
Kffi IT ENGINEERS HANDBOOKaild
Review Cuide
f v
IlIItIIIIIIIIIIII
I
I
III t t ' . ]
I
' r /
"PHILIPPINE COPYRIGHT @ 1993"
C} i IEF ENGR. FERDINAND G. MARCOS
No port of this book moy be reproduced in
by any meons without permission in
ony form, by mimeogrophinq or
writing from the author
By
Printed by: 55P Makati
ACKNOWLEDGEMENT
This book was exclusiaery prepared to hetp the Marine Engineers while re0ie(Ding the dffient
subjects in preparation fo, tlre glorrrnnr*,t licursur, ,ro*lnofion conducted by the Professional
Re gul ation Commission'
,[.t is a compilation of solutions to tlrc problents encountered during the recent examination'
Tltere are also exercise que.stions including an outline to examinees, to serae as an instant
refresher on *ru iost iitndanrentnl concept and principles in accordance with the scope of
the examination usually giaen by the Roarcl of Examiners at the PRC'
It is arso a complete practical guide -to.arl apprentice cadet, ship personnel and engineers
on board, on the ratest technology t0 bring yiu the most up-to-dafe coaerage possible of high
standard on the iob aboardshiP'
The author gratefully acknowredges and appreciatcs the support of the staff and students of
SEALANc COrvSuirancY AtlD GEAIERAL SERVICES' INC'
This book ts roaingty dedicated to my wjf!, Terry-y"l ryV daughters' Sarah lane' Christine
loy and my sans r-rrainond Ir., Ferriiianrtr' N[arcoi tt *ho iort bien my constant inspiration in
*y iourneY to the Port of success'
FERDINAND G. MARCOSChief Engineer
PMMA, Class 1'981'
Monilo, Phit iPPines11 l29le6
PAC E
PART I MATHEMATICS. Basic Futrdanrental of Flatlrenratic:,
( lncludes: Algebra, Ar i t l t tnet ic, ! ) l tys i , t : r , Strelrgth of l 'dater ia l )r Board Problems and Answers: 19t t7--91 ,A,! l l larr l ts (48, 3F-, 2E, CE). Board Multiple Choice: All Ranks. Useful Engineer Fr:rmulaso Conversion Tables - Cuide C)rrlrl"
PART f l ELECTRICITY AND El- [C] ' t t l ( :At- ! -V DRI\ i I t . , ] [ - ' r { ( iF l l . l l .5 lOl{ . . . . . . . . . . . . . . . . .71. Definit ions, Functions of Electl ic-;rl
- l-errrrs
. Board Questions ancl Answers: All Rarrkso Trouble Shoot ing of Electr ical Conrporrerr t
: Ili:,;tJ,.'ru;::"':l H,l?l',.,, and r,,re, ,.,, i,raLi. ro Motor: Operation and Mainterranr.-eo Switchboard Protectiorr. Electrical Formulas and Syrnbolsr Board Problem Solving: All Ranksr Board Mult iple Choice: Al l Ranls
PART III STEAM BOILER, TUIIBINIiS II{ 'TERhIAT. COI\,{ i IT'5]-!ON ENGINESSectlon | : Steam Boilers
. Type, Uses, Classification
. Boi ler Mountings, Accessories and l :unctiorr: ;r Boiler Terminology, Uses and Functions. Safety Valves. Boiler Water Level Gauges. Maintenanqe Operation. Boiler Corrosion Water l-reatlrrerrto Boiler Water Testing Procedures. Waste Heat Boi ler Problems arrcJ Mairrtenarrr-e. Boiler Safety and Descriptiorr. Emergency Procedures
Sect lon l l : In ternal Conrbust ion [ ,ng ine . . . . . . . 191. Definitions, Classificationso Principles of Operatiorr. Component Parts and Useso Scavenging Process
U-'-c Turbocharging Process. Definition of Terms. Board Questions and Arrswersa
o
SectlonO
o
o
Fuel, Lube Oil, Fresh Water SysterrrStandard Operating Procedures,
- lrouble 5lrool ing
f l l : Steam Turbines, Engines " . . " . . . . . . , ,722Definition, Classification, OperationFittings and FunctionsBoard Questions and Answers - All Ranks
IIIiIIilIIIII
IV
PART V
PART IV
' Reciprocating . Steam Engine : Definitions, Advantages, Construction and Operations. Board Questions: lr4ult iple Choice : Al l Ranks
REFRIGERATION AND AI I I -CONDIT IONINC MACHTNERY . . . . . . . , . . . , . . . , . 261' Defiuit ions, characterist ic, [ :r ' r ' rct ions of Typical parts. Safety Devices. Definitions of Technical l-errnso Operation and Maintenance Systerrr" Trouble shooting cuide to l lefr igeration problems. Board Problem Solvinqs - Al l Rarrl<s. Board Mult iple Ctroice: Al l Ranf<.s
PRACTICAL ENGINEER CTJ IDES . . " , , . . , , 317. Main Engine fndicator Di;rgrarn" Main Engine performance Test" Fuel-Lube Oil Tank Calculat iono Inspection, Measuremertt, Proceclures, Cyl incler Liner, piston Rings. Crankshaft Deflec - ion" Clrecking Clearances of lr . , lairr Bearinc-;, Crosslread, Crankpin Bearing. Reading on Enqirru Cclncl i t ion" Emergency Procedures in Lngine Cyl incler' Draw Diaqrams and Interpretationo Monthly Reports, Marit ime Reqr_rlat ions, Surveye Board Question and ,Answers: All Ranks
o
o
o
Test Procedure: Safety Maintenance prograrnPrinciples, Operation and N4aintenar.lce:
Fresh Water Dist i l ler, A,ir Cornprcssor, puri f ierOrdering Spare Parts, l iafet i , t l i l lBasic Inst rumentat ior - rWelding Safety arrrJ Tr:clrrr iclues
PART VI DRAWING
P/\RT VIISectlorr | : Safety of t. lfe lt l t,
" Firef ight ing arrd prevr. l r l iorr
" First Aid
" Survival at Sea. Li feboat Handl ing
Sect io r r ! l : O i l l -a r rker l ; l fe ty . . . . . . . . ,474Sect lo r r l l l : l rue l - t Cas Sys f .e t r r . . . . . . . . . . .4g7
PAi{"n- vil lSec t ion I : IV lach ine S l rnp . . . .503I Welding Techniques, I ' r io ls arrcJ l i r lu iprnerr ts, SyrnbolsSect ion l l : Fump 1- l reory, OJlerat ion and Maintenance . . .531sec t ion l l l : con t ro l Autorna t ionr In t roduc t ion . . . . . . . . . . .5s3Sect i< l r r l v : o rqan iza t ion o f F .ng ine Dcpar t rnent . . . . . . . . . s65
Watchl<eepinq, Safe Olterat ion, Bunker ing procedureso Board Exams Regu la t io r rs a r r r . l l tequ i rements
Sect in r r V : Coc le a r f F . t l l i c l . . . . . . . . . .5g1
o
|'
, , , , , , , , , , 4 2 8
MATHEMATICS
ln performing our dai iy dut ies as ship personnel ' engineers' and crew aboard shipwe
often solve simple problem, jn"or"ing iant< calculatiorls, sl 'r ip speed, horsepower' con-
sumptions unJ-ruinematicar carcutJtion which need ou. b"ric fundamental learning
pio.ttt in solvirr$ every day problems:
BASIC FUNDAMENTAL OF MATHEMATICS
t h e p r o c e s s i n w h i c h i t i s d e s i r e d t o k n o w h o w m u c h o n e
Examples:
MULTIPLICATION - is
number ls t ime another '
DIVISION - th is is t l re process in which
number wi l l go into another '
= 1 2= g20B= 0.00 1472= 1 7 0 . 3 6 1 1 5
is desired tc know how many t imes one
2 , 6 / 3 = 2cl
1036 .28298.93
2 x432 x
0 .32 x3.9472 x
o1 90.0046
4 3 . 1 6
it
ExamPles: 6
B 11 8653
1121
8 1 +
6 . 5 +
3 =9 =1 8 =3 3 1 4 =
+ 1 2 =- F " 5 =
6 = 2T
ADDlroN - adding numbers in s imi lar terms and add the numbers in each column
separatelY.
Examples:
53
7b + 3c
2b + 6c
946.758.42
.00842:
955. 17842
9B1 0
2a5a
f
7 a + 5 b + 9c
lI
I
Itr SUBTRACTION-Io subtract numbers or algebraic terms, change the sign of the term
I to be subtracted and then add'
tr ExamDles:II g z - 1 2 = 8 oI t z - 2 . s = s . 5I 8* - (-5x) = 13x
I t * - 5 x = 3 xII
tI oPEBATIoNs wlrH slcNED NUMBERS
I r' ADDtrloNl a . r o r n u m b e r s w i t h s a m e s i g n s , a d d t h e i r a b s o | u t e V a | u e s a n d p r e f i x t h e c o m m o n
sign to tho sum.II Examples:
I l;? I lti : :i:I
. b . F o r t w o n u m b e r s w i t h d i f f e r e n t s i g n s , s u b t r a c t t h e | o w e r a b s o | U t e v a | U e | r o mI ,nu trigner ausotu;;"ir.
"na pt.ri" tne sign oithe numberwith higher absolute value to the
' ditference.
Examples:
(+B) + (-4) = +4(-B) + (+'4) = -4
2- suBTRACrI9NI a. nnu ii"o niilO.rs with same signs, subtract the lower absolute lrom the higherI aU.ofut" ulfu" inJ pr.tir tn" sign of the number with higher absolute to the difference'
Examples:
b. Any.lwo nurnbers with different signs, add the absolute values and prefix the
sign of the nu!'nber with the higher absolute value to the sum'
FxampleS :
I!
T3. MUI.TIPLICATION
a. The product of two numbers having the same signs is always posit ive'
Examples:
(+6) (+3) =(-6) (*3) =
( + 1 8 )( + 1 8 )
( - 1 8 )( - 1 B )
b. The product of two nurnbers with different signs is always negative'
Examples:
(+6) ( -3) :( -6) (+3) =
4 . DIVISIONa, The quotient of Wvo
Examples:
numbers having the sarne s igns is a lways posi t tve '
(+9) i (+3) = (-t3)
(-s) / (-3) = (*3)
b. The quot ient of two numbers with di f ferent s igns is always negat ive'
Examples:
(+9) / ( -3) =
.., n, / (+3) =
TEMPERATURE SCALE CONVERSION
1'o convert 212"F to "C
Subtract 32 from 'F and divide
E x : 2 1 2 - 3 2 = 1 8 0 + 9 = 2 0
To convert 260 "C to "F
Divide bY 5, mult iPlY bY 9 and
E x : 2 6 0 * 5 = 5 2 x 9 = 4 6 8
remainder bY 9 and mult iPlY bY 5'
x 5 = 1 0 0 " C
add 32
+ 3 2 = 5 0 0 " F
( 3 )(-3)
$i[t
, F {
r Et s ,I \ N
DECIMAL$ a number less than a whole number may be expressed as a fraction or
as a decimal.
one ten th = 1 = 0 .1
1 0
, o n e h u n d r e d t h = 1 - = 0 . 0 1
1 0 0
onethousandth = 1 = 0 .001
1 000
o n e a n d t h r e e t e n t h s = 1 3 = 1 . 3
1 0
When decinral number are added together or subtracted, the decimal point must
be placed one below the other.
Examples:
a) Add 4.3785 to 29.46
4.3785
-?9-49_33"8385
b) Subtract 3.8648 from 48.82
48.82003.BS4q_
44.9552
Converslon of Percent to Declmal
E:<amples:
EB% - 0.88
0.35 : : 15%
1 .SB : 1SB%
99.34% = 0.9934
frnH
E
Conversion of Fraction to Decintal
1 1 2 = 0 . 5
5/B = 0 .625314 = 0 .75
powER - an index is a short met lrod of expressing a quant i ty rnul t ip l ied by i tsel f
number o f t i rnes"
tl 're square root of 49 = {gthe cube root of 27 - \ /27
6 2 = 3 2 = 9--T
RATIS - is a compar ison o f t l re magni tude o f one quant i ty w i th another quant i ty o f the
sarne kind; i t expresses the retat ionship 6f one to the other andtherefore stated in f ract ional
fortn. The rat i l l s ign is the colon:
E x a r n p l e ' \ - - r . r m a l a r o , . o o n a n t i r r o l v t h p
The lcngths of two bars are 250 mil l imeters ancl 2 meters respectively, the
ratio of one to another expressed'
250 . , 2C00 note: both quan't i t ies must be same units
o r 1 : B
pRopoRTloN - is an equation of rat ios, expresses rhat rat io of one pair of quanti t ies
is eqrral to the rat io of another pair. Tlre proport ion sigrr is the double colon:
F.x amPles:
Z 3 X 2 4 = 2 7
3 5 X 3 2 = 3 3
(2 r ) . = 26
ROOTS - is the opposi te of a power and
ExamPles:
Examples:
(addirrg indices)(a surtrtracting indices)(mult iPlYing indices)
the root sYrnbol is J-
4040
= 7: 3
hhil
I
t
I
I
I
I
5 :q
5 =o ro r
1 01 0
20
2 C :2 0 :
1 0 40
o. A pump takes 55 minutes to del iver 4400 t i ters of water. How tong wo'Jld i t taketo del iver 6000 l i ters?
Let X = t ime in minutes to del iver 6000 l i ters.Ratio of t i rnes taken : : F: lat io of quanti t ies del iver
5 5 : x : : 4 4 0 0 : 6 0 C ) 0X x 4 4 0 0 = 5 5 x 0 0 0 0
x = 5 5 x 6 0 0 0- 4400
x = 75 minu tes .
METI' loD OF UNITY - deals to proport ion problems especial ly with compoundproport ion with more than two pair quanti t ies.
Examp le :
A ship travel l ing at 12 knots can complete a certain voyage in 16 days. Howmany days would the sh ip take to do the same voyage a t a speed o f 15 knots?
At a speed o f 12 knots , t ime = 1 6 daysAt a speed o f 1 knot , t ime = 16 x 12 daysA t a speed o f 15 kno ts , t ime = 1 6 x 12
1 5= 1Z .B days
PERCENTAGE - is another rnethod of expressing a rat io in f ract ional form using 100as the denominator and symbol " /o.
Rat io of 4 to 21i= 4 in f rac t iona l fo r .m
25
= l 6 d e n o m i n a t o r o f 1 0 01 0 0
= "l l6"/,, in percentage fornr.
FACTORiING-is the reverse of mult ip ly ing, i t is t l re process of f inding the nurnbersor quant i t ies which, when mult ip l ied togethei wi l l const i tute the expressio]r given to befactorized.
rFExample:
Examples:
+ ZxY
( 3 + 2 Y
1 6
4 ) ( v
3 - F z- F 4
22
3x= X
X
(3
Y2
( y +
X
5)
xz
z)
4 )
EVALUATIoN - is the process of substituting the numerical value of the algebraic
symbols and woiking out the value of the whole expression'
E v a l u a t e 3 x Y + X 2 - 4 Y
w h e n x - - Z a n d Y = 3
3 x y " r x 2 4 Y
3 x 2 x 3 + 2 2 - 4 x 3
1 8 + 4 1 2
1 0
1 . F ind the va lue o f 0 ' 04218
Log of 0 .0421 B =
Log of 4750 =
Sum =:
an t i l og o f 2 .3018 =
LoGARrllMs - purpose is to be reduced the amount of labor and time involved in
multiplication and division and the sotution of po\^/ers and root'
Examples:
x 47501 .374893.67669 (add)
2.30 1 8200 .4 ans.
2. Divide 240 bY 4345
Log of 240
Log oi 4345
dif f erence
antitog of -1 '2578
2.3802
3.6380-1 .2578
0.05524 ans.
ILI
I
POWER - Find the value of ( 4.189 ) 'log of 4.1 Bg = 0.6221
multiply' bY the Dower =' 1
1 .2442
ant i log o f 1 .2442 = 17 '55 ans '
ROOT - Find the square root of 7365
log of 7365 = 3'8672
3 .B672 .d i v i cJebY2 = 1 .9336
an t i l og o f 1 .9336 = 85 .82 ans '
EqUATION - is an expression consist ing of two sides, one side being equal in
va lue to the o ther .
4 x + l 0 = 1 8 1 4 x - 2 x - 5 x = B - 1 5 + 2 8
4 x = 1 8 1 0 7 x = 2 1
4 v = B x - 3
X = 2
Simplify the following equations:
a ) ( a + b ) z
Ans. a + i l
x a + b
b ) ( a - b ) '
a b
x a b
a 2 + a b-r- ab + b?
a2 ab
a b + b 2
a2 + Zab -r' b2 a2 Zab + b2
b ) F ind the va lue o f x anc i y in the fo l lo l t ' ing equat ions:
l lx 5y = 50
Ir--r _9r*-:--i! -- 2l 2 x = 1 8 0
( = 1 8 01 2
) ( = 1 5
Substi tute:
c) Add the
5 3/8,
4 3 +
B
LCD
5 x 5 y = 5 05 ( 1 5 ) - 5 Y = 5 0
7 5 5 y = 5 05 y = 5 0y = - Z s
* 5
5
mixed numbers .
3 3 1 4
1 5
4
75
f ol lowing
1 2 1 1 4 ,
4 9 +A&i
4 3 + 9 8 + 3 0
1 7 1
Bor 21 .375
X =
B x =
8 x =
9 x =X =
smal ler nuntber
larger number
MATH EMATICS (AL\3 EB R A)
1. one number is g t imes another number and thei r sum is 45. F ind the unknown?
Let
45
45
4 5 =
9
5 srnal ler number
1 0
B ( 5) = 40 b igger number
iiI
IIt
II
II
IIIIIIIII
II
IIItII
IIl lttlil
2. lf a rectangle is 4 tinnes as long as its width andlength and the width.
i ts perimeter is 60 ft . Find the
(2x) = 602 x = 6 0
10x - - 60| = 6 width
width
length
+
+
therefore:4x =. ,4(6) = 24 length
3. How long4ryill it take oscar and Bong, together to plow a field which oscar can
do alone in dOays, an6 Bong do the iob in 8 days?
L e t x =4 x =
L e t x =
_ 1 =
x
1 =qv
1 =
B
Equat ion:
LCD:
2(ax)Bx
V,\
1
X
4 0 X =
3.08 days
number of days Oscar & Bong can plow the f ie ld together '
work done by Oscar & Bong in one daY
work done by Oscar in one daY
work done by Bong in one daY
{= l
X
{= l
_ 1 + * 1 _ .q Rv
5 + B40
1340
1 3 x
X
401 3
Let x
X +
X +
2x r-
1
1
I
X
1 s t n u m b e r
2nd number
26
2 6
2 6 - 125
21 2 . 5
4. tn" sum of two consecut ive nurnber is 26. What are the numbers.
Solu t ion :
X
1 1
Cl. When you add 5lB;7112 and 11124, what wll l be the sum?
httI
5 r ' L + l L8 1 2 2 4
1 5 + 1 4 + 1 124
* x + =
Q. The quot lent of 13 div lded by 317
1 3 + & =7
Cl. Solve fof x ln the equatlon 12x +
12x+ 25 - 35 = 14x r
12x - 14x -22x = -22
12x - 36x = 35 47- 2 4 x = - 1 2
X = - 1 2-24
x = J2
Find: LCD = 24
= 4 O o r 1 22 4 3
O. When you subtract 5/6 from B/15, what wil l be the dlfference?
. L _ 36 1 5
2 s - 1 630
LCD = 30
Q. What ls the product of 5/B and 417?
= -.lx or .33 0 1 0
6 1 - q-Y- \-/ J- -tl,, r n - ,z . r 14
l s :
1 3 v J - - 9 1 o r1
^ 3 - 3
30
+ 2 2 x 2
J3
25 -- 35 ;= 14x
22x 2
+ 3 5 - 2 5
1 2
O. A wire ls to be cut so that one piece is shorten than the other by 8 meters. How
long are the pieces if their combined length is 24 meters.
x + x B = 2 42 x B = 2 42x = 24 + I
x = 3 22
x = 16 meters longer wirex - g = 16 - I = 8 meters shorter wire
CONVERSION FACTORS
Temperature Scale:
' t . Convert 1000C oF and 212oF oC
Ans. oF = g C + 32 oC = -5- (oF 32)
= g x 100 + 32 = _5_ (212 32)
5 9= 900 + 32 = 5 (180)
S g- - 180 + 32 = 900
o F : 2 1 2
z. convert s;o'c oF
4000F 0c
BOOC OF
Measurements:
' t . Convert the fol lo 'wings:
a) 60 mi/hr. - FtlSec, meter/set-;.
b) 6.56 km/hr. FVSec.
c) 375 hp watts
d) 700 mm feet
IoC = 100
Answer: 572.'F204.44 "C1 760F
13
Answer: a) 60 ti xhr
)( 1000 m x 3'28 ft ' x t hr' x
1 km. 1 m 60 min'1.6 km1 mi.
1 min.60 sec.
= 314880 = 87 '47 tVsec'
6,o
= 87.46 tvsec = 26.67 m/sec
3.28fVm
b) 6.56 km/hr x 100-0 m x 3'28 ft' x -]-!1!-1 km 1 m 3600 soc'
= 21516.8 tt . = 5.gB ft . /sec.3600 sec
c) 375 hp . z4l,ff*
= 279,750 watts"
d ) 7 0 0 m m x 1 c m x l i n c h x 1 f t "
10 mm. 2 '54 cm' x 12 in '
= 2.30 ft.
o, A trucKs speed rncreases unirormry from 36 km/hr. to 108 km/hr' ln 20 seconds'
determlne the: \
a) average sPeed (velocitY)
b) the acceleration in meter/sec'
c ) t hed i s tances inme te rcove reddu r i ng th i spe r i od .
108 km/hr = 30 m/sec.
b ) a = V f - V o
t= _30
-_ 10
20= 1 m/sec.2
c ) S = V t= 20 (20)
s = 400m.
JJJJI
Solution: 36 km/hr = 10 m/sec ;
a ) ! = V f + V e2
30 + 10
2= 20 m/sec.
! = 3 6 + 1 0 82
' 72 km./hr.
1r
PYTHAGoREANTHEoREMoTRIGHTANGLETR|ANGLE
l. The base of a trlangle ls 5 ft. and altltude le 8 ft. What ls the hypothenure of the
glven trlangle?
c2
c
A 2 + b a
8 2 n 5 2
\ffivfgg
9.43 ft.
Note: SOHSine
Cosine
Tan
CAH TOAopposite = alc E! 3/5
a2 + b2
C2 a2
vlfzs - t -
\fJ64
hypothenuse=__ggisgnt = b/c
hypothenuse= opposite = alb
adjacent
4t5
314
e. State the phytagorean Theor€ln - expressed that the hypothenuse I,r equal t9!he8um of the squaie d't ttre two ht.. tt ts itso called rlght angle whose formula Cl s
ar + br; anb the angle sldes Cre opposlte, adf acent and base.
Figure \
a = 8,ft . | \ e = ?
t \l-
t\
b = 5 f t .
Formula:
C 2 =
b 2 =hv
b =
b =l"ru
Z. Flnd the values of the three trlgonometrlc functlons of an angle A ll lts elne lg U5"B
8 = 3
c\
By Phythagonean Theorem :
15
3. The diameter of a round steetnut that can be made from the bar.
bar is 50 mm. What is the biggest size of square
By : Phythagorean Theo rem.
a 2 + a 2 = d 2
2a2 = (50),
a2 - 2500-
2
a =\m-o-a = 35.3555 mm.
size of the square a2 = 1250 m2
4. What is the circumference of a c irc le whose radius is Tl l rnrcters?
tttJJ
Formula: Circumference of a circlewhere r
C
Area of sphere =
=,
=
21lr r7 ' ' , = 7 ' 5
2 (3 .1416) (7 .5 )
(6.2834) (7.5)
47.13 meters
JJIIIIIII
5. What is the lateral area of a sphere whose diamete'r is 10 f t.
Solut ion:
ff o,3.1 41 6 (1 0 ) '3 .1 41 6 (1 00)3 1 4 . 1 6
d = 5 0 m m
1 6
6. Find the area of a circle whose diameter is 3 ft. What ls the area In mlll lmeter?
Ans. A = n d 24
= tti" (3)'
= .7854 (g) {
? 7.068 sq. f t .
A = 1 I d 24
.7854 (914.4 mm)2
056694.42 sq. mm.
7. Flnd the helght of a cyl lnder tank whlch hold 250 gal lons and dla.24Inches?
= 250 (231).7854 (24\'
= 127 "6' approx. 1 0 1/, f t .
8. A cyl indrical tank 12 ft . longholds 2600 gals when ful l , what is the dlameter ofthe tank?
Volume
height
VolumeDiameter
= .7'854 D2 h
= volume.7854 D2
.795,4 (D)' .lVo!u[e.7854 (H)
2,600 x, 23_!_. 7 8 5 4 ( 1 2 x 1 2 )
= 600 600
1 1 3 . 0 9
= 72.87 inches
1 gal . = 231 cu. in .
1 gal . = 231 cu. in .\ =
D2
D2
D
D
1 7
g. A hexagon of equat sides is inscribed in a circle whose clrcumference lst95 cm'
What are th6 length of the sldes of the hexagon?
z i IR,zfrrC--
2 l l
95
2 (3 .141 6 )
956.2832
1 5 . 1 2 c m .
Since hexagon has 6 equal sides therefore length equal is 15.12 cm'
10. The service tank of a container ship is 15 ft . in diameter and 7 meters hlgh' How
much f uel oll can lt accommodate lf the speclf lc gravlty of a fuel ls 0.95 assumlng no
volume erpanslon.
Given:
Solut ion:
h = 7 m = 2 2 . 9 6 f t . S P . g r " = 0 ' 9 5
dia. = 15 f t .
Volume = area of base x height
\ = itrrli;i,, x (22 e6)= .7854 (225) (22.e6) (0.e5)
Volume = 8354.5 ft .3
11. what ls the minimum diameter of a round stock necessary to make a square key
5" on each slde?
By : Phythagorean Theorem.(5)',
Area =
Circumf erence =
Radius =
;nHTJIJHt{
*
{
,q{
{
{
qEIII
I
(s)' +25 inc.zf f i ;
x = 7.0'/ inches
18
12. Flnd the volume of the givenwhose speclflc gravity is 0.96 ?
dia = 5 ft.
Volume :
=
Volume =
Area of base x height.7854 (1.52) ' (5.2s).7854 (2.31) (5.25)
9.52 m3 x .96 s.g.9 .145 MT
its content In metric ton of fuel oil
where 5 ft . = 1.52 m
4) x .90231
42.34 minutes
cyl inder and
5.25 m
PUMPS PROBLEMS
1. A slngle actlng power pump making 200 rpm has dlmensions 5" x 6" x 4"" Sl ipls 4.57o. What ls l ts actual discharge In gal lons per mlnute? (G.P.M.)
1 gal ion = 231 cu. in .
GPM = 'rol. of cyl. x no. of strokes x Eff iciency231
= .7854 x 62 x 4 x 200 x 0.955231
-= 21 601 "64231
GPM = 93 .5
2. A double bottom tank holds 6530 gal lons. A duplex double-actlng pump 8" x 6"x 10" makes 35 double strokes per minute. Leakage 1Oo/". How long will lt take topurnp out the tank?
GPM = vol. of cyl. x no. of strokes x Eff iciency231
=: .7854 x 62 x 10x(35 x
= 35625.74
GPM
231= 154.224
therefore 6530 i - 154 .224 -
1 9
&H
t ,i l
i
1
iJ'l
ir
3. A duPlex double act ing PumP 4"
actual discharge ln G.P.M?x 6" x 6" makes 25 RPM slip ll%' what ls lts
G P M231
= .7851 x (6) '? x . 6x(25 x 4) x '96 l231
G P M
1 6286231
70.502
4. A ship covers 242.6 actual mi les in a day. Firrd the pi tch
eff iciency is 87'/" and speed ls 98 RPM?
Formula :Pi tch = 6080 x observed mi les
N x 60 x 24 x E
= 6080 x 242.6
98 x 60 x 24 x 0 '87
= 1475008
1 2 2 7 7 4 . 4
= 12 t l .
5. A ship travel s 5742 mi les in 26 days, 16 hour and B minutes. Find the average
speed in knots for the.ent i re voyage.
No. o f min . per voyage
= t(26 x 24)) + 16 x 60 + B
= 6 4 0 x 6 0 + B
= 38400 + B-- 38408 min.
Mi le per minute = 5742 rn i les = 0 ' l / 95
38408 mins.
M i l e p e r h o u r = 6 C x 0 . 1 4 9 5
= 8.97 or 9 knots .
6. A ship makes an observed speed of 17 knots per hour. The englne speed ls 17'5
knots. what is the propeller sl ip ln ohand how many nautical miles the ship makes
in 24 hours?
t
I
II
T
of the proPeller lf
i
i#t]tlF$
20
I
% s l i p = j S - O S x 1 0 0
ES= 17 .5 17 x 100
1 7 . 5= 0 .02857 x 100= 2.857%
Nautical miles = observed speed x 24 hours= 17 'x 24 hours.= 408 knots or= 408 lrtM
T. A merchant shlp navigated a distarrce ol 7,2O0 nautlcal mlles ln 22 days, 12
hours and 30 minutes. Cornpute the average speed for the whole voyage.
A n s . S = 7 2 0 0 N Mt - Z2daYs x 24 + 12 + .5
t - 540.5 hours
Ave. sPeed = distance = 7,200 mi.
t l ' " . 5405 h*.= 13.32 knots.
B. A ship crane l i f ts a 1,500 lbs. s teet beam to a height of 44 f t . in 10 sec ' F ind thepower developed.
Given: F = 1500 lb . x 1 kg = 681 "82 kg.
i - ;2k , .
\ d = 4 4 f t . = 1 3 . 4 1 5 M
t - 1 0 s e c .
Power : wOrk done
t*- . l l "p*d
lg:t - ottt*_t ime
= 681 .82 kg . x 9 .8 m/sec -2 x 13 "415 m.
1 O - t "
8963.68 ioule per sec. or watts
g. A wire 120 inch long with a cross sect ion of 0.125 in2hang vert ical ly when a load
of 480 lbs. is appl ied to t t ' te wire i t streches 0.015 inch. Find Young Modulus of
Elastlcity.
2 1
y = _ S t r e s q = r cStrain AUL
radlus?
SPeed '==
Cons' of oil Per 1 mile =
=
Fuel cons' at 2000 mile ==
Fuel on board =
=
Remaining steaming radius =
Y = 450 lbs' / 0'125 in'z
O.Of 5 in. I 120 inch'
Y = 3600 Psi0 .000125
Y = 2'BB x 107 Psi or 28'800'000 Psi
10. A shrp left port wrth 12000 barrel of f uer oil on boalt$ 18 knots'th'e consumptlon
rs 400 barrer p"i dry, arter tneGsser has trilJir"o aooo ,'iruc'-*-iiJt ls the eteamlng
1B knots x 2'l
432 miles400 + 432
.9259 barrel
2000 x .9259
1851 .B barrel12000 1 851 '8
1 01 48"2 barret
1o1gl.2.925910,960 miles
11" A ships make 310 mr/day at z0 RpM with propeller pitch of 21 ft' what ls the
proPeller etflclencY?
Propeller Eft. ED x qqqq ft'
P * R P M x T i m e320 {_ 6099
i : x 7 0 x 1 4 4 0= 194560L
2,116,800= .9191 x 100
"/" = 91.91
12. your engine consumes 130 grat::t{uer per BHp.-HR' How maly oallons of fuel
wl* your engine Jeveroprng ii06o e*p, fi;ffi" o"trv'riirtlp"t*l;ravlty of luel
at .92?
22iiii$i
$,
I
t
T
- , - , , i l l l t I I f 4 E
cons./day = f3Ogt./BHP-HR.92 x 1000,000 grms.
3744q000. .
e2q000= 40.7 m3
cons/day in gal = 40 '7 x 1 090 x -O'ZAQ g^l
1 m 3 1 L
= 10,752.94
1g. your dally use f uel tank has or dramete r or 7 ft. Every 4 hours watch the helght
level goes oown 15 lnches. what ls your average hourlyconsumptlon ln llters?
Given:Tank dia. = 7 ll. = 84 inches
Height dif f . = 15 inches
ConsumPtion Vol' = ll D2 h4
= .7854 (84)' " (1 5)= 83126"736 in3 Per 4 hrs'
= 20791.684 in3 Per hr"
Cons. in liters = 20781.684 {.-llI9I-61 .0128 in3
= 340.61 1 Liters Pe." hour
COMPUTATION FOR FUEL CONSLIMPTION ON BOARD
I . MV Dona Evelyn cbnsumes 20 MT/day salllng whose f uel speclf lc gravlty at 150c
- .g780 and correctlon lactor at 85oC neiteA ls-'9542. Flnd the cons' lrl llters' per
watch hour and mlnutes.
So|ution: 1. 20 MT x jjgq! = 20p00 Liters
1 Ton
2 _,.,?loog:!= = ffi
21.*1 uters
3.- 21'541 L = 3590 lJwatch' 6 watch/daY a 997 UHr'
= 15 Umin.
23
2. Find the tuel consumption in GRMS'BHP/HR whose cons. per day is 27.10 MT(metric ton) and actual BHP ls 7109.52.
Solut ion: = 27.10 MT x 1000 kg = 27'100 kg/day1 to"
= 27100kglday = 1,129kg/hr.24 Wlday
= 1 ,129k9 x 1000grmg= 1 ,129,166grms/hrHr. 1 Kg
= luel cons. in grms = 1 , 129.1 66actual BHP 7109.52
= 158.82 gms-bhp/hr.
'::D O. Find the cytinder oil in grm-bhp/hr. whose consumption 189.36 liters/day,maximum BHP 8200; Speclfic gravity = .95i ave.rpm = 'l41.30 and shoptrial rpm = 150
Form ula:Cyf . oi l cons. = Ne x Vd x V'x 1000 where Ne= shop rpm
W N -actual rpm= 150 x 189.36 x .95 x 1000 n" = rated output
14W ViJ =cy l .o i l cons .
-eA,9g9,B0A- \u/o = sPecific \ ?27 ,807 ,840 gravity
Cyl. oi l cons. = 0.970 grms-bhp/hr.
TANKS CALCULATIONS WHEN BUNKERING
O. Your f uel tank on board capacity is 1 500 M3 (cubic meter) at 1 00% f ul l . How manymetric tons are you required of fuel whose specific gravity is .9768 at 15"C lf tank tobe fil led up to 95o/o full of f uel whose temperature ls 45oC, coefficient of expansion ls.000720 given data:
Formula:Net vol. M3 = (Tr-- T., x coef. of expansion x vol. m')First = 1 500 m3 x 95% = 1425 M3Second = 1425 - (450 -. 15ox .00072Cr x 1425)
= 1425 - 30.78= 1394.22 m3 at 15"C (0.9768)
To be bunker = 1361.87 MT
24
tlhtI
I
I
Cl. Fuel Consumption per voyage distance? ,How much fuet be consumed to cover the distance of 7,000 miles?
Given datas: Bore =680mmistroke = 1250 mm;6 cyl inder mechanical eff iciencY_=gSo/o,MEp = g.5 Kg/cm2; RPM = 140; Pitch = 3"15 M, F.O. cons. gr-BHP/Hr = 156, F.O.s.G. at 150C = 0.9700, Heatlng temp. of F.o. + 850c, propeller sl ip =50/o-
where: Bore = 68 cm ; Stroke = 1.25; Area = 3,631.689
Solutio ns:1 .cy ' l in6ercons tan t = LxA = 1"25x3 '691€q
4500 4500
:= 1 .0088
2 ' Prop ' d is t ' = 3 '15 M x 3 '28 F t ' = l ! '39 F ! .= '00169736 Mi le
6080 FVM|.
3. BHP = cy l . constant x RPM x P. x ME x no' of cy l .1 0 0
= f .0089 x 140 x 8 .5 x 85 x 61 0 0
BHP = 61224. F.O. Cons. /Hr. = 6122 x 156 gms
:= 955,032+ ! .000,000-- 0.95503 MT
Prop" d is tance/min. = "00169736 x 140 RPM = 0 .2376? mi"
Prop. d is tance.hout = 0.23762 x 60 = 14.25 mi .Prop. distance/hr. with 5% sl ip
: f fJ ; ; : : =1354mi
13.54 mi /h r .' \ = 5 1 6 . 9 , 8 H o u r s .
Total consumption = (0.95503 Mr;/HR) (516.98): i 493 "74 MT
0. A 1 ,500 HP turb ine operat ing a t fu l ! load for an ent i re day requ i res the burn ingo{ 6.5 tons of f uel oi l . Calculate the f uel consumption i r r pounds per horsepower hour.
Given: Fue l cons. = 6 .5 tons
HP o f t u rb ine = 1 ,500
G.rS tons x 2000 lbs . = 13,000 lbs .
1 ton
Fue l cons . = 13 ,000 l bs .
1 500 HP= t ] .666 lb. per horsepower-hr.
25
16 hours and I minutes. Find the averageO. A ship travels 5700 miles in 26 days'speed In knots for the entlre voyage'
Given:distancetime
\Ave. speed
Q. A fuel oi l has a sPeci f ic15"C? Correct ion coeff ic ient
hhIt
hII
Ave;. speed
640.133 hrs .= 8.90 knots
O. A revolut ion counter reads 69,985 at 8:00 am at 11:00 am the clock wasadvance d 1T mlnutes and at noon the counter reads 87, 319. What was the averagespeed on the 8 to 12 o'clock watch?
Formula"
Ave. Speed advanced in counter reading
minutes in watch
8 7 , 3 1 9 - 6 9 , 9 8 5
3 hrs. (60) + 43 mins.17334223
77.73 RPM.
5700 mi .
26 days, 16 l r r . and I mins.
2 6 x 2 4 + 1 6 + . 1 3 3
640 .133 h rs .
distance travelled-t ime el lapsed
5700 mi les
gravity of 0.948 al 24'C. What ls lts speciflc gravlty atis .00063 per1"C.
Given:S G =T1 =
T 2 =
corr . coef f . =
Solut ion:a. T., - T, =' 24.5b. 9.5"C x .00063c. 0.948 + .005985
0.94824.50c150c0.00063
- 1 5 = 9 . 5 0 C
= .005985= 0.9539 SG at 1soC
26
Q. SPeclflc gravitY-of dig::l
correctlon ls .00037 Per 1"F'o i l i s 0 . E 6 5 a t 3 0 " F . W h a t i s i t s g r a v i t y a t S 4 o F ? S . G .
= 0 .865
= 300F= B4"F:= 0 .00037 Per 1"1 :
g 4 - 3 0 = 5 4 " F
0 . 0 1 9 9 8= 0.8450 at B4oF
Given:SGT1
T2
corr. coeff '
So lu t ion :Tr- T' , =
54 x 0.00037 =
0.865 - 0 .01998
o. Durrng Bunkering, how much shipownner wii l rose i f F'o' suppller supply you
F.o. at $g0 per MT. The supprier f igure_s.o_n the derivetv r"rl 'p;t" i g0'9785 at 15oc;
pumping temp. 25.C; l:9i uotui',. 515 rn3' Your t"q'i*htnt is 500 MT' Before
bunkerrng hydrometer test snows: s.G o.g; is at 35"c uit t t 'unkerirrg sounding was
taken and rounJ i t t *. at 40"c after apptying ship tr im ccrrection'
NoTE: ship owner w'r rose i f you use supplier f igure, wi l l rrot i f you use interpolated
hydrometer f igure:
Solut ion:a. SuPPlier f igure irr Metr ic Tons:
Mr ==::;:*;u1i] lT;; i(40 . 15x 000720 x 511)l
: .9785 (501 'Bo2)
MT = 491 .01
b . U s i n g S h i p F i g u r e b y h y d r o m e t e r t e s t : S . G . 9 5 2 5 a t 3 5 " CS.G at 15 "C - := '9525 + (35 - 15x '000720)
: . 9 5 2 5 + 0 ' 0 1 4 4
s .G = 0 .9669
Mr = : : : : l ; i i f inJu.
ooo72ox511)
: ' 9669 x 501 '802
MT = -485'19 - ShiP Figure
Therefore : 491 '01 - Sr rpp l ie r f igure
4 8 5 . 1 I
5"82 MTshor t o f de l iverY
5"82 tr4T x $90nr = $523'80 Losses
a.
b .
27
c. Using All SuPPliers f igures:
MT = '9785 x 515 - (25 - 15x '000720 x 515)
= .9785 x 515 - 3 ' 708
= .9785 x 511 .292 m3
MT = 500.30
Owner Losses = 500'30 - MT SuPPl ier
- 485"19 - Sh iP { igure
t5J 1 MT x $90 := $1 '359'9C
Formula of fuet mixed with specific gravity:
*
*+i
ftt
MTXED S.c. = (Oty.Bef o re L-oading rl5)-(Sived m3
d i s p l a c e l a r g e p i s t o n i n v o | u m e d i s p l a c e b y a s m a l l p i s t o n :A = 3o'n
4
= 100 ms ( .950\ + 200 q3 ("960\
100 m3 + 200 m3
= 9 5 + 1 9 2
300
S.G. = 0 .956
o. A hydraulic is f i tted with a raised reservoir to prev'ent cavitation and gives a 6
meter column of oil "t
rp."it ic giavity 91o r.g/r*3.'Deteimine the pressure worked
at the pump intake port'
Solut ion: '
l . F o r c e = 6 x 9 1 0 x 9 ' 8 1= 53,562 N
l l . Pressure = Force = 53,562
Area 1 m2=-- ?l ll'-liQ. ln a rorce murtiplication system the_area ratio is 1 00:1 . The large oiston diameter
rs 150 mm and rt move rh;;;h a drstance or 130 mmii i l; f iatipt'ston stroke 400
tlmes' Wrrat,O'itntt does iitravel per stroke'
Solution:l . Volume to
28
i l .
=,
Area of Small Piston
0.7854 (0. 1 5X0.1 5X() .1 3)
.0022972 m3= _lx 0.15 x 0.15 x 0.7854
1 0 0=
l l l . Total Stroke = VolumeAr*
.0001767 rnz
= 2.2972jx 10-3 m2
0.1 767 x 1 0'3 m213 meter= 32.5 r 10-3 m
= 32.5 mm
lV" Single Stroke = 1 3 m,,4 nnT I J V
BOYLES LAW:.l . An accumulator in a hydraulic system ls precharggd to 900 KPa and ls then fll led
wlth hydraullc fluld until the gas pressure shows 2,700 KPa. How much oll has been
pumped In, i f the accumulator volume is 0 '4 m3'
0.4 m3
9 0 0 + 1 0 1 . 3 K P a
2 , 7 0 0 + 1 0 1 3 K P a
P 1 V 2 = V ' P ,
Pr = .t oli .3 KPa x 0.4 m3
2801 .3 KPa
= 0 .1 43 ms\
CHARLES LAW:
z. A rubber gas reservoir has a volume of 0.1 m3 at -14"C. lts temperature ls raised
to gO"c. what ls i t volume increase i f the pressure remains the same?
V ' =P1 =
P a =
Formu la :
V r =
v2
I
IV', x T,
T1
= 0.1 m3 x (90 + 273)-14 + 273
= 0.1 m3 (363)259
= 0 . 1 4 m 3
V 2 =
O. Two days aftera tank \^ras f i l led with arrival ballast you eheck the oil content ln
the tank and fourrd 0.5 cm. of oil on top of the water. Dimenslon of the tank L = 43 m
ii': j l ' ;; l = ;t di 6li;k.y ro marittme regulation the amount of oil to dlscharged
29
I
IlI
Ftl
ti:
overboard? lfNOTE:
ii sea.Solut ion:
I
no. what shal l
By Regulat ion:
you do?
Required-Iof total oil30 '000
,roiume by Parts canbe discharged
l l .
Total volume of t lrc tank '. Length= 4 3 x 2 1
=
Total volume of oi l i r r the tarrk
x BreacJth x DePth
x22
19 ,866 m3
= - 4 3 x 2 1 < 0 0 0 5 n t
=: 4 .515 nr3
= I i_966 m'30,000
= 0.6622 m3
l l l . BY Regula t ion vo lun le can be
discharged
FOURTH ENGINEER - JanuarY 1989
1. A trapezoidar plane f igure with sides in meters measuring 8.3/1'.10 5/B' 5314 and
211r4.Find the per.imete.r. Give your unr*"r' in mixed n'ilnt']wrtut it the area of the
above f igure? ine paral ler; iJJt are the 10 5/B and the 21 114'
Solut ion:211 4
2 1 1 1 4 +
8 5 + 3 54 4
= 1 7 0+ 7 0 + 8 5 + 4 6
B 3/4 { ' 10 5"8
+ 8 5 + 2 3
B 4
Bt/o5t/o
+ 5 3 i 4Perimeter
P
Area
B
= y o r 463 /8
B= 112 \a + b) (d)
= (21 1/a + 1 0 5/B) (5 3/aJ
30
2
= 8 5 + 8 5 2 3
= , B ! + Q l ? 3B r G 4
= 170 + 85 ?31 6 4
= 586564
= 91 1] t'64
2. At the start of your 1:lo* watch, the reading of the revolut]gl couttter of the
main engine is 996,430. At.ihe enct or youi watch n" ""iii l
i; 026'430' what is the
average rpm.irin" tirne witi'n-e-uouunied zo i',in,it', d;;;;the watch' what will be
the readtng ai the end of the watch?
Given: Previous reading =' 996430
End o'; watch = 026430
Advanced 20 mins'
A
Solut ion:Revolu t ion before the counter set
1 , 0 0 0 , 0 0 0 ' - 9 9 6 , 4 3 0
Total revolut ion af ter the watch
to 0 i s 1 ,000,000= 3570= 026430 ' i ' 3570
= 30,000 rev '
= 30 ,0C0 rev '
\ 2a6 - 29 mins' advanced
R P M = 1 3 6 ' 3 6
3. A rook out rookirrg towards ttre bow of the strip is standing in the brldge with the
rever of hrs eyes about so *"ilr. "uou" ,nu 'Jutti' i in"' rnt diJtance ol the bow f rom
the bridge is 160 meters rnJ-,t* height i;;ihe rookoui n" able to see a floating
obiect? what i, *.,u distancJoil'r* rioutini oni"tt lrom the bridge?
5 0 m
3 1
By Similar Triangle:
ttt
501 6 0 + d
5 0 d
5 0 d
5 0 d
30d( 1 6 0 + d ) 3 0
4800 + 30 d
30 d = 4800
20 d = 4800
d = 4800
4. A 12-knot ship consumes 125 MT of f uer oir per d.ay. How many days will it take
her to navigate a distan., oi o,zso nauticat-miles and nolmanv;1:y'i,,f;:fJJffl
ffil:; l?'i'S;J".il:"#'l?",ii# "ilfiq"[r" ruer is about gx ano the arrowance ror
deray due to bad weather- that may 'be
encountered is 20o/o' what ls the fuel
,equitement to comPlete the voYage?
The distance of object f rom br idge:
Given: Ship speedFu0l cons.Distance
3"/"20o/"
Solut ion:
DaYs to navigate
Total allowance
Fuel consumed f or the voYage
20= 240 m distance from bow'
= 240 + 160
= 4 0 0 M
12 kno ts
125 MT/daY
6280 n. mi les
al lowance for unpumPable
allowance for clelaY and weather
6280 mi les
12 n .m/h r .
628! mi les
288 hrs .
21 .8 da1 ' s
3 + 2 0 =
21 .8 x 125
3351 .75 MT
x l d a y
24 hrs.
23n/"
x 1 . 2 3
32
THIRD ENGINEER - JanuarY 1989
cl. what slze circular bar is required to make a hexagonal nut of 16 mm sldes along
the clrcumferences? 16 mm
= b =
d - -
16 mrn2 x a2 x 1 632 mnt
Sin 30o=
a =sin 30o
a = 1 6 m m
the main engine rated at 12000 metrlc brakethe f uel consumptlon in metric tons to makethe speed of 14 knots? Allow 10o/o for the
8aB
2. The specif ic f uel consumption ofhorsepower ls 155 g/Bhp - hr. What isa voyage of 6,280 nautical miles atunpumpable in the fuql storage tank.
Given:
Fuel o i l cons. =
Day the ships travel
Fuel o i l cons.
1 2000155 g-bhp/hr
6 ,280 nm14 knotsal lotvance
155- g-BFIP/HR x 12000 bhp x 34 h/day
1 ,000,000 grm/tot t
44,640,000
1 , 0 0 0 , 0 0 0
44.64 M.T"/day
6,280 n.q x l_gsy_14 knots 24 hrs .
18 .69 days
44 .64 x 18 .69 (1 + 10%)
4 4 . 6 4 x " l 8 . 6 9 x 1 . 1
9 1 7 . 9 8 M T .
BhpSp. fuel consDistanceShip speed10"/" \
Solut ion:
33
;F.
r 1
ll
3. The revolution counter reading at ttre beginning-o t a 4 hour watch is 996'430' At
the end of the watcrp the counter ieading 02"6,43orq,urinO the watch the tlme was
retarded by z6tninu't"r. what is the uu*rui" rpm of the main englne? '
Given: prev ious read i r rg : : 996,430
end of watc l r = 026,430
retarded 20 min.
So lu t i on :T l te coun te r rese t t o 0 @ 1 ,000 ,000
Rev. before t l re cour t le r reset to 0 :
1 ,000 ,000 - 996 ,430 = 3570 rev
End of watc f t eng. rev . = 026430 + 3570= 3 0 , 0 0 0
RP M = _3_0r000*Ey240 r - 20 min. re tard
R P M = 1 1 5 . 3 8
4. The marn eng ine is an g cy t inder s ingrb ac l ing, .2-s t ro l<e cyc le d iese l w i th a
cyl lnder of 650 mm bore x 1,3s0 mm strot<e"" wnat iJtne cyl inder constant ' what ls
the ind icated horsepower i f the ind icated pressure is 11 kg/sq. . icm'a t 1110 rpm?
Given:
Solu t ion:
No . o f cy l .
Bo re
Stroke
rUEPRpnt
cy l . constant
cy l . constantIHP
B cyl . 2 strol<e
650 mm = 65 cm
1 3 5 0 m m = 1 " 3 5 m
1 1 kg/sq. cm.r 1 nI l \ . /
X L
4500
! (os) ' ( t .gs)4 4500
7854 (4225) (1 35)-
4500
0 .9954N4EP x cYl . constant x
(1 1 ks /cm' ) ( .9954) (1
9 6 3 5 " 4 7 H P .
Rpm x no" o f cY l .
1o) (B)
= T o ,+̂
IHP =
34
5. The pitch of the propeller of an ocean-going ship is 3600 mm. What is the engine
mif eage l i ,n24 hours i t t f ' tb propeller makes i te rpm? lf the apparent sl ip is mlnus 3ol"
What ls the observed sPeed?
Given: Pitch = 3600 mm = 3.6 m
RpM = ' i 1BSlip = -3%
Solut ion:Eng .Speed = P i t c h x R P M x 6 0
1 852
W1 852
13 76 knotsEng. Speed - O" Speed
Er ,g .Speed1 3 .76 - os
1 3 . 7 61 3 . 7 6 - o . s .13 :76 + (0 .03 ) ( 13 .76 )1 3 . 7 6 + 0 . 4 1
1 4 . 1 7 k n o t s .
SECOND ENGINEER - January 19Bg
1. A cy l indr ical water tank has a d iameterof 3 meters at the baseand 4 1/2 metershigh. How many metric tons of fresh water ls to be pumped into the tank In order tohave an ul lage of 1 meter? l f f uel oi l of 0.86 specif ic gravity is to be pumped into thetank, how many metr lc tons are requlred to have the same ul lage?
f"- 3 m
Q l i nv r r H
- 0 .03
- o .o3 (13 .76 )OS
=
Obse rved Speed =
l_l m-r
I
3 * t
I
35
ttt
I
i
Solut ion:
a) Vo lume of tank
For a F.W. Sp" gr . -
F .W. to be pumped ==
b) Sp. gr . o f o i l =M.T. o f fue l o i l =
=
= 'iT o'4
For an u l lage o f 1 m; h = 3 112 mVol . o f tank @ g 1 t2 m he ight = 1 l (g) , (3 .S m)
4= .7854 (e) (3.5)= 24.74 m3
1 0 0 0 1 9 = l t o nm3 m3
2 4 . 7 4 m 3 x 1 M T / m 3
24.74 MT
0 . 8 6
24.74 m3 x 0.BG (S.G.)
21 .28 MT.
12 kno ts12"/"
1 1 0
P x R P M x 6 0
1 852
E S - S E x 1 0 0
ESES - 12 knots
ESE S - 1 2- 1 2- 12_- 1 2
- O . B B13 .63 kno ts
P x R P M x 6 0
2' A vessel makes an obs_erved speed of 12 knots wifh an apparent slip of plus12o/o' The propeller turns 110 rpm. What is the pitch of the prodeffei in mmt
Given:
Solut ion:
Ships speed =
Sl ip =
R P M =
Engine Speed =
\
% S l i p =
0 . 1 2 =
E . S " ( 0 . 1 2 ) =E . S . ( 0 . 1 2 ) - E . S . =
- O . B B E . S , =
E . S . =
E . S , =E .S . =
1 8 5 2 m
36
II
1 3 . 6 3 k n o t s = P x 1 1 0 x 6 0
1 8 5 2 mp 13 .63 (18s2 )
1 0 x 6 0P = 25242.76
6600P = 3 . 8 3 m = 3 . 8 3 0 m m .
3. A shlp's provlslon ls loaded on board from a motor launch by means of amanual ly operated winch which work on the same pr inc ip le as the wheel and axlemaehlne. The revolving drum of the winch is 30 cm diameter and the crank attachedto the end of the drum is 40 cm. long f roni the center of the drum. What force isrequired to l i f t the provis ion weighing 300 kg?
*-l t
40 cm
'l
]_
Taking moment @ the center o f t l re drum:
1 5 ( 3 0 0 k g )
15 cm (300 kg )40 cm
1 2 . 5 k g .
4 . The mean ind icated pressure o f an B-cy l inder 2-s t roke cyc le , s ing le-act ingenglne wi th a cy l i r rder constant o f 0 .9954 is 11 kg/sq. cm. What is inc l ica tedhorsepower a t 100 rpm?
Given : No. o f cy l " = I cy l .2 cyc le . s ing le ac t ing
Cyl . constant - 0 . ! )954M E p - ' 1 1 K g / c m 2
R p M = 1 0 0 r p n t
Fo rmu la : : lH P MEP x Cy l . cons tan t x RPM x No . o f cy l i nde r1 1 K g / c n r ' r x . 9 9 5 4 x 1 1 0 x B
8759 52 l - rP
l.- rs -'l* ,s It c r n t o n l
fTol Ks
F x 4 0 c m =
F =
\
37
5. The speci f ic fuel o i l consumpt ion of the nta in d iesel engine at 12,000 rnetr icbrake horse power is 155 g/BHP-hr. Wlrat is the dai ly consumptionrln metrlc tons?What ls the equivalent consurnption in gra;n per kw-hr?
Given:
Solut ion:a) Daily Cons.
b) grams
Kw-hr
Volu me
1 55 g /BH P- l t r
1 2 , 0 0 0
155 gr . x 1?- ,000 BHP x 24 h /day
Sp. fue l cons.B H P
Bhp-h r= ff19800_qrtday
1 ,000 ,000 g r / t on= 44"64 MT
lg!. s'l9I,P-!L0.746 Kw/1 HP207.77 gms/ l(w- l t r .
CHIEF ENGINEER - January 1989
1" The cross-sect ion of a hol low brass slraf t ing has an outside diameter of 50 mmand an inside diameter 25 mm. l ts length is 2 meters. What is the weight of theshaf t ing i f l ts dens i ty is 8 grams per cub ic cm.
Given:
Outs ide d ia .r lnside dia.
Length
Density
Solut ion:D = Weight
Vr l r te
I oo, I o t ,5 n t
(Length)
- [ (oo ' - D1,) (L)Ar+
1 tt ' 2.s') (2oo)4
.7854 (25 - 6.25) (200)
.7854 (1 8.75) (200)
5 0 m m
25 mnr
2 m =
B grlcm3
: : 5 c m
= 2 .5 cm
200 cm
' :iii
38
= 2,945.24 cm3
I w.igh, = Density x Volumet ' = 8 gr/cm3 x2g45'24 cm3
I = 23,561'9 gramst - 23,562 kgs.
I| 2 . T l l e c y | i n d e r b | o c | ( o | a d i e s e | e n g | n e i s h e | d b y 4 r o u n d m | | d s t e e | t | e r o d s . | f t h e-
toad on each tie rod ls 66 MT, what Is tne aiameteiot the tie rods. The yield polnt of
r the rod ls az,ooo ibl' pli sq"fncn and the factor of safety ls 6'
IGiven:
No. of t ie rods = 4
Load on each tie rod = 66 MT.
Yield point of the rod = 47,000 lbs/ in2
Factor of safetv = 6
Solu t ion:Working Stress = Yield Point
Factor of safetY= 47000 psi
6:= 7,833.33 psi
Working Stress = Loadarea of rod
= LoadArea
\
working stress
= 145,200 lbs.
7.833.33 PSi
= 18.54 in 'z
Area
0 .7854D2 * 18"54 inz
1 8 . 5 4n2L:'
0.7654
= 23.6 inz
l] = 4.85 in
:= 1l o'4
39
3. A 12-knot ship lef t Manita on Jan. 19, 1989 at 2:00 a.m. for San Francisco' a
distance of 6,280 nautical miles. Find the ETA at San Francisco first by disregardlngthe dlfference In t lme between the two ports and second by taking lntoiaccount thedl f ference In t lme. Glve the date and t ime of arr ival in both cases.
l f the ship consumes 25 MT of fuel per day, what is the quant i ty requlred tocomplete the voyage. Allow 25%for the unpumpable quantity in ttre storage tank anddelays that may be encountered due to bad weather.
Given:
Solu t ion:By disregarding t ime di f f erenceTime of voyage = 6 ,280 N. mi les
1 2 N . M . / h r .
523.33 hrs .
21 .B days
21 days and 19 .2 h rs .
1989 @ 0900 h rs .
in t ime - - 1 6 hrs . beh ind
F e b . 1 0 , @ 1 9 0 0 h r .* 1 6 0 0 h r s .
ETA by t ime dif ference Feb. 09 @ 1700 hr.Ship cons/day = 25 MT/day
rVoyage fuel cons = 25 MT (218 days) (1 + 25%)d"y
= 25 (21 .B ) ( 1 .25 )= 681 .25 MT
4. Solve the metric indicated horsepower of an B-cyl inder, slngle acting,2-strokecycle diesel propulsion engine with MEP of 1 I kg/crn2 at 145 rpm. The cyl inder ls 650mm bore x 1350 mm stroke.
l f the specif ic f uel ol l consumption is 153 grams per indir:ated horsepower - hr,What. is the tuel consumption per day?
Given: No. o f cy l .
MEP
Bore
Stroke
Sp. fue l cons.
RPM
Ship speedTime of dep.
Distance
E T A = F e b . 1 0 ,
By taking di f ference
ETA -
= 12 knots= 2 :00 pm - Jan . | 9 , 1 989= 6,280 N. rn i les
B; 2 stroke
1 1 Kg/cm2
650 mm = 65 cm.
1350 mm = 1 .35 m.
1 5 3 g / l H P - H R .
1 4 5
40
I
I
II
I
I
Solut ion:I H P
I H P
Fuel consumption:
= M E P ( L x A ) N x R P M
4500= (1 1 Kg/cm') ( 'Tl 10S1' (1.35) (145) (8)
74500
= 571 612924500
12,702.5 hp"
1 53 gr./ lH P-hr. x 1 2702.5 hp x 2.11 000000
_166,€S!_1 .000000
46.64 MT/day.
II
I
I
I 5. The pltch orf the propeller of an ocean going vessel is 3,600 mm. The main enginedlrect ly drlving the propeller makes 145 rpm. What is the observed speed of thevessel l f the sl ip is minus 3%.
How manyr nautical rni les is covered per day?
Given:Pi tch = 3 ,600 mrn.R P M = 1 4 2
Sfip : : - 3%
Solut ion:\
% S l ip
Engine spet ld =
Irul-gggg - ship speedEngine speed
P i t g ! x R P M x 6 91 852
(3 ,600 mm x 1 m ) (145 ) (60 )
1 0 0 0 m m
1 85216 .91 kno ts1 6 . 9 1 - S h i p s s p e e d
1 6 . 9 1
1 6 . 9 1 - S h i p s p e e d
1 6 . 9 1 - S h i p s p e e d
- 0 .03
* 0 . 0 3 ( 1 6 . e 1 )- 0.5073
4 1
ShiP sPeed
Distance covered/daY
= 16 .91 + 0 .5073
= 17 .42 knots
= 17.42 Nm/Hr' x 24 hrs' ldaY
= 4 1 B . O B N M
FOURTH ENGINEER - JanuarY
1. The densitY of aluminumcentimeter, and to Pound mass
Solut ion:2,699 kg x 1C00 grn x
' . ] , t ' - ^=
1 m3 ll1g -
1,000,000 cm3
2,699 kg x 2.2 lbs. x :+g-
=
1 m3 1 kg 35.29 ft3
2. A tank is ti i led with water to a depth of 42 feet 6 inches' Find the pressure exerted
on the tank bottom?
Solution:Pressure = height x 0'434
= (42 tt . x 0.5 ft ' ) (0'434)
= (42.5 ft.) (0.434)
1 990
is 2,699 Kg/m3' Convert tttis
per cubic foot'
to grams Per cublc
2,699 grm/cnr3
168.26 lb/ft.3
= 18.44 Ps i
3. A 10-knot sl ip has a 16r.eet pitch propeller. t f the speed is 70 RPM' Find the sl lp'
ts the sliP Positive or negative?
ttII
I
{
I
I
I
I
J
Given:
Formula:
Pitch of ProP' =
RPM =
Engine SPeed =
1 . Engine SPeed
1 6 f t .7010 knots
-- 16 f t . x 7! RPm x 60
6080 ft '
= 11 .05 knots
6080 ft.
42
IIIIIIIIIIIIIIIIII
4. what rS the cro33 sectronar area of a rubber o-rrng packrng whose lnslde
dlameter ls Ag mm and lts outslde dlameler ls 64 mm?
% slip
= engine speed - observed speed x 100
errgine sPeed
= 1 1 .05 knots - 10 knots x 100
1 1 . 0 5= 1 .05 knots x 100
1 1 .05 knots= + 9.52
49 mm64 mm
jT (do, - d,,')4
= .7854 [ (64)',- (49)' I= .7854 [ 4096 - 2401 I= .7854 (1695)= 1331.25 mmz
5. Solve the followlng equatlo nz 2x+ 5y = 20; Glven y = 5' Flnd the value of r?
Sof ution : 2x + 5Y :i 20 lf
2x + 5(5) =: 2Cpx +25 = 20
\2x = Z} -Zs) i = - 5
2x = - 2 . 5
tan 25o15'
% slip
% slip
Given datas: inside dia.outside dia.
Find; Cross sectional area z=
Y = 5X = ?
THIRD MARINE ENGINEER - January 1990
.g. At a certarn Instant, a shrp was 4 miles south of a llght house. The shlp was
trave*ng *rJ;aru ano after io mtnute, tt. bearlng was-s zs"t5'wfrom the llght
hout". iind the speed of the shlp per hour'
= b _
a
€
tan 25o15'= p4
a=4 mi
but time
initial lengthcross-sectional area
\ force aPPliedchange in length
(4 mi) (tan 25"15' )(4) (0.47163)1.BBO miles
10 min
.10 = 0 .167 hr
60
b =b =b =
Speed = distancet ime
= 1 .886 m i
0 . 1 6 7 h r .
S p e e d = 1 1 . 2 9 k n o t s
Moduh,rs of ElastlcltY.
2. A wire 120 Inches long wlth a cross.sectlon of 0'1 25 Inch2 hangS
a load of 450 lbs. ls applled to the wlre, lt stretches 0'015 Inch'vertlcallY.WhenFlnd the Young
Giveit;
Fi nd:
Solut ion:
120 i r t
0 . 1 2 5 i n 2
450 lb.
0 . 0 1 5 i n c h .
1 . e
e
Young's Modulus of Elastici tY (E)
lonqitudinal stress
longitudinal strainf orce/area
.ht[t i. length/initial length
2. stress =
strain =
Forcearea
a I -L
_:Jressstrain
450 lb'0 .1 25 inz
0. .015 in =
120 i n3600 Psi '=
0 .000125
0.000125
44lI
r.l
h
b=?
e = 28,800,000psi
3. A force of 10 lbs. ls used to move a box across a horlzontal deck, a dlstance of
s ft. lf the force makes an angle of 30 oegrees *rtn the floor, how much work ls done?
5 FT.-.--.--.{r
F Cos 30'Solut ion:
Work = Forcexdistance== llffli3:J:lll ,u,,,= (10) (0.866) (5): 43"3 ft .- lb.
4. A house 15 meters high stancls on one slde of a street. what ls the angle of
elevatlon of the top of the lrouse I'rom tne oiner slde of the street, lf the street ls 20
meters wlde?
trigo function ofunknown angleopposite =
adjacent
tan 0
tan 0
A'-rI i l \
l l - - -1 s m l l
' - ' .i l \
I l l o) - -- L - . - \ ' :2 0 m
Formula:
tan 0
A
given sidegiven side
l gm2 0 m1 5 m2 0 m0.7536052'
45
f
I
J > *................ '.riII
SECOND MARINE ENGINEER - Janua ry 27 ' 1990
1. The gauge pressure of water rn the water marns ls 3-s lbs./lnchr. How much wort
rr requrred to pirmp 500,ooo ft.r of water, il;ir"gpnerrl'piessute, lnto the malnr?
Given: Pressure = 35 lb./in.2
Volume = 500,000 ft.3
Convert 500,000 lt.3 to in3
= 5O0,OOO ft.3 x 1728 in.3 = 8.64 x 108 in.3-
1 ft-,
Find: work Req = (35 lb/in'z) (8'i l x 108 in'3)
= 302.4 x 108 lb' in'
convert'o-: t:J::: ' 108 rb-in. x 1 ft. = 2s.2x 108 ft'-lb'
l 2 i . .
2. The hatch of a submarlne ls 100 ft. under the surface of the ooBan' lf the welght
denslty of sea water gc tus,rtt.!,Frnd tnr pi.rrir: at the hatch due to the water, and
the net lorce on the hatch u iiir r.ctanglJiit. *ror and 3 ft. long. T[re pressure Inslde
the submarlne ls the same as that at the surface'
Given: height = 100 tt"
wt. of densitY = 64 lbs./ft"3
d imens iono f r ec tang le = 2 f t ' x3 f t ' = 6 f t " 2
Solutionl ra) Pressure = densitY x height
= 64 x 100= 6,400 lb/tt.z
b) Force = Pressure x area= (6,400 lb./ft.2) (6 ft.o)
= 38,400 lb.
3.4.{ lqge-1.e$lPFDgum.es--1/!. to. lgftYqlol lpe-rdav'whenlt lsoperatlngatful lload.when thc unlt b operatlng at halt load, the consurnitton per BFIP Increales by
2loh.Determlne the lull consumptlon orc per hour ai one-rraft toad, allowlng2'2{'
lbsJton ln thls case.
Given: Cons. = 1/2 ton/day at full load
Cons.lincrease by 21'/" at half load
F i n d : C o n s u m p d o n r a t e p e r h o u r a t h a | f l o a d
46
tItIt
Solution: I1/2 ton x 1 day * W'
= 46'67 lb'/hr'
day 24 hrs. 1 ton
iln;;Hj;X1;ni#hl oj'ou u; :':T
= 56.47 lb./hr.
4. The tensron on outslde ol a belt lg 350 lbs. and that on the other rlde ls 150lb3'
The belt ls moylng at 3OO tt./mrn. rrno the horse pdwer dellvered to the pulley'
Given: Total Force Acting = 350 + 150 lbs' = 500 lbs'
SPeed = 300 ft'/min'
Find: HP deliveredPower ==
ltT,jnlJi:t!t/min)*it
Convert: Ft. lb to FIP
l ' t ;5o,ooott .- tb x 1HPmin. 33000 ft.-lb
150,00033,000
= 4.5 FIP
CHIEF MARINE ENGINEER - January, 1990
.!. The cro83 r"",,on or the tube at pornt A 1o Inch2, aqd at polnl plr 2lncht. lt the
verocrty of the .tr"r ano pot;i A rs i z ft./sec., what ls lt at polnt B?
Given: i area at Pt' A = '10 in'2
area at Pt. B = 2in'2
velocitY at Pt. A = 12 ft'/sec'
velocitY at Pt. B = 'l
BY ratio and ProPortionarea at A = velocity at A
iil ';'1?,, =ruarea at A
17
ttbhhhhIIIIIIIIlI
velocitY at B =
12 in.2 (1 2 ft./sec.)1 0 i n . z
2.4 tt. lsec.
2. A ref rlgerated contalner shlp's main engine ls consuminE;74 tons of fu_el per dayat 21 knotslthe ref. plant, aux. machinery and hotel load are consumlng^l!tons per
day. What l"s tne nautlcal mlle radlus of tiavel? The shlp has to travel 1'875 mlles toreach Fort, and only 275 tons of avallable fuel remain. Assumlng tlrat the conlumP.tlon virles as the cuUe of the speed, can the shlp make port with the fuel on boardlf the speed ls reduced to 19 lcnots?
Given: cons. A
cons, B
distancefuel left
74 r 10 tons/day?1875 mi .275 tons
Speed A
Speed B
21 knots19 knots
Find: ConsuC l =
84 tonscB
cB
Vt , =
v B =
mption B.Speedo
C, = SPeed,
(84 tons) (19 knots)3(21 knots)3
(84) (685e)9261
62.21 tons/day
1,875 mi. x t hr. = 98.68 hr. voyage leftf g mi .
98.68 = 4.11days of voyage lef t
24 hrlday62.21 tons x 4.11 days = 255 tons req.
dty to reach port.'Iherefore
since fuel left is275 tons, the shipcan reach port with stil l enough fuel.
3. A barge ls 30 ft. long and 16 ft. wide, and has vertlcal sldes. When twoautomoblles are drlven on board, the barge slnks 2Inches further Into the water. Howmuch do the a'rtomobiles weight?
where 2 inch = 0.167 f t .
Solut ion:Weight of automobile wt. of displace water
(density of water) (volume of water)(62.4 lb./f 13) (80.1 6 ft3)
5001 .984 lbs.
48
4. Flnd the specltlc gravlty of API 18.5 at 60"F
Formula: Apl = 141 .5S.G. at 6CoC 1 31 .5
19 .5 = 141 . sS.G. at 60oC 131 .5
1 3 1 . 5 + 1 g . 5 = 1 4 1 . 5S.G.
S.G. = 141 .51 5 0
s,,G. = 0.9433
FOURTH AND THIRD ENGINEERMay 1991
Q" What ls the volume of a spherical tank whose diameter is 10 feet.
Given: diameter = 10 ft.
Formula: Volume = 1T o.- 6
= 3 . 1 4 1 6 ( 1 0 ) 1
6= 3 .1 41 6 (1 000 )
6= 3 1 4 0
6Volunle = 523.33 ft3
Q. A 1 1 knots shlp has a 17 f eet pl tch propel ler. l f the speed ls 75 RPM. Flnd the sl lp.
ls the sllp negatlve or posit lve?
Given: Pl tch of proPel ler = 16 f t 'Rpm = 70
E n g i n e S p e e d = l 0 k n o t s
Find: a) Engirre Speed : : . Pi tch x RPM x 606080 ft.
17 f t . x 75 RPM 60
6080 ft.
49
= 17 lt. x 75 Rprn T 996080 ft.
= 765006080
= 12.58 knotsb) % sl ip = Eng. Speec - obs. speed x 100
Eng. Speed1 2 . 5 8 - 1 1 x 1 0 0
12 .58= 1 . 5 8 x 1 0 0
12.58= 0 .1255 x X00
Slip % = 12.55 (posit ive)
O. The Indlcated horsepower of an englne ls 15.448 and thc brako horsepower lt 12.What lg the mechanlcal efflclency of the englne and what ls thc MEP. lf tho cyllnder lr 0by 12 In and epeed lg 240 Rpm?
Given Datas: IHP = 15.448BHP = 12RPM = 240 RPm
Formula: Mechanical Efficiency = tsHP x 100IHP
= 1 2 x 1 0 015.448
= 0.776 (100)% .= 71.69
Find: Area = iT O'7
= .7854 (9) '= .7854 (81)
= 63.62 in.2
IHP = PLAN
33,000P = 3 3 , 0 0 0 x | H P
LAN= 33,000 (15.448)
(1 FT.) (63.62) (240)P = 33.38 kg/cma
h50
o. A cyllndrlcal tank ls g, 4,, hlgh 3' z" In dlameter. How many gallons wlll lt hold?
Glven: 'diamete f = g' 7' = 43 inches
'height = 8' 4' = 100 inches
Formula: volume of cYlinder = 'iT
Ot n1
:1llffi{[email protected] gallons
o. tt thc averags RpM lor 24hrs, and 18 mlns. ls 102, pltch of propeller ls 16'2 ft'
Dlstance UVloUsErvatlon it g6O mlles, What ls the sllp In percent'
Given: Pitch = 16.2 ft'
Obg. Dir;t. = 360 milesRpm = ",02
Time = 24 hrs' + 18 mins'
Formula:
Engine Distance = lP,itch x Ave' Fprl x Tiry
6080 ft.
= 16 .2 x 192 x 1458
6080 ft.
= 3'96.25 miles
S | i p % = E n g i n e D i s t a n c e - o b s e r v e D i s t a n c e x l 0 0Engine Distance
= 396.25 360 x 100
396.25= 36"2 x 100
396.25= 0 "0913 (100 )= 9 . 1 %
51
?*t:;-
j
il,l
ilIII
ando . l . W h a t a r e t h e f o u r | u n d a m e n t a l s o | M a t h e m a t i c ss'
h. ::,::T"?Tnil:'$:::"'1"'unsurar' temperature scareg
temPerature' See noteS'
SECOND/CHIEF ENGINEER - MAY 1991
o .F lnd thec i r cum|e renceo fac i r c l ewhosed iame te r i s l g l nches?
Given data: diamete ( - 19 inches
Formula: circumference = 'ii D
= 3 . 1 4 1 6 ( 1 9 )
= 59.69 inches
e. Find the area of a 13 inches diameter circre to one decrmar place'
Formula: Area of a circle = -1T Dt4
= 3 .1416 (13) '?
a= "7854 (169)
\ A = 132 '7 i n ' z
o . A c y l i n d r i c a l t a n k l s i n c h e s l n d i a m e t e r , l s 4 f t . l n h e i g h t .a' What is the volume ln cublc inches?
b' What ls the caPacitY ln gallons?
Given: diamete ( = 18 inches
height = 4f t ' = 43inches
1 gal ' = 231 cu' in'
Formula " a' Volume = '7854 D2 height
== i::;il;l
(18) (48)
b' Volume in gal lons:= 12,214'54
231
52.87 gatlons
abrolutc
52
Q. The stroke and bore of an B cytind "i,rstroke
dieset engine are 1l;'; rr and 650 mmrespectlvely from the engine indicator cards the IHP is tg,SO0 at 154 RPM. What is theIndicated mean effective pressure?
=
A =b) IHP = PLAN
4500P = 4 5 0 0 x l H P
LAN4500 x 13 .900
1 .35 x 331 8 .32 x 154= _qa€ggqq_
e,BgB7B.72P = 90.66 kg/cm2
0. A tank is f i l ted with'water to depth of 40 ft . 6 Inches. Find the pressure exerted on thetank bottom?
\
Given data: Depth,of tanlt =
Formula: Pressure -
:
Datas: Length of stroke =Cylinder bore =
IHP =RPM =
Solution: a) Find the Area
1350 mm = 1 .35 m650 mm = 65 cm1 3 ,9001 5 4= i T o ,
4
3 .1416 (6s ) '4
,7854 (4225)3318.32 cnrz
40 f t . , 6 inches = 0.5 f t .
hc ight x 0 .434(40 f t . + 0.5 f t . ) (0.434)(40.5 f t . ) (0.434)
17.57 ps i
o.
IIIIIII
IIIt
What is the
Given data:Formula:
I
volume of a sphere whose diameter ls 70 Inches?
Diameter, = 70 inchesVolume of sphere = ' iT
d'
53
F!-
t
= 3.1416 (70)'
6
Volume = 179,594'8 cu' in'
o .What lg the ta te ra leur |aceofasphere l0 lnchee lnd lametgr?
Formula: Area = 1T O'E 3 .1416 (10 )2
z 3 .1416 (100 )
= 314.1 6 in"z
Solution:
o.Arcvolutloncounterread6gsgsstsioqlryLll jgoAl|theclocltwa!advanarlTmrnl. and at noon the couniJr-ri,roi ez,glb. \lvtiat:was tne s'orago 'p""d on tho &12
cloclt watch?
Average RPM = Present - Previoqs readi'ng
Time in watch-advanced
= 87319 - 69895
240 - 17
= 17424223
"lur. RpM = 78.13
o. A rhrp reaves qort wrth Tz*Obarrer of fuer o* on board- At-15 knO'' tb ftnl
con8ump$on rg ioo'barrers/;rv. x*r the vesset nr. tiriirro lgP mllst' what lr tho
remainf ng rteamlng radlus?
Solution:1 .
2.
Total speed/day _
Cons. of oil/ 1 mile
-=
3, F.O. cons at"1642 miles
15 knots x 24 hrs'
360 miles
360 * 360
1 .0 barrel= 1642 x 1'0
= 1642 banels
72OO - 1642
5558 banels
3.1416 p13'999
64
4. Fuel on board
boanD euEsTloNs
Founnr, Txrno, secoND, cxter Enctrueen
MATHEMATICS
1. When you add 518;7112 anct 11fz4,whatwill the sum be?
a/i and2t3 B. 1 and 3/2 c. 1 and 1/3 D. 1/3
2. When you subtract 5/6 from 8/15, what will the sum bc the difference?
rf\
A. 1/s e.'i lro c' 2/6 D' 214
3. What is the Product of 5/8 and 417?
A" 4n a/ inq c" 10/14 D' 4t6
4. The quotlent of rl3 divided b)' 3fl is:
A . 1 5 a n d ? 1 B . 3 0 a r r d 3 / 6 c . 3 0 a n d 1 E D . 2 | 3 o
5. The quotlent ol36.744 divided by 24 is:
A. 1531 B' 15.31 c: ' 1 '531 D' 153'1
55
6 . Multiply .397 bY 41 the Product is:
A;' ' l 6.277 B. 162.77 c. .16277
7 " From 128 subtract 96.307, the difference is:
A', 31.693 B. 316.93 c . .31693
B. Solve for x in the equation 12x + 25 - 35 = 14x + 22x - 22
A . y = 1 1 B . y = 1 2 C.'u:x - 112
9. The quotient of 2.5 divided by .05 is:
A. .50 8.4'o c. .0s
-180 degrees farenheit in centigrade is:
n J r f i J 7 d . C B . - 1 7 7 . 7 7 d . C C . 6 8 d . C
Solve for x in the equation Bx - 22 : 12x - 1 B.
/A. 4/9 hours B. 2 and 1/4 hclurs C' 2 hours
14. -243 degrees fahrenieit in absolute is:
A. 217 d" A B. -217 d. A c. 217.29 d' A
15. -65 degrees centigrade in fahrenheit is:
A . - 6 0 d . F B . 8 5 d . F c. -85 d. i:
16. Given 7.5 cm. radius Pi is 3.1416. Find the circumference'
C: 47.124 cm.
{
{
{
{
IIIIIIIIl
I
1 0 .
1 1 .
D. 1627.7
D. 3169 .3
D . X = 6
D " 5 . 0
D. -68 d . c
D. X = -4A Y x = - 1 B . X = 1 C . x - 4
12. The height of an indicator diagram measured at regular intervals alonQ its heightare aS fOl lOwS: 27, gg,47,51 ,48,92,20 ,11 , 8, 5, mm. respect ively ' F ind themean height of the diagram in mill imeters'
A. 2BB mm. B. 2.88 mm. c/ za,a mm. D. .0289 mm.
13. A pump can empiy a tank in 12 hours, another pump can empty the same tank in 4
hours, and another can empty this tank in t hours. lf all three pumps are set work-
ing together on this tank, how long would it take to empty it?
D. 3 hours
D. -217 .29 d. A
D . 6 0 d . F
D . ] 2 cm
II
56
A. 47.1238 cm. B, 23.562 cm.
II
17. Given I cm. diameter. Find the circumference.l -I a. 25.1328 cm. B. 12,5652 cm. c,. 'a50.2656 cm. D. 50 cm.
| 18. Negative Fort;r mill ion eleven minus Six thousand one is:
t o.t -40,006012 B. -gg,gg4,01o c. 3g,gg3,010 D. 40,006012
I! 19. solve for x in the equatron -14x - 15x + 29 =: 2x - 91 -11
A. X=-1 and 4/27 B.u' x=2 and gl31 c. x = 27131 D. x = l
20. Negative Sixteen mill ion one minus negative Nine hundred ninety-nine equals:
A. - 1 5,ggg,002 B/ i5,ggg,002 C" 1 6,00c,g01 D. - 1 6,009
21. The distanceicovered by a ship on four successive days were 320,300,310 and330 nautical miles respectively. Find the average days run.
A. 5040 naut; miles B. 2520 naut. mites C. 1260 naut. miles O,fStS naut. mites
22' An automobile battery supplies a current of 7.5 amps to a headlamp with resistanceof 0.84 ohms. Find the voltage detivered by the battery.
A. 7"93 volts B,'G.3 volts c. B.g3 votts D. 6.395 votts
23' A wire is to be cut in such a way that .rne piece is shorter than the other by B meters.How long are the pieces, if their combined renght is 24 meters.
A. 1tj m shorter piece; B m longer piece B. 14 m shorter piece; lZmshorter piece
C. 12 m longer piri.; 12 m shorter piece D. 16 m longer piece; g m shorter piece
24. A revolut ion counter reads 69,985 at 8 a.m. at 11a.m. the clock was advance d 17min. and at noon counter reads 87,316. what was the average on the B-12 o,clockwatch'?
A. 135.6 rpm a/);2.t1 rprn c" 78"1210 rpm c. 156.2 rpm
25. Find the value of a in equation: 2(a+3) + 3(2a-a\ = 4(1 1-3a)
A . ? = - 2 1 1 2 B . A = 7 C . r I a = 2 1 / Z D . A = 4
26. A ship makes an observed speed of 17 knots per hour. The engine speed is 17.5knots. What is the p,ropeller sl ip in percent?
A. 28.5 " B. 28s./" c. .ozgsy" ntr.as/.
57
27.
28.
200 tonne of o* were bought at one port ql 960 per tonne and 600 tonne of oil at
another port at g70 per tonnu]wn"t'*", tne-av;rage cost of oil per tonnb?
Ay $ 67.50 B. $ 67'8s c' $ 67'60 D' $ 68
A motor boat travers up-river agains.t.the current from one point to another at alspeed
of 6 knots, and then down the riier with the curient oacr to int otiginal p-oilt at a speed
of 9 knots, taking a totar tims oiz ino 1/2 rLouii. niruting-theipeied ot the current
remains ,n.n"ni"o, tino the distance between points.
A. 9 naut. mtles B. 10 naut. miles c' B naut' miles D' 13 naut' miles
{
{
rdil
zg. How much water must be added to 400 liters of mixture that is 80% alcohol to
reduce it to a 60% mixture?
A. 80 l i ters B' 70 l i ters C. 20 l i ters D. 50 liters
{
IIII
30. A ship's hold, A, contains 250 tonne of cargo' alolhel hold B' contains 620 tonne'
How much cargo must oel"r.n from e ;E put into A so that A wiil contain flve
times as much as B?
A" 275 tonne B' 475 tonne C" 570 tonne D. 300 tonne
31. A ship covers the measured mile (one nautical mile) againstthe current' in a 3
minutes 20 seconds, and then In the opporitt oirection-over ther same distance with
the current in 3 minutes exactly" Find in knots:
32.
33.
A" The sPeed ga'rPst the currentB. The sPeed with the currentC. The average sPeed
A. 1) 18.95 knots 2) 20 knots 3) 18 knots
B. 1) 20 knots 2) 18 knots 3) 18'95 knots
C. 1) 18 knots 2) 20 knots 3) 18'95 knots
D. 1) 2 knots 2) 13 knots 3) 18 knots
A rectangurar is to cut so that the renght is four times the breadth and having an
area of one .qr"i, 'neter' Find the length and breadth'
A. 3 and 4 meters B. 2 and .2 meters c. 1 and 5 meters D. 2 and 0'5 meters
The actuar horsepower delivered by an engine was found to be approximately 12'5
the indicated horsepower from diagram *"r is.g6. Find the mechanical efficiency'
58
A. 19.2 "/" B' 50 "/" c. 81 .3',/" D . 1 .23h '
34.
35 .
A 56 in. diameter tank is 14 ft, 4 in. high and is tilled to v'ithin 16 in' of the top with
w a t e r . H o w m a n y c u b i c i n c h e s o | w a t e r a r e i n t h e t a n k ?
A. 285,340,3673 lB. 384, 2g0.2464 c. 495,341 .3575 D. 162,018,0242
A tank can be {i*ed by two pipe: il. 1 ii1 6 hours respectivery' lrt can -be emptied
by a third pipe in 5 rrours. tn what time ."n "n
empty tenk be filled in the three
pipes are oPen?
36. There are two intake pipes to a rarge storage tank...Using the smaller pipe alone' it
tat<es twice as long to fill the tank is it ooei using the laige pipe algne' The tank
can be f'red in 12 minutei if both pipes are used. Ho* io"ng'would ittake using only
A. 4 217 hours B' 4 8113 hours C' 4 4ft
the smallsr pipe?
A.24 minutes B' 36 minutes
D. 4.0 hours
C. 1B minutes D. 20 minutes
C. 1 ) 14 .1 kno ts2\ 15.9 knots
D. 1) 13.2knots2) 16.7 knots
C " 1 ) 1 6 h o u r s2 ) 1 2 n . m "
D . 1 ) 1 2 h o u r s2 ) 1 0 n . m .
C . 12 m i les D. 2 mi les
37 . rn 5 hours less time that it takes a certain ship to traver 330 nautical miles' another
ship which is 3 1/2 knoilaster can trav.i + niutical miles further' what aro the
sPeed of the two shiPs?
38. A ship travelring at 17.5 kncts reaves one port bound for anoth er 41/2 hours after
another ship wirose ,p..J is 16 knots leaves the same port set on the same course'
After how many hours an,r "t
what distance from port will the fast ship overtake
A. 1 ) 13 .5 kno ts2) t6.2 knots
B . 1 ) 13 .9 kno ts2 ) 16 .1 kno ts
the slower one? \
A . 1 ) 48 hou rs2 \ 840 n .m '
B 1 ) 2 4 h o u r : ;2 ) 1 6 ' n ' m .
39. An engine develops 2500 rHp and the BHp is 2000" what is the mechanical
eff iciencY?
A) 12.5 or 12o/"B. 1.25 or 1o/o C' '8 or B0% D. .08 or 8 / "
40. A shiP travel 9 mi les in 45 mins' What is
B. 6 mi les
i ts sPeed in mi les Per hour?
A. 3 mi les
59
FORMULAS
Area of rectangle = tength x width
A = L x W
Area ol circte -: 'il R'= ff o'
4
Circumf erence of circle = z' i l r
= I T D
Area of square = side x side
= S X S
Area of tr langle = 1 ab2
Area of ElliPse == fi 314
Area of TraPezoid A = 1 (b'' + b'?) h
2
AreaotS." to l A = 1 radiusxarc2
A = -1 12 0
2
A r e a o f P a r a l l e l o g r a m = b a s e X p e r p e n d i c u l a r h e i g h t
Area of Parabola = base x 2 heightT
Area of cyrinder = circumference x height + area both ends
Area of sphere = dt x' [ i where{l = 3'1416
V o l u m e o f r e c t a n g u l a r = L e n g t h x w i d t h x h e i g h t .solid
60
tt
I
T
IIIIIIIIIIIIIIIIIII
V = L x W x H
Volume of cyllndrical = area of base x heightvessel
V = .7854 D2 hV = f l R ' h
Volume of coal bunker (trapezoidal end)V = W r + W b x H x L
2
Volume of Sphericgt tank = ? O,6
TEMPERATURE SCALES
o F = I C + 3 2' 5
o C = 5 ( o F - 3 2 )I
Deg. absolute = oC + 273Deg. absolute = oF + 460
Phythagorean Theorem / Right Angtes:C2 = a2 I b2
Trlgonometrlc FJnctions :s i n e e = o
hCOS '& = 3
htan o = _o,
a
S e C e = 1 - h
cosec€- = =*
=+
cote = 'T"
it a n e h
whereO = opposi te l r = hypotenus a = aCjacent
Physlcs, Strength of Mater iats formulas:
TOrque = Fo rcexD is tance
61
a
Average Speed = Distance-lgvelledtime ellaPsed
Velocity = Distance -9- = m/sec' Ft'/sec' miftr'
time t
Force = MassxAcce lera t ion
Work = ForcexDis tance
Power = Worked dongtime
Acceleration = VelocitvTime
Eff lciencY = Output-lnput
K E e n e r g Y = . 1 M V t2
StreSS in Tube = P., x P^ x PD2 x .7854
\Volume = Weight
Volume
Dens:tY = - MassVolume
SPecific gravitY = Ig-V
ldeal Gas equation:PV = mRT
Avogadro's Law:VaMa = Vo Mo
tthI
62
III]
III
I
Enthalphyh = u + p V
. Potentlal Energy:EP = mgz
lnternal Energy:du = CvdT
Boy leLaw = V r x P r = V rx P2
Charles Law: V, T.,
% = , ,
Gay-Lussac [-aw: Pr T1
E = \pressure = rqlqglht)
nrcr trtl
Compress ive = Pressure= P-lrea -I-
Tensile Stress = Tensile = TAtea A
Stralrr = Yield pt. = Y
Flastic limit L
ENGTNE/LOG-BOOK REPORT FORMULAS:
lndlcated horsepower:lHp = PLAN
33^000
where: P = 33,000 x IHPLAN
A = 3 3 , 0 0 0 x | H PPLN
63
twhere: P
LA
N
mean etfective Presslength of strokeRrea l. D2
4Rpm
ttIII
I
I
I
I
I
IHP/cYlinder 4 stroke =
IHP/cYlin der 2 stroke =
Cylinder constant (Metric) =
Gylinder constant (English) =
MEP
Slip
Actual SliPActual BHP% Mech. EfficiencY
OutPut Ratio
Average RPM
Average SPeed
Engine Distance
MEP x cYlinder colstant x RPM
MEP x cYlinder constant x RPM
length of stroke Urrea where: L
4500 A
lenoth of stroke x area where: L
33,000 A
MeterCm2Ft.in.2
= Average height of the card x Spring const'ant
Where: nveiage height = (lt*t), ',n:i(length) in'
= Enq. distance - Observed distance = ED4D
Engine distance ED
Slip % = Engine gist?nce'-'Obs'erved dist' x 100-
Engine distance
Engine sPeed - Actual sPeed
ioiur IHP x Mectranical efficiency
BHP x 100
IHP
Actual BHPconstant (8HP max' shoP trial)
Advanced in count-er readbg
Minutes in watch
= Distance trayg].E'd in miles
Time in hr.
= (Pitch of the propeller) (Ave' RPM\ (Time)\ --
6080 f t ' or 1852 m/mttes t
64
II Propeller Constant = (Pitch) (60)
r 6080 ft.rTr Propeller Speed = Propelteu' constant x RPM
TI Propeller Sl ip % = _Prop. speed - ship speed x 100
I ' ProP' sPeedIrl
I PUMPS FORMULAS:II
G.P.H. = rr4ANg M = min. in t hr.
I 231 A = area liquid cylinderI G.P.M. = -ALNE N = no. of stroke
231 S = length of strokeI G.P.H. = ALNEx60 E = e f f i c iencyr 231
I Taper formula for Lathe Work:
I Taper per inch = D - dI L
where:D = dia,neter at large endcl = diameter a( small end
I Tape rpe r foo t = D -d x 12 L = l eng tS in inches
L
CONVENSION TABLE
ThePrincipal units of the metric System are:1. The metric for lengths2. The square meter for surface3. The cubic meter for large volumes4. The l i ter for small volume5. The gram for weights
I .1 mil l imeter" = 0.03937 inch1 cent imeter = 0.3937 inch
I I meter = 39.37 inches or 1.0936 yardsI
1 k i lometer = : 0 .6214 mi leI inch = 2.54 cent imeters
I i l foot = 304.8 mi l l imeters; 0.3048 meter1 yard = 0,91 44 meter
I65
1 mile =
10 mil l imeters (mm) =
10 centimeters =
10 decimeters =
10 meters =
10 decameters =
10 hectometers =
10 ki lometers =
1 square mil l imete( =
1 square cerrt imeter =
1 square meter =
t hectare =
1 square kilomete( =
1 square inch =
1 square foot =
1 square Yard =
1 square mi le =
1 l i ter ===
1 cubic inch =
1 cubic foot =-
1 cubic Yard1 gal lon U"S.it gallon British1 gram
1.609 kilometers1 centimeters (cm)
1 decimeter (dm)
1 meter (m)1 decameter (dm)
t hectometer (hm)
1 kilometer (km)1 myriameter0.001 55 square inch
0.155 square inch
10.764 square feet
107.640 square feet
0.3861 square mile
6.452 square centimeters929 square centimeters0.836 square meter
2.5899 square kilometers
61.023 cubic inches
1.0567 U.S. quarts
0.2642 U.S' 'gal lons1 6.383 cubic centimeters
0.02832 cubic meters
28.317 l i ters= 07645 cubiC meter= 3.785 liters= 4.543 liters= 0.03216 ounpe troy
= 0.03527 ounce AvoirduPois
tuHHHHtlHTt{
tI
tI
I
I
I
t)
= 15.432 grains
1 kilogram = 2'2045 pouqds avoirdupois
1 metric ton = 2204'6 Pounds
1 grain = 0"0648 gram
1 ounce troY = 31 '103 grams
1 pound -- 453'0 granis
f U.S. ton of 2000 lbs= 907 '2 kilograms
1 barrel oi l = 158'9828 l i ters
1 cubic meter = 1000 i i ters
1 cubic meter = 6'2899 barrels
1 long ton - 1 '016 MT
66
II
COMPUTATIONS iN VOLUME:
To geI :BARPELS = m3 x' lrletric Ton = m3 x
Long Ton = MT
Ctrbic Meter ' = MT
6.2899S .G . x C .F .
+ 1 . 0 1 6. S .G .
WEIGHTS & MEASURES
METRIC SYSTEM
LENGTH
1 k i lometer = 1 ,000 meters = 3 '280 feet ' 10 inches
t hectometer = 100 rneters = 328 f eet ' 1 inch
1 meter = 100 c f i ^ l . = 39 '37 inches
1 cent imeter = ,01 meter = '3937 inch
1 rni l l imeter = '01 meter = '0394 incf t
1 micron = .000001 meter = '00039 inch
1 mi l l im icron = '000000c01 meter = '000000039 inch
SUHFACE
1 s q . k i l o m e t e r = 1 , 0 0 0 , 0 0 0 s q " m e t e r s = ' 3 8 6 1 s q ' m i l e
t hec ta re = 10 ,000 sq " me te rs =2 '47 ac res
1 are = 100 sq. meters = 1 '1 9"6 sq ' yards
1 centare = 1 sq. meterS = 1 '550 sq ' inches
1 sq .cen t ime te r = ' 0001 sq 'me te r = 156 sq ' i nch
1 ; s q . m i l l i m e t e r = . 0 0 0 0 0 1 s q ' m e t e r = ' 0 0 1 5 5 s q ' i n c h
VOLUME
1 k i to l i te r = 1 ,000 l i te rs = 1 ,308 cu ' yards or 264 '18 ga l lons
t hectol i ter = 100 l i ter ,s = 2'83B bushels or 26'418 gal lons
1 l i te r = 1 l i te r = .908 qur r r t o r 1 '057 quar ts
1 cen t i l i t e r = .01 l i t e t = ' 061 cu ' i nch o r ' 338 f t ' ounce
1 mi l l i l i te l = .001 l i tcr = ' ' i1$1 cu" inch or '271 f t ' dram
WE:Cit IT
1 ki lograr l = 1 ,000 grarns = 2'205 pounds
t hectogrsul = 100 gran' '$ = 3 '527 ounces
1 gram = ' l gram = .035 oLlnce
1 cent igrs, f f l = .01 grarn = '154 grain (Troy)
1 mi l igra;p = .001 grarn ' ' - '015 grain (Troy)
\.'
67
I
VOLUME1 sar (u s ) = 13? l;l;,lu
t '= 0.833 ga l . (Br i t . )
1 cu. f t . = 7 .48 ga l . (U.S. )
WEIGI.IT OF WATEB
1 cu. f t . at 50"F weighs 62.41 lb.
1 ga l . a t 50"F weighs 8 .34 lb .
1 cu. f t . o f ice weights 57.2 lb .Water is at i ts greatest dcnsi ty at 39.2"F1 cu. f t . a t 39.2"F1 cu. f t . a t 39.2"F weighs 62"43 lb .
WEIGHT OF I- IQUID1 g a l . ( U . S . ) = 8 3 4 l b . x s p " g r "1 cu. ft. = 62.4 lb. x sp. gr.
1 l b . = 0 .12 U"S" ga l . + sp . g r .= 0 .016 cu . f t . + sp . g r .
FLOW1 gpm = 0 .134 cu . f t . pe r m in .
= 500 lb . per hr . x sp. gr .500 lb . per hr . = 1 gpm + sp. gr .
1 cu f t per min . (cm) = 448.8 ga l . h r . (gph)
WORK1 BTU (mean) = 778 f t . lb.
= 0.293 watt hr.= 1/1 B0 of heat required to change
temp. of 1 lb. water from 32oF
lo 212"Ft hp. hr. = 2545 BTU (mean)
= 0 .7 46 kwhr"1 kwhr = 3413 BTU (mean)
POWER1 BTU per hr. = 0.293 watt
= 12 .96 f t . l b . pe r m in .= 0 .00039 hp .
68
I
tII
IIIIIII
t h p
1 boi ler hp
1 k w
1 ton refr igeration (U.S.) = 2BB,0OO BTU per 24 hr.
12,000 BTU Per hr.200 BTU per min.8333 lb. ice melted Per ltr.from and at 32oF550 ft . lb. per sec.746 watt2545 BTU per hr.33,480 BTU Per hr.34.5 lb. water evap. Per hr.frcrm and at 212'F ) S5/l ,)9.8 kw.3413 BTU Per hr"1000 wat t
MASS1 6 oz. (Avoir)7000 grain2000 lb.2240 lb.
USEFUL i l / IEASUREMENTS(Metric System)
lb. (Avoir) =
ton (short) *ton ( long) =
OTHER
IT
LONG MEASI.JRE12 inches =3 feet =6 feet =5 112 yards =40 poles =8 furlongs =3 miles =69 1/2 miles =
CUBIC MEASURE728 cubic inches =27 cubic f eet =128 cubic f eet =24 1/4 cubic feet =
1 foot ( f t . )1 yard (yd")1 fathoml nucle1 fur long1 rnilel league1 degree
1 cub ic foot1 cubic yard1 core of wd.1 ph. c , f s tone
TIME MEASURE60 seconds60 minutes24 hours7 days30 days12 mon ths365 days366 days10 years20 years100 years
1 minutet hou r1 day1 week1 calendar month1 year1 common year1 leap year1 decade1 score1 century
SQUARE MEA.SURE144 sq. inches = 1 sq. feet9 sq. feet = 1 sq.vard30 1/4 sq. Yards = 1 sq. Pole
69
GENERAL CONVERSION FACI'ORS
tLtReclprocal
Conversion to
Linear Meaguremil (0,001 inch)inchfootyardmt lenautical mtlc
mil l imetremil l imetrernetremetroki lometrekilomstre
0,0254?5 ,4
0,30480 ,91441 ,60931 ,8532
39,370,039373 ,2811 ,09360 , 6 2 1 40,5396
Squaro Moasurosquare inchsquare Incnsquare lootsquaro Yardacreacr6square mllesquare mile
square mtl l tmetresquare centimetresquaro mctrssquaro metresquare melresquare fclotacresquare ki lometre
645 ,20 ,4520,09290 ,8361
4047 ,43560,
640 ,2 ,590
0 , 0 0 1 5 50 , 1 5 5
1 0 , 7 6 41 , 1 9 6
0 ,00024710,00002296
0,0015620,3863
Volumecubic inchcubic footcubic footcubrc (oot
cubic yardounce (U .S . , l t q , )quar t (U.S, , l iq . ;ga l lon (U.S")ga l lon (U.S )barrol (U.S" Petrolt lum)
barre l (U.S. Pet ro leum)
cubrc centtntgtrecubrc metregal lon (U S )I r t rocubic metrecubic centintetrel i trega l lon ( lmPer ia l )l i t roga l lon (U.S. ilitre
1 0 ,3870,028327 , 4 8
,21J,'J2
0 ,764629,570,94640,83273,785
42,1 5 8 , 9 8
0 , 0 0 1 0 23 5 , 3 10 , 1 3 3 70 , 0 3 5 3 11 ,30790,033821,05661 , 2 0 0 9D,26420,02380,00629
Massgra lnounce (oz)pound ( lbs)short tonlong ton
mil l igramgramkilogrammetric tonmetric ton
6 4 , 828,350,45360,90721 . 0 1 6 1
0 , 0 1 5 4 30,035272,2051 , '10230,9842
Work, Heat and EnergY
Br i t ish thermal un i t (B lu)
foot pound'forcecalorieBtukrlocalorieBtu8tu Per hourwatthourhorse Power
iouleiou leioulefoot pound-force
Btuki logram metrewattjou leki lowatt
0,00094790,73750,2389 I0 ,001285 i0 ,2520,0092973 , 4 1 40,00027781 , 3 4 1
1 055,1 , 3 5 64 , 1 8 7
7 7 8 ,3,968
1 07,560,2929
3600,0,7457
Miscel laneouspound Per gal lon (U.S.)
pound mole (gas)
gram mole (gas)
board footmil l iamPere Per fool 'ga l lons (U.S. ) Per minute
oound-forceki lopond (KP)
gram Per l i trecubic foot (STP)
l i tre (STP)cubic metremil l iamPere Per metre2
metre3 Per daYnewtonnewton (N)
1 1 9 , 8359,
22 ,40,00236
1 0 , 7 65 , 4 5 14 ,4489 , 8 1
0,008350,002790,0446
423,70,09290,1 8350r22480,1 02
70
Part II
ELECTRICITY ANd ELECTRICALLYDRIVEN PROPULSION
\
3 .
4 "
2.
5 .
ELECTRICITY - the effect of electrons in moving from point to point or thq excess or
lack of electron in a material. l t may be prodr.rced ihermally, mechanically or by chemical
action. on board as engineer simply can be defined by its effects. Electricity consist
of a f low of energy in a wire that cause the wire to become hot, which produced magnetic
field around the wire and can be put to works l ike driving, pumps, auxiall iaries equipments
etc.
6 SOURCES OF ENEITGY T}IAT ELECTRICI'IY CAN BE PRODUCED
1. Friction - charged caused by rubbing one material against another' Example:
wood/stone
pressure - produced erectricity by applying to a crystal of a certain, or by speaks
in te lephone.
Heat - electricity produced by heating the iunction of a thermo-couple.
Light - electricity produced by striking photosensitive material Example: iron,
selenium al loy.
Magnetism - produced by relative movernent of a magnet and wire r that result
i r , the cutt ing of l ine of force.
6. Chemi;al action - electricity produced by chernical reaction in an electric cell '
Exampte: Battery
DEFI}I-IIIONS AND FUNCTIONS OF EI.ECTRICAL TERMS GIVEN
TO ALL RANI$ PREVTOUS EXAMINATIONS
ALTERNATING CURRENT - is a current that clranges its direction rising from zero
to a maximum intensity and back to zero and cycle repeats'
AMMETER - instrument used to measure amperes/rate of f low.
AMPEBE - uni t of electr ical current.
AMpERE TURNS - the strengtlr of an electrontagnet can be determined either by the
number of turns of wire or by the strength of the current '
AppARENT powER - the power indicated by arr ammeter and voltmeter readings.
ARMATURE WINDING - is to cut l ines of forces passing betvl 'een f ie ld magnets and
transmit the developed eletromotive force to the commutator '
ATOM - the smai lest physicat part ic le into whiclr t ; lement can be div ided.
AUTOMATIC CoNTROL - a system in wlr ich the value of a process i f compared against
a rJesired value and corrective action taken to correct the deviation without the use of
human he lP.
BALANSER SET - i t is a motor generator, both uni ts are al ike, used in some wire,
w-voltage system to help the load balanced between the two side of the circuit '
thhhhhryIhhIhhiI
tItI
I
I
72
IIIt
I
BATTERY - a series of two or more cell that are capable of producing electricity byelectrochemical means. lt is charged by reversing the current through tire battery byusing DC to restore'the nraterial deposited in the electrolyte back on the plate in position.Type of Battery: Primary - cannot be recharge. Secondary - can be recharged.
CAPACITANCE ,- when voltage across an electric current changes, the circuit opposesthis change called and measured in Farads.
CAPACITOR - is a device for storing an electrostatic charge.
CIRCUIT BREAKER - a mechanical safety device that open a circuit when the currentin the circuit exceeds a pre-determined amount.
CONDUCI'OR - it is a substance that offers a lorv resistance to the flow of current.Example: Aluminum, Copper, Si lver, Steel .
COMMUTATORI- is to convert the AC from the armature winding into direct currentand transmit i t through the brushes to the external c i rcui t .
CONVERTER - an electrical device used frr convertir.g alternating current to directcurrent.
CONDENSER - a combination ol conrJucting plate separated by an insulator.
CONTACTORS - consist of two broa'J f lat copper surfaces that are pressed tightlytogether to close the circuit.
COUNTER EMF - is counter vol tage indu:ed in a conductor or which opposes a changein flow of the current in the cond.rctor. lrr electrical motor, CEMF is the voltage generatedin the armature which opposes the supply voltage.
DC GENERATOR - is a mechanical power turn the armature and the moving armaturegenerates electrical power.
DC MOTOR - etectrlcal power forces the armature to turn through mechanical system,belts, gears which produced mechanical load,
DEAD BAND - a zone within a change of value of an input s ignal does not causea change in the control ler . l f the dead band is too smal l , the steam valve may h' 'nt .l f the dead bano is too large, speed regulat ion wi l l be poor.
DEAD SHORT * is a short c i rcui t that has such low resistance that the circui t is madein operative.
DIRECT CURRENT - the current that f low only in one or constant direct ion.
EDDY CURRENT - induced circulat ing current in a conduct ing mater ials caused by avarying magnet ic f ie ld, Eddy currents are reduced by laminat ing the armature core.
ELECTRON - smal l negat ive charged part ic le of a nucleus (-) ,
ELECTROLYS1S - is the chemical action related to the conduction of electricity throughacid or salt solution.
IIIIIIIIIIIIII
73
J
becomes demagnot lzed"
ELECTROMAGNETISM - magnet isma coi l or wire.
havin$ a coili ron or steel
orocluced when electr ic current is passed r through
EQUALIZER - a connect ion between two generators of di f ferent capaci t ies ruhning in
paral le l so that the running load is div ided proport ional ly bewveen the tuto '
EXCITATIoN - the process of exi t ing; current to the rotor of an A.c. generatolr , or the
supply of electr ical current for the purposecl of prgducing a rnagnet ic f ie ld ' i
EXCITER - a smal l D.C. generator whicir suppl ies t l re exci t ing current to the A'C'
generator .
EXTERNAL clRculT - i t is the part of the electr i r :a l c i rcui t leading from ther source
of supply back to the source of supply.
FARADAY LAW - states that i f a magnet is moved past a wire, electr ical curr :ent wi l l
start through the wire. l f the magnet is stopped near the wire, the current wi t l stop'
Electr ic i ty * i t t f low only when t l re magnet ic f ie ld or magnet ic l ines of force arb being
cut by the wire.
FREOUENCY - means the number o f t imes per un i t o f t ime the cyc le is repeated.
60 cycLE - means the number of t imes which is 60 t ime per seconc a cycle is repeated.
FUSE - electr ical safety device to break of f the circui t in case of over ioad cf current,
consi t of low-melt ing metal in ser ies with the l ine at predetermined tomperature caused
i t t o m e | t t h u s b r e a k i n g \ t h e c i r c u i t a n d s t o p p i n g t h e f | o w o t c u r r e n t '
GALVANOMETER - instrument to measure or detect smal l l e lectr ic current by moving
magnet ic coi l in a magnet ic f ie ld '
GENERATOR - i t is a machine which converts mechanical energy into electr ical energy'
GROUNDED clRculT - a c ircui t that has corne in contact wi th the earth ei ther by
coming in contact somewhere i tsel f or leak of f to the ship hul l d i rect ly ' Typical s igns
of a ground are abnormal amperage, vol tage, resistance readingis, also shock and
abnormal c ircui t Performance.
GROUND LIGHTS - set of two l ightsinsulat ion of electr ical c i rcui ts.
which are usec l fo r r ;heck ing grounds or low
GROwLER - an electro magnet ic device with two adjustable pole pieces for f inding
short c i rcui ted coi ls and for magnet iz ing and demagnet iz ing'
HORSEpOWER - uni t of rnechanical energy equivalent to t horsepower equal to 33,000
ft . lbs. per minute. !
HYDROMETER - instrument use for checking the charged capacity of a battery with
ful l charged approximately 1,300 s.G. and low 1,000 spec;f ic Gravi ty"
74
ELEcrRo MAGNET - a piece of soft steel or iron that is magnetized by
of current carrying wire *r"pp"o around i t , when current is shut off ' the
'
*
rtttttI
t
I
I
I
I
IINDUCED CURRENT - Consist of magnetic lines of force that cut a wire, electric current
is induced to flow in the wire.
INDUCTIoN colL -L operates on DC current and gives an instantaneous voltage when
the primary circuit is made or broken'
INDUCTION MOTOR - is an AC motor wnose speed is not proportional to the frequency
of the system; Mostly squirrel-cage type consist of statorwhich is outer, hollow, stationary
laminated steel, slotted for armiture winding and having an inner cylindrical motor' lt
is usually found on; board where sources is alternatirrg current.
IMPEDANCE - in an AC circuit with combined effecis of resistance xl and Xc and
measured bY ohms.
INTEHLoGKS - operating levers are interlocked mechernically to prevent incorrect op-
eration like reverses, astern or ahead'
INTERpcLEs - used on DC rnotor in crder to offset armature reaction and give better
commutation.
INSULATOR it is a substance that ,rffers a high resistance to the flow of current'
Examples: rubber, cork, Porcelain.
INVERTER - is a piece of electrical equipment for converting DC to AC.
JAMMING RELAY - fitted on rnotor serve as cevice that inserts resistance in series
with a motor armature in case of excessive overloacls and overheating, thus motor
armature current is cut down to a safe value.
K.W. METER - electrical meter that shows the operator the amount of electrical power
in Kw.
LENZ LAW - an induce current sets up a magnetic field which opposes the motion
that causes the currqPt.
MEGGER - instrument used tO measure the effectiveness of an insulation resistance
of electrical equiPment.
MEGOHM - equivalent to orre mil l ion ohms'
MILLIOHM - equivalent to thousand ohms'
MOLECULE - combination of truo or more atonts-
MOTOR - a machine device which converts electrical energy Into meclranical energy'
NEUTRON - neutral particle in the nucle'ls consist of electron and proton'
OHM - unit of electrical resistance'
oHMETER - instrument USed to measllre consumption of electrical energy'
oHMS LAw - states that the current flowing in a electrical circuit is directly proportional
to the implesqed volt4ge and inversely proportion to the resistance'
I
75
ovERLoAD RELEASE - device autonratically breaks tlre current if an excessive current
through its llfe.
is drown bY the motor'
'ARALLEL ctRcurT - is an erectrical connection in which the various parts are so
connected together that there is more than one patn tor ine flow of currdnt or when
the apparatus are connected side by side
'ERMANENT MAGNET - a piece. oJ steer ttrat has been hardened and placed under
the Infruence or a magnetrc fisrd, when removecl, it rotains its magnetisnl of the tield
pHAsE BALANcE RELAY - lt act to trip out the circuit breaker on the transformer
and open the generator and motor field contactor, if unbarance excess of 2S percent
It shows short circuit if phase unbalance or ground in one phase'
powER FACTOR - ratio between true power and apparent power' lt is expressed
as a percentage of the apparent power'
P R o T o N - p o s i t i v e c h a r g e d p a r t i c l e o f a n u c | e u s ( + ) .
RECTIFIER - an electrical device used to change alternating current to undirectional current'
RIGHT HAND RSLE - in every case where an EMF is inducecl b1' a conductor moving
through stationary rines of rorce, the direction of this EMF can be found as fQllows: Place
the right hand with the thumo. forefinger and middle finger all at right qngles to one
another; point the forefinger arong tnJtines of force.nithumb along the direction in
which the conductor is moveJ, th; middle iing.t will then show the direction the EMF
induced in the conductor'
RELA' - is a device that is operativ, gy a variation in the condition of one electric
circuit to control the\ operation of other devices in the same or another electric circuit'
RHE.'TAT - an instrument composecl by a combination of resistance used for regulating
the strength of an electric current through the field windings of a generator"
RE'ID'AL MAGNETI5M - is the magnetism remaining in the. field after all exciting
current is shut off. rt is important because the D.c- g.nrritor could not built up a voltage
without it.
RESlsroB - a cevice in which the flow of electric curt'ent etlways produces heat'
REVERSE powER RELriy - protects the generator from a power reversal'
R o T A B Y c o N v E R T E R - u s e d t o c o n v e r t A C t o D o .
sERrEs cr'curr - is one which ail parts of the circuit are connected together so that
there is oniy-one path for the flow of current.
sERrEs-pARALLEt- clRcurT - is one in which the parts are connected botfr in series
and para l le l combinat ion. . . r , - r -^ ,^ . . . .^^ ia lanno r r
' tused by insurat ion
sHoRT crRcurT - is a circuit with too row resistance to the system ca
being damaged of t*o "op.rnt
.tr.tric wires permit the current to pass from positive
7 6
to the negative wire without passing the usual resistance. Typical signs of short circuit
are blown tuses, increase fieat, low voltage, high amperage and smoke or burn.
SLlp BING - purpose is to supply D.C. current to the field winding of the motor.
SoLENOID - an electro magnetic coil that contains a movable plunger.
STATOR - stationary part of an electric motor which produces the rotating magnetic
f ield.
syNCHROSCopE - an electnlcal apparatus used in synchronizing two or more D.C.
generator.
SYNGHRONOUS MOTOR - the average speed of normal operation is exactly propor-
tional to the frequency of the system which connected, and their main application in
marine work as main propulsion motor. lts construction is similar as AC generator parts.
THERMOCOUPLE - two dissimilar metals are joined together; when heated, a voltage
is produced.
TRANSFORMER - it is an electrical device used for increased or decreased voltage
of alternating current.
sTEp DOWN THANSFORMER - is one that lowers the AC voltage and increase the
ampere. The change in amperes is inversely proportional as the turns in the primary
are to the turns in the secondarY.
sTEp up TRANSFORMEH - is one that raises the Ac voltage and decreases the
amperes. The change in volts is directly proportional, as turns in the primary are to
the turns in the secondarY"
TRANSDUCERS - a device capable of converting pressure, temperature or level intoan electrical equivalent.
TRUE POWER - actual pcwer as measured by watt-hourmeter.
WATT - unit of electriPal Power.
WATT HOUR METER - instrument used to measure consumption of electrical energy.
VOLT - unit of electrical pressurs.
VOLTMETER - instrument used tc measure volVelectrical pressure.
VOLTAGE REGULATOR - rrsed to maintain the generator voltage within specified limits
at constant with different loaci.
77
(1987'1991) ouEsTloNs AND ANSWERS
FoURTH, TH|RD, SEcoNt| AND CHIEF ENGINEERS. .t
e. Enumerate 10 causes whlch may resurt to a poor commutatlon of Dc generator'
1. Overload2. Hard or high resistance brushes3. Rough comrnutators bars4. High mica on th'r commutator grounds
5. Short circuit in the armature6. OPen circuit in the armature7 . Poor brush contact8. Uneven air gaP9. Weak magnetic field10. Inaccurate brush sPring
Q. What are the causes of fallures of a DC
1 . Field connection reversed2" Brushes are not in proper position
3" Wrong direction of rotation4. SPeed too low5" Field circuit oPen6" Not enough residual magnetism7. Machine short circuit
o. Name the causes of low voltages In generator"
1 . Overload2. Low sPeed3. lmProPer setting of brushes
O. What are the bauses of too hlgh voltage?
1 . Field too strong2. SPeed too high (generator)
o . W h a t a r e t h e c a u s e s o f h o t c o m m u t a t o r s ?
1 . SParking under brushes2. Poor contact of brush3. Near some hotter part of machine'
O. Causes of sparklng at the brushes?
1. Overload2. Brushes setting is wrong3. Poor brush contact4. Rough commutator5. Weak field6. Armature winding broken or short circuited'
generator to bulld uP?
78
o.
o.
IIIII
Causes of too low generator speed?
1. Overload2. Brushes setting wrong3. Excessive,friction4. Short or giound in armature5. Too little field resistance
Causes of too hot fleld?
1. Overload2. Damp windlngs3. Too large field current4. Short circuited coil.
What general care should a generator recelve whlle In operatlon?1 . lt should be kept clean and dry.2. The bearing should be kept well oiled.3. The governor should bre kept in good condition"
Causes of too hlgh generator speed?
1 . Brushes setting too forward.2. Open field circuit"3. Wrong connection4. Too much field rheostat resistance.
What are the results of shorts In DC armature colls?
1 . Overheating2. Sparking at brushes.3. Bu rn ing4. Discoloration.
what are some\causes of fallure of a generator to bulld up?1 . Field coninection reversed2. Brushes not in proper position3. Wrong dlrection of rotation4. Speed too low5. Field circuit open6. Not enough.residr{al magnetism7. Machine rshort circuited.
Reasons why a self-elrclted DC generator mlght fall to come up to lts ratedvoltage when startlng up?
1. Brushes not in proper posit ion.2. Field connection reversed.3. Wrong direction of rotation.4. Speed too low.
5. Field c ircui t open.6. Not enough residual magnet ism.7. Machine short circuited.
o.
o.
Q .
Q .
o.
79
trL
o. A generator ls vlbratlng, what check ups should be made before changlng
5' -"ni balance welghts
\ I
1. Misalignment2. SPring shafting3. Somethings changrng the rotating element
4. Foreign matter shaft'
5. Uoose bolts' foundation
o. lr::ll;:Tj,ffi::'sdnuo by rotarns the *erd rn an Ac geneiator rather
l:"" # ;tJ"ffit rrom the stator is connected directlv to the external circuit
without using sliP rittg'
2. onty two slip rings 3re nTT?:'y t9''up-qll*:*tit"tion to the revolving field'
3. The stato' winding is not subiecreo to mechanicar stresses that are due to
centrifugal force '
o. what four thrngs determrne the amount of lnduced voltages and amperes?
1 . The strength of the field
2. The number of conductor
3. fne sPeed of cutting the fields
4. The angle wnicrr-irr; conductors have to the field"
o. Name some generator check-ups whrch should be rnade at least once a month'
1 . Check load condition2. Uubrication sYstem oPeration
3. Governor action of Prime mover
4. Bearing temperature and vibration
o. Gtve the method of synchronizing by the use of bright lamp lmethod'
ln synchronizing by the use of the bright ranrp method, the paralleling connection
shourd be compreted at ih; instant tn"iiri, ramp srrines at their maxirnum brilliancy'
o . G | v e t h e m g t h o d o f s y n c h r o n | z l n g b y t h e u s e o f d a r k | a m p m e t h o d .
rn synchronizing the use of the dark ramp method, the paraileling connection should
bo compreted at the *iiJre of the intervar between the disapperance of the last glow
a n d t h e t i m e t h e s a m e a m o u n t o f g l o w r e a p p e a r .
o . N a m e t h e m a t o r p a r t s o f a n A C a n d D c g e n e r a t o r .
I r 5C)generator1 . Tl,e stator2. The rotor
B. DG generator'
1 . The stator2. The rotor
80
which contains the armature wirrdings'
*ni.n contains the tield windings'
vrhich contains the field windings' !
which contdins the armature rrvindings'
I O. Name the ktnds of AC and DC motors;
AC motorsII 1. Wound rotor motor 3. Repulsion motor
2. Universal geries motor 4. Synchronous motorI oC motorsI'
1. Series motor 3. Compound wound motort ah' 'tt motor 4. Universal series motorI -' '"-'
! O. What are the types of transformer accordlng to the method of wlndlng thecoll?
I r. core type- 2. Shell type
3. H{voeI
' 'I O. Upon what factors does generated voltage depends?
1. Speed that the magnetic lines of lorce are cut| 2. Strength ot the magnetic fietd.r 3. Number of turns ot wire.
r Q. What protectlve devlce are Installed In an electrlc drlve system?TT -- Fuses, circuit breakers, phase balance relays, reverse power relays, ground relays,_ interlock alarms such as klaxons and bells.II O. What are the Instruments used In synchronlzlng two or more AC generator?
I 1 . Voltmeler1 2. Synchronoscope
Q. Name the Instruments tound In DC and AC swttchboard panet.II Circuit breaker, voltmeter, ammeter, rheostat ground tight, synchroscope, vottage
regutator, p.F. mete( Kw meter.I
I O' what condltlon must exlst In order that two Ac generator wl operate Inparallel? They must have:
I 1. Same voltage| 2. Same frequency
3. Same phase rotation.I
I O. What are the factors that effect reslstance on a wlre?1. Length of wire. 3. Type of materia
1 Z. Cross sectional area of wire. 4. Temperature of wire.I g. What are the condltlons \irhlch would cause an AC generator to overheatt
| 1. Overload 4. Dirty wtndingsa 2. Short clrcuit in coils S. Fan or air cooler defective
3. Damp colls 6. Low oowcr factor load
8 1
o. A generator ls vrbratrrrg. what check-up shourd be nrade before changlng
"nY balance welghts' "
Misarignment, sprung shafting, sornetrring ciraf ing the rotating element' f oreign mattgr
on shaft , overfoading, loose l - 'o l is ' faul ty speed governor '
a. Name some generator check-ups which shourcl be made at reast once a day'
check road condit ion, cornn- lutator condit ion, rubr icatror, system operat ion' governor
a c t i o n o f p r i m e m o v e r , | r e a r i n g t e m p e r a t u r e a n d v i h r r a t i o n '
o. what means are emproyetr to prevent t l re outer c i rcui t f ront overheat ing?
1. r t must have a proper s izc of wire to t i re proper ar*ount of current to be suppl ied'
2. Overlcad3. Short c i rcui ted connect ion
o. what are the tactors to be considered when synchronizing two or
erators?
TheY must l ' rov€ the fol lowing:
1 . Same vo l tage2. Same frequencY3. Same phase rotation and be in pnase
o . W h a t h a p p e n s w h e n a 6 0 l . | z m o t o r | o a c l i s c o n n e c t e d t o
The motor rated capacity to drive wil l be underated or less to
because of the generator f requency is low'
o. whlch motor (AC or DC) can be smoothry controi led In terms of speed and
why? \
AC motor can be smoottrry controted in ternrs of speed. Un'ke Dc motors; Ac
motors does not use commutaiors therefore most occured troubles encountered in the
oJeration of DC motors are eliminated'
o. As a marine engine officer, you are duty bound to malntarn and preserve the
erectrrcar power system on bouro youi'uesser. state brlefly what you know
about electricitY?
As a marine engineer of f icer my dut ies in regards to erectr icar equipment on
board ship are as follows: , - r,--. ̂rr^a| n{By definit ion basicaily Erectrici ly may be defineg ur the effect of erectron Inovlng
from one point to point and exist in stai ic form which may be produced thermal ly '
mechanicltfy and through chemical actions
proper erectrical maintenance methods of a[ generators, motors, anc auxil l iary
machiner ies such as checxing for st oi t and grounoeo circui t , over loading' megger
test for insuration resistances battery, wiring iystem for l ighting and starting motor
etc.
more gen-
a 50 Hz generator?
its rotational caPacitY
82
I
]
o.
checkrist maintenance test and records shourd be done on board regarding
safety ararm test,,insuration records, overhauring and repairs. Instrumentation like
pressure and terlperature gauges, alarms must be in good order'
Advantages of turbo-electrlc drlve shlps'
1. Allows high speed prime mover and low-speed propellbr at highest effieciency'
2. Allows full power of turbine when astern'
3. Less noise and vibration'
4. Does away ,with line shafting from turbine to propeller'
5. The erectric instruments indicate the power output and can be used to improve
oPeration.
what ls meant by power factor? Express lt mathematlcally'
I
o.
Q .
Power factor - is the ratio of
as a Percentage of the aPParent
P.F. = true Power =apparent Power
How does the slze of wlre affects lts
true power to apparent power' lt is expressed
power.
Kw = WattKVA
reslstance?
Volt-AmPere
I
o.
0.
a.
o.
The resistance of a wire is inversery proportional to the square of the diameter'
the length remaining the same'
G | v e 4 | a c t o r s t h a t a f f e c t r e s | s t a n c e | n a w l r e .
1. Length of wire2. Cross sectional area of wire3. Type of material4. TemPerature of wire.
As the rength of a wrre Increases, what happens to lts reslstance? lf the
cross sectlonal area Increases, whtlt happens to the reslstance?
As the length of atwire increases, the resistance remain the same.
AS the cross sectiOnal area increases, the resistance decreases'
What klnd of metal ls used for pole pleces of generator fleld'
Metal consist of rouird square and rectangular copper wire wrapped about a
soft iron core.
Degcrtbe a serles electrlcal clrcult when resistance are connected In serles'
What mlght be sald about:
1 " Current Flow3. Total ,voltage droP
1. The current in every circui t is the same'
2 . T h e v o | t a g e a c r o s s t h e . c i r c u i t e q u a | t o t h e S u mseParate I resistance'
\ . .
of the voltage across each
2. Voltage across each4. Total resistance
I
83
3. Totat voltage drop is equal to the total line current multiplied by total resistance'
4" Totar resistance is equar to the sum of the individ,rar resistancs'
o. Descrlbe when reslstance In parallel.. what can be sald about (1)"lthe voltage
drop across the enilr" pur"rier crrcurt; (2) vortage drop across each branch;
(3) amount of current ito* through each branch'
1 . The voltage drop across the entire parallel circuit is the same as the voltage
each branch.
o, what are the three thlngs necessary to Induce a voltage in a wlre?
a) Magnetic fieldbi A conductor in a closed circuilc) Relative motion betvveen the two
across each branch'2. The voltage drop across each branch is
3. The total iurrent through the combinationthe same.is the sum of the current through
types of DC motor.
load, at no load it oversPeeds,very high starting torque. Used
o. Glve some characterlstlcs and appllcatlons of
SERIES WOUND MOTOR - speed varies with the
at full load it decreases speed. This motor has a
for street cars, cranes, elevators, locomotives'
SHUNT WOUND MOTOB - constant speed over load range, constant load over
speed range, has a good contror and used mainly on machirte tools wlhere variable
speed is desired.
coMpouND WOUND MOTOR - has desirable features of both aboveltypes. 9.oo9starting torque, f lexibil i ty of speed contror, constant road speed applipation. Used
for centrifugal pumps, cargo winches, boat hoist, air compressor drive'
O. Glve some characteristlcs and appllcations of DC generator'
sERtES ry9UNDED GENERAToR - which has its t ield coils wounded in series
with the armature. The field coils has a few turns of large wire. The voltage wil l
r ise with an increase in load" They are not in general use, but malir be used for
boosting voltage in transmission of D'C"
SHUNT WOUND GENERATOR - i t is a generator which has i ts f ie ld,coi l wounded
in parallel with the armature. The l ield coil wounded in parallel withlthe armature
consist of large number of turns of srnall wires. The voltage droqt .:JL -Y',h an
increase in load. Used for batter:y charging and A'C" generator excitation'
COMpoUND wOUND GENERATOR - has two fields on each pol€ piece' Olg
of the coils is made up of a few turns or heavy wire and wounded in series with
armature. The other coils is composed of a great armature. This kind of generator
is used for armost generar purposes where oc current is required and also voltage
- is fairly constant from no-load to the full- load.
o. what are the two general types ol Ac motors? Describe their chanacterlstlcs
and thelr uses?
1" synchronous motor - has a rorating field with salient poles which are excited
by direct current speed is constant and torque is moderate. lt is suited best
for shiP ProPulsion.2. lrrduction motor - has a stator, the stationary part and the rotor as the rotating
part. The speed is nearly constant, low starting torque and high starting current.I t is used forrgdneral PurPoses.
o. what are the two'dlfferent types ol Inductlon motors, and lts appllcatlons?
1. SQUIRREL CAGE TypE - lras no winding but rather has bars and end rings
in the core of the rotor.
Uses - hrlower, machine shop motors, steering gear, motor generator and fans.
2. wouND ROTOR TypE - has windings on the wire of the rotor and slip rings
on the shaft which are used for inserting resistances to vary its speed andfor starting.
Uses - Boat hoist, capstans, cargo winches and elevators.
O. What ls the meanlng of alternatlng current?
It is the current that between any two consecutive instants of time is eitherlncreasing in strength, decreasing in strength, or reversing in direction.
O. Descilbe one cYcle of A.C'
Start at zero strength and increases in strength to maximum in one direction,decreases in strength in the same direction to zero, reverses direction, increasesin strength to maximum in the new direction, decreases in strength to zero, whereit reverses again to the original direction.
O. What ls meant by frequency of A.C.? What ls 60 cycle A.C.?
Frequency means the number of timos per unit of time the cycle is repeated.G0 Cycle A.C. means that the cycle is repeated 60 times per second.
Gl" What ls meant by "staggerlng the brushes'n of a generator?
It means placlng them on the commutator so that they are not in line, so asto prevent thenr from grooving the commutator.
O. What ls the effect of brushes ahead or behlnd neutral In a DC generator?
The voltage will not be lts lrighest, more field current must be used to getthe required voltage thus heating up the tield poles" Sparking at the brushes willcause the commutator to run hot.
e. Why do most DC motors deslgned to operate at varlous speeds have com-pensatlng colls and Interpoles?
These poles are placed miclway between the main poles to induce the voltagein the coil being comrnutated.
' l-his helps in a quick reve rsal of current in that coilwhich reduces sparklng.
O. How does a DC generator dlffer from an AC generator?
The DC generator has a commutator, the AC generator has a slip ri,tg.
85
f
Exp la |nwhycompoundwoundDCgenera torsaresnips and now ls the voltage controlled?
This type of generator develops a constant voltage at
controlled bY msans of rheostat'
o. state two ways to reverse the polarlty and two ways to
o. most commonlY used on
\al l loads Voltage is
vary the strength of
an electromagnet.To reverse the polarity, either reverse the winding of the coil 0r reverse the
d i r e c t i o n o f t h e f l o w o f c u r r e n t i n t h e c o i l .To change the strength, either change the number of turns of wire or change
the amount if .urrrnt flowing through the wire,
e. How wourd you reverse the porarrty of a 4-pore compound wound dc generator?
Lift the brushes and places of cardboarcl untJer each brush' connect an outside
erectricar suppry either another generator or a battery, and throw.in the switch for
a few seconds. pulr out the switch, remove the cardboard and startrthe machine'
o. How rs speed control obtarned for drrect current motors? speed control tor
DC motors obtalned bY:1. Varying the strength of the field'
2. Varying the voltage in the armature'
3, The shunt field nls a rheostat connected
o . G l v e s o m e g e n e r a | r u | e s t o | o l l o w l n t h e o p e r a t | o nof a DC mptor?
Keep the motor clean and the commutator smooth
Keep the brushes in good condition, properry space and on the neutral point'
Do not overload the motor'Use the ProPer voltage'Use the motor only in the temperature
o . H o w w o u l d y o u t e m p o r a r | l y r e p a l r . a n o p e n c o l | | n a nsparktng-rni {ashlng untli the shlp reaches port?
lsolate the coil completely by cutting both encjs of tl'le coil
lf you fo,rnd a generator had been wet and had heavy molsture grounds, what
w o u | d y o u d o - t o g e t t h e m a c h | n e r e a d y f o r s e r v l c e ?|f heating grids are instal|ed in the unit, use them. |f nc,t, run a low voltage
through the windings.
How would you proceed to locate a ground shown by ground lamps on a
240 volt DC auxitttarY PCIwer bus?
cut out different line suritches on the switch board urrtil the ground disappears'
To rocate the groundeo circuit, go to. that circuit box and cut out each individual
switch untl the ground disappears. work "iong
this final circuit until the ground
is located.
O. ln general, how ls the sPeedof DC motors controlled?
are controliecJ by il varying the strength of
the armature. Usually, the shunt field has
it.
1 "2 .e
4.5 .
in series.
which it is designed.
armature to Prevent
and taPe thoroughlY'
o.
o.
In general, sPeed of DG motors
the fied-or by varying the voltage in
a rheostat cont'rected in series with
86
o. what ls meant by overload and no-load protectlon of a Dc motor?
Overload protection means that the cunent ls autonatically shut off if the load
becomes greater that which the motor ls built.No-load protec.tion means that if the load falls off, the current is shut off to
prevent the moto( from running away and damaging iiself.
O. Suppose your motor falled to start, explaln the sequence to correct the trouble.
1. Look for broken leads to the motor, for the connection may be hooked up wrong.
2, Field may ber weak.3. Motor maYbe too overloaded4. There maybe, excessive friction in the bearings.
Q. What four thlngs determlne ths amount of Induced volts and amperes?
1 . The strength of field2. Number of conductors3. Speed of conductors through the field4. Angle of conductor have to the field
O. What care and malntenance would you glve a lead acld battery?
1 . Avoid high rates of dischargeZ. Never discharge a. bettery to a specific gravity less than 1 ,1503. Never allow a battery idltl in discharge condition4. Use distil led water5. Never add acid to electrolYte6. Avoid charging cell rapidly at high rate7 . While charging never e>lceed temperature of 1 100F
0. Descrlbe an alkallne type storage battery?
One of the type of storage battery usually consist of nickel plates, caustic soda,water electrolyte and rubber case. lt has a longer life but a lower voltage and cannotstand nigh current discharge rate.
O. Descrlbe a lead acld storage battery?A type of storage battery where positive plates are lead peroxide, negative plate
are pure lead. Thetelectrolyte are mixture of sulfuric and water and active material
are porous and have aOsorptive qualities similar to a sponge. The pores are fi l led with
elecirolyte as the battery discharge acicJ contact, form chemica combination change into
lead sulfate. Thus result specillc gr.avity cJecreases when fully charge material of positive
plates gain lead and negative plate pure l:ad"
a. what causes short clrcult In storage batterles and how are they detected?
Causes - by faulg separators, lead particles and metallic particles, forming contact
between positive anO hegative plates, buckling of plates, excessive sediment, crack in
partition, and use of imPure water'Short are detected by overheatrng, voltage drop, and low specific gravity of electrolyte.
Cl" What are the tlve reasons why a lead acld battery wlll not develop lts rated
capacltY?1 . Contirruous discharging at high rates2. Longer age of service time3. Sultation will form lead sulfate
87
- ' 'r-- ddilIIIj
4. lnternal short circuit caused by impurit ies in electrolytes
5. Mechanical faults cause by poor connection' crack and buicked
o. what general care does a storage battery in operation required?
coverl the Plates.
plates.
1 . KeeP cool and well venti lated
2 ' M a i n t a i n p , o p " ' | e v e | o f e | e c t r o | y t e a t | e a s t l 1 2 i n c h3. Mainta in proper speci f ic grav i ty of e lect ro ly te
4. KeeP terminals c lean '
TROUBLE SHOOTING OF ELECTRICAL COMPONENTS
0. What are the causes for electr ical equipment ts breakdown?
1. Heat -. increases the resistance of the circuit thus increases the ourrent which
cause the material to expand, clryout, cracl<, and wear down rnuch quicker
a n d S o o n e r o r | a t e r t h e d e v i c e w i | | b r e a l < d o w n .z. Motsture - cause also circuit to draw more current and eventually ore{09y1'
Moisture l i l te water and l iquids cause expansion, warping and abriormal current
flow or short circuit'
3. Dlr t and other contamlnants - such as fumes, vapors, grease' oi ls etc that
cause electrical devlcs to crog o, lunl up and operate abnormalty unti l break-
down.4. Vlbration - and physical abuse can cause also these types of breakdown'
5" poor Instal lat ion - which of ten work of unqual i f ied personl le l who is careless
o r i n a h u r r y c a n c a u s e a l s o b r e a k d o w n S o o n . I
O. What are the effects of breakdown causes and their characterlstlcs?
a. open clrcult - is the result of an incomplete circuit, wl-rich preveirts the current
from flowing in a complete path. lt has a infinite resistance reading. ?,:d l?'ocurrent sincb its path has been broken when checking to instrulnent l ike mul-
t imeter.
b. Short circuit - often result when the current takes a direct path across its
source. lt draws more current because the resistance in the circuit decreases
and as a result the voltage decreases" Typical signs of short circuits are:
blown f uses, increased heat, low voltage, -high
amperage and smok'e'
c. Grounded clrcui t - resul t of a defect in the insulat ion br placement of a
wire or equipment component causes the current to take an incorrect or abnormal
route in the circuit. l t result also when part of the windings make electrical
contact in the frame of the motor or other equipment body. when grounded
in a circuit i t shows the following signs. Abnormal amperage, voltage and
resistance readings, shock'
d. Mechanical breakclown are clften result c,f too much friction, wear or
vibration which moving parts l ike broken belts, worn contactss wot'|1 bearing'
loose belts damage 6lectrical controls are some examples of mechanical
problems,which you can determine by means of noise, abnormal, c i rcui t fa i lure
and visual inspect ion dur ing operat ions through our senses'
88
III]
I1IIIII
II
I
II
I
I
Sourc e Open w i re
MOTOR GOODC I R C U I T
OPEN MOTOR
GROUNDED MOTORSHOR TED I'4OTOR
e. What are the baslc methods In t roubleshoot lng an electr lcal or electronlc
devlces?
1. Vo l tage measurement - o f a c i rcu i t i s usua l ly taken by us ing a vo l tmeter ,which zero vol tage reading indicate an open circui t , whi le a low-vol tage readingmay indicate a shorted component. Remernber, always connect a vol tmeterin paral le l wi th the circui t wlren measuring vol tage'
Z. Amperage measurement - of a c ircui t is usual ly taken by an ammeter ora "clam on" ammeter which indicate and lccates common circui t faul ts, suchas short , open and grounds. Always romember, connect the ammeter in ser ieswi th the c i rcu i t when measur ing cur rent .
g. Reslstan"a trrasurement
-- an ohmeter is used to n easure the cont inui tyresistance of a c ircui t or a component" l t is used for locat ing shorts, grounds,
and open circui ts" Remember, always shut of f the power before measuringresistance.
4. Subst l tut ion - is a technique of replar: ing a suspected faul ty compolrents with
a good spare component ro save t ime and effort in locat ing faul ts.
S. Br ldglng - when electr ic ian suspects a component l ike a capaci tor, to be faul ty,
he "jumps" or places a known good component across suspected faulty componentfronr the circui t , tnus save t ime by br idging.
6. Heat ._ by means of applying hr:at , to a suspected therrnal intermit tent com-ponent wi l l break and most ly using hot blower as device in order not to damage
component especial ly plast ic type,
I
B9
7g.x1,ff :?:$il1ffi :lliii{iJT.lt,f :3:?ft ilTnLIifl i3;lfil'l"l"il3'lievery 'o*Po*nts in' a circuit'
Note: one approach lilr^"ubroshooting is: define.the- probrem investigate the
B:t;;1.!"irjrT;"ilt'rffi id1;!;i*:t.;:!jilft yff 'll:'l';q:?'$iil:when, what, which ano *r,ere. n.*unilLl,lirp ov ,trp'pil"ro*" ls important
when approaching " prourl'm, wiilr t.,e'-aio'oilr*i*-i"g'"ms
available' see
f igure below'
*
htt,
Always connect a voltmeter
;;;;i.l with the circuit'
AlwaYs connect the ammeter in
series circuit'
AtwaYs turn off the Powel.li tl'
fii.uit before measuring the re-
sistatrce-
90
It
IhIlIllrIIrI
ofrN *flrcH CtOSfO Snrrcr/
KIq+J-OP?n .C,arrlinuituNo turirui\ i;Oh;;.
Nr.$
Nobttinuity
Continutg
Checking a switch for continuityusing an ohmmeter
Checking a fuse lor continuityusing an ohmmeter
r F'^._- __,_I Reversing the rgtation of a three_ptraset indudion motorby switching the c,uterf two leads wlir i le dc motor simplyt reverse the polarity either the fieldI or brushes.
-{-{-a
-{-a
9 1
TROUBLESHOOTING AND REPATR OF DC MOTORS
The symptoms encountered In defectlve dc motors are given below'
1 . lf the motor fails to run when the switch is tumed on, the trouble may be
open fuse or protective device d. opan field circuit g. Worn bearingsa.b. Dirty or clogged brushes
Open armature circuit f. Shorted armature j. Defective controller
v . v r v . . . . v r Y v t ' r
e. Shorted or grounded field h. Groundedbrushholder
2. lf the motor runs stowly, the trouble may be
a" shorted amtature or commutator c. open armature coils e' overload
b" worn bearings d. Brushes set off-neutral f. wrong voltage
3. lf the motor runs faster than nameplate speed, tho trouble may be
a. open shunt-field circuit c' shorted or groun*1ed field
b. series motor running without a load d. Differential connec;tion in a compound motor
4. lf the motor sparks, the trouble may beShorted or grounded field i' Open field circuit
Revorsed aimature leads i' High or lolv bars
Wrong lead swing; X" lfiqn .mica , -._-Brusries set off-n-eutral l. unbalanced armature
a"b"c.d .
Poor brush contactDirty commutatorOpen circuit in the armatureWrong interPole PolaritY
e.f.g .h .
5 " | f t h e m o t o r i s n o i s y i n o p e r a t i o n , t h e t r o u b | e m a y b ea. wom bearings b. High or row bars c. Rougtr commutatar d. unbaranced armature
6. lf the motor runs hot, the trouble may be
a" overroad b. sparking c. Tight bearings d" shortecJ coils e. Too rnuch brush pressure
The typlcal troubles occur In manual DC Controller are:
1. rf the motor does not start when trre handre is moved several points, the trouble may be:
a.b.
c.d"e.f.g .h .
2. lfa.b.c.
Open fuse, breaker, or relaY'Open resislance unit: test by placing apointt; the lamp should light: if not' the
Foot contact betvyeen tlre arm and the
Wrong connection starter'Broken wires may cause open circuits
Low voltage or excessive load'
11S-volt test lamp across adiacent contact
resistance between the two polrnts is open'
contact Points; arcing may occur'
in the armature or field circuits'
3.
Loose or dirty terminal connections'h?"n"il ;:H,j|',Jlil1:'i;;;",nt box: this win oause an open neld circuit'
, L - ,
,^;;;';;;";-il;;" it is brousht to the last point, the troublel mav be:^- r^aic ^" r1rrnr cnntaetS-
^rffi"ffi,lg""il"or"-ro ourn-out, broken leads, or poor contacts'- ) l A f r a a a n n n n a n t i n n
Low voltageShorted coil
d. Wrong connection'e. Overload contacts open
| f t h e f u s e b | o w s w h e n t h e h a n d | e i s m o v e d u p , t h e t r o u b l e m a y b e :;. Grounded resistance units' contacts or wires'
b. Handle brought uP too quicklY'
;: open shunt-iield circuit on starting box;
d. Resistance shorted out'
lf the starting box overheats, the trouble may be:
Overload motor.Handle brought uP too slowlY'Shorted resistance units or contacts'
4.a.b.c .
92
Ihl-t-ll-IIIIIItIIIIIIrr
Procedure lor us ing mul t lmeters:
1. Zero Correction of Indicator
place, l tE pointer on, ,0, ,on the lef t hand s ide of scale by turn ing the zero
corrector.
Red lead ptug into posi t ive (+) jack
Black lead plug into negat ive (-) jack connect ion.
Se lec t ion o f Funct ion and nange. Note : Put your se lec t ion f i rs t on h igh range '
2"
3 .
a) DC vol t (DCV)c .1 v )0.s )2 . 5 v )1 0 v )5 0 v )2 5 0 V )1000 v )AC vo l t (AVC)b)
d )
1 0 v5 0 v250 V1 0 0 0 v
DC current50u A2 .5 mA25 rnA0 .25 A
Resistan0eX 1x 1 0X 1 KX. 10 K
(DCA)
FiOures show maximum vol t reading for that range"
f igures show maximum vo l t read ing for that range.
f ioures show maximum cur rent read ing for that range '
ind icates mul t ip l ica t ion o f read ing for that range.
4 . Measurement
Forr vo l tage and cur rent measurement , care must be taken to ensure that the
range ,* l t . r , is f i rst of err l set to the highest range. l t is then to be switch
down to lower ranges unr i l opt imum def lec t ion is obta ined.
a) Ammeter
1. Current must f low t l r rough ammeter '
93
Note:
The murti_meter must never be connected in the current ranges to a voltage
source that can suppry "
righ., ,urrgntitiun atto*aole maxi-muml lf current
range is connected ro, e*irnple, oireciri io izo V mains' the' apparatus
woutd be immediately ili;&'Ji. rn" operator would be in extreme
danger.
to rneasure ernf across 2 points in a circuit. simply
".t"tt tho voltage to be measured'
c) Resistance an O Q adiustment
l . R e s i s t a n c e m e a s u r e n t e n t i s p o w e r e d . b y i n t e r n " a l . b a t t e r i e s . F o rcorrect reading of resistan.r, tti, sensltiv:rty of the indicator must beladiusted
according to in" voltago supplied by batteries'
To measure reslstance the power supply to the circuit must be 'switched
off tirst betore apprying tnu *uitimeter. rr,'lrir zerc adiustment with multimeter
Probes shorted'
2 . T h e r a n g e s e l e c t o r i s p l a c e d a t t h e r a n g e b e i n g . u s e d ' W i t h t h e + a n o-com terminal shorted together: tl9 pointei moving towards O O is adiusted
by turning o o ADJ to in, right or tett in orr,er to prace it exactly on
o o of th-e scare right. The pointer must be adiusted each time the range
*
ntt
B) Voltmeter
A voltmeter is used
Prod the voltmeter
is moved.
o17' /i'\fr=: @
L*-'
< ?
MULTIMETER
94
trhtI
tLI
Ll.
L
LLt
Enumerate some test equlpments and used In troubleshootlng electr lcal clrcultand cbmponents. I '
1. Dlgltal.mult lmeter - usual ly used for electronic technician who need extremeaccuracy in work and digital equipment testing and servicing. lt measure correctvalue of voltage, resistance and current.
2. Oscllloscope - used for measuring a visible display of waveform, peak topeak voltage, frequency, time periods, phase angles and frequency response.
3. Tube tester - is a fairlv accurate way of testing electron tubes.
4. Translstor tester - used to check in accurate such as diodes and transistorswith their perforfflance, and also rneasure transistor leakage, collector leads,base and identi fy emitter.
5. Capacltor tester - check the qual;ty of the capacitor but also determine thevalue of unknown capacitor. lt also identify power factor values, leakage, open"Remember remove to the circuit to check the correct value and don't touchthe terminal of capacitor tester whe' l the voltage is turned up. Severe shockcan result.
6. Frequency counters - are used to measure the frequency in hgrtz of anelectronic cor,rponents. Usually used to adjust the frequency of radio receiversandr transmitters"
Megohmmeter - is atr insulat ion-resistance meter, used to check the electr icalresistance of an insulator by indicating the resistance on a scale as i t suppliesa voltage. l t is a self-contained hand operated generator. or power supplysource.
Voltage testers - commonly used by electr icians in measuring ac voltage.These te.sters are portable, easy to use.
Growler consist of two l<inds: internal and external, are used to testarmatures and stators of electr ic motors, generators and other equipment.
10. Test lamp - is a s irnple test device used to check cont inui ty of a c ircui t orcomponent rrrhich easi ly shows i l luminance of the bulbs.
Clam-on ammeter - used to measure the current on a circui t , conductorwithout interrupt ing the circui t"
Neon vol tage tester - is used to check the presence of vol tage in a circui twh icn o f ten used in t rouh leshoot ing housewi r ing"
95
7 .
B .
9 .
1 1 .
12,
ELECTRICAL SAFETY
Erectricity can be dang^erous and even fatal to those who do not underdtand and
Rr$L:il:i":,IBf, j::T.i'-'n'iirli*::##l jilm:'lir*:ulK'1ll':g?rlt-tH, ;;;i;"ot
-P"'o nar s AF ErY
current that does the damage. gurr-ults above 100 milliamperes or only onq tenth
of an ampere are fatar. n *"iri""" who rr".io"t"cted"';;;;tt above 200 milliarnperes
may rive to ,"i "notner
dav'iru;;; iigio.trr"tnirnt. c"rrrir below 100 milliamperes
can be serius and painfur. n J"t. rule: oo-nnt place yourself in a position to get any
kind ol a shock
N l n e r u l e s l o r s a | e p r a c t l c e a n d t o a v o l d e l e c t r l c s h o c k s :
l . B e s u r e o t t h e c o n d i t i o n s o t t h e e q u i p m e n t a l | t h e d a n g e r s . p r e s e r r t B E F o R Eworking on a prece or equipmgnt.' Many rponrrln "tr
killed by supposedly
rrnloaded guns; ,"ny tochnicia;; ;;; [*rdo uv *pJtsed "dead" circuits'
z. NEVER rery on safety device.s such as fuses, rerays and interlock systems
to protect you. ir,ry may not be working unJ'mayiair to protect when most
needed '
3 'NEVERremove theg rou td ]ngp rong ' ] - 1 . I : , ew i re i npu tp lug .Th i se l im ina testhe grounding trrtr* of the Jqriphent matiing ', "'potent'lal
shock hazard'
4 ' D o N o T w o R t ( o N A C L U T T E R E D B E N C H . A d i s o r g a n i z e d m e s q o f c o n .necting reads, conrponents 3;
toors onty ieaor to caieress thinking' short
circuits, shocks and accidents. oevetop i;i;;t systemized and organized
procedures of work' -. -^A.,, \./arr ' ;tance to ground is
5 ' D o N o T w o A r o N w E T F L o o R S . Y o u r c o n t a c t r e S | Ssubstantiarry reou..o. work on a rubber mat or an insulated floor'
6 . D o N , T w o R K A L o N E . l t , s i u s t g o o g : 9 T ' t o h a v e S o m e o n e a r o u n d t o s h u tofi the power, to give artiticiai rispiration and to call a doctor"
7. woRK wrTH oNE HAND BEHTND You oR oN YouR PocKET' A current
between two members .rorrJ, vo* heart ;;;;; be lethal' A wise technician
;l*;tt works with one hand"
B" NE'ER TALK To ANyoNE wHrLE woRKrNG. Don't ret yourserf be dis-
tracted. Also, don,t you-talk tl '"nvone, if he ir *.*rg on danger'us equipmetrt'
Don't be tha cause of an accident'
9 ' A L W A Y S M o v E S L o w L Y w h e n w o r k i n g ? . . o Y r y - ' ] : . I . ' u l c i r c u i t s . V i o | e n tand rapid movements read io'"r.iornt"ishocks and short circuits'
Burns
Accidents caused by burns,,a\l:rgn usua'y not iatar, can be painfully serious' The
d i s s i p at:r oir-o i " r u ttt i car u n e tgy p rod u ce s h e at'
*
$++LlU'd
JJ
J
96
I
Four rules for safe pract ice and to avoid burns:
1' Fesistors get veryhof, especially those that carry high currents. Watch those five andten watt resistors. They wi l l burn the skin of f your f i igers. Stay away from them unt i lthey cool of f , .
2' Be on guard'for all capacitors which may stitt retain a charge. Not only can you get adangerous and sometimes fatal shock, you may i l lso get a burn from an electr icaldischarge. f f the rated voltage of electrolytic capacitors i i exceeded or their polarit iesreversed they may get very hot and may actually burst.
3' Watch tha.t.h2t.soldering iron orgun.Don't place it on the bench where your arm mightaccidental ly hi t i t . Never store i t away whi le st i l l hot. Some innocent unsuspect ingstudent may ip ick i t up.
4. HOT SOt-DER can be particularly uncomfortable in contact wit\ ,,our skin" Wait forsoldered joints to cool . VVhen de'-solder ing jo ints, don' t shake l rct solder of f so that youor your ne ig l , ibour might get h i t in the eyes or on h is c lo thes or body"
I
I
,l
2
2
6
7
6
TERMINAL BOX
LOCKNUT & WASiHER
FAN BoSS I
F A N
COVER FOR COOLING FAN
END BRACKET
ROTOR CHAMPER
ROTOR CORE
STATOR CORE i
CP ST IRON 10
MILD STEEL ] 1
CAST IRON 12
M I L D S T E E L 1 3
MILD STEEL r 4
CAST tnoN ,5
CASf IRON i r l
S, ILICON STEEL ) ]
S IL ICON STEEL 1B
SECTIONAL D IAGRAM
PART LIST AND
OF INDUCTION MOTOR
MATERIALSFRAME
STATOR CRAMPER
I]OTOR 8AR
END RING
STAI 'OR COIL
END DNACKET
BEARING COVER
BALL BEARING
SI-IAFT
CAST IRON
MILD STEEL
COPPER
COPPER
INSULATION WIRE
CAST IRON
CAST IRON
CARBON CHROtvilUMBEARING STEEL
CARBON FQRGED
97
DisassemblY and AssemblY
o " 1:l;"::: ii u n, n' rar proced u res 1i1 i ::T ifiil"^i"'T,?:'"ssembrv an d
assombry of *otoi. rie sure tJ reao them tnoroughrv before stariing the
1 3'::T,?*?,ili'f::l?ilo', bv ?l:,l^u"31i'^:':",'J',t"'il','ffi'',1'.i:t,;;1:;1 J:cause fatal damage to tfre machine. Hence, r* io it that the job is carried
out bY two or more PeoPle '
z. Keep the place of disassembry in good order and well arranged to preverlt
mixing up of other;;rt, and to i,riirou" the work efficiency' I
3. cover the disassembred parts, particurarry the important rotating parts such
as bearing, etc., with vinyt or jotlr to protect from dust,
4. Betore puil ing out'o, ' inserting the rotor from or into the stator' f i t their shaft
centers so that the two may not corne in contact. Take particular care not
to scratch the Stator wincting coil, rotor bar, shortcincuit r ing, core, etc.
5. Lay the rotor on u stand, and be sure to cover with vinyr or cloth, and wrap
t h e b e a r i n g p " , " t o t s h a t t w i t h c | o t h f o r s t o r a g e .6. when separating ir,. fan and fan boss, be sure to put f i tt ing marks' and use
u, g:;,k*.Xl'.1'I,:di T."i;8TlY,;' carerurtv to set the outrine or the
const ruct ionbeforestar t ingdisassemb|y,DisasseHjl.",
ail externar cabres connected to the motor'
? ffilil: lH ffi:t;'.',|JlLn ,n, motor with auxiriary machine stand
4, Suspend the whole motor unit, and carry to the place of disassemb|y'
5 . l n t h e c a s e o f v e r t i c a l t y p e m o t o r , | a y t h e m o t o r d o r v n h o r i z o n t a l l y .6. Pul l out the couPl i r tg '
7. ln the case of motor with open type bearing, remove the grease nipple and
B hd;ili il:f:F,#'[':xf iil3':x^:Ti:?li*H'i{,'::}:':H: ilig " R e m o v e t h e b e a r i n g c o v e , , o n b o t h t h e c o u p | i i g : 1 1 : : i . t h e o p p o s i t e s i d e .
(Motor witr smatt Japacity may not have these covers')
10" Remove the end brackets on the coupring side and the opposite side' when
these bracKets are removod, ,'n, ,pigbt iJini detachecj and, at the same time'
the rotor drops down to the rrulr bqrivaleni to the air gap' causing the rotor
and stator to collide viotentty, and this may gumust-ry::^;t and winding coils'
Hence, support both ends "tin,
,t "tt
*itn a *ane or iack, or with rrar'd (in
case ot motor with smail .up'".iii _oetor.e l-ryoyr1o lhe qtd-brackets'
1 1 ' Pull out the rotor trom the stator'
Assemb'::ffT:::y.:rbry norm",y^,LI:, :u,",."e
order of disassembrv- Before
reassembly, thoroughry *ipe ort the dust oir-rt.., from the disassembly parts'
2 . D o n o t f o r g e t t o r e p l e n i s h g r e a s e a f t e r i n s t a | l i n g t h e b e a r $ g .
IJ
98
3. Remove the protectors ' ,n r I section before installing the parts, andafter carrying out corre of direct coupling, make connection ofelectric circuits. This ends tne , -*.3S€rTlblt^
Troubleshootlng
Cause
Disconnection or shortcuircuitof winding coi l and lead wire
Slackening of connecting term-inals, etc.
Disconnection or nrisconnectionof starter
Inadequacy cr unbalanceof supply voltage
Single-phase operation
Excessive over- load
lnadequate supply vol tage
I
I
Trouble
Fails to start.
The rotation againstspecified rpm is abnormal
Motor getsexcessively heated
Variation in power
Excessive sl ipping
frequency
Inadequacy or unbalance ofsupply vol tage
Excessive over-load
Shortc ircui t between phases
Defect ive vent i lat ion
Countermeasure
Rewind or repair
Carry out additionalt ightening of theslackened portions.
Repair the disconectedpart or make changeaccording to the connect ion diagramMeasure terminal vol tage and adjust it tothe specif ied voltagel f the motor snar ls,after the power isturned on, but fa i ls torotate, check for dis-connect ion and repair .
Check the auxi l iarymachinery side "Measure the terminaland adjust to thenorrnal vol tage
Measure the frequencyand adjust to thenormal f requencyCheck the rotor bar forbreakage on check thejoint of shortc ircui t r ing.Measure the terminalvol tage, and adjust tothe normal vo l tage.Check the auxi l iaryrnachinery side.
Rewind
Remove lhe obstruc-t ion pre !ent ing thevent i la t ion, and c lean
99
Three-Phase lnductlon Motor
The 3-phase, cage-rotor, induction motor is the most commonly usedlotot onboard
,,hips rt i, popurarbeca:,' iiJ' 'i*Pl"r;;dt ?"-1 In"i::i;i:g'-:H',3i!:'.x:l ^l
is also readily controlled by
"'tir*
reliable direct-on-ttnt
sources available "
Constructlon
The induction motor.ha: t*o main components, the,stator and thelo^tot' Thel stator
:? ril:',[# f,rxil,! r,t i:,#]$.'1r,l[:$lr'll.ffi rn: r Li i'il; J?ffll :to the incoming 3-phase--ffiit.r"b]?r-^;;;
stator *inoings "'*.,*o:nd for specitic
numbers of pole-pairs ano -i"n
ou .onnttt"t in either ttut or delta connection'
,u*,1"'i:?JJ:':J'J3[ilFHq]:i"hlttiffilft,:H"ii1ly#;##tin the airgap]titttoy,minimizing
the rtpp
opun ;: il, " ,.. l;se nduclti jl?'T ffi ffT:,;,['lJ:lJJl ;f..'iillil6[*;'n
The conor.il,, consisting,;i;ilput ot aluminum bars trl'.'"in'r"*i1*utt shortrcircuited
:i:ilf :ffiff y;J r # fr J i Tfr : il t1;I i i :l ; w :, Jffi "'1'
? * ;' ; s'* i : M s u nthe rotor and irre stator i, Ji*or* ano mal; ;; small u' 'i it *tghtlltully possiPlu Inu
reriability ot irre induction ;;i;;'.0*., t,.oio ["uing this'ry;; oi ti*prt' tougtr rotor which
hasno insu ia t ionandoouJ .no i t rouo te ; ; ,b ruches , : - ' , . i . ' -%
#'t'l##
if
HtrtHTJJI
6 a 7 5 / S o 5
i g " 8 o a 6 b
100
STAR.DELTASTARTERDIAG'''tAM
operatlon of star'Delta Motor starter control clrcult-schc mailc DlagramCircuit breakerr 52 is closed.when BS 1 start.push button is pressed reray coil 6 is energised.Contact 6a closes and 6b opens.Main contact 6 0n motor suppry rine arso croses.Timer deray coir 1g anrd main contactor coir gg get energised.Main contactor 88 on the motor supply circuit closes and motor runs starconnected.Auxiliary contact gga afso closes.
,!tj3[*?us contact of timer retav 1e a closes. lt is a hotding contact when BSI
l:::: predeterrmined tirne delay of 25160 sec., detay contact 19b opens and 19a
Relay coif 6 gets energised and its contact d.2 tb opens and contacts 42a closes.The main contacto r 42 on the moto,. suppry rine ctoses.Motor is now nunning delta_connected.with 42b open' timer delay coil 19 gets de-energised and ail its contacts returnto its original position.
contact 42a now functions as a hording contact.indicating lamp L is now on.To stop the motor press BS2.
Comparlson of star delta anddlrect-q.n-ilne starilng methods: Advantages:
Dlrect On Llne Star Delta1. starter at fu l l phase vol tage.2. starting current 6 to B times full load
current.
3. start ing torque about r .5 t imes ful lload torque.
4. motor can be started on full load ifrequ ired.
5. high acceleration torque so has lowstarting time.r
starter at reduced phase voltage V3.start ing current Z to 2.5 t imes ful l loadcurrent.
start ing torque less than hal f fu l l loadtorque.
n' lotor can be started only on no load orl igh t load.
low acceleration torque so has long start_ing t ime.
1 0 1
Goumo'r TnouBLEs AhrD Repruns Tnnee Pnnse Morons
The symptoms encountered rn defectlve three-phase motors are giu"n below'
under each symptom are *sted the po"*rit" troutlres and remedles'
l . l t a t h r e e . p h a s e m o t o r i a r | s t o s t a r t , t n e t r o u b l e m a y b ea. Burrred-out fuse (1)' i ' Open rotor trars (6)'
b. worn bearingi (2). g ilrong internal connections i(8)'
c. Overtoad (3). t'
ii. Frozen bearing (9)' l
d . o p e n p h a s e ( 4 ) . i . D e f e c t i v e c o n t r o l | e r ( 1 0 ) .e . S h o r t e d c o i | o r g r o u p ( 5 ) . i . G r o u n d e d w i n d i n g ( 1 1 ) .
2 , l f a t h r e e . p h a s e m o t o r c | o e s n o t r u n p r o n e ! , ' | u . . ' o u b | e m a y b e :a. Burned-out fuse (1). I. open parallel connections (13)'
b. worn bearings (2). g' Giouncled winding (11)'
c. Shorted coil (5)' '
[' open rotor bars (6)'
d . R e v e r s e d p h a s e ( 1 2 ) ' i ' l n c o r r e c t v o l t a g e ( 7 ) 'e. OPen Phase (4)'
nray be:d. Overload (3)
e 'Wrongconnect ion( reversed]phase)(12) .f. L.oose rotor bars (6)
4. rf the motor become$ excessively hot, the trouble may be
a" overroad (3)
\vvvvr I v'r. -
.' d. Motor running on single phase (4)
b . W o r n b e a r i n g s ( 2 ) o r t i g h t b e a r i n g ( 9 ) . e . L o o s e r o t o r b a r s ( 6 )c. Shorted ccil or group (5)
1" Burned-out Fuse. Remove fuses and test with test lamp, if the larnp lights' the
fuse is good. A burned-out fuse is indicated when the test lamp does not light'
To test fuses without removing them tior the horder, a vortr:neter must be used'
rf a test right designed for 23d vofts is mistakenly used on 460 volt$' it will blow
out and may trigger a severe erectricar exprosion. lf the fuse is open' there will
be a line voltage read across it'
z. worn Bearrngs. rf a bearing is worn, the rotor wirr ride on the stator and cause
noisy operation. when the b-earings "r"
,o worn that the rotor restsl firmly on the
core of the stator, rotation i, irporlibi;. To chect< asmat motor for"this condition'
try moving the shaft up "nJoown.
Motion in this manner indicates a worn bearing'
Remove and inspect the rotor for smooth, worn spots. These indicate that the
rotor has been rubbing on the stator. The or,ry remedy is to replacei the bearings'
3. oVerroad. To determine whether a three-phase mctor is'overroaded, remove the
bert or road from the motoi,and turn-ine-shaft of trre load by hand a broken part
or dirty mechanir* *iiilrevent the shaft from *ouing freely. Another method is
to use an ammeter on ""irn
rine wire" A higher current rJadingihan on the nameplate
aY indicate an overload'
3" lf the motor runs slowly' the trouole
a" Shorted coil or grouP (5)
b. Reversed coils or groups (u)
c. Worn bearings (2)
4' open Phase' lf an open occurs whife the motor is running, it will continue to runbut will have less power. An open circuit may occur in a coil or group connectionlThe motor will continue to run if a phase opens while the mot6r is in operationbut will not start if at a standstill. Ti're conditions are similar to those of a blownfuse. .
5. Shorted Coll of Group.. ShortedAfter locating such defective coilsshould then be rewound.
coils wil l catrse noisy operation and also smoke.by means of the eye or balance test, the motor
6.
when the insulation on the wire fails, the individual turns become shorted and causethe coil to ibecolne extremely hot and burn out. other coils may then burn out,with the result that an entire group or phase will becorne defective.
open Rotor bars' open rotor bars will cause a motor to lose power. one signof open bars is when a motor is conne.tg.d to the right voftage at no load, it hasa very low' amp reading. A light load will prrll oowri the speed, and at full loadthe motor wirr run berow the nameprate speed"
lncorrect voltage' some T-ft'anre motors are designed for a definite voltage" Thusa motor designed for' 208 volts wifl overheat when operated on 250 volts, and amotor designed for 250 volts will not have enough power if operated on 20g volts.ff the motor is rate 208-220-440 volts on the nlmeplat", it will operate well on arange of voltages.
wrong Internal connectio rs. A good method of determining whether or not apolyphase motor is connected properly is to remove the .rotor and place a largeball bearing in the stator. The switch isin"n .roiilrrpprl, current to ne winding.ff the internal connections are correct, the ball bearing will rotate arr.rund the coreof the stator, if the connections are incorrect, the bail dearing witt remain stationary.Froz:en Beartng' lf oil is not supplied to the part of the shaft that rotates in thebearing' the shaft will become so hot that it will expand sufficiently to preventmovement in the bearing. This is caffed a frozen br.,aring.
fl""T],f e_?,ir{:,,,i:rJjj:. contaos on the controner do not make good contact,
Grounded wlndlng' This will produce a shock when the motor is touched. lfthe winding is grounded in more than one plac€, o short circuit wil l occr-,r whichwil l burn out the winding and perhaps btow a fuse. Test for a grounded windingwith test lamp and repair by rewinding or by replacing the defective coil.Reversed Phase' This wil! cause a motor to run more slowly than the rated speedand produce arr electrical hum indicative of wrong connlctions. check the con-nections and reconnect them according to pran.
open Pardltet connectlon- l'his fault will produce a noisy hum and will preventthe motor firom pulling full loacJ. check for complete parallel circuits.
7.
8.
9.
10.
1 1 .
12.
13 .
1 0 3
TnouBLESHooTlNG AND Reprun AC Conrnolrcns
Assumed that the motor and fuse are in good condition. To make certain that
the motor is not at fault, connect a voltmeter at the motor terrninals and determine whether
voltage is available when the contacts of the controller are closed. lf theie is no voltage,
the trouble probably lies in the controller, ltke push button switch starters, drum, wye-
delta, braking controllers.
Because there are many different kinds ancl makes of corrtrcllersr a general pro-
cedure for locating the source of trouble is given.
1. lf the motor does not start when the main ccntacts close, lhe trouble may be
Open overload heater coil or poor connection'Main contacts not making t!'re contacts become dirty, gritty or burned'
Broken, loose, or dif i terminal connection'Loose or broken pigtail ccnnection'Open resistance units or open autotransformer'Obstruction on the magnet core, preventing the contacts from closing.
Mechanical trouble, suCh as mechanical interlocks, gummy pivots, and poor
spring tension.
Z. lf the contacts do not close lvhen the START button is pressed, the trouble maybe
a.b.c .d .e.f.g ,
a. Open holding coil fflris can be testedcoil terminals when the START buttonthe START button is Pressed, but thecoil is defectil'e.)
b. Dirty sTART-button contacts or poor contact. f.
c. Open or dirty STOP-button contacts. g'
d. Loosb or open terminal connections. h'
e. Open overload'relaY contacts.
3. lf the contacts open when the START button is releaseo, the trouble may be
a. Maintaining contacts that do not close completely or are dirty, pitted, or loose.
b. Wrong connection of station to the controltier.
4. lf a fuse blows when the STAR'I button is pressed, the trouble may be
a. Grounded contacts. b. Shorted coil. c. Shorted contacts.
5. lf the magnet is noisy in operation, the trouble may be:
a. Broken shaded pole causing chatteringb. Dirty core face
6. lf the magnet coil is burned or shorted, the trouble may be:
a. Overvoltage.b. Excessive current due to a large magnetic gap caused by dirt, grit, or mechanical
trouble.c. Too-frequent oPeration. t
by connecting a voltmeter across theis pressed. lf there is voltage whencoil does not becorne energized, the
Low ,voltage.Shorted coil.Mechanical trouble.
1 0 4
PROGEDURE OF SAFETY Or^--_{.TfONS
SINGLE GENERATOR RUNNTNG
Before starting the engin€.for driving the required generator, confirm that the circuitbreakers for loads, ,air circuit breaku,', 61.., are "oFF;. Then start the engine.By virtue of thq under-voltage tripping device (uvc), the air circuit breaker (AcB)has been put to itsi OPEN (tripped) , iate.As the engine rspeed risr:.s,RUN pilot lamp ,,GL" (green) wil l l ight. Then, adjust the voltage to the rated onthe voltmeter by means of the voltmeter-transfer.*,rcn rVS) and the frequence to therated value by means of the frequency nreter transfer switch (FMS). The rated valuesare indicated by red marks on the corresponding meters.After the rated frequency3nd voltage have been reached, ctose the aircircuit breaker(AcB), and the pi lot lamp ' i61"
lgreei l wit t l ight. Then, closs the objective MCB tofeed power
when the ACB'is closed, i t the hreaker (McB) of the feeder circuit is closed, thegenerator will immediately be loaded. This instant, a small voltage oiop will be found.However' there wil l occur a quick voltage recovery. so, there is no need to worry abouti t .
STOPPING OF GENERATOR
In order to stop the generator in operat ion, f i rst unload i t and then push the ACBoPEN push button switch, for manual opening. Thereafter, stop the engine, in doingso' i t the ACB should be opened whi le the generator is loaded, there would occur suchadverse effects as an instarrtaneous rise i; the engine speed. so, it is advisable tolessen the load to a lowervalue ( the lower the bettef before tr ipping the ACB, becausethe engine, the generator and tt 're ACB wil l then be less affected lnd wil l be capableof stable operat ion for a long t ime.
PARALLEL RUNNING
start the second generator by foi lowing the same procedure as for start ing the f i rstgenerator ' After conf i rmat ion of the vol tage of the second generator, al ign the vol tagesof both generatol t by means of the vol tmeier t ransfer switch (vs). s imultaneously matchthe frequencies by means of the frequency transfer switclr (F'NIS). once i lre voltageand frequency_ 3!
toln generators are identical, change over the synchroscope (Sys)to the second generator and check the synchronous stJte by means of the synchroscope(SY) .
ln accordance vyi th the l ight ing and going of f of the synchronizing lamp the pointerneedle wi l l revolve. See the direcrt ion of the revolut ion, and i f i t is reuol i r ing to the , ,FAST,,s ide, inch the governor swi tch (GS) o f the second generator to the, ,LOWER,,s ide. l fthe opposi te - is t rue, then inch i t to the "RAlsE" sic je.
1 0 5
,he,:,.ffi 3l'.i'J:'!$ilil,}fi1 iliHi:i:i?ili$ili .Tl ?:'$" JiH'? #l''f,i
Hsft ,,?::ixr,,.*,,':in?udllj.;py#rui*l"iT*iffi fr iTi'I:':J;is not maintainJJ, ,il,re th3 J',-, ,ir.,,ii nr."lr'i inceJ *itt't"ip by means or the reverse
;'q:*:il1.:::::,'::'l!it",::.?ri;.'pFT$:;5f !ii[Fii*'""**;if'$ffi Jr*il,JiJ*'i,l"if;t"I{iulf i,iir-F:nir*q.'"wilrir'il:*";r?:,3ru;iff ip:,p:ilTfi :tilfl "ilffi :ffi:'^ii'"x"fl ::'f il:pointer *il .lol,luorur. w,ri ,ni, in n,,ino,;Jrr* tne go;;rri* tiitth (Gs) to decrease
I
this difterence. . --- ra rho hrrs and the other frequenctl meter to
swnch one ot the rrequencv T*:tJffi ?i'ioilntthe atter-run"n"ig
-gtn"rator' and compa
t"^";
#:operatiorr has been achieved bv the. procedure mentioned so lar' 'Then
,ff r?irff ,rj,?xJ,rli!1$}$;;H:{ri$tr$::;.l;'nil..Ji:'"ii*ff;:it:r : "r .^ i.'{;:fr. 4lgi.i;ilft'jffi $;.r'ffi {ff {-${'nthe trequJnry t? Ii?3:,, the ,,LowER"';il;. This.
"'iion also tt"t tt"tt load
:-::,must be turned tow1r1;':'";;"il;;, the senerator ha:,:::"firi'io-r i;;i sharing'transrerred to rhe first g.;;u.l' ^y:'il'
'gtt"ut* n"t enbleg the stago of p
parallet opu,ation. .ro,,iop tn, op,,.iion, ieuerse the procedure
Procedure for Parallel Runnlng:
a. start the generator and a*ow the speed to rise to the rated value'
b. Raise the vortage to the rated varue by means of the voltage regulator "VR"
c. confirm that the bus vortage equars the vottage o'i t'he generator to be put
ffi:i ilT:::: f reque n cv e qu a s . : l':::' : ,,l i'::::':,T
n e rato r
e. set the synchroscope switch ,,sys" to the side of the secondi generator
f . To synchronize, adiust_the engine speed by means of the governor switch
"GS" "nO
-tontii* tht equality of voltage'
s i,::,JTJ.ll?,;,:ii TjlH;' ?l;'l3lia',rJ"li'J.:' ffJ:3'J,:'i#'is:'ilfiindicating pttfttt synchronism'
'
ITI
1 0 6
Inch the governor switch "GS" of the second generator toward the "RAISE'side to have a small portion of the load shared.
Inch tho govelnor switch "GS" of the first generator toward the "LOWER" sldeto have a smail portion of the load alleviated. By so doing, equalize the loadof the two generators.
In stopping a generator, reverse the preceding procedure.
EARTH LAMP CIRCUIT
The earth lamp circuit makes it possible to examine on display lamps if the circuitis earthed or not, by, manipulating the pushbutton switch (ES). The circuit , tho voltageof El 3 will be apptied to each of the three lamps so that the lamp for each phasewill l ight up with the' same brightness, which is a litt le lower than that of other displaylamps (regardless of the earthing condition).
When the switch is set to "ON" the neutral point of tlre star connection will be earthed.lf this setting does not cause a change in the brightness of the lamps, the clrotlt lsnormal. Now we assume that the line of phase R is earthed. Then the lamp for phaseR will be suppliecJ with a voltage of the same voltage of the same voltage and wllf gooff, whlch the voltage E is applied to the lamps for phases S and T, which will therelorebeeome brighter.
It is rare that the circuit is completely earthed (lamp off). The three lampc maybe different in brightness. Ho',vever, by repeating change-( ver of the switch bgtween"ON" and "OFF" even slight earthing can be found. Make periodical checks. lf, uPonthe setting to "ON", any of the lamps has become less bright, even slightly, han whenthe switch is "OFF", the line of the phase can be considered to have been eartterl.So, proceed without delay to inspection of the circuit.
INSTRUMENTS AND O)U,".S INSTALLED
The generator panel are equipped with ammeter, voltmeter, frequency meter, wq['meter and running hour meter for measuring the output of the generator, the alr drcultbreaker, reverse power relay, over current relay for generator protection, the decon-necting bar for main circuit, the protection fuse, the transformer, the spacs heater atdtransfer switch, various types of signal lamps, etc. 'fhe external wire connection termlruXsare on the back side of the Panel.
The synchronizing panel is equipped with double frequency-meter, double vol[neterand wattmeter for measuring the output of the generator, the voltage relay and frequeneyrelay for generator alarm, the instrument transfer switch and auxiliary equlpment thosynchroscope necessary for parallel operation and the synchronizing lamp, the prolectoftfuse, the transformer, etc. The e,xternal wire connection terminals are on the back Sfdoof the panel.
h.
i .
t.
l
I
ItI
107
B 9
Reanrruo HuecrRtcAL$cHunnAflfi Llncnnnn oF Flne Pump
C P I
ti{tii,t
METHOD OF OPERATION:
When circuit breaker or l ine s'ruitch 89 is put at ON posit ion, lamp Source LP glow,introducing power at control circuit from 440V to 220V which is step-down hy controlpower transformer CPT.
To start, pushtbutton 3C energizes the contactor coil @, closing normally opencontacts 4/13-1 4,4133-34 and 4143-44 sirnultaneously, thus energiz-es the contactor coil(5g-\ anO closing normally open contactor @, then 3-phase motor is connected to supplyline 440V and running lamJ: L inclicated on operation.
To stop, push button 3-0 is presserJ, tlre contactor coil @ is cle-energized, openingthe closecl contacts 4/13-14, 4/33-34 and 4143-44 simultaneously, thtjs de-energizedcontactor coil @ and opening tlre closed contact 88, and the 3-phase motor is discon-nected from supply l ine and running lamp off.
Symbols Designat ic ln
- r , 3 - o t r ( - .h-r*
I- l
{
{
IIIqIIS t a r ' . ; a : J i l ' , 3 i r r L g ' l ; : S . . p p , ' S J u i c e
Standard marking .for Motor connectionStandard marking for Contactor coilDesignated number of WiresStandard mart<ing for nornrally closed Overload
R . S , TU , V , WA 1 , 4 20 1 , 0 2 , - 1 095, 96
1 0 8
Contact
IIIIIIIIIIIIIIIIl
I
t
FORMUIAS FOR ELE.CTRICI\I, PROBLEMS
a) Ohms law i '
Ampere voltsresistanceamperes x resistance
voltsamperes
volts x ampere.swatts
amperes
wattsvolts
output-17rput -
true powerapparent power
loof_glles1_rpm120
VoltsResistance
Power Rule
Watts\/otts
Amperes
Eff lclency
Power Factor
V
R
AA = W
V
RA xV
V x AW
Ab)
W =V =
c)
e)
d)
Frequency of AC Generator =
volt-ampere kva
= P x N1 2 0
AC - Three phasef) Dlrect Current
H P
746 hp
E ) : e n -1000 kw
E
l x E1 000
l x E x e f f746
I
Kva
t(va
l-lp
746 Hp1.73 x E x Eff x pf .1000 l(w1 .73 x E x p f1 000 Kva1 . 7 3 x EI x E x 1 .73 x p f-
1 000I x E x 1 . 7 3
1 000l x E x e f f x p f
746
1 0 9
where:I
E
eff
pf
1
R , o , "
V ,o,n
I biul
i) Frequencv
Rpm
Poles
amperes
volts
efficiency in
power factor
H,{r$ .s..il,,Iirri;II
itJ,t],TiiI\
l<w
Itva
ht:
kilowatts. \
k i lovol t - amperes
horsepower ouput
I
decimals
in decimals
s) laws on Serles circuit:
Current ,o,o = 11
Resistance ro,n = [11
Voltage ,o,, = El
Laws on Paral lel clrcult :
t
R.. .
F- 3
E2
l 2
no. of poles x rpm
120
120 x frequency
poles
120 x frequency
rpm
h)
' r lz ' : :
'f R, n"
-+- E, *-
1- t - -
R3
= E 3
+ 1 "
= E1 =:
= 1 1 +
1 1{-
R, Flz
\
1 1 0
BAgIC SYUBOLS
SYIIBOL DESCRIPTION DESCRIPTION DESCRIPTION
ONE CONDUCTOR OR A GROUP OFSEVERAL CQNOTJCTORS DISCONNEE.TINO SWTTCH OR MOLOED
CASE CIRCUIT BREAKERTWO CONDUCTORS(MULTILINE REPRESENTATION} --qtts;l
=f,-&-t9_"i-
MOLDED CASE CIRCUIT BR€AKER(wrTH SHUNTTRTP COtL)
I YY{. , g(JNUUg|9H5(MUL']TILINE R EPR ESEiTTATTO N
, f ,n CONDUCTORS(srNcLE.t-lNE REpRESEitTA'nON)
UNDER VOLTAGETRIPPIN.3 COIL OFCIRBUTT EREAKER-+- CROSSINO I\'ITHOUT EI.ECTRICAL
CONNECTION
I JUNCTION OF CONDUCTORS ---hc-- swrTcH (GENERAL)SINOLETHROW
c TERMINAI. CONNECTION OF CONDUCTORS {Yl= SW|TCH (OENERAL)DOUBLE THROW
€_-9_9 JOIMT TERMINALS
TERMINALS..1- R RESISTANCE OR RESISTOR
-r$ftn_ INOUCTANCE OR INbUCTOR TERMINAL MARKCABLE NOCABLE SIZE
-v\AAA/- WINDINO
t- CAPACITANCE, CAPACITOR \-e-9-9r-G- RELAY COIL, GENERAL SYMBOL r - - - l
i r = - l
{_g_o_9- EOUIPMENT OF OUTSIDE=5 HULL CONNECTTON (EARTH)
EAUIPMENT OF OTHER UNTTMECHANICAL COUPLINGGENERAL SYMBOL
-d:+- SWITCH, GENERAL SYMBOL
POWER & RELA CONTACT_-o.''^o_ THIIEE POLE SWITCH. SINGLE
REPBESEMTATION
J o e+O szCr.i_+o o{-
CIRCUTT BREAKER_q__-.dc.
__!_
@coNTACT (CENERAL) OFMANUAL CONTACT
_&o- CHANGE OVER CONTACTBREAKE BEFORE MAKE
-t---o O- -Grf-IIANUALLY OPERATEDAUTO RESET CONTACT(wrTH LOCKING DEVTCE)MAKE BEFORE BRAKE CON ACT
(gvER LAP CoNTACT)llEl-o o, *as- MECHANICAL CONTACTt- CoNTACTOR NORMALLY OPEN (MArN)
4? CoNTACTOR NORMALLY CLOSE (MAIN *O (}-- -4-8- H.ANO BESET CONTACT
-Q O-MAKE CONTACT (a CONTAGT)GENERAL SYMBOL
I
I-<l cr-. I -.(x--O-I
. _ - _ . t _ _
NELAY CONTACTOR ORAUX. SWITCH CONTACT--{--o- EEEAK CONTACI (b cONTAc'r')
GENERAL SYMSOT-<) O-- 1 --A-$-
I
CONTACT WITH TIME LIMIT OPERATION(oN DELAY TYPE)-<e- PLUO ANO SOCKET
LM4(E AND FEMALE)_r={- RESISTOB WITH MOVING CONTACT
GENERAL SYMBOL CONTACT WITH THE LIMIT OPERATION(oFF DELAY TYPE)- - . f - _ FUSE -tr!r
i::::_-t- I -,-*-
t l I
/ r I
NUCHING RELAY CONTACT@ OENERATOR
MAIN CONTACT OFELECTFO MAGNETIC CONTAdOR@ MOTOR
a4a8-,-4lrM\A--
SINGLE PHASE TRANSFORMERWITH TWO SEPARATE WINDINGS OANO SWITCH
MANUAL OPERATEORESIDUAL CONTACT- , E f | --:.a#. AUTO TRANSFOFMER THREE PHASE
-__)f- SEMICONDUCTOR DIODE OR RECTIFIENCENERAL SYMBOL ):{O----- C CONTACT
o VOLT METEB -n\- CONTROL SWITCH ORCONTROLLER CONTACT
@ AMMETER
ELECTRICAL SYMBOLS
-ff_ CURRENT TFANSFOBMER
P I L O T L A M P(FOR EUECTRIC SOURCE "ON")@
@ INDICATINC LAMP(FOR MOTOR RUNNjNG) _-STAND-BY lNDICAI ING LAMP@
1 1 1
PROBLEM SOLVING
FOURTH ENGINEER ' 1989'90 BOAI:ID ENAMS
1. A generator ls producrng 150 Amp. at zzg v- Flnd the Kw output ahd total
external reslstanoe'
SOLUTION:Volts x ArnPeres(150) (220\
33,000 watts 100U
33 l(w
P-fz-
33,00
(1s0) (1s0)
= 1 .46 ohms.
A 150 BHp engrne drrves a g0 percent, efflclent 220-v generator' Flnd the
current Produced.
fiqIII
Ip =
=
R =
SOLUTION:hp outPut of gen" =
=
watt outPut of gen. =
current =
SOLUTION:
1E
R"
RT
input
1 5 0
1 3 s
watt =voltage
X
1 00,71 0
efficiencY
. 9 =
746 =
1351 hp
1 00i,71 0 watts
220
current = 457,772 amPS'
A resrstance or 1g ohms rs connected rn serres wrilr 3,4 and 6 0hms ln parallel'
Wn"i ls the total reslstance?
= 1 + 1 +3 4
= 1 2 =I
' f = 4 + 3 + 2 = I I
6 1 7
1.333
= , R s + R "
= 18 '+ 1 .333
= 19.333
112
I Twenty 100-Wthe current.
SOLUTION:
Total watts
Ampere
input in watts
bulbs ancl Fourteen4. 60-W bulbs are In a 120-V clrcutt. Ftnd
1 1 3
t-.
I
I
I
I
I
I
tI
I
I
II
IIIIIII
( 20 x 100 )
2,000
( 1 4 x 6 0 )
840 = 2B4O W
_?q{a_120
\v611
voltage
284A
120
23.666 arnp.
Tl-f I FID HNGI f',,| H [: tjl
'r ' f ;ii"ii',L33lV
motor is 75 percerrt erricierrr. I?incr the cur.ent required to drive
SOLUTION:
output in watts output i r r f rp ; : T4g1 0 0 x i 4 674,60A wnt ts
elJtpu.l "zil,s!_()ef f ic iency 7 l :
99,46{: j .( i f l
watf :: 9"9,"4$.C*f,i(1vo l t . ( \ . . 1
current
= 23.660 amp.
z. A 40 ohm resistor is connected to a 20 ohm relay. The operating voltage is 120 v'
Determlne the current and power in thls relay clrcuit.
SOLUTION:
R r = ? o l l a= 60 ohms.
a) Current = VPltResistance
= 2 amperes
b) Power = current x vol ts
: 7oo i*^r,r' 'o
3. A 50 Hp englne drlves a DC generator. l f the generator has an efflclency of
840A. How many a) Kw b) HP. does lt dellver.
a) Kilowatt delivered
= 5 0 H P x 7 4 6 w x 1 k w1 H P 1 O O O w
= 5 0 x 7 4 6
1 000\
= 37.3 Kw
b) HorsePower delivered
= 50 x 0 .84
= 42 HP
4. An AC generator ls rated at 227 KVA at 86% power factor. What ls the Kw
ratlng.
POwerFactor = .KwKVA
Kw = Power Factor x KVA
= .86 x 227
= 195.22
rdII
= 12060
1 1 4
SECOND ENGINEER - 1989-90 BOARD EXAMS:
f ' il::Tj"ll,T lJ;:i :s:5""""i"ected
In serres wrth 4,5 and 6 0hms In pararer.
SOLUTION:
1 - 1 r . 1 + 1R a q R r %
, = + + + + +1 5 + 1 2 + 1 0
60
1 /Ra = 3760
Ra = 60 = 1 . , i 2 ohms37
RT Ra .i, I_1b
: = 'r::,
J;j
2' IIo",TrlJ#:"Kw
generators are in parauer" Find maximum current, vottage
SOLUTION:
current in sen. = !g Ilgg_? Jg __ T\ 220 \/
*-Current ,o,-u = zz7.27 arnps.
:J 227 .27 + 227 .2V= 454.54 amps.
Resistance,o,, = V _ ZZ0,i fia= 0 .494 c lhms.
V o l t a g e l ' o t a l = l r X R f
: : 454"54 x 0.484
= 22A V
[vz \r,L
1 1 5
3. srrnpre serles crrcuit In whrch two batterres, whose emfs are 5 and 12
vorts and two resrstors of 4 orrms arrd B ohms. Negrectlng the reslstbnce
of the batterles, determltte t lre current ln the clrcult '
GIVElI:
E l = 6 V F l l = Q o l t r t l s
F:2. = l2V l tz = B o l t t t ts ;
SOLUTICIN:
E r = T ; :
E , : : 6 V
r'r' - T;"11,Cunent Total -- El
| 1 l^ t- o
iCurrent Total = 0.5 anrp. I
4. Determlne the requlred horsepower of a prltrlelrlover havlng 80o/o effl-
clency to drlve a 5OO l(W generator' I\
GIVEN:
Gen.output = 500 kw 1kw = 1'34 hp I
EffeciencY = 80%
Ef{iciency = output Checked:
input
= B0 " 500 El1 = 500 kw
loo x 625 kw
x = 50000 : ;u^.1 too
80
HP = 625 kw x 1'34
HP = 837 5 Requirecl B0% of 625 = 500 kw
B0% of 837.5 = 670 HP1.3$
500 kw
1 1 6
wlth another In a Z2O V.
,.----,nrr\u\---
-.--21,,'\,i\, -
I IISOLUTION:
a) Rr
RT
= ' R 1- = Q
= 1i5
58.64 V
73.30 v
87.96 V2 1 9 . 9 0
d) Power = ilJl 21e so
3,223.7 watts.
2" A s lng le phase A,CFlnd apparent and
SOLUTTON:
Apparent power
generator . ruppl lestrue powe, ?
6
V x A100c)
- !eo_:fJgn_| 000
= BB KV/\
l-rue Power:: app.power X power
factor- = B B x . g s: 83.6 ltw
CHIEF ENGINEER
1. Reslstance of 4,5 and 6 ohms are rlr serlesCfrcult. Calculatel
a) Total resistanceb) Line current;c) Vortage drop across each resistanced) Total power consumed
+b
b) A = yHT
14 .66
c) V1 = ra.beV Z = 1 4 . 6 6
V3 = 14 .66
+ -12
+ l - +
ohms
= 3 j1 5
amps,
;r Fl1
X R ?' (
[ ' : j
R3
1 4 , 6 6 x 4
1 4 6 6 x s
1 4 . 6 6 x 6\ /v l .
400 aunp . at A2,\ V wlth a p.F. of 0.9S.
- \, r' ,'J, Y l \ \
' t -
. [d \ t , , t - "
'\ ' '
_--*/
1 1 7
I
I
t I
m . ( R ' R A )
Three resrstors or 100,120,150 ohms arg.:onnected ln parallel' PqtPrmlne value
otcurrenttopar4| lel"y"." i i ; ; i ;h*rrrmal-e"u,,entinrzo.oh}nsreslstorsequal to 1'0 amP'i
GNEN: t"*tiltto=
3. F-'Rl- = 1oo E" = Ib' Rb
ri" -- 120 *o
= (1 ) (120)
H: = 1?o E, = lt:: Ec = Et = 120\l " ' = 1A E; = Ea
d{
II
\ / i
7,.d;,, t vt., t1 ) # u i ' . t
\ ,,t', \
" t i ' '
E E T
R,/r.
l ; " ,R t = Ro RB Rc
100 (120x150)
(100 x 5 y . 6 2 0 x 1 5 0 )+ ( 1 5 0x 100)
lr1 800000
w,. l r
, r - \ ) ' 'I r Y
12000 +| - \= 1 800000
1 8000+1 5000
----45000
= 120 V
40
= 3 amPs', , q l , :
i ,. 'r - 'r . f.
Y 1
v r't1" Rt = 40t . '
4" A storage qa$er! ut ii'uji. supply as shown-ln rlri qvr-
:.-rv to llmltto be crtardeJ I91]^ rnrret te ot#ei"rn turles wlth the batt
reslstance Bi 0'2 ohms ls
A storase eattry 9tjyl,.?,? #l",T:JTf;trl f'1[f *:*il,*to be cfr.argect lrom I I ' 'ii'u,
iiaieO ln serlesiig,;i..w n 1I re-1:l'.1' : Ji,l,, o * u .ltil';;tg"s rate to 15 amPere'
Solutlon:
rotar potentiar d1o.p l1^c'lTJt ST'il;='?".1'ffit ti
?*lr droP + Potential droP o
(15) (0 '2) + 24 15R
3 + 2 4 + 1 5 R = 1 1 7
2 7 + 1 5 R = 1 1 7
1 5 R
15R = 90
R = 90/15
R = 6 c h m s
= ; t t z vd r o p = i 1 1 7
1 1 B
BOARD QUESTIONS
Founrn ErucrNesR
. ElEcrRrcrrv1. lf two gen€rators are connected in series:
A../voltags is added and current stays the samoB. current ls added and voltage stays the sameC. both current and voltage stay the sameD. none of the above
2. A generator intorpolo always has lhe same potarity as tho:
4. pot" preoeding it C. opposite the main poteB. pole following it D. none of the above
3. Interpoles ar6 conn€,cted in;
A. serles with the armaturs C. parallel rvith the armatureB. sgrles with the shunt lield D. parallel with the series field
4. A.DC.compound wound generator that has a voltage drop trom rio load to tu,,load is said to be:
A./ under compounded C. flat compoundedB. over compounded D. none of the abovs
5. The part ol a D.c. generator into which the working voltage is induced is the:A. yoke B. field poles C.r armature D. commutator
6' The proper sequence for securing a D.c. generator in paralel operation is to:A. reduce current to near zero, open circuit breaker and switclr and secure the
driving unitB' open the circuit breaker, secure the driving unit and cut in resistance io the
field.c. opeir the circuit breaker, reduce the current tr zero and secure the drivino unitD. none ot the above
7 ' Interpoles or icommutating poles are connected in compound D.c. generators in: s
A. series wilh tho shunt fleldB. serles with the series fletdCl sories with the armatureD. series with shunt and serles field &E. series wilh the armalure but in parallel with each other
1 1 9
o+4eTiltq
*{IttI
8 . The clnly typtr of compoutlrl gunelratnt
A. stabilizecj rslrunt C'
B. flat comPoundetJ Il'
What aro contrnutatot's trltltla of i
A. soft coppor bars ittsulattld with tnica
B. hard drawn copper [:ars insulateld witlr rnica
C. soft soliO copper witl'r cutaw'gY slott: for tnica
D. hard drawn solio copper with cutaway slots for mica
A shunt-worrrrcl gerrerator is one i^ wlrich *re f ield windings are in parallel with
the:
f\. arrnature B' brttsltes C' r;ontntutator D' f ield poles
11. Ar l "exci t ing current" is required to:
A. L,uilcj up a cleacl circrrit u" excite a synchrorrous motor
B. create a rnagnetic f ierd tl. btrirt j up the vortage in a battery
12" wl,ich of the followirrg are not in a L)'C t;otnmtttator and armature?
A . i n t e r p o l e B ' t n i c a 0 0 o p | . / 0 r b a r s D . V e e r i n g
13. lf the brushes in a gerrerator are not posit ionetl to the neutral plane' sparking may
occul' between the brushes and the:
A . y t , . k e C . a r r n a t u r e w i n d i n g sB" commutator D. f ield pole wirrdings
14. A rheostat is aleuire that regulates tlre strength of an electric current by:
A. varying the resistance in the cireuit
B. uatying the voltage in the circuit
c. increaiing the magnetic f ield in. tfre circuit
D. varying tfre current in tlre clrcuit
15. which of the fol lowing is not founcj on a D'c ' generator?
C. stationary armatureD. brush holders
16. Which of the lollowirrg wil l not cause a generator to vibrate?
(;or-lltl 'l()rrly usecl t$oilrd ship is the:
ovet' comPounded . \cumttlative comPounded
9 .
1 0 .
A. pigtailsB. brushes
A. loose PigtailsB. loose bolts
C. rnisal ignmentD. trrritY sPeed governor
tttIII
\7 . Most generators will withstand as overload of :
A . 1 5 p e r c e n t B . z s p e r c e n t C " 3 0 p e r c e n t D . 3 5 p e r c e n t
1 2 0
18' A series-wound generator rrss tfre fiefd winclings in series with the:A. armatureB. Orusn{s C. comrnutator
D. fietd potes1e' ,lliJ:?,5;3'?,inf6:?ff,1',J, o.. seneraror are buirt up or sheet steelA' fit the curvature of the frarne c. afrow for necessary air gapB. reduce eddy current losses D. allo,v fo,, ear' assernbly20' what is the prima4r t'eason for commutating pores in a D.c. generator?A' prevent sparki'g of the brtlshes c. neutrari::e armature reactionB' rncrease iielo srrength D. aid in a commutat,on21 . sparking and grooving of commrtator may be caused by:A. overfoad
B. strength of fietd C.D. ffiT',il1"'J,::,'n"22' The voltage of a D'c' generator depends on which of the forfowing?A. speed; of armature C. nurnber of arnrature conductorsB. strength of field D. alt of tire above23. To correct the pofarity of a generator, you shoutc!:
A. Rotate armatureB. fift brushr,
"nJ rotate arrnatur.eC. fift brushr,
"nJ appty D.CD. lift bru1sh",
"nJ l'rn generator
24" which of the forowing groups of motors ar' D.c. motors?A' series, shult and compouncr c. compound and synchronousB' series ano l'nouttion D. indr-rction ano synchronous25'
ffTfi;ytffl motor is usec, t' ^rrr a pll*p driven with a bert. rf the bert breaks,
A. overspeed and run out of corrlro,B. stopC. slow downD. keep running at the .sarne speecl
26" AC circuits jcontain resistance, incJuctitance of a circuit is iupresser.l in: ance anrl cetpacitance. The capacitive reac-
A. ohri is B. mhos C. lrun ry,s D. farads27 . A shunt motor woufcj be best ruitecl lor.:A. constant speed resuftsB. an ancllor'winotrlJ""" c' a cargo winclr
[). any of ilre above
1 2 1
28. lf the resistance is increased in
A. sPeed uPB. slow down
30. Which of the tollowing wil l
A. loose brushesB. insufficient lubrication
31 " ln an induction motor' rotor
A. sl iP rings and brushes
B. armature and brushes
shunt motor?
not cause a l rot mcltor bear ing?
C. over loadD. misal ignment
currents are circulated in the rotor by:
C. lnductive action of the rotating stator f lux
D. external variable resistors
the shunt t ield uf a motor'
C. run at theD. stop
the motor will
same sPeed
2 9 . W h i c h o f t h e f o | | o w i n g i s t h e d i s t i n g u i s h i n g f e a t u r e o f a
A. it has a high stading torque
B. a lead wii l not affeci i t i f running at high speed
G . i t h a s a s t a b | e s p e e d t h r o u g h a w i d e l o a d r a n g eD. it wil i not drop in speed if overloaded
32. A device which normaily prevents an actiolr occurirrg until all other required conditions
are met is a{an:
A' interlock B' monitor C' nrotjulator D ' l imit
3 3 " A c i r c u i t b r e a k e r a n d a f u s e a r e s ; i m i | a r b e c a u s e t h e y c o t h :
A. can be reset to energize the circuit
B. sfroJO open the circuit when overloaded
C. burn out when an over current flows
D. anY of thb above
94. The erectropryte in a read-acid storage battery consists of water and:
A. sulfuric acid c' hydrogen chloride
B. calcium chlorid D' muriatic acid
3s. The state of charge of a read acid storage battery is best indicbted by the:
A . s p e c i f i c g r a v i t y o f t h e e | e c t r o | y t e C . i n d i v i d u a | c e l l v o | t a g eB. ampere hour capacity D' total cell voltage
36. Electrical leads and insulation or' a motor should be painted with:
A. insulating varnish C' heat-resisting enamel
B. heat-resist ing aluminum D' insulat ing white' lead
37 . Vortage generated by most Ac generators is brought from the machine to the bus
by means of:
A. brushes on a commutatorB. brushes on sliP rings
C. sl iP r ings on a commutator
D. direct connections {rom the stator
122
38. A degree of control over the speed of a s l ip r ing induct ion motor can be obtainedby:
A. insert ing resistance into the rotor c i rcui tB. changing the number o f phases to the motorC. insert ing resistance into t i re stator c i rcui tD. ad jus t ing governor l inkage
39. A circui t breaker di f fers f rom a fuse in that a c ircui t breaker:
A. melts and must be replacedB. is enclosed in a tube of insulat ing mater ial wi th metal ferrules at each endC. gives no visual indicat ion of having opened the circui tD. tr ips to break the circtrit and may be reset
40. The bas ic un i t o f inductance is the:
A . cou lomb B . ohm C. f arad D. henry41 . Bat tery rooms must be wel l vent i la ted to :
A. prevent su lphat ion dur ing d ischargeB. supply oxygenC. dissipate explosive gasesD. prevent moisture forrnat ion
42" The alarm system for an engine order telegraph uses smal l selsyn motors at tachedto the indicators. The alarm sounds when the rotors are.
A. not synchronized, current is f lowing, and the relays are closedB. in synchronous pos i t ion , no cur rent is f lowing and the re lays are c losedC. not synchronized, current is f lowing and the relays are op.nD. in synchronous posi t ion, no current is f lowing and the reiayr are open
43. As a general rule, the f i rst t roubleshoot ing act ion to be taken in checking faul tye lec t r ic cont ro l apparatus is to :
A. draw one l ine..diagram of the circui t ryB. tes t a l l fuses and measure the l ine vo l tageC. take megger read ingsD. insu la te the apparatus f r rm t f re ground
44. The most common type of AC service generator f ound aboard ship is the:A. armature'rotat ing electromagnet ic f ie ld typeB. electromagnet ic f ie ld-osci l latory armature typeC. armature-osci l latory electrornagnet ic f ie ld tyeeD. e lec t rornagnet ic f ie ld- revo lv ing ar rmature type
45. The main purpose o f the aux i l l ia r5r w ind in0 on a sp l i t -phase s ing le_phase motori s t o :
A. l imit the start i r rg currentB. increase the s tar t ing cur rentC. starl the rnotorD. keep the motor runn ing in l l - ie event the main wind ing should fa i l
123
46.
4 7 ,
for et particr-rlar application maiol considerationWhen You are choosing a batterY
should be given to the trilttet'y'si
A. amP-hour
A. Ambient ternperature stroul<J [:e
B. lncreased ambient ternperature
stabilitY uncJer clrargeambient temPerature rise
is arnbient tentperat t t t '0 i r t re la t ion to the serv ice l i fe of e lect rontc
as higlr as possible to drive ioff moisture
Oecruases tlre service l i fe of electronic com-
u"D .
c. l"ffi:ti temperature is rrot significant as lorrg as the relative hrumidity is kept
lowD, A reduced anrbient temperature carrses a corresponding reduoed service l i fe
48. which device srrourd arways br cclrrrrected in series witlr a circuit?
A. Ammeter C' Wattmeter
B. Megohmeter D' Vol trnoter
49. A f l ic lser ing ground det;ct ior l lamp on a D() systern would indicate a
A , g r o u n d i n a n a r m a t u r e c o i | o f a n o p e r e r t i r r q l t t a c h i n eB. short between ,.,vo acijacent r:ars of the generatol' comlrlutator
c " m u l t p | e g r o u n d i n t h e d i s t r i l : u t i o n s y s t e n lD. ground in a motor accompanied witlr a short
50. A fuse wil l "blow" if
A . t h e e | e c t r i c a | c u r r e n t e x c e e ( J s t h e r a t e d v a l u e o f t h e f u s eB. the flow of current to tlre device protect" is reversed
C. un.quJ lesittots ttt connected in parallel
D. an electricat motoi is stopped sudclenly by openi'g a switctt
51" Which bus is norma||y located in the ntain switchboard?
C. the emergency Power bus
D. the lighting bus
52 .E tchedorbu rnedbandson t l recon tac t faceso r tcould be caused bY
A. copPer embedded in t lre brushes
B. brushes imProPerlY PositionedC. copper drag on tlre cornmutator
D. high mica segments
hrushes in a direct current generator
53. What is indicated if a leacl-acid battery begirts to
B. terminal Polari tY
Of what signif icance
comPonents?
A the 24 volt DC busB. the shore Pcwer bus
on charge?
A. normal charging rate
B. excessive charging rate
gas violentlY when it is f irst Put
C. Insuff ic ient c i rcui l in a cel l
D. A short circuit in a cell
124
J
J
I
I
I
II
I
II
I
54' An accidentat path of fow resistarrce which causus alr abnormal ltow of currentis known as a/an
A. ground, rgfgrence point C. polarized groundB. open circuit D. short circuit
55' When a megohmeter is usecl to test insufation, the initial dip of the pointer towardzero is caused by
56.
A. the dielectric-atrsorption effect of the insulationB' the leakage of current afong the surface of nearby insutationC. good insulationD. the capacitance of the circuit
The main purpose of an electric space heater installed in a large AC generatoris to
A. prevent the wincrings fronr becorning britileB' prevent moisture condensation in t ie wirrrj irrgs during shutdown9 keep the tube oul warm for quick stafi ingD. prevent acidic pitt ing of the ,i ip rings
v1/hen a flourescent lamp has reachecl the end of its r.rseful l i fe , i t shoufd be replacedimmediately, or the resuftant f lashing may
A. blow the famp's breal<er? explode, causing glass trc f ly in all di 'ectionsC. short circuit the bittast transfornrerD. damage the starter ancJ ilre ballastwhen you are choosing a battery iclr a partictrfar appficatlon major considerationshoufd be given to the battery's
57.
58.
59.
60.
A. amp-hour capacityB. terminaf pofarity
\What statement is true concernirro
C stability uncler chargeD. ermbient temperature rise
t l re cleaning of contacts?A' the contact surfaces should Lre greasecl to increase contact resistanceI Magnetic brushes shoul<J be ,r*J.J to renrove metafl ic dustc' Delicate parts shor-rld be cleaned with a bruslr and an approved safety solventD' Compressed air shoulcj be usecj to blow out metalf ic clust
61' what type of battery charging circui t is usecJ to rnaintain a wetcel l lead-acid storagebattery in a fuilry charged state over rong periocrs of disuse?A. Normal charging circui t ( ) . euic l< charging circui tB' High ampere chargino circui t i l . l ' r ickle charging circui t
What do you call values rnrhich ()atlpressure, or level?
A. digi ta l vdluesB. hunrpless values
change cont inuously such as temperature,
(- : . b irrary valuesi l . analog values
I
I
125
A. number of poles ( ; t l r t t r r t ' lc - l r t ' {
B. prirne mover spe' lc ' l t l I l lal j t tet i t :
6 3 . T h e t o t a l n u m b e r o f w l ' l t s i i i { ) i l t r i t c > t s e p o w t : l t s
A. 746 watts | ; ' 500 watts
B, 663 watts l i ' l ' ( )0( ' ) watts
6 4 . W h y a r e t r a n s f o r m e r a b o a r d s | r i i . l t r s e d w i t i . t A 0 g e n e r a t o r s ?
A ' t o p e r m i t h i g h e r v o l t a g e t t l t ' t t t t l t c t r c : p e t a l t i t t t l i r n d l o w v o l t a g eB. to change frequencY
C. to increlse Power outPttt
D. to decrease Power ot t tPtt t
THtno Exctnesn
1" When a lead-acid stora-qe l - rart lu i l ' rJ ischAr$es' what woutd the ei f fect be on the
electrolYte?
A. sPecific gravitY decreases
B. sPecific gravitY increases
C. specific gravity remains tfie :";i'lrl'le
D. none of the above
2 , T h e l e a d p | a t e s i n a s t o r a g e ' . . r i r t | e t i e s a l , u : ; e p a r a t e d b , , y :C . !t lassD. any ot the above
3. In cold weather the speci t ic gtavi t l r of a battery:
62. The vultage of all
the
A. rubber \
B. Wood
A. nses
o l le i ' u l i t r t i t i ( ; l t t r r t : : a l te r t ta i to t l sI
gerrerallY adiusted bY varylng
sr:ries conduictorsiielcj strength
IItJII
for l ighting circuits
the samethe above
what hYdrometer reading wil l be
battery?
t o 1 . 1 5 0to 2 .7 50
off with:
II
C. rernalnsD. none o f
B" lowers
4 .Accc l rd ing toba t te rymar l t t f ac tu r t i t , , sspec i | i ca t i onsobtained f;;; u tirv clrar:gecl 1;ortable lead-arcid
A . 1 . 2 8 0 t o 1 ' 3 0 0 C ' 1 ' 1 0 0
B . 1 . 1 8 0 t o 1 ' 1 8 2 D ' 1 ' 7 5 0
5. Dirty lead-acid type batteries sltoirlcl be clearred
A. soap and water
B. sodium chloride
C. baking soda (sodiurn iticirlt-ronate)
D. Potassium hYdroxide
1 2 6
tt
6. A ful ly charged batrery rearJs frr:r l :
A . 1 .280 t o 1 .300 O ,B. 1 .025 .to 1 .075 D .
A . 1 2 3 . 6
10. The rating of a storage batttery
A. 180 ampere hoursB. 150 ampere hours
A. t r jck le charg ing c i rcu i tB. quick charge c i rcu i t
HrSoo is.
A. sulphur ic acidB. hydrochlor ic acid
The total rroltaoe andrs :
| 12 vol i ts, 50 ampsB. 12 vo l ts , 100 srnps
l . ( ) i r 0 t o 1 .350I l ; l ( l ( ) to 1.S00
I
tII
III
I
7. A dead cell of a reacj-acicj batter;r is c;rrer.. i .0rt hy:
A. megger C. r r rs t t igh tB. hygrometer D. hvr l rcrrreter
How many 1.5 vort batteries are req,irecJ ro s;tr1:1.rry a road ofare connected in ser ies?
A . B 8 . 6 (i !, ' ,1
8.
9. How many 1 .5 vo l t bat ter ies are reqt i i ru r l io ; ; r r1r1 l ly er loacJ o fare connected in paral le l?
D . 1 0
12 volts i f the batteries
O, t i D. none of the above
i l r i l l de l ivcr$ l5 a l l l [ )s lc t r 1Z hours is :
i. l . : i i an tf)ere hoursl) t , l { i (J ; t f l lpere hor:rs
v o l l q , l 0 ( ) a m p sr. 'ol l .r , i . ; f) AmpS
'tr2 volts if the batteries
11. Which of the fol lowing i tems; is ne,c;essi . rrv l r . r l l l : i , i r l t stgrage t iat tery in goc,,d operat ion?A. maintain proper speci f ic gr; , lv i ty? keep cool ancr well-venti lateclC. maintain proper fevel of r ; l r :ctroly leD. af l of the above
12' what type of battery-charging c' ir*tt i l is ri:,;r:r i rf.r 'arrl srrip t ' rnaintain storage batteriesin a condit ion cf readi , lLr* ov(:r j ic .rrrcJ Irer i , r r , lq r t f rJ isrrse?
1 3 .
: - ' , - ) ( ) . r1y1J1 r :ha-g ing rate c i i ,cu i ti ) f r r ' : : f r l i sc l ta rqe C i fCu i t
I . l r y r i i , ; i r l t r ; a C i C Ji ) t r t i r r i : ' i l t r : ; , r i : i f l
amperaCJe o f iwr , r l l 0 - . t r l J ; { i . , ,o l t l l a t te r ies c ,nnec ted in Ser ies
1 4 .
( - : .
i . r .
127
15., The total voltage ancl anrperallewi l l be:
A. 6 vol ts , 100 ampsB. 6 volts, 50 amps
by:
A. blow out coilsB, gov?rnor relay
22. How is the rotation of a D. C.
A. reverse field connectionsB. switch armature leads
of two-50 arrrp 6-volt batteries
O. l l i t . volts, 100 arTlPSD. l i ) vo l t s , 50 a lnps
C. undervol tage tr iPsD. roverse current tr iPs
generator reversed?
C. switclt armature leadsD. bot l t B and C
Fctedconn in paral le l
16. The vol tage of a battety is equal to the:
A. vol tage of a s ingle cel l t i r r res t l te t tut t t l te l r t : f cel ls in ser iesB, amperage of a s ingle cel l t i rnes the r tuntbel ' of cel ls in ser iesC. ef f ic iency of the nurnber c l f cel ls t imes t l te resistanceD. vol tage of a s ingle cel l t imes t t re t tuntber of cel ls in paral le l
17. Three 12-vol t storage batter ies conrrecter l i r r y lerral le l wi l l g ive you a total vol tage
of:
A. 12 vol ts B. 24 vol ts O. l i ( i vo l ts D. 48 vol ts
18. Indicate the proper procedr:re for rrr ix ing bnttery elect tolyte:
A. use disti l led water, add acio to waterB. use alkaline water, add acicj to waterC" use disti l led water, add water to acidD. use alkaline water, add water to arcid
1 9" D.C. generators are classi f ied accordirrg to the tranner in which:
A" they are usedB. the f ie ld windings are conrtected to t l te loadC" the armature circuit is connected to ttte lcladD. the f ie ld windings are connected to t l re art t tature circui t
20" The purpose i f , f , , conrnr:r tator arrd brusl tetJ ot" t a D.C. generator is to:
A. change A.C. to D.C" currentB" change D.C. to A.C.C" neutralize armature reactionD. carry current to the outside circuit
21. When two D.C. generators operate irr parallel, ttrey are protected against motorizing
l 'l iil
, l ii i l; i rI i l t
r, ili: F ii l lq , i i iL r ,t l: l
i r t .) /1i l,.ii i1r l i l :rt i l i
,i l lt
ifr [i
128
24' which of the following D.c' gene,'ators has the largest percentage of voltage dropbetween no load and full load?
A. under compoundedB. f lat compounded
25. A.D.C. generator that has
A. under compoundedB. over compoLtndecJ
23. On la D.C. generator vrhere is
A. feather springB. condu ctors
26,
27.
28. With an increase in load on a
A. remain the sameB. decrease
29. D.C. generators are ratecJ i r r
A. KVAB. KwA
30. The voltage ogtput
A. in ser ies withB. in ser ies -with
a D.c. gener'ator was rotated irr the wrong direction, it w'urdvoltage because the:
the pigtarl located?
C. bruslr holt jerD. spriral adjusting spring
C. shuntD. stabi l izeid shunt
a vollage rise frorn no load to fufl load is said to be:
C. f lat compoundedD. urrder f lat compounded
faif to come upl fto
A.B .c.D .
A
A .B .c.D.
armature field wourd oppose ilre fierd cur'errtgeneratort would burn outbrushes would burn outcircuit breaker wr,rulcJ not enerqize
generator operates on the principle that:
when a field revolves, current is generatedwhen an armature revorves, a magnetic fierd is inducecjvoltage is induced when a conductor cuts a magnetic ftuxa small voltage in the prirnary high voltage in the seccndary because of thelarge number of coifs in the seconclary
f lat-r;ornpor"rncled D.c. generator, the vortage wii l :( l increaseIt r eclrrce tc l l ra l f
(i" l(wn. [- lr)
of a cornpclu^rl l ] .C. gr:nerator is adjusted by rtreostat placed:
the shunt f ie lc ! C. across the ser i r .s f ie ldthe ser ies f ie td n across the shunt f ie ld
129
3 1 .
32.
The electrolyte used in a nicl<el-cadmium battery is hydroxide. I
A. potassium C' sodium ' \
B. cadmium D' calcium i
The device which most commonly uiil izes the principle of electromagnetic induction
is the:
A. transf ormer C' transistorB. diocle D' rheclstat
A tubular fuse should always be removed from a fuse panel with:
A. a screwdriver C" any insulate objectB. a pair of irrsulatod pl iors D. fuse pul lers
34. One of the factors wlrich determine frequency of an alternator is controlled by the:
A. number of magnet io PolesB. number of turns of wire in the armature cell
C. strength of the magnets usedD. output voltage
g5, Whlch of the followlng logic gates islare consicJered to be a BASICI bullding block
(basic logic gate) used in logic diagrams?
A. OR B. NAND c. NoR D. A l l o t the above
36. Which motor is f i t ted with an instantaneous over load relay?
33.
A" winch c ' Farr
B. PumP \ D ' Machine Tool
g7. A molded-case circuit breaker provides protection against short
aJan:.
c ircui ts bv using
A. electromagnetB. shading coilC" arc quencherD. burn away striP
38. The rated temperature r ise of an electr ic motor is the:
A. normar temperature rise above the standard ambient at record hold
B. average temperature of any given latitude
C" uuar"!, temperature rise due to resistance at 10"/" overload
D. permisliole oifference in ttre ambient temperature of the rnotor due to weather
39. The number of cel ls in a 12 volt lead-acid battery is:
[ ,I
$r!i
Itril l l
H Ifi:fit
1 3 0
A. three B. four C, s ix D. twe lve
tT
40. The Wheatstone bridqe is
A. resistanceB. capacitance
41 . The greatest detrimental effer:tmot,:rs is:
43. What does a wound-rotor incjuct iorrnot?
A. s l ip r ingsB. end r inos
45.
A. overvoltage releasets" thermal acting tr-ip
46.
a prec is ion ins t rument used to measurc :
C. inductanceD. arnperage
on idle electr ical equipment such as cargo pump
C. thermal over load re lavD. crtrrent c lver load relav
I
I
I
I
I
A. loss of , residual magnet isrnB. absorpt ion of moisture in the insurat ionC. insulat ion varnish f lakingD. dir t col lect ing on the ruincl ings
42. The frequency of an operat ing arternator is controlred
A. relativer speed of the rotor rrolesB. number of turns of wire i r r the armature coi lC. strength of the magnets useclD. output vol tage
by the:
motor have which a squirrel cage motor does
C. a centr i fugal switchD orlcJ plates
The current 'at which a mi lgnet ic type over load relay tends to t r ip may be decreasec,by ra is ing the p lunger runther in to the magnet ic c i rcu i t o f the re lay . Th is ac t ion:A' increasles magnet ic pul l on t l re plurnger and requires less current to t r ip therelayB' reduces magnet ic pul l on t l ie plunger and recluires less current to t r ip the relayc' increases magnet ic pul l on t ' ,e pl i rnger and requires mors cr i r fert to t r ip therelay. \D' reduces maonet ic ptr l l orr l l t t , ; p lunger i - rncJ requires rnore current to t r ip therelay
Protect ion against sustainecJ clver loarJs i r i r"nolc lecl-case circui t breakers is providec!by an/an:
44 .
I
I
II
t
Motor izat ion of an a l ternator is r r r r iJes i r .a t l le r )oce. luse
A. i t puts an ac1dit ional load on i l re i-rusB. a l l o f t l re aboveC. the a l ternator wi l l be darnagerJD. h igh voi l tage purses are i r rcJt rcer j in the bus
1 3 1
47 . The unit "hertz" is equivalent to
A. revolution Per minute
B. cYcles Per second
48. How are fuses rated?
A . a m p s a n d v o l t s B . a l n p s o n l y C . w a t t s D . v o l t s o n | y
49. Ttre unit of electrical resistance is the
A. ohm B' watt C' amper D' volt
so. -r-he line voltage generated by arl alternator is acliusted by varying the
A" Prime mover sPeed
B" equalizer busC" excitation voltageD. resiOuJ magnelism of the tield
S l " T l t e s t a n d a r d u n i t o t w i r e c r o s s - s e c t i o n a l a r o a u s o d i r r A m e r i c a n
vvire tatrles is thd
A" AWGB" square mill imeter
5?. Which of the following characteristics is
to be u,uJ in a Particutar circrrit?
A" voltage ratingB. current ratingC" inductance fer unit length
D. Weight Per unit length
53 ,Ag round i s i nd i ca tedby theg rou r rd -de tec t i r r gsys tem.the actual ground is to
A. ChecK circuit with a megohnteter
B. change over generators
c. crose alr switcr,es in'itru oirtriuuti'n panel until the grournd detector indicates
normalD . o p e n t h e i n c J i d u a l c i r c u i t s o n e b y o r | e u r r t i l t h e l $ r o U o d d e t e c t o r
s4. A Dc generator supprying cJirect current to maintain an gonerator fleld is (nown
C. revolutions Per second
D. coulombs Per secono
C. cubic inchD. circular nril
as alan
=A. stator B' rotor C'
55. The frequency of an AC generatcr is
A. equalizing reactor
B. Prime *6uet goverrlor control
132.
most criticar in cjetermining the size of cable
The first steP in tocating
armature D' exciter
adiusted bY means of the
C. main alternator field rheostat
D. exciter field rheostat
56' The inductance of a conductor is measurecJ i'A. henriesB. vorts ohms
c. ohmsD. amperes
57' The voftage of an operating AC turboCIerrerator is raised or rowered by adjusting
I
I
I
58' Under normal conditiofls, Storage batteries for s.tarting the emergency diesergeneratorare maintained in a chargecl state oy wrrich or ine foilowing methods:
A. generator field exciterB. phase sequence switch
l. trickte chargingB. r{}verse charging
9 generator governor controfs:). synchronizing switch
I equafizing chargingD _ rear charging
o'f cleaning dust and foreign particfes from erectrical
5s' fiJg[l'-3it3'tn
conductor ttrat makes ere*rical contact rvirh a wiring conduit isA. reading of 1.0 on the pclwer factor meterB. totafry dark switchboard ground-detecting fightC. low iwitchboarO-*lttrrter readingD. high switchboarcJ wattmeter ,*rJing
60' what statement is true concernincr the cleanirrg of contacts?A' deficate parts shoulcl be cleatrecJ with a brush and an approved safety sofventB' compressed air sfrourd he ,r*o to brow out metarfic dustc' the contact surlaces shoulcj ne greased to increase contact resistanceD. magnetic brushes shourd be ,irJ,r to ,'rr,,ouu nietailic dust
61 . What is the preferred methocJequipment?
A. wipingB. cleaning sofvent
r-
D .cor,'lpressed airvacuum s l rc t ien
62. Sparking at the brushes of a runninq motor coulcj be an indication afA. flofn",?l operationB. increased brush capacfty fr fljl$rrfinifflonl,,nn
63' what is the overall result of increa:;.rrcl the roar] orr the seconc]a ry ofa transformer?A. decreaset in the pr i rnary curref l tB. decrease in the primary voltageC. increase in the jr imary vr:ftageD. increase in tfre primary r:rlrrerrrl
1 3 3
6 4 . W h a t i s t l r e p r o c e s s o f r e v e r s i n g t h e d i r e c t i c l r r o fa s t h e c o m m u t a t o r s e g m e n t s t o w | r i c | r t h e c o i l i scal led?
the current in an armature coil
connected Pass undeq a brush
rtr{r{f{r{h{
d{
{
A. dynamic excitation C' c;onttrutation
B. artnature react ion U ' s l iP
65. Trre air gap in i .cJuct ion motor.s srrourd be checl<ecl per iodical ly
to guard against an uneqrtal air gap and
A. increased Power factor
B . d e c r e a s e d m o t o r n r a g n e t i z i r r g c u r r e n tC. lrYsteresis losesD" meclranical darnage to the rotor
66. whictr is a funct ion of vortage regurators used with Ac generators?
A . t o c u t i n g e n e r a t o r s a u t o n r a t i c a l l y a S t l r e y a r e n e e d e dB. to div ide the KW roao equal ly between generators operat ing in paral le l
C, to cut out generators when they are no |onger needed
D. to crivide reactive current between generators operating in parallel
\
wi th a feeler gaugeIl
67 , When ' r megger insulat ion tester
meter Pointer wil l diP toward zero
value i f the motor insulat ion is
is being used on a direct currert t machine' thg
and then gradually rise tc the true resistance
gooci D " grounded
temPerature of an electrolYte?
A. alcohol thermqpeter G' mercury thermometer
B. thermocouple pyrometer D' potent iometer
6 9 . V o | t a g e f a i l u r e o f a n A C g e n e r a t o r t n a y b e c a t t . ; e d b y
A. a triPPed bus circuit breaker
B. excessive Prime mover sPeed
C. tailure of the exciter generator
D. high mica segments on the stator hrus bar
T O , W h y a r e t r a n s f o r m e r a b o a r d s h i p u s e d w i t | i A C ' q e n e r a t o r s ?
A. to decrease Power outPut
B. to increase Power outPut
c . t o p e r m i t h i g h e r v o | t a g e f o r m o t o r o p e r a t i o n a n d l o w v o | t a g e f o rD to change frequencY
71" when a battery is cont inuously exposecl to low temperatures' the
to keeP it from freezing is to:
A. shorted B" d i r tY C '
68. What s irould be used to tneasure tne
A. disconnect the batteryB. remove the battery caPS
C. furl lY charge tlre batterY
D. securelY cover t 'he battery
qIqIqIl ighting circuits
best Procedure
1 3 4
72 ' A three-phase, squirrel-cage, incjuct ion motor could rLtn hot due to alan
A. high power factor
73.
B. reversed commutat ino oolrrC. improper 6rush posit i-onD. shorted stator
The reversal of an AC,3-phase i rrc luct ion motor is accornpl ished bv:
A. changing al l three motor leaclsB. interchanging any two of the three motor leads9 reversing the posi t ion of the sl ip r ingsD. interchanging any two brushes
Brushes in a generator must be posi t iorred in the neutral plane to avoid sparkl ingbetween the brushes and the
74.
7 5 .
A. commutatorB. yoke
The cycles per seconJ of t i reboat are determined by
A. current decreasesB. current increases
Electr ic current is thecal led:
A. voltageB. antperage
C" f ie td po le wind ingsD " armature windings
al tcnrat ing clrrrent f rom the al ternator aboard vor.rr
C. cu rrent remains the sameD. current increases by the square
A. the resistance appl ied to i l re f i led rheostatB. the adjustments made to the rol tage regulatorc. the speed of the engine dr iv ing i l re arternatorD. the synchronous speed of i r rcJuct ion
Seconro EruclrurEn
1 ' what happens in a series circuit when the voltage rernains constant ancJ the resistanceincreases?\
2"
J ,
The magnet ic f ie ld arouncl a cut-rent,carr i r ipg wire:
A. exists at al l points along t l re l r : r rgi l r of t l re wireI is paral le l to the current f lorru in ine conrJuctorC. moves in the direction c,rf current f lowD. exists only at the beginning of electron rnovement
f low of e lect rons throrrgh a conductor . Tlr is is commonly
t l . coulornbsD. res is iance
1 3 5
4 . One megohm is equal to:
A. 1,000,CI00 ohnrs C' '100'000 ohms
B. 10,000 ohms D' I '000 olrms
A multiconcjuctor cable:
A. has a number of sepat'ate circuits
B' is a singie 'i"uit ca'ote contpt"o6 of a trutnber of strands
c. ii a ttexiute cable to carry motor current
D. is a sPecial heating conductor
l r r D . C . e i r c u i t s , p . ) w e r i s e x p r e s s e c J a s t | t e p r o c l u r c t o f :
A. volts and amperes C' volts and coulombs
B. ohms and amperes D' amperes and coulombs
5 .
6 .
7. A mil is:
A. 1/1 0 inchesB. 1 /1 00 inches
8. One l<ilowatt is equal to:
A. 1"34 horsePoviterB. 1.25 horsePower
1 1 .
C. 1/1 ,000 inchesD. 1/1 ,000,000 inches
C. 1.50 horsePowerD. 2.00 horsePower
9 . Defects in wiring which permit current of junrp trom one wirer to another before
the intende{ puin has besn completocj ars callad:
A" grounds B' shorts 0' opens D' breaks
which of the following is not a gootJ conductor of elelctricity?
A. mica B' copper O' s i lver D' raluminum
One horsePower equals:
1 0 .
i"Iii'rii,r l l
Iifiillili'iliil1il1$l:g!fIil',!lra
A. 1 ,000 watts B' '746 watts 0' 100 watts D' 94C vratts
rz. An instrument often used to checr< the degree of mot.r shaft misalignment is the
A. VoltmeterB. ClamP-on ammeterC. GrowlerD. MegohmmeterE. Dial indicator '
136
13. The electrical power is kilowatts used by a 220 volt motor drawing 15 amps is:
A. 3.3 B. 3.6 C. 3.8 D. 4.0
14. A horseshoe magnet has:
A" two potes C. four polesB. three poles D. one pole
15. Retentivig is the power a metal has to retain:
A. the current in a circuitB. magnetic lines of forceC. electron flow within tlre circuitD. electricity when moving at high speeds
16. When selecfing the size of wire to [:e used in a circuit, the most important itemto consider is the:
A. amperage of the circuit C. resistance of the circuitB. voltage of thc cil 'cuit D" amount of wire to be used
17 " lf a wire is increased in circular rnils.
A. its sizo is larger in diameterB. its resistance is fower per focltC. its size is smaller in diameterD . A a n d BE . B a n d C
18. The following formr:la is used lo compute power:
A . P = l 2 R \ C " p = F _ 2 F - lB . P = R 2 E D . P = E + R
19. High vol tage and low current gain are character is t ics of the:
A. common base c i rcu i t 0 . contmon col lector c i rcu i tB. common emitter circuit D" boi lr A and C
20. Which of the fo l lowing statenrenis is t r t re?
A. l ike poles repel each other C" unl i lce ; ro le repel each otherB. l ike poles at t ract each ot l rc , t ) . none of the abovt :
21 . How is a lead-ac id ce l l tested ' i
A. hydrometerB. hygrometer
( ) . l rogornetert l . r regornr : ter
1 3 7
I
22. A 24-volt lead-acid storage batteni cr:rtsists of"
IIII
A. 12 ce l l sB. 6 ce l ls
(. ; Ll cel lsl - ) . r t0ne of the above
O. arnmeterD. potet t t iorneter
C. An OpenD. Al l of the above
C, carbon monoxideD. carbon dioxide
23, l f the charging rate to i l battery wi ls tor. t t r igh, i t would:
A. increase the terrninal vol tageB. increase the sPeci f ic gravi tYC. increase the rate of hydrogen l iberatronD" decrease the ternt i r ral vol tage
24. In a 12-vo l t bat tery t l re lo i t re l tOw r i ' la r ly 9 l ; l l s?
A. 6 B. 4 c. ' ;). D' B
ZS. lf the specif ic gravity clf er l2-volt L-rattery i i t 800 is 1.225, t lre battery is:
A" dead C. shortedB. ful ly charged Li . part ia l ly charged
?_6. The state of charge of a nickel-cadrniurn battery is detei 'mined by the use
of alan
27. The ohysicat s ize of a resistor that c leterrnines the abi l i ty of the resistor to
abslrb heatr is rated in :
A. Ohms B ' Vol ts C' Watts D ' Farads
28. A c i rcu i t that has in f in i te res is tance is ca l led circui t .
A. vol tmeterB . hyd ro mete r
A. A shortB. A ground
A. chlor ine gasB. ni t rogen gas
29. Whart determines the vottage of a lead-aci f l cel l?
A. the type of electrolyte c; . the size of the plates
B. the strength of the electrolyte D' rrone of the above
30. sal t water in contact wi th storage batter ies wi l l develop:
1 3 8
31' Which stiatement is true.concsrning the maintenance of solid-silver contacts in ,rly,and auxiliary control circuits?
A' When nqcessary, they should always be dressed with a wire wheelB' They should be filed with a fine-cut file when pro.lections extend beyond thecontact surfaceC' When btacksilveroxide is present, it should always be removed from the contactsurface with coarse sandpaperD' lf necessary, they should be held together with m,cderate pressure while emerypaper is drawn between the contacts
32' Whlle you are starting a maln propulsion synchronous motor as an induction motor,the ampere meter pegs out at maximum and then returns to the proper value aftersynchronization. This means the:
A. ntotor has start,ad properlyB. fiefd wlndings are grounOeOC. slip rings are dirtyD. power transmisslon cables are grounded
33' The purpose of a short circuit forcing module (short time trip) instalted in a branchline is to provide:
A' high speed clearance of tow impedance short circuits in the branchB' continulty of sen'ice on main bus under short circuit condition in a branchc' lsolatio4 of short circuits by selective tripping of branch circuit breakersD. all of the above
34. Efectrolyte in a nickel-cadmium battery is:
A. potiassium hydroxideB. suffuric acid zC. slip rings ars dirty
A soft iron core with wire coiled around it and direct current passing through thewire is the description of a simple:
A. magnetic shieldB. electromagnet
To properly use a hook-on-voltFIRST:
35.
36.
A' hook the Jaws of the instrument around the insulated conductorB' de-energlze the clrcult to allow connection of the instrument in seriesc. connect the vortage test reacJs to the appropriate terminafsD. short the test teacjs and caribrate tne instrument to zero
C. piezoetectric deviceD. electromagnet ic domain
amnreter when checking current f low, you must
1 3 9
37 , Autotransformer starters or compensators are sometimes used with, polyphaseinductlon motors to:
A. reduce the voltage applied to the motor during the starting periodB. increase the voltage for "across the line starting"C. provide a back-up means of voltage regulation for emergency startingD. allow the voltagr to be either stepped up or down depcnding on the application
to ensure full torque
38. A magnetic blou,out could in a DC contactor function to:
A. prevent contact meltingB. open contact rapidlyC. adjust opening sprilrg tensionD. provide "srrap-action" in the contactor
39. In an AC synchronous motor Turbo electric power plant, propeller speed is controlledby varying the:
A. turlrine speedB. electric coupling field strengthC. number of energized main motor polesD, propulsion generator field strength
40. A molded-case breaker provides protection
{
IIIIIIIIIII
41 "
against short circuits by using alan:
shading coilholding coi l
A. electromagnetB. arc quencher
The method used to produce electron
A. photoelectric'B. secondary
A microprocessor is:
emission in most vacuum tubes is:
C. cold cathodsD. thermionic
C. vibrationD. all cf the above
C.D.
42"
43.
44.
A. Another name for a computer C. A name for a calculatorB. A CPU integrated circuit D. A small scale integrated circuit
What device measures pressure and converts it into an electrical signal?
A. transducer C. transfbrmerB. reducer D. rectifiel'
Grounds found in electrical maclrinery due to insulation failure are usually causedby:
A. deterioration due to ageB. excessive heat
140
C.D.
IIIII
45' The amount of v-oltage induced in ttre windings of an AC generator depends on:
A. the number o conductors in series per windingB' the speed at which the magnetic t ieio passes
".ros the wincJing
C. the strength of ' the
magnetic t ielfD. all of the above
46. The type of motor that usescalled a:
A. wound-rotor inductionB. regenerative braking
47 .
4 8 .
49.
50 .
a rheostat in the rotor circuit to vary the speed is
C. amperesD" vo l ts
capacitors on the output of the power suppfie.s
squirrel-cage inductionsynchronous
A motor controller contains three push buttons labeled,,start,,, ,,jog,,and,,stop,,. whenthe jog button is pushed, the motor:
A. will run continuously after the ,,jog" button is releasedB. wil l run unti l the ,Jog, ' button is releasedc. cannot start until both the 'Jog" and "start" buttons are pushedD. cannot stop unless the "stop"-button is pushecJ
which of the following precatrtions should you take when securing propulsiongenerators and motors for an extended period of time?
A' Lift the brushes from commutator collector rings and use the built-in heaterto prevent moisture accumulationB' Disconnect.the brush pigtails frorn their contacts and discharge carbon dioxideinto the units to keep them dryc' Disconnect the brush pigtails from their contacts and circutate air through theunitsD' Lift the brushes from conrmutator or collector rings and circulate cool dry airthrough the units
Non-adjustable tolorJ case circuit breakers are classified by frame size, ampererating and interrupting capacity. l 'he frame size is expressed in:
A. degrees cent igradeB -.circular mils
What is the purpose of theused in today's consotes?
A. They f i l ter out r ippleB. They act as a permanent loadC. They prevent overloacJsD. They increase the output f requency
1 4 1
nS1. Autornatic v0ltage rergirl*lrnri ,r i l UL {.tr}hti)r ittol 's cJetec;t voltage change$ and adjust
5?.
53.
the
A. speed of t l ts Pr i t l tu l i i t r l r r l
B. resistance rrf t l tet i t t t t t i lLtt te;
What condition irr,.Jicatcl (r ';) t lr; 'r i ;r k:rlr l-t 'rt; ir l t. lattery is being charged too quickly?
A . u n u s u a l l y l r i g h e l 8 < ; l r ' i i i i r i ' : ' ; t ' t " r : : i i i r : 1 l 1 i ' | r r i { 1 '
B. low Plate 1:otentialsiC. spark ing a t t l r0 5 ;ou i i i ' ' ' ' . . r r i I i r i ' t !
D . gxcgss ivg tgmpg l f l l l l i ' t : r , , . l l l l i : x r ; { r l l : ' ; i r r r r i J i l ss i f l0
H O W S I t O U I C J t l f e S l t t t t t t 9 l r i { , r i i i i l r i : i r l r l i t , r r r i l ) l i f l e C t e d ' ?
A. In paf al te l nr i t t r t l r r . : l r : , i i i . r i r , , r i t r ; r ; t , r r iu l ; vvi t l . I thre ntetef mOVement
ts. In paral le l wi t l r t l ts l ( ) ; t ( i i . r i r r j i i r p i l ia l lc l wi t l r t t re meter movement
C. In $er ie$ vv i th t l re l t , i r r l i l r r r t l r r 1 :a ra l le l r rv i th t l re meter movement
D. In Ser ieS w i t l t t l r s l i . , ; t t j i t l r t l i t t l " : c r i c ;s w i t l t meter mOvement
54" Chattering of cr:l lsctur r i lrg l. i i r rslrer; oi r a (lt lnerator may b(} remedied by
A. reinsulat ing t t te brt ts l rosB. lubricating bruslt holclers
. \(;" centertap of the balance coilU. r 'esistance in the field circuit
O. cleaning the collector ringsD. increasing length of Pi$tail
55. When an alternator goverfri;r ' r.:orrtrri l switclt is nloved to "raise", this wil l l
A. lower the percentags 0{ slreeel t irtr i t corrtrol
B. lower the no-load slrcud :;eti i t tg of the governor
c. raise tlre no-load setting of t l to goverrrol
D. raise the percentage of freqtrency cvcle
s6. when you sse a rnegolr ; rreier to tur; t insrt l i r t ion, good insulat ion wi l i l be incl icated
by:
A. a downward dip foltowed t-ry a graclual clirnb to the true resistance value
B. the init ial diP of t lre 1>ointerC. sl ight kicks of the rteedle cJowt't scale
D. a gradual r ise in the poi l r ter readincl at t l te outset
57. when electrical cables pass througlt watertight bulkheads'
A. A 'vatertight stuff ing tube capable of t i l l<ing packing should
B. they musi be bent to a rac1ius of six diameters
C. they should be secttred by a clarnp
D. t l-,ey should be grounded on either side of the bulkhead
be ernploYed
142
IIII
58. The force thaticauses free efectrons to urove ilr a corrriuctor as an electric currentis called force.
A. die-electr icB. an electromitiue
59. The resistance in erectr icar wir ing rJr:c;ruase as i r rc;rease inA temperature 0. rnetal i lrrrrr lr i t iesB. cross sect ional arei i i t . lenoi l r
What is the first step in removittc, i :r gorrerator f rorl parallel operation?A. remove the load from the ol . t c lo irrg qcrrr , rr t lorB. tr ip the generator off the switr:hf:oarriC. turn off all electrica, equipnrelr rtD' increase the cycles of the qoncr.rr t r l r st l , rTrrrr . r { )n t t rc l ine
60.
Cnrrr ETcINEER
A standard wir :e is given the sl i r r r tA,,?oss.sect ional areaB. weight per foot
wi re i f i t has the same:
2. Counter e fec t romot ive force is nr t , r ; r r ; r l ' r l i i r :
( ; ; : t t f i l ) l j
i ) l . l r i l r , i r i ,
3' , t ' f : t :1,nt i t : , : : i l ," ' ; i i l9
oorrr i l i ' } i i r , , ' ' r)" frrr ' : i111rri .r i vorrasc is dorrbred, current
'4t .
A/-voltsB . ohms
A,r doubleB. remain t f re same
4" The resistance of a copper ur i r r ;
C. resistarrcr:n. inducf ive
i i , ; , l i \ , , i , i t , : r l 1 , , , , l r y i ri l i , l l ' J r r u t r l r ) l , t r i o l t t
l , l i i i , : l i r , r , ' . , n l , r l r , . : l i i < : i t y :
, ( \ l \ / { j l { ) i l l t l l i t ) i , l r l ( r , i
' , f l , r t i r r i r t c t i l r y l lj r t i r r r i r t l r : ; I
A{ncreases as i lre lenotfr olB. decreases as i l re diJmeterC. decreases as thei lengt l r ofD. increases as the cl ianreter
l\ Which o f the fo l l ow ing f o rn . ru i i t s wr r r i l r ,
A . R d iv ided by EB . R t i m e s E
1 4 3
I
tnhqhqhftl,I'lIt, lIIII
o . which of the fol lowing expression correctly states
A, volts equal amps time.s resistance
;hilt ebuar volts divided by resistatrce
C. resistance equals volts divided by amps
Ohm's Law?
D. alt of the above correct
7. ln a pararer c ircui t which of t r re fortowing is the sane throughout the circui t?
A. imPenoance C' vol tage
B . c u r r e n t e r r v v D ' r e s i s t a n c e
B. When using Ohm's Law' E div ided by R would solve tor:
A,/ampelage c ' resistance
B. voltage D' watts
9. When using Ohm's Law' E div ided by I would solve for:
A. amperage C/resistance
B" voltage D' watts
10" A wi re gauge is used to measure:
aGize of wire C' current carrying capacity
B" insulat ion value D' tensi le strength
11. The uni t of electr ical current f low is the :
aA./amp B. volt C' watt D' ohm
12. The unit of the electrical resistance is the:
e6frm B' watt ' C' volt D' amp
13. Volts t imes amPS equals:
A. ki lowatts B'lwatts C' ohms D' watt-hours
14. The uni t of electr ical pressure is the:
RJvott B' am C' watt D' ohm
15 . | f t he tempera tu reva r i esw i t hsuchconduc to rsaE ,coppe r 'of the following statements is correct:
A. as temperature increases' resistance increases
B. u, trt[u'"t"t decreases' resi$tance decreases
C. a, trtbtttt"t increases' resistance decreases
D. temperature has no effect on resistance
144
si lver, and aluminum, which
1 6 . A circuit th'at does not provide a' complete path for the flow of current is:
an open circuit C. as series circuita closed oircuit D. a grounded circuita series of circuit the total current is:
Ar'B .
1 7 . l n
A. the same as that of the largest branch circuitBfthe same throughout al l parts of the circuitc. the same as that of the smallest branch circuitD. none of the above
18. stat ic electr ici ty is most often produced by:
19. The total resistance of a parral lel l circuit is always:
A' larger than that of the branch with the greatest resistanceB equal to the sum of the rndividuat oranJh resistanceC' equal to the reciprocal of the sum of the individual branchD' smaller than that of the branch with the lowest resistance
20. Dielectric strength is the:
A abi l i ty of the insulator to withstand a potential dif ference? ability of a conductor to carry large amounts of currentC. opposite of potential differenceD. strength of a magnetic f ield
21' Ir:hiTifrtil|t.of
a circuit is cloubled and the applied voltase kept constant, the
A. heatB. pressure
A. doubledB. quadrupled
A. quadrupledB. halved
C" magnetismD. friction
C. the sameD. cut in ha l f
C. doubledD. quarterecl
is reduced to one-22' ff the length of a wire is doubled and tlre cross-sectionaf areahalf , the change in resistance wi l l be:
23. The purF,|ose of a rectifier is to:
A. change A.C. to D,C.B. change D.C. to A.C.9 change the frequency of A. C. currentD" change the voltage of D. C. currenr
1 4 5
24. Which is the smal lest diameter wire?
A.4B B . 1 0 c . 6
25. ln a D.C, ser ies c i rcu i t , a l l t l ie
A. power exPanded in themB" vol tage droP across thel t t
26. An increase in current:
A. increases tetnPeratureB. decreases temPerature
27 . The horse power of an 1 ,800
D . 4
C. natural magnetD. so l id magnet
the magnet ism:
conductors have the sarne:
C. resistance to t lre f low of currentD. current Passlng through them
C. has no effect on temPeratureD" wi l l double the temPerature
(ki lowatt) motor is:
D. 2,421 ,
I
I
I
A. 1 ,800 t3 . 2 ,142 c . 2 ,412
28. Soft i ron is the most sui table for use in a:
A. temporary magnetB. permanent n tagnet
29" Res idua l maqnet ism is
A. in a f ie ld co i lB" in the motorC. remaining in a substance after i t has been removed from a magnet ic f ie ldD. ga ined in conver t ing D.C. to A. C.
30. Magnet ic f lux is best insu la ted by:
A. ceramicB. cambricC. rubber
31. A semi-conductor that decreases inknown as a:
A. resistorB. thermis tor
D. porcelainE. impossible to insulate
a resistance with an increase in temperatureis
C. d iodeD. thermopi ie
32. The shunt of anrmeter should be connected in:
A. ser ies with the load in paral le l wi th the meter movement
B. paral le l wi th the load and in ser ies with the meter movement
C. parallel with the load and in parallel with the meter movementD. ser ies with the load and in ser ies with the meter movement
1 4 6
34. An operating characteristics which appears on the name plates of shipboard AC motorsis :
33. Brushless generators operate
A. brushesB. sl ip r ings
A. temperature riseB. Input kilowatts
35. Low horsepower polyphase inductionmeans of :
A. compensatorB. autotransformer
I , t
l l 1'. , '
without the use of:
C.4ommutatorsD. all o f the above
C. the type of windingD. locked rotor torque
Imotors can be started with full l ine voltage by
C. across-the-l ineD. primary-resistor
36. What i tem is normally instal led on a large turbine electr ic propulsion alternating currentgenerator?
A. temperature detector coi ls inserted in the stator slots for measuring statortemperature
B. A CO2 f ire extinguisher systemC. electr ic space heaters to preventD. al l of the above
condensation of moisture
37. What type of battery charging circuit is used to maintain a wet cell lead-acid storagebattery in a ful ly charged state over long periods of disuse?
A. normal charging circui t C. tr ickle charging circuitB. quick charging circuit D. high ampere charging circuit
38. A ground can be defined as an electr ical connection between the wir ing of a motorand i ts:
A. metal framework C. shunt f ieldB. circuit breaker D. interpole
39. External shunt are sometimes used with ammeters to:
A. increase rneter sensit ivi tyB. permits s[unts with larger resistance to be ut i l izedC. prevent damage to the meter movement from heat generated by the shuntD. enable the construction of a compact meter vr i th a virtual ly unl imited range
40. The output voltage of a 440, 60 hertz, AC generator is conirol led by' the:
A. exci ter output vol tageB . pr ive move r speed
C. load on the alternatorD. number o f po les
147
41 . Any electr ic motor can be constructed to be:
A. short B. ground C. exPlos ior D, overload
42. what is the main difference between a relay and a contractor'/
A. contractors can handle lreavier loads thatt relays'
B. A relay is series connectecJ; a contractor is parallel connected'
c. contractors control current; relays control vol tage'
D. contractors are made from si lver; retays are made from copper '
43. Which of the fol lowing is t rue concerning a polyphase synchronous propulsion motor?
A. The motor is started as an induct ion motor.B. Resistance is gradually added to the rotor circuit '
C. The start ing current is held beiow the rated current 'D. The f ie ld winding is energized for stetr t ing purposes only.
44" Where a thermal-act ing breaker must be used in an area of usual ly high' low, or
f luctuat ing temperatures, an ambient compe,rs?t ing element must be used consist ing
d , "
A. second b imeta l e lementB" conical spr ing on the contact arrnC. cyl indr ical spr ing on the contact arm
D, second electromagnet
43" What eou'd be an appl icat ion for a s i l icon control led rect i l ier?
A. to provide power for a main propulsion motor
B" for use as a vol tage reference Ciode
C. f or sensing \ lame is an automated bu rner
D. to et iminate oowel suPPlY hum
46" When using an ohnrmeter to ident i fy
A" zeroB. in f in i te
47. An accidental path of low resistanceis known as alan:
A. open circu i tB. short c i rcui t
a short, the ohmmeter reading should indicate:
C. 100 k i lohms.D. 1 megohm
which passe._ .r abnormal amount of current.
48. An unknown resistance in a circui t is to
meters should be connected such that:
po lar ized groundground reference Point
be tested using the 'roltmeter method' The
D .
A. the ammeter is in ser ies and vol tmeter is in paral le l wi th the resistance
B. both meters are in paral le l wi th the resistance
c" both meters are in ser ies wit f t the resistance
D. the ammeter is in paral le l and the vol tmeter is in ser ies
r { 8
with the resistancP
49. How is the Dc output obtained from a brushress exci ter?A. f rom coi lector r ings mounted on the armatureB' f rom the'semiconductor rect i f ier mounted on the exci terc. direci lyr f rom the commutator by indicat ionD. f rom a semiconcuctor rect i f ier mounted on the stator
armatu re
50. lnof
A.B .
general, polyphase induction motors can be started on full l ine vo l rage by meansstarter,s:
C " compensatorD. primary-resistor
51. The speed ro f a synchronous motor is var ied by:A. changing the vol tage of the systemB. changing the input f requencyc. interchanging any two of the three r ive readsD. increasing the f ie ld exci tat ion.
52. The frequency of an AC generator is adjuster l by means of the.A' equal iz ing reactor, c. main al ternator f i les rheostatB' exci ter f ie ld rheostat D. pr ime mover governor control
53' The true power indicated by the pointer moveinent of a wattmeter depends on thecurrent through the load, the magni tude o f the potent ia l across the load and the:A. power factor of the load c" inert ia of the movable coi lB" angle of coi l d ispr lsssment D. high resistance from the load.
54' H:?!rrt#'tl,"'tJ,,ilr!f;t'otncv
switchboard suppries power ror ararm sisnars under
A. the 120 vo l t , 3 phase,B. the generator ano busC. the 450 vo l t , 60 cyc le ,D. the 24 vo l t , DC bus
55. Which insulat ion rry i l l beginconductor i t sur rounds?
A. vanrshed c lo thesB. asbestors
across-the-l ineau totransf ormer
56. Which cou ld you use to
A. vol tmeterB. rnu l t imetbr
60 cycle bustransfer sect lon3 phase bus
to deter iorate f i rst as a resul t of heat generated in the
C. ru bberD. s i l i con
locate a grounded f iercj coir in a synchronous motor?C. f requency meterD. megohmeter
1 4 9
i.liil1il
iii i ,
1i
s7 . when the operating h,andle of a morded-case circuit breaker is in thei mid-position
it indicates inat tne 'i"u-if oieaFer is: ,
' \
A. of f B' on C' triP D' reset
5g. A miriameter with a fu* scale defrection reading of 1.00 milliampe.les has an accuracy
of + or -z%.A mete*u"lY,,ig-o]io muriam}reJwould-inJitutt a line current between:
A. 9.8 and 1O'2 mil l iamperes C' 9'8 10'0 mil l iamperes
B' 8"0 and 10,0 mil l iamperes ;: B.c and 12.0 mil t iamperes ]
59, When the current ttrrough a copper wire increases' its
A. temperature will increase C' insulation will burn
B. conductivity will increase D' resistance will decrease
60. which type of flux should be used when soldering wire connection?
A. Rosin f lux C" Acid f lux
B, Sol id f lux D' Si lver l lux
61" when praced in a magnetic tield, what material will have the highest permeability?
A srass 3: 3:llil'JB. bakelite
6 2 " A s h o r e p o w e r c i r c u i t b r e a k e r s h o u l d b e c l o s e d o n l y
A" in a shipyard . L - . .^ r ranr" , rorn^VAq from thg bus
B . w h e n t h e s h i p . s g e n e r a t o r s l a v e b e e n r e m o v e s f r o m t h ec" when the ship.s [enerato|,-:,I.uu been para||e|ed to those on shore
D. it 'a quicktisconiect coupling is used
63. whicn meter uses a shunt connected in series with the load and parallel with the
meter movement?
A" Power factor meter C' voltmeter
B. ammeter D' wattmeter
64. when using an ohmmeter to test a diode, you find a row resistance in both the lorward
and revers-e bias directions'
A. open diode--^n nrra,irv 3: !:%Tlri.',ilHff;o''.n
6s ?;, ;ffi::Ttili#?::: power reray in ship's service arternator paner is to trip
circuit in the event of
A. alternator motorization C' high power o'/erspeeding
B. main circuit overload D' geneiator overspeeding
66" An internar resistance wourd be praced in series with the meter movement of which
instrument?
A. AC ammeterB. main circuit overload
150
C, DC voltmeter !
D. generator cversPeeding
49' How is the DC output obtained from a brushless exci te r?A. f rom coi lector r ings mounted on the armatureB' f rom th+ semiconluctor rect i f ier mounted on the exci ter armaturec. direcily: from the commutator by indicationD. f rom a semiconductor rect i f ier mounted on the stator
50. In genera l ,of
polyphase induction motors can be started on furll ine vo l (age by meansstarters:
C" compensatorD. primary-resistor
51 ' The speed 'o f a synchronous motor is var ied by:A. changipg the vo l tage o f the systemB. changing the input f requencyc. interch'anging any two of the three r ive readsD. increaging the f ie ld exci tat ion.
52. The frequency of an AC generator is adjusteci by means of the:A' equal iz ing reactor^^ main al ternator f i les rheostatB. exci ter: f ie ld rheostat D. pr ime rou., governor control
53' The true power indicated by the pointer moveinent of a wattmeter depends on thecurrent through the load, the magni tude o f the potent ia l across the load and the:A. power factor of the load C, inert ia of the movable coi lB' angre of coir disprracement D" high resistance from the road.
54' ff|?!rr?}t'il,,iJ,uTr!f;t'o"ncv switchboard suppries power ror ararm sisnars under
A. across-the-l ineB. au totransf ormer
A. the 120 vo l t , 3 phase,B. the generator ano busC. the 450 vo l t , 60 cyc le ,D. the 24 vo l t , DC bus
55. Which insulat ion rry i l l beginconductor i t sur rounds?
A. vanrshed clothesB. asbestots
56. Which cou ld you use to
A. vol tmeterB. mul t imeter
60 cycle bustransfer sect ion3 phase bus
to deter iorate f i rst as a resul t of heat generated in the
C. rubberD . s i l i con
rocate a grounded f ie lc l coi l in a synchronous motor?C. f requency meterD. megohmeter
1 4 9
of a molded-case circuit tlreaker
breaker is:
is in thei mid-Position
57 . When the operating h,aldle
it indicates inat the circuit
A. of f B' on C' t r iP
58. A mil l iameter with a full scale detlection reading
of + or -2o/o'A meter reading ol 10 milliamperes
A. 9.8 and 10'2 mi l l iamPeres C' 9 '8
B. 8.0 and 10'0 mi l l iamPeres D' B'C
instrument?
A. AC ammeterB. main circuit overload
150
D. reset
of 100 milliamperes has an accuracy
would indicare a line current between:
10.0 mill iamPeresand 12.0 miltiamPeres l
C, DC voltmeter !
D. generator cversPeeding
59. When the current tfrrough a copper wire increases' its
A. temperature wil l increase C' insulation wil l burn
B. conductivity wil l increase D' resistance wil l decrease i
6 0 . W h i c h t y p e o f f | u x s h o u l d b e u s e d w h e n s o l d e r i n g w i r e c o n n e c t i o n ?
A. Rosin f lux C" Acid
" '* ,B. Sol id f lux
D" Si lver f lux
61" when praced in a magnetic t ierd, what material wil l have the trighest permeabil i ty?
A srass 3: SLiiI|HJB " bakelite
6 2 . A s h o r e p o w e r c i r c u i t b r e a k e r s h o u l d b e c | o s e d o n l y
i. llni.'l,lrt?"lo'' senerato': li:.: P::: '"'*iH:"J1'JtJle busc, when the ship,s fienerator:,l.ui 6il paralleled to those on shore
D" if i quicx ctisconilect coupling is used
63" which meter uses a shunt connected in series with the load and parallel with the
meter movement?
A" Power factor meter C' voltmeter
B. ammeter D" wattmeter
64. when using an ohmmeter to test a diode, you find a low resistance in both the forward
and reversL bias directions'
A. open diode-- ^ nrra,irv 3. lfl.ryH.,i;fiffit''n
65 ?;, :::,1,::':?ilT:?:y. power rerav in ship's service arternator paner is to trip
circuit in the event of
A. alternator motorization C' high power o'/erspeeding
B. main circuit overload D' generator overspeeding
66" An internar resistance would be praced in series with the meter movement of which
IIII
tIIIIlI
I
tIIItIIlIIIl
PART III
STEATVI BOILERS, ENGINES,TURBINES, INTERNAL COMBUSTION
ENGINE.
THEORY, OPERATIONSAND MAINTENANCE
1 5 1
*ihi
I
t{htH
I
tJI
J
STEAM BOILERS
o .Wha ta re the two typeso |bo l | e rbaseon the l rwo rk lngp r l nc |p l e?
Frre tube - consist of rarge tubes i::ry pressure l:-ling
plants Td lht product
of combustion p"rr-thror.rgh the rnsif,e of the tuorr,?[J outstoe the tubes is
sorrounded bY water'
water tube - constructed ry.ith .Til tubes and etficient production of higher
steam pressure, *n.ru the wate, ir-.ont"ined insioe the tubes, with product
of combustion p"tri^g around the outside of the tubes'
A. USE OF STEAM ON MOTOR VESSEL
1" Heating duties: ME Fuer oil hea.ter, purifier.heater, oil tank heating' cargo
neatinJ, Rir conditioning and.heating'pi;i, caroriti.i, cuttty supply' sea-chests'
tt".ttTin" tot pipeline heating' etc'
2. Run Turbine Qenerators
3. Run 'Jargo pump turbines in Tankers
4 .D r i r , es teamdr i vendeckmach ine r i es l i kew inches ,e t c .
5 .Ope ra teb i l ge ' s t r i pp ingando the rs teamdr i venpumps
6 .Dr i vebo i l e r i eedpun . | p tu rb ines
7 . Evaporator/Frcsh water generator heating media
8. Tank washing in tanker ships and general cleaning
g .Fo rbo i l e rSoo tb low ingand fo r t hes teama tom isedbu rne rs
10. Fire f ighting as used in steam smothering system
11. Main engine Jacket F.w. preheater and rub oii surnp ant, drain tanks
12 .Use in thewas teo i l ' i n c i ne ra to r ' s l op tanks
l 3 . U s e a s a s t e a m e j e c t o r m e d i a f o r e i e c t o r p u m p s a n d V a c u u m d e v i c e s
14. Main turbine propulsion ( lF Turbine ship) ' etc'
JJ
152
CLASSIFICATTON OF BOILERS
HeavyGasWater
lrlatrrral
f uef
BOILER TYPES
Main Boi ler - proput l ion of i l re vessc, l .
Aux i l ia ry Bo i le r - A ids the propu ls ion in sorne way; e .g . , heat ing o f heavy fue l o i l us ing asteam heater ' nec.essary toi propulsion would qual i fy tht 'supplying boi ler to be referred toas an auxi l iary boi ler.
ffiH,f,T'fi:tffJ:twtiich is used onlv ror the "hotet" needs of the ship; o.s., supptyinsTank Bol ler - Arboi ler wi th large water carrying capaci ty where the shel l is being used asthe pressure vessel . Most low pressure auxi l ia-ry b 'oi ler i wi l l come into this category.
Vert ical lEoi ler - Any boi ler where the shel l is upr ight and the furnace is usual ly containedwithin the shel l at the lower hal f .
Hor lzontal Boi ler - This is also referred to as cyl indr ical boi ler; here, the boi ler cyl indr icalshel l is ly ing across i ts length paral le l to the structure of the ship or i t t r grouhd l 'euer. --
Classif icationCrlteria
For Steam ships
High Capaci ty
100,000 kg/hr
For Motor Sh'ps Addit ionalInformation
Capaclty Low or lr,lediumCapacity1,000-5,000 kg/hr
Low Pressure6- 1 5 barsMedium Pressure17-30 barsCyl indr ical ,Vertical both ofTank rype or,D-lype on tankersAuxil iary Boi ler;Donkey boi lerl- ight Dieset,Heavy fuel, GasFiretube,Watertube
Units in tons/hrOI,kg/hour
High Pressure60 bars andabove
Low pr. on mostmotor vessels;Med. Pressureused on tankers
Drum Type,D-type Package, Tubular,
Coil type areother shapes forLow pr. units
Main PropulsionBoiler or Mn Blr
Assist PropulsionHotel Purpose
Coaf, Electric,Exhaust GasWorklng
Pr lnc lp le
Clrculat ionType l
Steam raisingmethod
NaturalForced
Tank & Drum;Exh Gas, Coil
1 5 3
Exhaust Gas Boller - Boiler operated by hot gas f rom engine or other exhaust gas sour@$
Drum Type Boller - Waier tube boilers employing steam and watbr drumq. Tllty are also
known as bent tube tYPe boilers.
package Boller - Fully automatic, low capacity boilers packaged inside a box type casing'
capable of quick steam proouction and trexinie'in oring positiirred anywhere; could be coil
type or firetube tyPe.
o. Glve the advantages and dlsadvantages of a Flretube
Advantages of Flretube Boller:
1 . Firetube boiler can uso impure water, without serious damage'
Z. They contain a large amount of waier'-{lg^9":not require ex-acting supervision
aS regards to wate? level. Also steam pressurs is steadier'
3. Their first cost is relatively low"4" They are accesible for maintenance's. Because fire is on tn. inside of boiler and is surrounded by water radiation losses
are lower.
Dlsadvantages of Flretube boiler:
1 " Because they contain a rarge amount of water, they require llolg interval ol time
to raise steam "nJ"rJ
noiflexibre as regards to cnahges in dteam demand'
2. They are most susceptibre to.erpiosion, ino in such as a case, the rarge volume
of escaping wateifllining into steam upon reacning the atmosphere might
cause serious damage to personnel'
g. High steam pressure would require extremely thick boiler plate,iand thus flretubo
bo*er are not uruliri ."J.orr of prooucing sieam at high pressure and tempora-
4. HtlS; require large entrance into the fire room because they are generally
riveieO in tne Ooiier snip and shippod in large. section'
5. T;i;;'rri.L..Vlriu* than thai of water tube boiler.
Advantages of watertube boller:1 . fn.i."n produce steam at high prossure and temperature'
2. They are very ffe'xible ",
,.g"ra, [o .n.nges in steam demand because of thelr
small volums of water'S .Permi tuseofnear rec |a imingdev icesandsoareveu 'yd i f fe ren t .4. Steam pressure ;ilil raisid in a relatively short timo'
5. They aie not liable to explosion'6. They are .rrr*UtrO iri the fiie room, and so large entrance into the fire
room are not required'
Dlsadvantages of water tube boiler:
,' T[:l T,1:\',::i'lf SXtSi;., supervision as resards to steam pressure and
temperature.Boilers must be heavily insulated to minimize radiation losses'
io t"rt repaiis on tu6tt, boilers must be emptied'iirst Jost ishigher than that ol scotch boilers. !
3.4.5 .
154
Medlum .Pressu re:Water tube,Drum Type
Lowpressure:PackageColl type,flre tube type
Low Pressure:Tank typeOll flred/Composlte
LowP ressu re:Erhaust gasForcedclrculatlon
TankerVessel
All types ofvessels
All Types ofvessels
All types ofvessels
Babcock &WilcoxM 1 1 , M 1 1 M
CochranChieftain
AalborgAQ3,AQg,AQ12AQs,AO2,AQ7
Aalborg AVseries
FosterWheeler D4
Steamblo: SunrodCPH,CPDB
SunrodPL,PT
CombustionEngineering
Stone-\'apou r OsakaHowden-Johnson
Kawasaki Clayton Hitachi ZosenHV
AalborgAT4, ATB
Miura VWS Span nerSwirlyflo
lH l : ADM-6 | lHt-cvCoch ran
Mitsubishi-MAC
Mitsubishi MC,MC-C
SOME EXAMPLES OF POPULAR BOTLER IN INDUSTRY
Llst of Bolfer M.ountings and Functlons of Each.SAFETY VALVE - Protects the shell or drum against excessive pressure from building upin a steam boiler, thus guarding the boifer from explosion.
MAIN STEAM STOP VALVE - Aliows steam to leave the boiler to go into the main steamline, and from there, to the main engine or turbine.
AUXILIARY STEAM STOP VALVE - Allows steam to leave the boiler to pass into theauxiliary steam line, and fl 'om there, to pumps, generators, and other auxiliaries.
WATER COLUMN - Provides a-stil l ing space so that its water tevel will not be greatlyaffected by pitching and rolling of the snip. Water irr ths column is cooler than that in theboilgr shell o-r drum. Thus, no ictual boiling takes place inthe column, and the water levelis more easily detected,
GAUGE GLAS$ - Attached to the water cotumn or to the drum and indicates the level ofthe water in the boiler.
1 5 5
TRy cocKs - attached to the shell or to the water column, and are used to prove the
ieading indicated by the gauge glass' ' ' t
suRFAcE BLow vALvE - Ailows ilght impurities, such as oil or greaste' to b'e blown off
ftot the surface of the water in the boiler'
BorToM BLow vALvE - Ailows sediment to be blown oft from the bottom of the boiler'
It also alrclws a rapid reduction of the water'tev.t o', a partial emptying of the boiler'
SALINoMETER COCK - Ailows a sample of water to be drawn off from boiler so that the
Jtntity of the water may be measured'
MAIN FEF-D-WATER srop VALVE - permits or prevents entrance of the feed water into
6.i f t i from the main feed-water l ine'
AuxlLlARy FEED-WATER srop vALvE- Has tlre same f unction as the main feed-water
stop valve, urt '[ located in the auxiliary feed-water line'
MArN FEED-*ATER cHEcK vALv E - Regurates,the,tl?* ot water into the boiler f rom the
main feed *ne and prevents waie,, in the boirEitror backinf up i. the main feed line in event
of failure of the main feed-water pump"
AUXIL IARYFEED-WATERcHEcKVALVE-Hasthesamefunc t ion las themain feed-water checkvarve, but is praced in the ur*il i irv feed-water line betweeri the auxiliary feed
stop and the auxiliary feed-water pttmp'
AIR vENT -Allows air to be released f rom the boiler prior to cutting in the boiler on the line'
and to break the vacuut *nln the boilers is being emptied'
wHlsTLE VALVE - Furnishes steam for the ship's whistle'
pRESSURE GAUGE - rndicates pressure being carried in the boiler.
FUSIBLE pLuG - Installed on scoth boiler use to give alarm when water became too low'
made of oionie and melt, steam passes activate alarm'
BELLY PLUG - Fitted on scotch boilers f or the purpose of allowing water to drain f rom ths
boilers into the bilges'
H'DRO'NETER VALVE - Found onry on gggrch-boilers, and supplies ste-a1 to the
hydrokineter, which i, urro to speed up'.ir.rtation and cause even i' leating of the boiler
when ttre iatier is started up from cold.
Q. What are ihe additional accessories of modern marlne boilers?
EcoNoMrzERs - An economizer is a boirer accessory that util izes-tfie heat in flue gases
to increase the temperalui, of feed *"t* before thatieed water enters the boiler drum'
rts consrruction either single loop o, .6niin*us roop tvi-e-*i*' y'eaoJr for expansion arrd
maintenance rePair'
156
Advantages:a) A saving in fuef from 5 to 1B percent resurts.b) Reduction in thermat shock- fne higher th.lurp.rature of feed water, the fess
[flf: ttre contraction stresses upon the injection of *ririinto tne hot steam
c) Increase in storage cPacitv. The^large quantity of water contained in an econo-mizer provides reserve space in the-evr'rf;i ; sudden boiler overtoad.Disadvantages:a) Original cost is highb) fncreased maintenance cos;tsc) Space occupied by the rronrr izer also needed"
AfR HEATERS -Air heaters are often installed on mc,dern boirers to heat the combustionair before the air enteit-ir,t uoireilrrn".r. The mori ,orron type consists of tubessecured in a tube sheet at each end. A forceC_draft fu-n ,ornted dt tne top of the boiler,forces air throuo.n 9e top nalf of tneluue
1anr, in one Jiiection and then through the fowerhalf of the tubes-in tne ofposite oireciilnl in, r',ot uiiir,rn trrver through an air duct outsideof the boifer proper' arohi tr't , iou, u,ij ' ir,rn under the furnace froor, derivered to furnacechamber.
Advantages:1 ' lt increases boiler efficiency, since the stack temperatures are reduced.2
Hi:Tuo?n'.[:'trj,:m#HH iliTJin;,;u.;;-r-u,l".. temperature,sooT BLowERs - are often instalfed on econo mizerto keep the tubes free from carbon,soots coming from exhaust gas of the engine. lt arso fitted on modern marine boiler rocatedin generating tubes' *upt't ' 'ater tubes, and air heater in order to maintain the workingeffeciency of heat transfer thereby producing a befter output f of the boirer operatingperformance' lt uses ssuperheated steam for oetter cleaning method which start from top-air heater - economizer - superheater and generating tubes, for free passage of burnedgases from furnace to funner to prevent soot fires.
SMOKE INDICATORThis is apparatus usually consist of aseries of mirrors.so located thatthe f iremen can':,iy :'?',' il'r'""rlfl i. i i: "'J iff it;1 j : m : t *l:' i l, l' i' ". e 0 o n o n L, i o, o r r h e u p ta [e
o' what are boller mountlngs founds on a modern water-tube boter and funcron.sTEAn/t DRUM;' a cylindrical forged steel with both end fitted with manhore cover for repairpassage' f nside the drum mounted with internal f i tt ings fike drypipe, surface brow fine, feedwater l ine and desuperheater on higher pressure boirer. on typicar row pressure water tubeboiler same mountings on outside connection l ike satety valves, main and aux i l iarysteam::T,,:il",::.tJ:,i::': sase, ai.,arve, *iir, rever sase, surrace brow varve, main and
157
*ATER DR'M - its main functron are to equalize the distritrution of water to the generating
tubes and to provide space tor tne accumul"tion or scale and other solid or sludge which wasa
;;;. out bY bottom blow-valve'
DowN coMER - consist of nipple tubes connected between steam drum and front section
headers, where water reaves the drum, passes to heade" lo' expansion without strain
occur.
DBy prpE - A ctry pipe is a perforated or srotted pipe placed in the highor part of the steam
space of a boirer to prevent priming. The steam ouitrt val'res are connected to the dry pipe'
The steam m,rst pass down tnro,in the noreu (o, slots) into the dry pipe on its way to the
s teamva lves . .onmak ing thesetu ,n , , tnemois tu re in thes toamis th rownof fby iner t ia .
WATER*ALL - A waterwail consists of a series of vertical or inclined water tubes installed
arong one or more walrs of ine combustion cnamber and "*pot"o
to direct radiant heat of
the fire. These tubes "r,
*nnected directry,or through headers anci connecting nipplss' to
the circulatory system of the bciler'
Two purposes are served by the waterwat: (1) Added heating surfaca and boiler
capacity are secured. Revqmping and .d;;g waterwalls to an exis'ting boiler may even
doubre its capacity" (2) ru"",itrn.ice ot the refractory wall is reduced greatly'
F'RNA'E - lt provide space ih which the f uel and air mix and atomize thus creating perfect
combustion. rt also increased totar heat transfer to the sorroundec water wall and generating
tubgs. - , - -^^ r .naAr '
F,RNA'E REFRAcToRy - is made of bricks or tiles titted around lower base header in
order to maintain turna* iurperature ln;t providing ;;;; tt*otltion' lt also serve to
transter hot combustion gases through the oanr of gellrating tubes and preventing heat
from escaping to the "tr;pnere
therenv tn"intaining boiler efficiency'
supERHEATERs - one of the most important mounting on a rnodern boiler where it
receives steam from drypipe "ng
tni, ,i""lo, being n""t"ioy combustion gases passing
around outside of the tuds: thereby increased in temperature but pressure rerrlain constant'
consist of first and second stage rows of superheated installed near the furnace but
protected by rows of scieen tubes in ori* to avoid oitttt contact of heat' Prime purpose
is to use on main turoine engine thus eriminate ,,otion on turbine bladilngs' prevent
condensation in steam lines, carry-over, ress steam consumption thus increases plant
capacity. superheaters Jro fitted with safety varve, to be set lower than the safety valve
::::::Jr^TrrR - instaned onry on hish pressure boiler' where superheated steam
passes through piping to tunes that are i-**""d in the water space of lsteam drum'
to reduce the temperature equal to saturation stea* to the drum for auxilliaries equipment
rike cargo pumps, ,oo,iblo*Lrr, rrroiump, "rr. wh'rch use only low temperature steam'
158
LIrl
Il
J
l
GAS BAFFLES - usually fitted on three way
combustion gases from furnace to uptake'
STEAMBAFFLES-. topreventsteamcomingdirectly into the water in the steam to avoid
SCUM PAN - fittedthe floating imPurities
pass boiler, used to divert the path of
back through return tubes from blowing
turbulence effect.
on steaffi drum where surface blorv valve connec'ed' to collect
such as oil, grease to overboard'
I
I
Q . W h a t a r e t h e r e q u i r e m e n t s o f e | | i c i e n t o i | b u r n l n g l n a b o i | e r ?
1 . ProPer amount of fuel2. ProPer an'ount of air3. ProPer atomization4. ProPer fuel and air temperature5. High furnace temPerature
o. what are the methods by whlch the rate of combustion is varled to meet
changed in the steam demand?
The rate of combustion may be var'ied by changing the following:
1. The size of the atomize used'2. The nurnber of atomizer used'3. The oi l Pressure used'4. The fuel oi l back Pressure'
Wha ta re thecauseso |excess i veo i l t empera tu re?
1) Insuf f ic ienio i tc i rculat ion2\ lmProPer viscositY of oil3) Overloading4) Overheated bearings5i Jacket cooling system not effective6) Late burning of fuel.7i Sludge coating on the crankcaseB) Oil cooler.clogged'
wha t t \ r uopa r t sdoesabu rne rcons l s t?wha t l s the func t i ono feachpa r t?
The burner consist of fruo Parts:1. Atomizei - it is used io aromize ihe fuer into tiny spray which completely fi l l the
fu rnaceopen ing in the fo rmo tho l | owcone .z. Air regiister - it ailows.entry of a stro.g bi".i of whirling air which. catches the fuel
fog ,mixeswi th i tandenters the furnacewherecombust ion takesp |ace
a.
Q -
1 5 9
Q. State four operating condition that decrease the l i fe of the furnace refractoryl in lngs.
The l ife of refractory l ining of furnar:e is influenced by:1 . The high sustained furnace temperature2. Rapid changes in temperature3. Vibrat ion or pant ing of the boi ler4. Flame impingement.
Q. What causes pant ing in a watertube boi ter?
1 . Defficiency of air2. Excessive oil temperature3. Poor fuel-air mixture.
cl. what Information is found on the name prate of a boi ler?
Inspection Bureau Number; Tensi le Strength ( ) lbs. per sq. inc. (p.s. i .) ;rHydrostat ictost ( ) p.s. i . ;OriginalWorking Prsssure ( ) p.s. i . ; Bui l t By;Steel By; Date and Inspector 'sInitial.
O. What Information is stamped on the body of a safety valve?
Name or registered trademark of manufacturer; Serial number; Inlet diameter;Operating pressure; Discharge capacity; Safe working pressure and Blowdown in psi.
Q. How would you make a hydrostat ic test on a boi ler?
1. Clean the boiler thoroughly both on the fire sides and tlre rrrrater sides.2.. See that all workers are clear.3. See that all foreign matter, tools, rags, etc., are removed from r the boiter,
and close up thd manholes and handholes.4. Al lvalves on the boi ler must be in good condit ion. Al lvalves except those through
which the water for the test is to be let into the boiler should be closed.5. The main steam line may be tested along with the boiler. In this case, it may be
necessary to put a blank at the far end of tlre line immediately before the throttlevalve to the main engine or auxiliary engines. lf there are two stop valves in theline, it may be unnecessary to blank off the line.
6. Hydrostatic pressure should not be put on one side of a vatve which has steampressure on the other side. This is important when steam is up on one boi ler oron a donkey boiler while another boiler is being given a hydrostaticitest. Blankshave to be used if there are not two valves on the line. Two ,valves maybe considered sufficient.
7. Provision must be made for a test gage8. The safety valves must be gagged.9. The air vent (air cock) at the top of the boiler must be left open until water runs
out of it. Then it may be closed.1 0. The pressure, applied by means of a pump, rnust be applied and released slowly.11. A hydrostatic test must never applied to a hot superheater or boiler.
160
tililqqqniqiIiltIqqIIthti
O. What ls the procedure In lay-up the boi ler?
wet storage: Used for short lay-up of less than a month and the boi ler is maintainedin a stand-by condit ion. Not sui table for boi lers exposed to f reezing condit ions.
The boi ler is cornpletely f i l led with hot dist i l led de-aerared alkal ine water. The watershotr ld overf low through the I 'ent dur ing f i l l ing-up. Dai ly checks are necessary to ensurefu l lness and a lka l in i ty are main ta ined.
Dry storage: Used f or longer lay-ups of more than a month. The boi ler is completelydr ied out using heatqrs or on l ight f i re or passing hot air through the boi ler parts. When drycompletely, al l the boi ler out lots are sealed t ight af ter placing Iehydrant isuch as Si l ica gelat the rate of 2.7 kglcu. metre) inr ; ide the boi ler.
g - r - . ' ' i
o. what ls the nrdanrng, funct lon of the fol lowlng tenms?
Boller Capaclty- is the amount of work a boiler can produce a steam expressed in poundsper hour designed to generate.
Prlmlng- carryover of entrained water with the steam irrto the engines that affect the turbineblade, break cylir ider heads, piston, valves.
Flareback - mostly occur during init ial f ir ing or attempting to relight a burner from a hotbrickwall without proper purging caused by explosion of mixture oil vapor or gas in thefurnace.
water Hammer- consist of condense moisture in a steam line, which form slug ahead ofsteam f lowing through that produce soundr; l ike a hammer hi t t ing a metal against elbows,fitt ings, valves' l t can be prevent by draining and slow pre-heating of l ine by opening by-passvalves.
Foamlng - a process condition of producing steam bubbles from the water f evef in a boilerto the steam s[race cause.by oil presence that feed water carried over from machinery.
Pltt lng - is a form of local corrcrsion usually found on boilei-rvater f ine system.
Groovlng - usually found around seams rivets head or where the metal has been bent orstrained.
Carry-over - consist of particles of water leaving the boiler,ruith steam caused by highalkal in i ty, h igh disolved suspended sol i r1s.
Gag-a special clamp tools for hotding the safety valves closec] rluring a hydrostatic pressuretest.
Accumulatlon Tesf - ' the actua: test of the abil i ty of the boiler safety valves to relieve theboller of all the steam !hat generate during f ir ing at f ul l capacity. Firing time for f iretube boilersforced to maximum capacity is 12 minutes while water tube boiler is 7 minutes, not cxceeds67" above.maximum allowable working pressLrre.
1 6 1
Hydrostafrc fest-filled up with water and pressure build up to boiler, to determine wether
the boiler is tight and capable of safety holding its working pressure. \
Combustton- is the rapid combination of oxygen with fuel, accompanied blthe evolution
of fire.
Rateof Evaporatlon-the amountof waterevaporated into steam persquarefootof heatingsurface per hour.
Rate of Combustlon -the amount of fuel burned per square foot of heating surface per
hour.
Tenstte Strengtt> is the ability of material to resist stresses of tension, such ab stretching orpulling it apart.
yletd polnt -sudden yielding of the material while under tensile stress, without any increasein load.
Etastlc Ltmlt - is the maximum stress to which the material can be subjected without
causing its permanent deformation.
Elongatton - is the increase in length of specimen under tensile stress.
Gatvanlc actlon- is a fornt of corrosion in which the metal is eaten away by the galvanicaction on non-homogeneous parts of iron and steel.
Caustlc Embrltttement-nrade of molecules that produce on metalwhich usually occurredon riveted joints with higher concentration of alkalinity and mechanical stress.
Corroston - is th6l process of deterioration on wearing away of some of the metal parts, forwhich exists in three forms, pitting, rusting orwearing and grooving. Two types of corrosionare general and local corrosions.
Duclllty- is the property of a material which allows it to be drawn, by pulllng on its ends to
a smaller diameter.
Factor of safety- is the ratio of the ultimate strength of a materiat to its maximum workingstress.
Anneayng - consist of allowing material to cool, after forging or rolling, to a temperaturebelow the critical range, reheating it to proper temperature to refine the grain, and the
allowing it to cool in the furnace.
Normalztng - same method to annealing except that after reheatirtg to ref ine the grain, the
material is allowing it to cool in the air"
Rlvelng-method of joining metal plates. A cylinclrical length of metal, called rivet, is placed
into holes dril led in the two plates to be joined, then each of the rivet is forced into a shape
of larger areathan the cross section of the rivet shank. !
162
SAFETY VALVES
The function of a safety valve is to prevent excessive pressure from building up in a
steam boiler, t\us.guarding the ttoiler against possible explosion"
TYPES OF SAFETY VALVES
Ordinary l i f t ; High l i f t ; Inrproved higtr l i f t ; Ful l l i f t ; Ful l bore;Pi lot<penated; and Electro-magnet ic safety valve.
Exampte: Blr. Design Press = 1 0 barTest Press = 15 bar : + 50"/"Opera t i ngPress = BbarH. P. A larm = 9 barSet Press Safe ty Va lve 1 - 10 barSet P:ess Safe ty Va lve 2 = 10.3 bar : + 3 /oC losed Sa fe ty Va lve = 9 .6 ba r : 1 - 4 / "Accumulat ion Press = 10.6 bar : + 6 ' /"
Boi lers with a heat ing surface in excess of 46 ,4 m2 mustbe f i t ted with at leastTWOsafety valves.
Safety valves must be set to l i f t wi thin the designed pressure of the boi ler. Sincemarine boi lers, l ' rave normal ly two safety valves, the second valve may be adjusted to l i f t ata pressure o f 3% above the bo i le r des ign pressure.
Nornral blowdowri range of safety valves: 1 - 4% of set pressure.
To prevent leaking or "weeping" of saf ety valves, the boi ler operat ing pressure shouldbe lower than the des ign pressure.
The ideal l i f t for a safety valve is 1/4 of the valve ( throat) diameter.
DESIGN FEATURES OF AN ORDINARY LIFT TYPE VAI .VE
1. Li f t of th is type of safety valve wi l l be 1124 of i ts throat diameter.2. A spl i t compression r ing is f i t ted to f i l l the gap between the col lar of the adjust ing
nut (compress ion screw) and top o f the va lve cover bush. Th is preventsany al terat i .on of the valve sett ing.
3 . Through s lo ts in the cap and sp ind le , a cot ter can be pad locked in p lace.4 . An eas ing gear f i t ted enables the va lve to be l i f ted manual ly f rom e i ther a loca l
or remote pos i t ion .5. Adequate clearances are provided in t l re assembly so that the valve can open
f reely.6. A drain from the valve chest avoids the possibi l i ty of hydrostat ic loads act ing on
the va lve and se izure o f t l rc va lve due to cor ros ion.
DESIGN FEATURES OF MODERN SAFETY VALVES
1. Increased va lve d isc area to promote va lve l i f t .Z. Single r ing btowdown control :Raising the r ing towards the valve disc increases
the va lve b lowdown and v ice versa-lJ. Upper and lower adjusling rings:The upper ring controls the valve blowdown and
the lower r ing promotes t l re popping act ion and removes the valve simmer.(The c learance be tween bo th lne ,e r ings con l ro l the hudd l ing chamber p ressure)
4. A back-pressure control valve gives a rouglr adjustment for the valve blowdown.
1 6 3
1I
234567I911111
BodyCoverValve Disc HolderValve DiscSeat R ingGu ideSpind leBlow Down RingSett ing Screw
0 Valve Disc Bal l1 Sp ind le Ba l l2 Spring4 Dome5 Adjust ing Screw
17 Locknut18 Spr ing Plate20 Disc Retaining Clip21 Body Gasket23 Seat Securing Pin24 Securing Pin Plug26 Body Stud27 Body Stud Nut28 Nameplate29 Nameplate Screw
1 6 4
Safety Valve
PROCEDURE FOR ADJUI}TMENT OF SAFETY VALVES ON TANK BOILERS1. At least two pressure gauges, v.rhose accuracy has been ver i f ied recent ly, must
be made avai lable to give the reading of boi ler pressure.2. Screw down the compression screw on the valves a few turns more than the
previous sett ing.r3. Steamipressure in the boi ler raiseC and the boi ler put on banked f i re.4- Slowlyrb{ng up the boi ler pressure to the desired set pressure of the safety valve
being adjusted (adjust only orre valve at a t ime).5. Slacken the compression screw of the safety valve stowly t i l l the valve blows,q. Stop f l r ing the boi ler, and note down the closing pressure of the valve.7. Try out again for l i f t ing ( f loat ing) of the safety valve to check the set pressure and
to make minor adjustments to the compression screw as may be necessary"B. The valve sett ing is done with a bi t of t r ia l and error procedure andwith pract ice
can be achieved fair ly quickly.9. On valves with blowdown control , rhe blowdown r ing is in i t ia l ly set at a part icular
posi t ion as per the maker 's instruct ions and f ine adjusted Oui ing the f loat ing of ihe valve"1 0. The safety v 'alve adjr . rsted slrould be gagged ( the gag must be f inger t ight only),
and the other safety valve shourd now be f loated ind id justed.11. The gag f rom the f i rs t varve should now be removed"12. Fire the boi ler to conf i rm the sat isfactory operat ion of the safety valves.13. Spl i t lock r ings can now be made arrd f i t ted to lock the compression screws in
place.14. F i t back the eas ing gears and l i f t the safe ty va lves manual ly .
OPERATING TROUBLES
Chat ter : Meta l l i c hammer ing sound or v ibra tory ' no ise. The reasons be ing bentsp ind le , improper c learances, loose b lowdown r ing, i rp roper pos i t ion o f upper and/orlower adjust ing r ing posi t ions, excessive bacl<-pre. iure, etcSimmer: The f i rs t leakage o f s teem before the safe ty va lve pops oper , wh ich isal lowed within 1i .5 to 2"h of popping pressure of the valve. Prolonged simmering may bedue to impropeq posi t ion cf adjust ing r ings, distorted vafve parts, etc. (no,rmal)
Leakage: Constaht hissing souncl . The reasons being damaged seat ing, defect iveparts, scale or foreign matter on t l re seal ing surfaces, distoi t ion due to waste steam pipef i t t ing, interference from easing gear ancl spindle, etc.
t lanq:upt Safety valve f a i ls to r e-scat. Tlrc reasons being improper blowdownadjustment , rnechanica l in ter ference f rom sp ind le , e tc"
ROUTINE CHECKS
a. Checlq for leakages daily. Do not stop the leak by over-tightening of thecompression scPY olgagginqthg valve.Try blowing the valvewith the aid of eaJng gearand turn the spir i rd le ( i f possible, for low pressure boi lers only) along with the disc in bothdirect ions to dis lodge foreign matter or scale from the seal ing surf jces.
b. Manual ly l i f t the vaives (rvhen the boi ler pressure is above 7Sy. of workingpressure), to check that the valves are operat ional once a month.
c . F loat the va lves on s team every s ix months.d . Overhau l the va lves complete ly once a year .
1 6 5
WATER LEVEL GAUGES
REGULATION
Every boiler is to be fitted with at least Two indeoendent t-tat,:f indicating the
water level in it; one of which-tJ to u' a gtass g;Gi T!^" other means is t0 be either an
ffi"- ft fJ ffi j $;3,; j :f ,: U 1ffil ilU \1i S ir',"ffi; o r w at e r r e v e I d e te ct i o n w h i c h
are to be independent of any ;;r; mountinq ;; ihr;;lrr' eotn the systems are to operate
audible anO vfsiOle alarmt "ni
auton:atic Jhut-off device'
TYPES
l. Tubular gauge glassll. Reflex Plate gauge glassl l l . Double Plate gauge glass
TUBULAR TYPE GAUGE GLASS
Suitable for low pressure boilers of design presisure below 17'5 bar:
saf ety f eatures incruiJ'a ,trit oatt vitieln inu *"*r'sde connection to shut off the
water in the event of grass';,;;kifu and i'itii-iisert g6,si r"gtto prevent iniury to the
personnel .
REFLEX PLATE TYPE GAUGE GLASS
i,:lfJ i :T iil[??J'li':',?:'1 ffi ::iff'U i{i iffi ' n ated' th e s e ri e s o r r ib s at th ebackof the grassprate..u* ine righirrv, to be reflect.Jn"tkitot the steam space and
absorbed in the water rp"rr.-ihis-givri " urignt silvery appsarance.to tfre steam space
whire the water space appears. !ark".Th, ,ir6ng contiasiSrwrrn the two enables the
ruil;;;i::iNi$:,T:'[';,{,i:tifi^li:r*n," sheet or mica is to be pracedbetween steam/water spa-cr'.nitn, giurrl J,l. tl tne rih's on this glass' the reflex type can
not make use of this form'JiJroirctio-n, "no t[rruforc is not suitable for higher pressures'
DOUBLE PLATE GAUGE GLASS
This gauge assembry is suitalp lqr use when the pressures are in exces s of 34 bar'
as the flat stass ptates.un nr effectivei;;i$fli:tf, tiotion' bv sfreets of mica'
The assembry .onrirt, of a hoilow centre piece iittua with two plates of toughened
gras;i herd in prace uy mein, oi "
cramp pr"t, A rouvre ir"ir "t the back of the glass directs
the right rays at an angte-io maxe tnr ri'rnlrcus of the water level glow'
oPERATINGINSTRuCTIoNSFoRAREFLEXPLATEGAUGEGLASS
:, Vl1;;:.ff::'f,ilS.?il'fi:';,:ed5ffi:?ff1'ilil; tre aid or rotatabre s'assho ldersontheupperand lowerconnect ionp ieces .
1 6 6
5 .
6 .
IIIIItI!
IIIIIIII
3' Wheneverthe boi ler i : prt into operation after i t has been cleaned, some foreignmatter eould exist in the shut-off valves. Avoid eventual damage by frequentiy draining tXesystem via the drain valve.
4. Blowing-throughprocedure:a' ' Close the steam and water side vatves and open the drain valve"b' Blow-through the steam side by opening the'upper valve for 1-2 secondsand close.c ' Blow-through the water s ide by opening the lower vatve for 1-2 secondsand close.d. Close the drain valve.e' Open both steam and water s ide valves by turning them slowly.
Replacemerit of gtassa'r lsolate the a-qsembf y by shutting-off the steam and water connections andby opening the drain.b ' l Take off the screws of the glass holder and remove the pressure ledges.c. l Remove the glass insert wi th gaskets.d. pRare glass surfaces to be cre-aned thoroughry.e' Instail the black gasket, the spare glass witn ine grooves facing inwards, the_ red gasket and f inai ly the thin stel l sheet.f ' Put on the pressure iedges and t ighten the screws uni formlystart ing fromthe middle and proceeding cross--wise up and downward,g' Heat the new glass slowlyby keeping the water s ide valve shut, the steamside valve crack-open and the drain-fuily openh' After about 30 minutes, the screws shoulo Ue t ightened again by applyinga torque ol 2.4 kp-nr"i ' The assembly can now be put cn load by shutt ing-off the drain and openingthe steam and water s ide varves compretery"
v
Reasons for a false water level indication by a gauge gtassa' Choked valves and passages on the steam anoloiwater s ide by sediment,. scale, packing or use of a rouncl glass which is too long.br
*3lI 9:?'t valve or proffusive lteam and/or warer leakages from thegauge assembly .
c : Foarn ing condi t ion ins ide the bo i le r .d ; Sudden changes in s team denrand.
167
COMBUSTION AND EQUIPMENT
ROTARY CUP BURNER \
The burner asssembry consists or a rotary cup a!.0|t\er, which is hinged to the a.ir
register and the combustidn cnamblr with i.ii".i.i.v lining' The rotary atomising cup rs
ritted on the burner shaft, oriuen uy "n
electric motor through v-belts'
The f ue r oir is m etered in th e oir co ntpund reguratorand f lows th roug.h ttre oil inlet pipe'
the oil nozzre, and the oir oisiriuuio. inio th;';; i;ry .up, Here the fuel oil is spread out
uniformry by centrifugar force on the inner wa-ll and ilo*s to i[u uoge of th.e cup where it is
thrown off tangentiaily at higtiverocity (rrp-lotutes ar 4000 to 6000 rpm)"
The atomising air (primaryarr) enters betwee n the rotary cup anditne cup shroud'
where it strikes thebit fi lm direcity as it.reavel t 'u .rp.The ;li rir* it broken into very fine
droprets by the impact ot tre'ii;"q, "ir. rt'ri pri,i"iv aitfloi is controlled by a primary air
damper activated by the .on.,5ornJ ?rgui"tor.in. pii*"ry uir ir nor*ally dirbcted through
a swirlringwhich rotates the air in the same-ctirection as the rotary cup'A small quantity
of primary air (Tertiaryatr) is Jir..tuo to keepthe burner coor during operation'
The secondarv air is supprirg t,o the_wind box, where tlre uniform distribution of the
secondary a,,7Fa.hieved ov a rad,iat ,rnr"r),'n6irl;i'p.-lr''d;J *iin fixed guide vanes' The
combustion air is guided into ltre frame by individuaity adiustable air vanes'
correct control of the secondary air is the most important factor which contributes to
the high combustion efficir..v th-rolghout-the turn4owi-rt'ng' of th.e' burner' Draught
contror is performed by means of a ,rro,iJ"iy air au*piitointtted to the compound
regulator-
"'^l!{"lLro air representing tess"than 1o%of the total air requirements' establishes
a stabie primary frame Th;;; irrv air nizzto convertsJhe high piessure primary air into
high verocity air, vrlhich thei fi;;; ttrrougrr, Jaiottudes"rnr r*in btades rotate the air f low
in the oppoiite direction to'tt ui of tn. o'ir ronu derivered by the fuel burner'
SecondarY air
The secondary air frow, representing about g07. of totar combustion air requirements'
is used to estabrish a ,urpunJed seconoluu!"1, of .orir.t rn"pr ancl dimensions to suit
the furnace shape, as oirru**d earrier. swirr vanes Jeliver the secondary air to the
furnace in the desired manner to promote conrplete combustion
Htfffo*t:rean the rota'y oil cup (sharp edse in the front of cuprTtust be clean and
smooth without any cuts. Do not use any scrapper or any hard too )
Monthry: check flame scanner f or dirt, dust and carbln oeposits and clean' (caution:
rf the two cabre connertiii, ib interc;;;;'g"i, tie photocett witt not function!);---
Primary & secondary air switches;Test safetY interlocks;Clean the igniter tube & electrodesCheck the conditiorr of refractory'
hlr{'lJ
I
I
YearlY: Clean & lubr icate burner motor/shaft bear ings'
Clean al l combust ion air ducts '
168
frouble Indlcatlon Poss ib le cause Remedy
No lgnltlon/fallureof lgnl t lon f lame
lgni t ion burner f aul ty.Dirty electrodes.Too high sec. air pr6sFaul ty burner control .Faul ty t ransformer.
Check olUalr settingClean/re-adJust.Close air damper"Check & repair.Replace transformer.
Maln f lame fal luredur lng lgnl t lon
No pi lot f lame.Oi l v/v not opened.Oi l pr l temp - h igh/ow.Blockage in oi l systcra
See aboveCheck air pressure.Checldadjust.Check and rectify"
Unslable mafn f lameOil l low/temp too low.Too much primary air.Cup dir ly or damaged.
Ralse oi l f lowlemp.Re-adjust primary air.Clean or replace cup.
Black smoke / Incompletecombust lon
lmproper oil temp/visc.lnsul f ic ient a i r supply.Increased lurnace and/oruplake back pressure.Poor qual i ty of f uel .
Check and re-adjust.Check and re -adJust.Clean the gas passagstu rsmove blockage.Can not be ellminated byadjustment"
ROUBLE SHOOTING
PROBLEM
Problems In' the botter due to feed water can be categorlsed as:1. corrosion2. scale formation3. carry-over
INTERNAL WATERSIDE CORROSION
Electrochem ica I Corros io n
. l f the hydrogen ion concentrat ion ( low ph) is increased, the rate of corrosion woulcjincrease since there u/ould be more H* ions to receive elec,trons at cathode.The metal ion combines with t lre OH' ions to form atoms of ferrous hydroxide whichdissolves in the water thus wasting the rnetal avvay.Therefore, electrochemical corrosion cel ls with cathodic and anodic areas wii l have acurrentf low through the electrolyte from anode to cathode and backthrough the metalfrom
cathode to anode;during this process, material from anode is transferred'to the etectrolyteresult ing in corrosion of the anode.
FORMS OF ELECTROCHEMICAL CORROSIONS1. General Wastage2. Pit t ing
a. iAir bubble pitting
b. Scab pitting
1 6 9
1 . Genera! Wastage TYPe Corrosion
Generar wastage is a term expressing.electrorytic corrosion of a more r'irniform nature
rather than serective attack tt F-qg. it 'ii'iprie!
reouction in metal thickness over
comparativery large areas in "Jiirrv
un',Torm riinur. Here, ine anodic surface constantly
changes position, hence attack occurs over "*iou
irea. lf dissolved oxygen lis present' the
hydrogen porarising rayer ir;;;;;yed by formatioi' ' of v*,ater and euehln the absence of
dissolved oxygen, this form of corrosion ."n'i"[r pru"e wnen water has pH values below
6.5 .
2. Pitting
Apart from the general wastage type of electrochemical corrosion, another form of
corrosion which form pits on the iretif sr*a.e can be termed under corrosion due to
diff erential aeration,,oxygen absorption or simpty pitting type corrosion' There are types of
pit t ing corrosion:
(a) Air bubbre pit t ing -f ound.i l lhg roof of steam drum in the boi ler. In the air bubble
type pitting, an erectrorytic action is initiateJ ort*ren the oxygen reach surface under the
bubble and the surrounding water areas which are less ricn irioxygen' By experiment it is
found that it a portion of a metar becomer puitiurly inaccessible to oxygen' it becomes
anodic and so, differential oxygen levels on asurface."n-tiut rise to actite corrosion cell '
The ferr ic hydroxide as the corrosion product sett le over the bubble, forming a semi-
permeabre ,i.,emorane which permits.free pasrugr of ions but not oxygen' when oxygen
gets exhausted, a ,,ruurrui or galvanic .uirent. -o..ur,
thus causingihe metal under the
,,cap" less noble and hen.. ni inty local ised corrosion proceeds'
(b) scab pitting - A hard cap of corrosion product occurs in hotter areas of
generating surface; moltty found on tl-re side of the tire row tubes' The hard' blackscab is
d i f f i cu l t todetec t , removeandar res t ,once in i t ia ted .
scALE FoRMATIoN rN BoTLER & TRE,ATMENT oF BOTLER WATER
SCALE FORMATION IN BOILER
scale forms in boilers due to the presence of various satts which cotlle outof solution
and deposit because of the effects oi temperature and density'
when steam bubbre forms on a heating surface, the evaporation of water involved
causes rocarconcentration of sorids, sorng 6t *ni.n uo noittloittolve lvhen the bubble
escapes, but remain, to form smail circres oi.rvrl"rr oT the surface' Repeated formation
of these, build up the s.ar, oepoiil, often-foiming in a series of layers of different
compositions.lh; rate of ,.irloimation inrieares u-y tne pt-$n.e of corrosion products
and oir. The latter wi1 not onry increase the rate of sciting, but also give further insulating
eff ect.
170
Composltlon of scales
Chemical analysis shows that the chief constituents of hard scales are calcium
suphate, and calciugr and magnesium silicates, while the softer loose sludge is composed
il;t of calcium carbonate inrl magnesium hydroxide. Corrosion products of iron and
copper are also,found in scales"
Effects of scallng
The serious results caused by scale deposition are:
i) The efficiency of the boiler reduces due to poor heat transfer across heating
surface.
ii) Lack of prqper heat transfer, may cause overheating of tube metal with possibility
of distoriiori and failure, in effect reducing the factor of safety of the boiler"
NATURE OF SCALE FORMING DISSOLVED SOLIDS
Dissolved solids in the water which can lead to the formation of deposits can be
divided in the three l tardness groups:
a) Atkaline hardnes.s: or temporary hardness, is due to the bi- carbonates of
Calcium (Ca) & Magnesium (Mg), which are slightly alkaline in nature.These decompose Iporr heaiing, torming COu and corresponding carbonates which thendeposit as a soft scale, or sludge. /'
Ca(HCO.), - CaCO. + CO, +t-{rO
b) Non.Alkaltne Hardness Sa/fs: also known as permanent hardness salts, aredue t; the presence of sulphates. chlorides, nitrates and si l icates of calcium andmagnesiu'Tt"
With the exception of si l icates and the calcium sulphate, the permanent hard-ness salts are all very soluble in water and do not normaly produce scale, but they areelectrolytes and their presence, therefore, favours corrosion by galvanic action.
Calclum Sutphate (CaSO) is the worst scale forming agent in the water,deposit ing as a thin, hard gray scale at temperature above 140 deg. C, or at densit iesabove 96,000 PPrn.
Solubility of this salt decreases with a rise in temperature of the water. When asteam bubble is forrned on the heating surface the evaporation process causes alocalconcentration of soliCs in the water surrounditrg the bubble. In the cdse of CaSO.saturation point is very quickly reached and this solid precipitate forms a hard grey
scale on the heating surface
171
Magnestum Chtoride is soluble under normalboiler conditions but can to some
extent breakdown inside ths boiler to form magnesium hydroxide (which $enoljjs.3sa soft scale) and hydrochloric acid-this can sef up an active corrosion action with the
boiler metal.
MgCL, + HrO = Mg(OH)r+ l-lOl
Catcium carbonafe, whiclr is an alkaline hardness salt, by itself , deposits as Iwhite sluogs but with casoo present, form a composite scale of carbonate and
sulphate. Greater percentage of carbonate makes the scale pr{)grsssively softsr'
Sillca- is founrJ in most water and is also present in the plant, especially.when
nsw, from erection detritus (dust particles), casting sand and welding flux' In low
pressure Ooiters SiOz combines with Ca anO Mg to form calcium and magnesium
silicates which can precipitate, and form hard scale. In high pressu.re boilers, silica
volatitizes wirh steam and deposits in turbines, causing severo loss.in efficiency; thesilica scatet are gtassy, exteimely hard and difficult toremove" At high pqformance
boiler, of say 100 bar, rnust not have silica content over (highest value recommendedby Drew Chemicals).
c) Non-Hardness Sa/fs: These consist mainly of sodium salts which remain in
solution, and do not deposit under norma! boiler density. lt can come out of solution at very
high densities above 225,000 ppm and deposits as a soft incrustation.
Other scale forming salts may be present in the feed water in very small quantities and
can be generallY neglected.
Nature of the scale dePosit
The minerals most often found in scale deposits are:
(a) Calcium carbonate.(b) Calcium silicate.(c) Magnesium hydroxide.(d) Magnesium silicate(e) Calcium sulPhate.
There is also possibility of getting a large amount of iron and copper in a scale deposit'
Both copper and iron are picked up from the pre-boiter circuit; copper from the
evaporator condenser and iron from the service piping and storage tanlcs.
TREATMENT OF WATER
Boiler and the feed system has to be treated to inhibit corrosion a,nd scaleiformation
anO ittpossible contaminants in the form of metalsalts, gas, oil, suspended particles must
U. gu"'rOed against and this is done by both extsrnal and internal treatment.
172
Contaminants t lrat cause rnost trouble in the boi ler:
Contaminants frrcm SourcesExternal to the Ship
Contaminants from SourcesInside the Ship
1 . Calcium salts2. Magnesium salts3. Chlorides4, Si l ica5. Carbon dioxide6. Oxygen
1 . O i r2. l ron3. Copper4. Carbon dioxide5. Oxygen
External Treatment
This refers to the treatment given before feed water enters the boi ler.In both high and low pressure systems on board, the boilerfeed water used is normally
good quality disti l led water obtained from evaporation of sea water by the disti l ler. Theevaporation by itself is a process of gettinE rid of many harmful constituents but themake-up feed produced by the evaporator does entrain some of the salt water particlesand produce an acid feed water rich in carbon dioxide. The feed system is also prone toatmospheric contamination at various points of the feed system.
Even a very good quality disti l late may not produce a pH of more than 6.5 and wouldcontain certain amount of sea salts of Ca and Mg whioh rnay cause problem.
In high pressure systems atlove 20 bars, a mechanical deaeraton by having aDeaerator helps ir l 'r I€moving most of the oxygen and the treatment is completed with l iquidhydrazine dosingr at the deaerator outlet, The problem from COn and acidity is counteredby dosing amines (morphol ine and monocyclohexylamine or CHM) at another point in thefeed system andra mi ldly alkal ine pH condit ion can be easi ly nraintained.
For a lower pressure system, the feed system is of an open feed type and thedissolved oxygen does not cause a ser ious problem provided correct alkal in ig is main-tained.
The make-up water should be a good qual i ty dist i l led water with a low T.D.S. and thesystem normally would have simple feed fi l ters in the hotwell or the cascade tank to keepcontaminat ion under control . The hotwel l temperature should also be maintained above 60to 70oC to prornote oxygen deaeration through the open vent of the honryell tank.
In some auxil iary boiler system, raw fresh water make-up is used. This water shouldbe 'soft ' and have minimum of 'hardness' sal ts of Ca and Mg.
But in all auxil iary low pressure system, the boiler may expect to have contaminantsof calc ium and rnagnesium sal ts plus a good amount of harmful gaseous products.
The reconrrnended chernical parameter' l imits are more generous in a low pressureboiler system due to the low heat rate and lower rates of evaporation prevail ing; thetemperatureswithin the low pressure boi ler also remains moderate and some of the sal ts,whose solubi l i ty decreases with higher temperatures const i tute less of a problem.
The treatment consists of chemical injection into the boiler and regular'blowing downto remove tlre precipitated sludge deposits while keeping the boiler water within a safedensi ty or T.D.S, level ,
173
lnternal Treatment
This refers to the final stage of treatment given lo llr boiler water and thd chemir:als
are doged lntolne boiler proper for the following obje.ctives:1 . t<eep uoiler water in a siignity att<aline iond-ition and removal of dissolved oxygen
and carbon dioxide'2. To precipitate any scale forming salts which may be in solution'
3. Keep the precipitated solids in a non-adherent sludge form so that they can be
easilY removed bY blowdown'4. Prevbntion of carcy over and foaming'
The chemicals which are in use, serve the dual purpose of precipitating.hardness t."lF
and counteract any acidity tl'rat develops in ttrgsysiern. Thess include sodium hydroxide'
various sodium phosphates and sodium .uruon"ie. Apart f rom the aLrove chemicals for'the
provention of scaling and corrosion, other chemicals for conditioning sludge, iremoval of
slight oil contamination, preventing carry over and oxygen scavenging are also added
along with the phosphates and alkalis'
BOILER WATER TESTING
Boiler and feed water are tested regularly for Alkalinity, Chloride level, excess
phosphate and hydrazine and also for narJness, pH-value and total dissolved solids or
conductivity.The recommended limits of boiler water conditions vary f ro.nr one maker to the other
but remainini gsneraily within the given parameters mentioned in the following pages'
An increase of T.D.S. and chloride value indicates S.W. leakage and the solution is
to identify the leakage source and isolate the leakage plus blow down to ireduce the
dissolved solids.Low arxarinltv requires alkaline chemieal dosing in the form of caustic soda or sodium
p h o s p h a t e . - ' t
. - ^ ! - - - . , r . . . r r ^ ^ . . n aLow hydrazine reserve indicate inferior de-aeration and further need of hydrazone
addition.
Hydrazlne lesf
Hydrazine is a volatile compound and highly solub.le in water. To safeguard the boiler
system from O,- corrosion it is continuoutiYiOig{ usinq, a dosing pump' The bulk of the
NoH. turns inlo'r.rHliiH "ioi.g
to the arr.ari'niiv of the bo'lter watei. However,lif too much
dosage of NrH. is added, at bo]ter temp. abovi 1750c, it can decompose to forrn ammonia'
3N2H1 ---- 4NH. + N,
Ammonia can attack copper alloys in the condensate system in the presence of
oxygen. so, presencs of nvd-[line in e*cess of 0.3 pprn shouid be guarded]against.
Dlssolved Sollds
The basis of this determination lies in the faot that the electrical conductahce of water
is proportional to the quality and nature of tfre substance dissolved in itl
174
Conductivity in microfrms per cm at 200C x 0.67 = TDS in ppm.A permanently installed instrument can be used for the above giving direct reading for
TDS in ppm. H,ighly alkaline solutions tend to affect the above reading and for a moreaccurate result, strong alkalis (NarCO.) should be neutralized before ths test.
Methods of Drawlng Samples for TestlngAny water samples for testing must be truly representative of the whole, othenruise the
results would be misleading.A sample cooler fitted with cooling coil is very good for this purpose.Before drawing the sample, water from the boiler is run to waste for a time sufficient
to flush out the sampling lines. The collecting vessels should be rinsed twice with water tobe tested, Samples should be tested as soon as possible after drawing.
Problems ln Handllng Water Treatment Bnd Testing Chemlcals
Care should be taken in dealing with all chemicals used in water treatment and testing.
1. Concentrated lWlneral Aclds. Can cause extensive damage to human tissue,specially to the B!€s.
2. Concentrated Alkalls . Caustic Soda can cause severe damage to humantissue. Substantial heat is release when NaOH is dissolved or diluted and small controlledadditions with c0nstant stirring is recommended" Careful handling and storing is importantas spillage can cause damage to the ship structure.
Hydrazone is destroyed by contact with air and the fresh sample (after filtration,if required.) should be immediately tested to avoid atmospheric contamination. Use of asample cooler to obtain water sample between 2A - 30 deg" C is good practice as thesampled water and ambient temperature would be similar.
3. Alkallnlty Test. The two part "p-alkalinity' and 'Total Alkalinity' tests revealpresence of hydroxyl (CH), carbonate (COJ, and bi-carbonate (HCO'), which aro respon-sible for making boiler water alkaline.
The P-test actually finds the presence of Ol'.|, and half of carbonate and the nexttest picks utl the prqsence of tt:e remaining carbonate and bi-carbonate.
ln a 'sample, OH and HCO3 cannot be present simultaneously. From therespective readings, a tair judgcment Can be made of the identity of salts, (e.g. NaOH,NarCOr) responsible for alkalinity in the sample.
4. Chlortde lest. This gives the quickest indicaticn of any saltwater leakage intothe boi ler and must be oarried out dai l ly"
5., Phosphate Tesf . Presence of phosphate in sample means there won't be anyhardness salts present. The Na.PO. added to the boiler is very efficient in preclpltatlng allscale forming hardness salts of calbium or magnesium. So with a phosphate test done,there is no need to do a "hardness" test.
6. pH-Value.Once the alkalinity has been nteasured with titration tests, there is noneed to check pH-value as alkalinity & pH-value are proportional. Howe',rer, as a quickreference, a litmus strip can be used using raw sample and colour change comparedagainst the ones given on the litmus case to indicate the possible rangs of pH.
175
RECOMMENDED CONTROL LIMITS
Means of AdlustmentBollers uP to 32 bars
< 1 . 01 0 0 - 1 5 0200 - 3002 0 - 4 0
0.1 - 0 .2300500 - 5501 0 . 8 - 1 1 . 3700 mmho/cm
Total hardnessP-alkalinitY (CaCO.)Total Alkalinity (CaCO.)PhosphateHydrazineChloridesT.D.S.pH-valueConductivitY
nfrttnhnih
to:
GCGCAdjunct BAmerzineBlowdown
ADVANTAGES OF CHEMICAL TREATMENT
The focus of any water treatment should be to minimize the abovo problems and try
maintain a clean, scale-free heat-transfer surface'prevent metal loss due to corrosion'ensure efficient production of steam withcut priming, foaming or carry-over
contamination.d" prevent formation of deposits in steam/condensate systems'
e. minimize heat loss through excessive blowdown from boilers'
f. acfrieve-all of the above it minimum cost and best efficiency'
pH-value is a measure of aci"lity or alkalinity irr water. p(power) and h(H. ion conc')
makes the pH-value whicQ is th6 logarithm of tne reciprocal of the hydrogen ion concen-
tration in water.$+ OH-
10-5 x 10-e solut ion ac id ic ' Ph = 5
10'7 x 1 0'7 solut ion Neutral ' Ph = 710'e x 10's solut ion Alkal ine. ph = 9
TEST PROCEDURE
1. CoNDENSATE pH TEST: TEST IMMEDIATELY AFTER DRAWING SAMPLE.
1. collect 50 ml cooled condensate sample and pour into dish'
2 ,Add3dropspheno|ph tha le in .Sarnp |eshoy l ! tu rnp ink3. Add sulfuric acid f.fliO drop by drop until pink color disappears'
4. Refer to chart for dosage adjustment"
2. HYDRAZINE TESTprepare iresn Hydrazine Reagent every two weeks.
1. Empty one celpsule of Amerzine Reagent A into amber bottle'
z. Measure 45 ml of A[erzine Reageni B in a graduated cyrinder and add to the
Powder in amber bottle'
176
hha.
b.c.
3. Shake to dissolvo. Ke€p tightly closed in a cool place. ' rr:
Alternate Method: Measure 1 plastlc spoonful of Hydrazlne Rsagent A.Measure out and add 45 ntl Hydrazin€ Reagent B.
TEST PROCEDURE: TEST IMMEDIATELY AFTER DRAWING SAMPLE.
1. Collect a coolod boiler water sample and fill amerzine test tube to 5 ml mark.2. Add prepared Hydrazine Reagent to 10 ml mark.3. Compare bolor with standards in block. Refer to chart for dosage adjustment.
3. EXCESSPHOSPHATETEST
1. Collect and tilter cooled boiler water to 5 ml mark on phosphate test tube.2. Add molybdate to 17.5 ml mark.3. Add one brass spoonful Drv Stannous Chloride.4. Stopper and mix well. allow to stand 3 to 5 minutes.5. Compare'color with standards in block.6. Flefer to chart for dosage adjustment.
'T. PHENOLPHTHALETN ('P") ALI(ALINITY TEST1 . Collect 50 ml. of cooled boiler samole.2. Pour into dish. Add four drop phenolpthalein.3. Pink color Alkallne. No color- ,'p" alkalinity zero.4. Add sulfuric acid N/10 until pink color disappears.5. Note thellevel of ecid in buiet. convert ml to ppm using chart at right and record
result in ppm as "P" alkalinity. Keep sample lor'T" alkalinity test. Reter to chartfordosago adlustment.
5. TOTAL ('T') ALKALI$IITY TEST6. Add 3 drops Total alkalinity Inclicator-cP.7 . Add sulfuric acid lrl/10 until pink color develops.8. Note ths level of acid in buret. Convsrt ml to ppm using chart at right and record :l
result in ppm a{ 'Total Alkatinity". Koep sample for Chloride Test. Refer to Chartlor dosage adJustments.
6. CHLORTDETEST l
9. Add one dropper lull Potassium chromate Indicator. 'l
10. Add silvdr nitrato N/10 until first permanent yollow to red brown color change.11. Note l€velof silvor nitrate in buret. convort mlto ppm using chartatrightand record
result In ppm as chloride. Refsr to chart to adju€st blowdown.7. CONDUCTIVIiTYTEST
1. SEE METER INSTRUCTIONS.2. Fill cylinder to 100 ml (top) mark with cooled boiler sample.3. Add 2 drgps phenolpthalein and mix.4. Add gallib acid to pink sanlpte,w hile mixing, untit color disappears.5. Measureitemp€rature of sample and adiust tcmperature dial.6. Rotrate conductivlty dial until both tights remain lighted at the same time.7. Refer to chart to adjust blowdown.
177
BOILER WATER TREATMENT - CONTROL AND DOSAGE CHART
steam Generating Equipment - up to 32 kg/cm2 (450 psig, 3200 liN/m3)
CONDENSATEPH TEST
HYDRAZINETEST
PHOSPHATETEST
MFANS OFAtUUSTMENT
TEST RESULTS (control limitr in Bluel oos{ef CALCULATIoN
sLcc-A
CondenrrteCorrorionlnhibibr
NO PINK WITH PHENOI.PHTHALEIN INCREASED BY 25J6
PINK COLORI.2 DBOPS N/IO ACIO TO CTARIFY
SATISFACTOTY -
NO CTIANGE
PINK COLOR-3 OR MOREDROPS N/IO ACID TO CI.ARIFY
DECREASEO ]BY 25*
lNlTlAL D0SAGE 0.15 LTR 10.3 PTI X T0NS=
AMERIZINE
Corrosionlnhibitor
l,fSS THAN 0.10 PPrn INCRNSED BY 2515
0.10 - 0.20 ppm SATISFACTOTY-NO CHANGE
OVER 0.20 pprn DECREASEO BY 2595
lNlTlAL DOSAGE 0.15 LTR (0.3 Pf l X TONS=
ADJUNCT.B
PhorphcteBciler WatrrTreaEnent
\
0 - l0 pptt
l0 - 20 ppm
I30 gm (1 oa x TONS ir l
, l
15 gm (0.s Oa X TONSf
20 - 10 ppm SATISFACTORY
10+ ppm i mrcx BLowNDowNI neouce DosAcE
lNlTlAL DOSAGE st GRAM ll 0Zl X TONS=
GC
ConcontrrtodAlkrlincUquid
MLSULfI,|RIC PPMACID N/to
0-0.3 0-3 0.15 hr. (0.3 PT) X TONSI
0"t- ot l0 - 70 0.10 ttt. (0.2 PT) X TONSr
0.E-0,9 80-m0.05 hr (0.1) X TONS
1.0- 1 .5 lm- lg l SATISFACTORY
1,5+ 150+ HIGH. BLOWNDOWNREDUCE DOSAGE
TOI'ALATJGUNITYTESTRESULT MUST BE I.ISS THANTWICETHE'T AUqUNITY,
IF NOT, OOJ I LTR(2 PTS) OF GCREGAHDLESS OF THE.T ALKALINITY.TEST AEilIN IN 2 I{OURS
a
.P- ALXAUN-ITY
TEST
178
CHLORIDETEST
BLoWDowN
NOTE:
LIOUIDI COAGUIAMT - NO TEST REOUIRED
Daily dosage 28 ml (1 .0 ounce) per day for each ton of water capacity to conditionsuspended sofids (oil and sludge) for removal by bottom blowdown. Flash bottom bfowand scum blow several times at 20 minute intervals after dosing the liquid coagulant.Dose tor 2 weeks or until oil renioval is compete. lf severe contamination persists, thepossibifity of continulng oil leakage shouH be inveslijated and etiminated.
WASTE HEAT BOILER PROBLEMS AND MAINTENANCE
Probfems in exhaust gas €conomizer can bo classified under categories such as:
a. low temperature cqld end corrosion.b. fouling of the gas and the water side.c. tube failure due to vibration.
Gas slde foullng could be kept under controt by wider lube pitching or in-line fitt ingof fins on to ther tubel and use of regular soot-blowing at individual tube' ;i l:;. ff i!quality combustion goes a long way in reducing the "roi,ni;;1'giilpol,r,
arthough thequality of fuel is constantly oeteriorating, proper centrifugirg "rfJ-tl"iirrnt
woutd behelpful in reducing the harmful combusiiod piocucts promoting fouling. Many shippingcompanies use some fuel treatment chemicals to reep the harmful contaminants undercontrol' Tube externals would stil l get fouled and periodic cleaning by water washing is themost effective way of keeping the tube externals clean. Cleanin! i l eitnlr done throughfixed nozzles inside the boiler banks or done through spgy nozztes and connecting pipeswhich are moved around as required. Water at about oooO ihould be usedtor cleini;g 5roprecautions should be taken to ensure that the drained water with high acid content do notflow into the main engine exhaust cluct. '" 'v'
SA'I'ISFACTOBYNO BLOWDOWN
Blovdown should be carried out ar per bcfler manufacturer,s instructions.Elqrdown ir necermry to roduce dirrolvsd and suspended solidr" lfrrponded rolidr are noticed in boirerwaterrampler. blo,vdo$rn regardlessof chlorides test rerultr. weekfy flarh blow is advirable to remove normalsludges and to ensuro clear operational l ines.
UP T0 7$ pmhos
1 7 9
Water slde scaling and corrosion is mainly attributed to the poor guality. of feecl
water used. lf ths water used is alkaline with low T.D.S. arrd has less contamination.ftgto*igrn, tubular boiler tubes should run for long time without giving_ any.problem. But, the
water used is normally the water from the openleed system hotwell and scaling/corrosionproblem would be impossibte to overcome completely. Certain improvementrs and reason-able running period could however be aclrieved by keeping the T.D.S. content and chloridelevel low byi6gular blowdown and chomicaltreatrnent and dosing of appropriate chemicals(e.g., NaOHI iould maintain the water in an alkaline condition;oxygen leveloould be keptwitflin acceptable margin by chemical treatment (hydra-ine) and keeping thelhotwell temp.high. Certdin operatiinal precautions like venting while starting, draining the boiler orkelping it full up, as shutting down would help in reducing corrosion.
Fouled water side could only be effectively cleaned by chemical cleaning.
Tube problem from vibration is sometimes a problem. Modern boilers are madeconsiderably large and takes up a sizable part of tlre uptake. The supporting box-typecasing built on i system of beams are rnade fairly rigid. lf the arrangement is too rigid'problem from fatigue failure is again possible. l- ' leavily stiffened support steelwork andcasings do reduce tne eff ect of pulsating gas stream. There is no easy solution to avibrationproblem if i t starts, but this is a problem better considered at the design stage.
lmportant mai ntenance steps
1 . Regular soot blowing2. Maintain good main engine combustion3. Adhere to correct centr i fuging and other f uel treatment methods4. Take advantage of additional chenrical treatntent on the gas side (e.g., soot
sticks, etc.5. Correct water treatment and test ing procedures6. Maintain right hotwell temperature7 . Vigilant\watchkeeping, particularly in rnonitoring exit gas temp from the EGEB. Rdgular in port inspeition and manual/water wash cleaning of the gas sideg" Coirect operation in terrns of circulation, sftut down, by-passing, etc.
SURVEY AND MAINTENANCE OF BOILERS
Boiler are surueyed to maintain the classificatiort of a ship. Regular internal andexternal examination during such survey constituta the preventive maintenance schedulethe boiler goes through for t safe working condition'
FREOUENCY OF SURVEYS
Water tube main propulsion boilers are surveyed at2yearly intervals. All other boilersincf uding exhaust gas boilers are surveyed at2 yearly intervals until they are I years oldand then surveyed annually.
For auxiliary boilers of water tube type, the classrfication may allow the 2-yearinciden:e to continue even after the expiry of 8 years period. .
180
SCOPE OF SUHVEYS
A complete boiler survey allows us to check out if any buildrrp of deposits has takenplace, and deformations or wastage of platework, piping or E,1t of the various parts, whichmay compromise the saie working order of the unit. ine.survey should inciude iinoingreasons for any anomalies found and should atso ensure that any rcp"ir carried out doesnot affect the s,afe.working order cf the hoiter. n compiete survey means ful internal andexternal examination of ail parts of the boiler and accessoriei such as superheaters,sconomiser, air-heater and all mcuntings. The examination may lead the surveyor torequire hydraulic te.sting of pressrte p.ais or thickness gaugings of plate or tubes thatappear to be wasted and ev'entually asiign a lower working pressure. The collision chocks,seating stools and rolling stays are alsito be checked for good working condition.The survey is not conrptbte untif the boiter has been examined under steam and thefollowing items dealt with:1 . pre.ssure gauge checked against a test gauge.2' testing of water level indicalors and protictiie devices.3' safety valves adjusted under steam io oio* otr rt the required pressures;4. the oi l fuel burning system examined.5' testing of remote 6ontrol gear for oil fuel shut off valves"
ARRANGEMENT BEFORE SURVEY
a' Boilerl rnust be sufficiently cleaned and dried to make a thorough examinationpossible' Sludge d.eposits continue to be the primr mrrc of non-operation of internal$.i[gr:,,ill iJ:i!:,?ilg fl:H$?i?,j:,1:;,,;;i b"ir;; Boirers should be manuany
In case of difficulty in manual.cleaning, a chemicat cleaning with hydrochloric acid plusan inhibitor to prevent acid attacking the rietal without affecting removal of deposits is thebest procedure.For oil contaminaticn, alkali boil-out.using trisodium phosphate sotution (whichproduces a detergent action). is essentiar prior tiacid cteaning.A thorougtir water ftushing must be carried out after acio cleaning to avoid acidconcentrating in crevices and clptive spaces.b' Alf internals which may interfere with the inspection has to be removed.c' wherever adequate visuat examination is hot possible, surueyor may haveto resort to. dril l ing, ultrasonic or hydraulic testing.d' All manhole doois and other doors must be opened for a reasonabte tinreprevious to sunrey for ventilation.e' l f another boi ler is under steam arrangement of locking bar and other securitydevices must be in posjtion preventing ine aomission of steam or hot water to theboiler under survey. The srnoke. tri lnking lseparating devicel, exhaust-gasshut-offs etc. mrrst also be jn pos.ition
"no"in ploper working condition.f ' Ship's staff or repairer's staff should rt"nJ6v tii* manhole in iase of emergencyand to note any repairs required.
SURVEY OF SUNROD CPI{ TANK BOILERPoor condition in this type of boiler may stern from:
Poor werkmanship during construction or repair.Deterioqation due to leaks or deposits.
1 8 1
Local overheating'Gornbined effects of mechanical stress and corrosion'
Damage condition would show up lnthe form of
wastage, 'grocving' or'pitting' corrosion or
distortion orcrack.
SurveY Boutes
Any boiler to survey, the inspector must pr1l out a route.for fis Jnollement' Almost
arways, the inspection mus.t start "t
tne f urnaci. The ,r"ron being, the furnacs reveals the
quarity or comLrriion ano itJerr.tJ ano aiv o]ltogo.n at the crown or the tube walls
signifying the prourrrs originating "1tne
wai;r side. In fact, a good cleanrlurnace with no
signs of distortion coutd aJsure ttie inspu.toiin"iin" boilei is-in good ru.nning condition'
The next in succession should be the burner-unlt, the bottom header and the boiler bottom'
Mounting attachments on tn. iJnllsheil *iil lorrow before entry is made through the
manhore to inspect the water sibb or the ri;;r ;p".r. Top mountingl wil be checked
before entering the gas ,p.., iniorgn the inspectibn door for a look at the sunrod tubes'
The inspection-will Jnd with a check-on the dismantled mounting parts arranged in order
for the purpose. rf in doubt oig,, side .orro.ion, checks on the gas uptake could be done
as a final steP in the survey route"
I. FURNACE
overheating distortion on the f urnace crown is due mainly t9.a deqosit of oil ' scale or
sludge oeposiis 6n the neatiig rrirr.r or duie to water shortago. Direct flame impingement
resulting in oeioimation of the crown ot rro..l bulge in witt tubes opposite the burner
opening is arso possibre. rf ih; to*., section of the crown around the u-+haped area is
affected, it could be due to the sludge deposits on the boilsr bottom causing overheating
distortion. In the sam, .rr.-*hrrc tFe furnace u is conrrected to the shell' there may also
be welding cracks due to rapid fluctuation oiin.rmal and mechanical stresses' results of
improper itarting up/shutting down procedures'
Furnace crowns which have suffered a gradual deformation can be iacked back to
their original shape with o, *iifiort heat. lsnirper deformation may require the plating to
be srotted so that the metailan extrude inio fi; g.p during heatin6,and Jacking' The slot
is butt welded on completion. A much nr.iri repiit is to 6rtn ouitne aifected area and
replace with "
uutt werdeJ insert section cut from a satvaged furnace' For a severely
damaged furnace with "
pionounced large Gtty, replacement could be'the only answer'
Dry cracks in furnace mouth, crown or the furnace tubes caused by flame impinge'
ment is possible due to scale encrustationJaiihe water side and forcing of the boiler' Areas
suffering from poor circutaiion; ;a rrt"ti'i.! unrooiro areas are also susceptible to the
above failure.
Deep cracks on prating shourd be stopped by drii l ing a hgle at each end, opening up
and then welding.
182
Indifferent feed water may cause pitting of the furnance crown. A careful examinationthrough the bottom manhote door would be required to detect the above 'grooving'
Furnace tubes must be inspeeted for correct alignment and the tubes together mustform a circular tub6 wall: anywhere the tubes are deformed, the furnance shafie will showup as missaligned. Distortion to a very small extent could be accepted, but beyond thatrenewal of tubes will be mandatory.
Furnace lube , if damaged (cracked, hoted or deformed) need be renewed with newtubes;only under emergency conditions, one could be allowed to operate boilerat tow load,*'.th plugged furnace tubes; plugging could be carried out with tapered steel plugs on ejchtube ends. The, botto.m plug will have to be inserted through thd bottom heade]; difficultyin doing that may also compell cutting windows on tubis from the furnance end andmanipulating the tapered plug in position (similar to that done in membrane walt boilerpanels).
Brickwork protecting the foundation, if damaged, may oause distortion of the bottomplating underneath the furnace. Damaged brickilork ne'ed be removed to inspect thebottom plating for distortion before repairs to the brickrruork is uarried out.
llY sign of corrosion on plating should be chipped ctean brushed clear. lt is alsopossible to build.up the. weakened aieas by means'of electric weldinj.-eittrd areas aredifficult to protqct from further corrosion du6 to the difficulty in maintaining thc protectivemagnetic oxide layer.
II. BOTTOM iHEADER
This contains the furnace tubes and the down comer tubes" lrlo of handhole dcors areprovided for illepal.inspection and repairs to the tubes. Inspection for deposits of sludgemust be carrierJ out during.th.e gurvey. Regular utowinf down from this header will benecessary to keep it clear of sludge deposits.I I I . SUNROD TUBES
Internalwasta$e due to waterside corrosion and pitting is the main reason for renewal.It is diffucult tq'determine the conditiorr of tubes by visual eiamination and the tubes sufferrnore at ends towards the fire; A metal rod inserted at the tube ends and worked up or Co*nmay reveal a weak tube - a method sometimes employed to tubes selected at random.The reason for corroded tubes is almost always the bad quality feed used giving riseto heavy scaling and corrosion.
Thermal cracks may develop at the trrbe ends at the hot gas entry zone.
The elements could be corroded on the outside due to the hot gas containing Sodium(Na) and Vanadium (V), referred to as high temperature corrosion;Tn this collection of ashcontaining Na and V may promote nrelting of oxide deposits across the tubes and causescoring of metal at the tube externals.IV. SHELL
Internal examination is made for cracks, corrossion wastage or deformation of shellplat ing.
183
Any oil trace must be removed by alkali-boilout. Corrosion may be expected atpositions with poor circulation and places which can harbour deposits. r \
Pitting corrosion in way of water level to be checked for, speciaily on idle boilers whereliberated Hissolved gas was not removed from the boiler with the steam. Boilers left wlthundisturbed water level for some length of time can develop serious pitting.
External corrosion can be caused by persistent leakaEe at mounting flanges andmanhole or handhole doors. Engine room floor underneath the boiuer may have occasionalbilge water and possess a damp atmosphore; there may also be oildoposit and stored ragsor paints drums; these are all potential hazards.
The wasted shell plating may be reinforced by welding but in case of extensivewastage, renewal of plating is the only remedy.
V. SUPPORT AND SECURII ' IG AHRANGEMENTS
Attachment between boiler and ship's structure should have adequate provision forexpansion. Restriction of movement imposes loaCs on the connections and if the part isunable to yield or bend, cracking will occur.
Welded attachments such as cradles, feet and rolling stay lugs should always beinspected carefully. Cracks due to stress concentration at the welded connections maypropagate into the shell plating.
VI. MOUNTINGS AND FITTINGS
Major mounting are removed, dismantled and inspected. Gauge glasses, safetyvalves, feedcheck valves, steam stop valves, are erll checke'd for corrosion, erosion, stengthand correct operations. Internal feed and chemical injection pipes are inspected for oxygenpitting and corrosion. Waste steam pipes are hammertested and all drains in the exhaustsystem checked. Soot blower nozzles are vulnerable to burning and to lbe checked forcorrect sweep pattqrn. The air registers are to be checked and cleaned. Clearange at themanhole and mudhole doors to be clrocked and should have a spigot- clearance notexceeding 1.5 mm all around. Leakage from manhole doors has been dause of seriousshell wastage. Where this is exceeded, the clearance can be restored by building up thedoor spigot with welding and hand-drossing to suit.
..Wastage of manhole landing faces is difficult to rectify by welding - fitt ing a falsesealing ring could be the recommencJed repair.
A careful check is made lor strained door studs, stripped and slack nuts and distorteddoors . A badfy fitted door can cause a joint to blow out under pressure.
Vtr'hen under steam, the surveyor always checks if manhole doors have been pulledup when hot and the doors are correctly positioned.
Cracks can occur in valve body due to water carry--over and quenching or mayoriginate from shrinkage defects in the castirrgs propagating in service. The only positivesolution is to replace the manifold entirely witfr a similar but fabricated construction. Repairby wolding the defects in the steel castings is also possible but this presents the problemof distortion.
1 8 4
r(D
oF I R E D
5. Gaq1g6 Glass/ F.d. Fan6" Steam spac€7. Furnacs CrowrrB. Uppor mounta ins
S U N R O D O I L B O I L E R
.at .
2 .3.4,
FurnaceBurnerBottom HeaderBoiler bottom
9. Gas Space10. Vertical tube11. Sunrod tube12. Gas uptak€
SURVEY ROI.JTE T'ROCEDURES
1 8 5
BOILER OPERATION ,\ND SAFET.V
Before the boiler is put into service for the first trrTre, it is to be boiled ouli fo' removal
of al l protecting i t*;Ofui anO impurit ies in tubes and drums'
BOILING OUT:
1 . Boi ler is f i l leclwith a solut ion containing 4-5 kg Tri-sodium Phosphate (Na. Po.)
z. i:'Ji*tJf#ti,ii:';?tti?'tl''unnoru ancJ top up with rvater until the solution is
just visible in the water level gauge'
3. Raise the steam pressure in the boi ler to working pressure and maintain
the pressure to, 6-g hrs with crosed main stop uirue, afiel which fat and
other impurities snluto be boilecJ f;; '" the interioi surtaces of the boiler'
4. Make sure that the water level is 20-30 mrn abo've the scum funnel and skinr off
the f loating contaminants through scum blow'
5. After the boir ing out operation has been compreted, the water in the boi ler
is blown out, the boiler internar is fluinecr. The rroiieiis now f i l led with f resh treated
water to a litt le br:low normal water6. lf ouring service, the boiler shows a tende.cy to priming, it is recornmended to
cara] out an extra boiling out.. ln any case'. after a period of 2-3 months
after commissioning, another uoiling oui op.raiion is strongly recommended for
new boi lers.
porNTs ro NorE wHrLE STARTTNG A BoTLER: (with no "superheater")
7. check that the boiler is properly closed-up (after repairs)'g. check (physically) that all approJri"tr valves are shut or open for safe starting
of the boi ler.9. Aoiter f i l tel to sl ightly below normal level.
l 0 .S ta r t i ng t rea tmen tchemica l smaynowbeadded to thebo i l e rwa te r .1 1 . Check and cleat lnt f urnace of any flammable materials'
12. Eniure that the boiler uptake passage is clear.
13. pre-purging of furnace ior a specif iJd amornt of t ime is necessary to cleartha
gar-riOd oiflammable gases, to avoid starting explosion!
14. on a cotd boiter, the firing-up must nctue speaded up too much l1-119-:::.:ttooverstrain the boiler mateiial ,nnrrcrsarily by quick, uneven temperature ralses'
15. Keep the boi le, u.nt, of rn unti l a hoavy steam iet is f lorving out (unti l a pressure
16. Blrl;l;ttfiSoirry is put on toad, blow-throush the sause slasses' testthe saretv
valves using ."tinf gear and try out the safety cutouts'
PoINTS To NoTE WHILE THE BoILER lS oN LoAD:
17. Operate the boi ler at a load where i ts eff iciency is l lhe highest '
1 g. Maintain correct air/f uel ratio; under perf ect conditions a brownish hazy colour of
exhaust smoke is noticed from uptake' .19. co, Co,, 02 contents aS monitored in the exhaust gas wilt indicate the
combustion iondition inside the boiler.
1 8 6
20.
CapacltyOperatlng PressureDeslgn PressureFeed water temp.Efflclency (F/Load)F.O. ConsumptlonWater volumeOutslde dlameterHelghtDry welght
BOILER DESCRIPTION
Sunrod CPH-S
5,000 kg/crn26.0 bar g18.0 bar g85-900C85"8%360 kg/h5.7 m32,600 mm5,720 mm13,000 kg
21.22.
Every morning mud is blorvn from the boiler through the bottom blow--off valvesand float ichambers.Ensure that all safety cut-outs are operational.Maintain t[e feed water qualrty as recommended by the manufacturer.
BOILER DATAS
Sunrod CPFI-45
45,000 kg/cm216.0 bar g18.0 bar g85-900C81.4%3,440 kg/h17 .1 m34 ,100 mm9,660 mm50,000 kg
1. Vertical design with 2 combined steel compartmenrs or cylinders2. Lower cylinder contains the furnaco3. Upper cylinder used for steam evaporationI. 9Vstem of piping connects the upper and the lower cylinders forwater circutation5. Furnace is water cooled with riser tubes forming the wall6. Fing shiaped distribution header at the furnace bottom supplies water to the
furnace water call7. The lower end of the upper cylindricat compartment is dome shaped which
makes the furnace roofThe bottom sUpport for the boiler is provided by the support ring and steel ptatefabricationThe support ring is welded to the distribution headerFlue gas flows through the vertical uptakesVerticaliuptakes contain sunrod tubes which is connected to the water and thesteam placeEach vertical uptake and its sunrod tubes makes one sunrod element, acting asconvection unitFlue gas is discharged into flue gas receiver and then to the atmosphere viathefunnelDowncomer tubes are fitted between the lowermost part of the pressuro vesseland the distribution header to improve the circulation
THE SUNROD EUEMENTThe sunrod element consists of a plain steel tube, enclosing a Sunrod pin tubeLarge n,umber of steel pins are welded around the outside of the seamless steelnin.tube
9.1 0 .1 1 .
8.
12.
1 3 .
14 .
{t .
2.
187
The Studs increase tlre heating surface area and also creates turbulence in thegas flow, thereby improving upon the heat transfer and making the sunrodelement more eff lcient than a conventionai plain tubing \
The number of sunrod elements depends on the boi ler capacity
CIRCULATION AND STEAM ITAISING
1. Water c irculat ion is on the pr inciple of natural c i rculat ion ordensi ty di f ference offeed water
Z. Water occupies the pressure vessel , the st tnrod tubes, the furnace wal l tubes,the downcomer tubes and the distr ibut ion header
3. Under steady state operation of the boiler, the radiation heat of the frurnace wil lcreate steam water emulsion within the water-wall and the fluid wil l r ise throughthe risers into the pressure vessel, drawitrg fronr the distribution header
4. As water is fed into the risers f rom the distribution header, a suction isrcreated atthe downcomers which feed the header
5. The emulsion r ises througlr the furnace roof and lnto the sunrod elements; thewater at the sides of the pressure vessel tends to be denser and flows down tothe downcomersRapid evaporation inside the elements and steam bubbles formed and thegreatly decreased density f luid r ises rapidly in the tubeThe upward flow of water/steam mixture creates a suctiorr effort at the lower end,causing the boi ler water to f low into the tubeThe steam/water mixture is discharged into the steam space, where the treavierwater particles separate from rhe steam and fall back into the water50% of the steam generated is through the Sunrod tubes and the rest by radiantheat from the furnace
EMERGENCY AND ABNORMAL RUNNING CONDITION{i
The fol lowing are the guide l ines for an engineer on duty to respond to emergencysituation in a boi ler plant:
High water level:a. Check and reduce f ir ing rate.b. OPerate blowdown sYstern.c. Throttle feed check valves.cJ. lf bad water hammer due to carry-over is experienced, close steam outlet valve
to prevent damage to pipe |,ines and macltinery.
Water level below gauge glass:a. Shut-off burner (if not cut-out automatically)'b. Take the boiler oui of load.c. Ensure no internal damage due to overheating.d, Do not bring-up the watei level in haste until the boiler parts are cooled down-
3 .
4 .
6 .
7 "
8 .
9 .
JJJJJ
188
Tube fai lure:Small leak:1. More make-up feed required.2. Drop in totalt issolved sol id content of feed water.3. Diff iculty in water level maintenance.
Large Ieak,:1 . Water level vanishes.2. Burst ing noise.3. Drop in steam pressure.4. Flame may be put-off by steam.
Actions:1. Put off f i re, (by stopping the burner i f necessary).2. lsolate the boi ler"3. Try and maintain the water level unti l the boi ler is cooled.4. Test and plug the tube as per the recommended procedure.
EMERGENCY OPERATION DIJE TO FIRE
Fires can occur in the air heaters, economisers, superheaters and exhaust gas heatexchangers. These heat extracting units are all situateO in the path of combustiJn gasesand under certain condit ions, fortunately rare, can experience disastrous f ires. These f iresare two types:
1 . Soot f i re2" Hydrogen f ire
Soof F[res:1. The ignit ion of ?Fr sccurTlulat ion of soot immediately after l ighting-up or during
periods of l ighl load operation.2. Air heaters and pin-tube elements are prone to this f ire.3. Indicatel bv a very high uptake temperature of gases.4. Shut-off fuel and air supply to the burners and Jlose al l dampers.5. Flood the area with water and cjo not use watcr spray.
Hydrogen f ires:1. Steam breaks up into Hydrogen and Oxygen at a temp of 25000C.2, lron wil l buf n in steam with reproduction of free Hyclrogen at much lower tempera-
tures of about 7000C.lndicated by a tube rupture and very high f lue gas temperature.cut-out the burner and stop feed water supply to the boi ler.A Hydrogen f ire stops only when the supply of steam/water is exharlsted.
3 .4.5 .
1 8 9
HEMICAL SELECTION GUIDE USE ON BOARD
fypo Syctom Problem DrewChomlcal Uge
Type Syctem Problem , DrewChemlcal Ure
rffirEllg|Iltryil
:vr9ctl ltdrdr rtpn*r d EpIdr, tl.tn .gld'.5. frd CD lpc
8*. Fornhg rtxlcrry ovs
AEROVA|. errpo.dottreolflFfil
Daad qtgha cLcoolorr, trrbod|gg|g, krtofaoolofs,lltrit. eic.
o|Ucgo.ic d.fitl ACCa rL cod.. d.Jre..ACG,9RCIIXIIEX rircools deang
Boale,, do6nlgFntrolg andovapordorg
CXI qgn|lbrbpocltrSc8lo. Crrdgp 8ndodtqarn
Ho/ETn hcs/y fityqrulanct8A!\ACIO ddcalingdnpo/ald
th r.lt9rrI|wgrrEr d thc,tpd gnp.tadoalmd gry rn brPcs|Indtt ||.d hhc Oitrcr }rf.6l
SceftFormang r|d ca,ryo\rr
AERET orapo.ardro&nont
B.rfdroads, dedrr.raLngr snd 06.r.tucnral sjrfEr
Fkrd s|d cqr6bnCIUoAE ic d€p€it80lo6\4t Drrty)
UCtt drty
AEROIO B8AOIOR oal and groaror€|novlg,DEOREABER AP getoralgrrpao dogesrcAEFo|O OU3 qlcrre.rdne deg.ro.,EDOC h6,y cfrry drts
EIIVIROIATE I al pulpccdoen r
trd.|y. odrrdp rt*.n bolar|[r C{.d wrmrda}{.b
Cqrorim. ScCe,D.po.l btn do.lrid ary os
AOK - tm boalgr rtd fo€durdoa rootmont
U trrrt (!9 bne/€|l' {lO Fa)*f St trllff mC.}{p
Conorbn. 8ode.D?oda bm.dd!r$ oJry o,.'
Sludgo. 6nd Olqrtanlndon
l-* Prcau'r Eoab. ond tocdw!b. fo.lnc|rt .nd CofitrolProgurlAAllf,ET€ Cro.phe bdbwru fcln .t
Ebortcd oqfpdrcnlu|d pertr
o|! Aoporib(Fed Dry)
DRnt ELlcTtUC nrobr r'|dprrt d{no.
AERDI|E sraian hhatibr.ItCgAsrdcn d.qroaonflibito.UO||O OOAOIJ|'AXT boal€.*dgp co.rddqror (r.p b 4akCc,nr ff, Fa olry)
Prrtfiorfscprdddsca
hcaarn olud0pdfodtt
AIEROIO DC dsc dosu
Engine codlng waorryrrloana
OVoAsrc d€poilt
Ught o{. rcab andrut|
Scafg ard ruc
jlDe-TTl ltoail'y dfysnJdllsAI:RCXD O8C onosodoanef
tAFAC|D e.cel|tg.q'||:rlrr tF.oIra trCnH. Plb,rleE rrd d|€r!*lg qrbflr.
gcrTilon
Carabn and rceb
D€WT LC drd ooghowdr rcdna.n
UOUOAilT coding wdsboafiiontlrcL ddd €rtrho wttorrodnmt
&qino phicn . rhgs,Ydrr6, pertloOoed bcsnbudldt
Csbon epo.itr,vFlrh andgunmy mstref
CAR9Oil REr|CI/ER Dhrsrcilsrs
BUXKERSO|II) .l/dgedvonudrp.nsrf
rut.rrlhtgh rpocdfra reh.nilrg ryfmt
Gorabn, Scab mdCaftr[on
IAXXIARO de.cl enghcurdd rcainfit
Fuel hoeb.t endlno ot coolci (olddc)
quo.ge.fc dtpoltr l|DE tTt Itc.try dryanuhiftr,
CARBOII REHwER .ofrqi(!E rca
td tda Slrdgo h,tl4q,
\
Bloaoghdcofuindon ofdtdllr. i,Far
AI:ROY Ut r.d dlsddoneB(.|lIGfltoI'O *JdgorctvfitlCqprrrr,F,O.T. Irrol oU rodnsrt
AERSTAT 10 tlolrloobaoddc
Cil rfl{s (on wdor,co., erc.)
qUpebol€irm
dgsrtcro8qLY dl rpl Cl|pqt rr
ft\rLe rop6 Cmelcr llE\rAIElT *ire mpcsrddoner
Boflart T.nlc Ell md mttd ruo @flofnoilEn bcr.dlBril( r,sr tr!|tm.nt
)drtdstfDarubmDlea
Ioa
lrEnCot!oonb.Jdqr
tlqdo endfsnptoconbudo.r
A):ROY 10@ qnburdqrkrprore
AEROtrE d€polt tnodttq/csnbudg| lfip.or/s
Lay up Befrd Corrolan PROTECSOI'I@ recrdcra,rrdon hhblbr
BdLd T..ila grdVdd Sp6
Cor6lqt IAOI|A|(OTE n d pf5re.rirrgod.rg
Ee.wS. @olng
ayrtlmrEbb$cC fqrhg AIIRS€PEREI D
lo.wrbr odane fe{fnonlfo|r rtfetng &taftrlvrrdsrr
laT d?altrETOIIATE f.Eid. rlrend crqbn lfilblbr hd(| wdcr
rycoanaCqrclm ,ClL csrqlqr lillbito.
ilsf Ai.ntLd
Lrn
8a U.{d'up
8a U.{+rp
LT. t@T RELEAIG .oolomhdar odlynl@T 3nGKl Esnbudgt cry
Bl196r Ollagrntoco.firnanetbn
o|l Ndor tcper8b.tyfb.na
TC ta t|rt d.x..ATWROIJ. KlIEll Ei(deanerAEROID OtVf qrd(EAtrdng dcffu|r
)rlo rt V4etrbao rnddrml ofr
Fud 6 srdcru'b 6lh
lmt hcvt, dny €5rrctlC llqfd dldrp drno.TC f4 trt( dcoa.ATrt/ROLLKLEET{ tenkffffOCORIAICR TK trcrry dny
Stcrrdr Depl,Grloy .r|d HoblAccqnodd[qr!
OUdrt r.rderMrorYnonld aoab
ENVIROIATE I d nryorldoorFrAII Pt'RPO3E D€TEROITNpo*e(BO dotsrgsf
iiiiiiii
r90
INTERNAL COMBUSTION ENGINE
Cl. What ls the diflerences between the followlng?
INTEBNAL COMBUSTION ENGINE - an engine in which the fuel is bumed directly withinthe working cylinder. Both gas and diesel engines are examples of internal combustionengines.
EXTERNAL COMBUSTION ENGINE - is one in which the fuel is bumed outside of thepower cylinder. For example, in a steam engine the fuel is bumed and heats the water ina boiler which produces the steam that is sent into the cylincler
DIESEL ENGINE - ls an engine which uses a tow grade oil for fuel and ignite itdirectly in the cylinder by the heat of air compression.
GASOLINE ENGINE - requires high-grade gasoline for fuelwhich is ignited by an electricspark after the gasoline has been mixed with air in a carburetor, injected into the cylinder,and the mixture compressed.
FOUR CYCLE ENGINE - four stroke of the piston are required to complete one cycte orseries of events which nrust take place, in regular order, to operate the engine.
TWO CYCLE ENGINE - two strokes of the piston are required to complete one cycte orserles of events lnust take place, in regular order, to operate the engine.
SINGLE-ACTING ENGINE - is one in which the pressure produces the power stroke isexerted upon only one side of the piston.
DOUBLE'ACTING ENGINE - is one rryhich operates similarly to a single acting engine,except that pressure producing the power strokes is exerted first on ons side of the piiton,then on the other end, which makes each piston stroke a power,stroke.
O, Cf assif lcat lon of Internal Combustion Englnes . ,1. As to power motion 4" As to ignit ion
a. reciprocatingb. rotary
2. As to cycle useda. ottoh. d ieselc. brayton
a. two-strokeb. four-stroke
a. spark-ignitionb. compression ignit ion
5" As to general designa. single-actingb. doubf e-acting
a. in l ineb. \/-type
c. X-typed. radiale. barrel type
7. As to method of coolinga. liquid-coolingb. air-cooling
8. As to method of supplying aira. naturally aspiratedb. superchargedc. scavenged
3. As to method of charging 6. As to cylinder arrangement
1 9 1
Q . W t r a t a r e t h e | o u r s t r o k e s l n t h e | o u r c y c l e D . E . . ?
1. |ntako stroko - means drawing or supplyilg. air into the cytinobr
z. oompression stro\e - moa*s .orpi..rin" aiiuy upwaro motion-ot the piston
3. pcwer stroke _ hot ;i;;.; ruri',i,ilo prooutu'po*"r bv the buming
gasgs ' -^r^^^n " , { r r rncl t rct of combusl lor l '
4 , E > c h a u s t s t . ' o k e - e x p e | o r r e l e a s e o t p r o d u c t o f c o m b u s t i o n
Q . L l s t t h e s e r i e s o f B V i } I . l t S i r r t h e 4 s t r o l t e c y c l e D . E .
The serie s of events taking place in a cylinder of a lour-stroke cycle engine and making
upon,'.*?f5,:il:?ff"f:il'Iil!:s, permittins air to be drawn into the cvrinder bv the
?2 S:*ln:ffi'l'ff,'lJ:i.3:i'l;9 9:Jl::ol,:l",,upward, compressins the air ror
3. ?',.'..'#'lffi lm'lxir:3::;""fJi.frJi3Jl3li is injected into the hot air whereit ignites'
4 .Four th , theburn ing fue l fo rmg '1S9S* 'h . ' . : | : :1? t 'p ressureandsendthep is ton
; PikH?'s; lli nil::ru1iiiq"l'ffill'?l3i'oke' the exhaust varve open
; a?f,,11rui;?"[: :.lil:i. 3 i,"T"ti ff,'ffJ., t th e re m ai n i n s s as e s i n th e cvr i n d e r'
Theexhaustu"ru ' ' rose-sandthecyclerepeats.
Q. What are the tluo strokes ln a two cycle D'E"?
l . o n e s t r o k e c o m p r e s s e s a i r i n , t h e c y l i n d e r t o i g n i t e t h e f u e l o i | .2. Th-e other strokJ is produ.uo ovin-J Uurnir,g g;*r. rt is the porver stroke'
Q .L l s t t hese r i eso feven ts i n t | r e two -s t rokecyc leD .E .
1. Air, under sright pressure, is blown into and f'rs the cylinder through the
;pt. valves in the head'
z. The piston is starting upward to compress the air f or producing heat to ignite the
fuel.
? : i[: ffi l'" :iH : rT'fli ?xT f' : i 3' I'3' L illl;' *'= *? J:ffi : SffJ'J*IT :5. The burning fue| form gases which creatc
" p,.,,,re and send;the piston down.
+f,:'#JlJ?irt:ff:i':?Xilr u"ly:,:liin' head then op€n and air under
oressure forceJout whateuu,. 7u*uining grr!r',""vur in the cylinders' leaving
:i;;ffi iotint next compression'
Q. what are the relative advantages and disadvantages of a.'cycle Diesel engine?
Advantages:1.
' lt i i*eight and space per'horse power'
2 .Grea te rho rsepowerpe rcy l i nde r .
192
3. More uniform turning effect.4. Less complicated cyl inder head. r,Dlsadvantages:1 . Less volumetric efficiency.2. Greater fuer consumption ttran the 4-cycre.3. A scavenging air pump is required.4' Trouble with cylinder liners due to intake or exhaust ports.
cl' What are the relative advantages and r:tisadvantages of a 4-cycle Dieselengf ne?Advantages:1 . Better vof umetric efficiency.2. Lower fuel consumption.3. No air s.cavenging pump needed.4. Less cyfinder iinel irou6le, since there are no ports"5. Higher engine speeds.
Dlsadvantages:1. More weight an,C space than the 2_cycle.2. More complex cylinder_head casting.3" More varves and moving parts than the 2-cycfe engine.
o Describe the operating princrpre of an opposed prston engine.
All opposed'piston ertgines are the 2 stroke cycle type" They have two pistonsin each cylinder and as they come together, air is compressed tretween them. when thepistons reaches a point ai which tfrev are closest iogether, maximum compressionpressure is reached. This pornt is referred t.o gs-;;rrp;;=.ion dead..nirr." As the pistonapproach the combustion dead center fuel is injectecliDue to the heat of conpression themixture of fuel and air burns and expands forcing the pist,cns outwarrl to dcllverthe power.
Q' State the advantages and disadvantBges of an opposed-piston engine.
Advantages: Light weight per horsepower; absence of complicated casling (nocylinder heads); absgnce of vllves and valve-operating gear; convenience anc; ease inoverhaul, repair andrinspection, due to accessibi l i ty "ni
f .*er parts.
Df sadvantages: The principal disadvantage is the inaccessibi l i ty of the towercrarrkshaft ' The.opposed-piston engine el iminat6s most of the dif f icult ies, however,encountered in design of double-acting engines, exposure of the piston rod to thetemperature of combustion, unsatisfacto-ry combustion in the-lower cylinier, piston coolingand'seizure of the piston rocJ in the lowei cyl inder-head stuff ing box. - '
0. Describe the Otto cycle?
The otto cycle is a 4 stroke cycle in wl"r;ch the volume of the cylinder is constant at thepoint of ignition' The first stroke (down) of the piston suct in the gas-air mixture and
1 9 3
clmpress it during the second stroke (upward) and ignite it at approxinrately top deadcenter. The expansion of the ignited gas dri'res the piston downward agaip and on thereturn upward stroke forces the burned gas from the cylinder.O" What are the two types of llner?
Dry Llner - usually a very thin liner, which does not come in direct contact with thecoollng water.
Wet Llner - a cylinder used on larger engines, which comes in direct contact wlth thecoollng water and fltted somo rubber sealing on top and lrottclm portion of the liner Inorder to prevent leakage of cooling water into the engine surnp that might contaminatethe lube oil system.
Cl. What are the types of plston usuatty used on merchant shlp now?
Crosshead-UPe -fitted on slow and medium speed engines, consist of a shortskirtand has a plston rod either bolted or screwed to the piston. The plston rod,ls connectedto the connecting rod at the crosshead. Usually two stroke cycte engine built this tpelike a main engine.
Trunk-type'plston-usually used on small high speed engines, which has a long skirtand connected rod directly attached to it by means of osciltating wristpin tb thecrankshaft. Four stroke cycle engine like arrxiliary engines design to it.
o. what are the two mafor types of f uel Infectlon system?
Alr Inlrctlon type - an air compressor produce air at a constant pressure of 600to 1000 psl to all spray valves on the engine" A fuel pump discharge enough amountluel oil into the spray valve chamber, at proper time in the stroke, ths valve gear causesthe needle valve tb open and air blows the oil in the chamber violently Into ihe cylinder,breaking lt up into a fine mist particles.
Mechanlcal solld lntectlon type-usually f itted on individual fuel pumps each cylinderof the engine,consist of plunger and barrel, when the injection check timing occurredby tho camshaft, fuel inJeutlon check valve open producing higher pressure leading Intohigh pressure pipe to fuel Injoctor valve for atomlzation.
Q. Descrlbe varlous method of plston-rlng constructlon and folnts?
@mpresslon rlngs - usually close-grained cast iron, square in section with a thick-ness of approxlmatoly 1140 of the cyllnder bore. lt ls also tapered on top of the crownvicirtity to allow expansion being introduced to the hottest part where combustlon takeplace. Tile purpose is to have gas tighi seal during the process'in order o have higherengine output.
Scraperrlngs-is beveled on the bottom to form a scraping edge and a number of smallholes drilled through the plston skirt to drain off the oil scraped from the cylinder wall.Fitted mostly on a trurrk type, high speed 4 cycle engines.
194
Plston rlng deslgn ends cut as follows:
a. Square buttb. Bevel jointedc. Step cutd. Overtgpped
O. What Upes of metal are used In the fotlowllng dlesel englne parts?
a. Bedplate -cast iron or steel plateb. Holdlng Down Bolts - high corrosion resi.sting steelc. Framgs - alloyed cast iron or wefded sterel fiamed. Crankshaft -cast or forged steele. Connecting rods- soft steelf. Plstoins, - farger engine : hoad forged srsel, skirt - east iron
smaller engine: aluminum alloy.
g. Llnelg - closed grain cast iron or cast steelh. Watar Jackets - cast ironI Cylinder head - cast iron or aluminum ailoy.J. Fueltvalves - forged steel or cast ironk' lnlet'- Exhaust'valves - cast iron cage or carbon steel with stellite seats used"I Af . Cams - forged steelm. Camis roller - forged steeln. Valve sprlngs - spring steelo. Piston rings - cast steel or cast ironp. Bearlngs - shell; cast lron or cast steel; surface babbitt or copper nickel atfoy.
Gl' Descrlbe the operatlng prlnclples of a governors; types and klnds?
Govemors -consist of two weights attached to a splndle, drlven by the englne. As theenglne speed up and slows down, centrifugal force actuates the fuel control lintcage bymeans of attachbd weights, thereby control ther fuel, measuring and stabilizing enginespeed by varying fuel flow.
Types:a. Centrifugalb. Inertiac. Inertia and centrifugal combinedd. Hydrautic
KINDS
l. lsochronus Govemor - maintain constant speed from zero up to full load.
% speed Reg. = no roadspee.cr; fuil road speed x 100full load speed
1 9 5
Speed drop actuate governor rotating speed output shaft (fuel control) to
move from full open to f ull i losed. Momentary speed changed causes hunting
due to sensitivity and quick action for correction. \
2. Constant Speed Governor -single speed type from no loads to full load vice
versa.
S. Variabte Speed Governor - speed regulation can be selected, from idling(zero) to full (max) sPeed.
4. Speed Limiting Governor -control minimum to maximum speed.
S, Overspeed Type Governor - does not regulate the enginet speef, but.it willprevent ine engine from exceeding a certain predetermined maximumspeed, usually found on main propulsion engines.
Q. Describe at teast fcur different types of pre'combustlon chamber?
1 . The antechamber- it is an added chamber to the main chamber in which the fuelis partially burnod and thon injected into the main chamber for complete burning.
Z. The air cett-it is modification of the antachamber. lt is placed in the piston crownand furnished highly t'rrbulent air to the combustion chamber on the upwardstroke of the piston.
g" The energy cett-used in the lanova system of combustion. lt is similarto the air-cell except that it is divided into two sections by a narrow throat.
4. The turbulence chamber- it is an auxiliary chamber that is placed to one side ofthe cylinder head and is used to give increased turbulence.
What are the different parts of a modern diesel engines and operational functions?
I. BEDPLATE AND* HOLDING DOWN ARRANGEMENTS
Bedptate is the most heavily loaded (especially the main bearing saddle) structural
component of the main propulsion engine" Propulsion engine berJplates ars fabricatedfrom mild steel plates, cross girder is steel casting and welded together. Main advantageof fabricated bedplate is lightiess and lower cost. These are of deep box pattern with flat
bottom.
Bedplate connected to engine seating through chocks which are part of holding down
arrangement. Chocks are eithei made of slee/ or epoxy r9si.n. Holding down arrangementsuse ldng bolts with spacer. Engine uses sides and end chocks to take up side and end
loads. Bolts are free through the chocks, bedplate and tank top.
Most heavily loaded part of the bedplerte is central portion of the transverse girder ndthe junction welds between transverse girOer and longitudinal girder..All parts of bedplatecontribute to strenght. The cross girdeiis made of cast steel according to requirements.The construction lrovides good resistance to twisting along ilt length. [ongitudinal
strength obtained by makingine each side of the bedplate in the form of girder. Bedplate
1 9 6
fr il5?:fftJ[:?:t chocks atons the lonsitudinaf sirder. tt has no sLrpport at the centre
Folrowirrg parts otbedptate requi.e utmost care:
1' :.#Hiart
of cross girder or bearing saddle which is very heavity toaded and has no2' Junction welds between cross girder and longitudinal girder;3. All wefded joints;4. Alf tightening holes, tie boft lroies.
Followlng parts of hofdfng rlown arrangements requlre attention:
1 Bedplate hording down borts often run trose;2. Loose chocks (supportirrg, sicle anO end) i3" Crack spacers ;4' Bolts are hydraulicalfy,tig.h.tenecJ (never tighten in a running engine)5' These are heavily loadel bo'ts, so Lott aiis and nrt rrrting to be normat;
II" FRAMES
on large main propuf sion engines frames are basically transverse members straddi'gon each cross girder' They are strong trans'rersely and to impart longitudinar strength,girder type of construction iaue b;;;;Jopted in fongitudinat directionFrames in way of guides are extremely. heavily loaded. during engine operation. Theside thrust due to ine donnecting too
"rgularity is transritted through the guide to theframe' Frames need to be strong longitu?inafly to giur:the cyfinder block a substantialsupport so that cylinder liners remain it clamping points.
Frames are prone to cracking behind guides, in way of wetds, any bolt holes, atchange of sections' Pronb to frettini on top ano bottom if tie bolts are running foose.III. TIE BOLTS
The firing foad' from the cylinder covers is transferred. through cover studs to thecylinder blocki or beams' rne beam tranrters the load through the tiebort nuts and tiebortsto ther bedplate cross girder. Ttrbri[ krrp il e strucirie'Jno* compression.Tiesbolts are subjected to severe tensile loads on mocern highly rated engines. Theytend to vibratt glggsdively during r*on"nrr ronr, so guide bushes or pinching screws areprovided' slack tiebolts may resutt in fretting and seu-ere structurar misaf ignment.Refer to engine builder's manuat for tiebofts'checking o.f pretension, slackening andtightening' stack tiebolts *il l tt.rl i in'sJr"re structural oarnag;.-ri"tort srackening,tlghtening should always oe oone in ,tlir*, correct sequence and pairs. start trorirmldship then athwarship, alternate from iorward and aft. cylinders.
197
;l
JJ
IV. GUIDES - \
Guides are litted in 2 stk crosshead type engine with high'stroke " bor€r'ratio to takeup the side thrust due to connecting rod-angulality. This side thrust is enormous whichmakes the guidos heavily loaded.
Guides keep the running gear aligned anrJ take up side thrust due to connecting rodangularity, so in ideal cases liner will not be subJected to side thrust.
Large mdn propulsion engine, guide and guide shoe clearances have very littlelatitude. lmproper clearance may result in guide shoe, crosshead bearing running hot andresulting crankcase explosion. lt may also result in piston misalignment, excessive wear ofpiston rod and stuffing box.
V. BEARING
Bearing -- Following parts require special attention:a. Main bearing bottom half ;b. Bottom end bearing top half ;c. Crosshead bearing bottom half;d. Bearing surfaces for damage and marks;e. Bearing clearance in admissible range; (Excessive and less clearance, both are
detrimental)f. lmproper clearance may result in severe damage to the shaft, bearing surface
and eventual crankcase explosion.
VI. BEARING BOLTS
Following areas to bs inspected:1, In way of fi l lets and any change of section;2. Bolts surface foilany damage and scratch marks;3. Overall stretch in the bolts by trammed gauge;4. Healthy sound from the bolt.
VII. CYLINDER LINER
Cylinder liners are centrifugally cast with the upper end like a flange cast integral withthe liner. Underside of the flange rests on the cylinder block. The cylinder cover holds heliner in place when the cover studs are hardened down. Lower portion of the liner is usuallyof thinner section. Most of the modern engines have been using bore cooling rto combatboth high mechanical and thermal stresses. Larger engino liners are of wet $pe wherecooling water comes directly In contact with liner metal.
Cylinder liners of modern large highly rated engines burning extremely poor qualityresidudl fuel are subjected to severe mechanical and thermal stresses and possibilities ofcold corrosion is high if corre<"t liner metal temperature and cooling water outlet tempera-ture not maintained as specified by makers. Liner flange is subjected to bending momentespecially if the cylinder cover unevenly tightened.
1 9 8
JJJJJ
J
J;
tJtJ
Durlng overhaullng of unlts
1. Inspect liner surfaco without ctearing, the state of liner lubricating oil lPread, carbon-isation,s hand pump lubricators to eitimate lubricating oil flow through quills, cafion-isatlon In way oJ scavenge ports, etc.
2. Clean thoroughly and check for cracks and burning marks at top part of liner, cracksin way of scaierige ports, scoring marks on the surfa@, cracks in way of liner flange.
3. Calibrate linerthoroughly using maker's template giving special attention to the toppart (wear rato of l iner should be <.1 mm/1000 hrs).
4" In case the tiner has to be renewed, lollow engine builde/s instructions step by step.
Exampte; Cylinder liner bore = 900 mm; change should be 1% inside diameter of the
b o r g - 9 m m . m a x .
For: Slow speed (liner wear) - 0.1 rnm/1000 hrs.Medium speed (liner wear') - 0.015 mm/1000 hrs'
Formula:Wear rate = increase in dia. (total) x 1000
Running hrs. (total)
= mrn/1000 hrs.
Reasons for maxlmum wear
1. gas load behind ring minimum2. cylinder hottest in this regiong. cbrrosive wear - cylindei ternperature high but may lower than dew point4. viscosity oil tilm minimum, film may breakdown5. 2 stroke engine have higher wear abovo parts
Causes of excesslve vlear
1 . low sulphur fuel with high TBN cylinder oil2. Inelficient combustion3. scavenging air temperaturo too low4. overloading engine5. contamination of lubricating oil6. unsuitable liner material
Gyllnder Lubrlcatlon
Modern large engines are highly loaded and at the same time have been using
extremety pooi "qraiiti fuel. Cylincler lubricating o!! has to be thermally stable at high
temperature and at the same time roduce the posiibilities of cold corrosion. Role o.f cylinder
i'ruri."ti"g oil in modern highly rated enginbs is extremely dema.nqlp. oif with proper
characteristics, correct teedraie and at the right time are essential. S.G. 0.948; Flash pt'
238€; Pour pt.-?0o0; Viscosity 89-85, TBN 70'
7. piston ring clearance incorrectf. inadequate oil supply9. distortion of cylinders
10. misallgnment of piston1 f . improper running-in of engine
199
Lubricant Requirement
1 . s l id ing fr ict ion minimurn2. adequate viscosi ty at high temperature3. ef fect ive oi l seal (r ing and l iner)4. burn without deposi t5. neutral ize corrosive acids
[.ubr icat io n Consu mption
Depend on design, load, fuel construct ion, fuel qual i ty, temperature gradiont acrossl i ne r "
VI I I . P ISTONS
Pistons of large highly rated engines are subjected to very l 'r igh mechanical andt l rermal stresses. To combat the same, number of engine bui lders have been using borecooling. Modern approach has been also to ulse forged alloy steel for piston crown towi ths tand h igh thermal s t resses (n icko l chrome s tee l or molybdenum stee l ) .
During operat ion, the piston is subjected to very high compressive ancJ tensi lestresses due to gas pressures, inert ia ef fects and thermal stresses. Gas pressures andinert ia l ef fects resul t in bending act ion of piston crown. Thermal stresses in piston set updue to difference in temperature across a section. Hottest part of piston crown iq at thejunct ion of s ide wal l and top plate. ldeal ly, t l re piston is not subjected to any side thrust incrosshead type eng ine.
During overhaul ing:1 . lnspect , w i thout c lean ing, p is ton crown and s ide wal l fo r carbon isat ion, accumu-
la t ion ur f o i l , water , lubr ica t ing o i l p resence, r i , rg mcvement , e tc . ;2. Thoroughly c lean - inspect crown for cracks, burning, external contour with tem-
p la te , in terna l area for cok ing, c racks;3" Side wal l and r ing grooves for cracKs;4. Wear r idges on skir t , i r iston rods;5. Piston rods for any scratch and scor ing marks.Faults:a. Crack in crown - t l termal/mechanical stress.b. Crack in piston wal l - f luctuat ing gas load.
Reasons:Mater ial , scal ing, ineff ic ient cool ing, local inpingement, poor atomizat ion, water
i n fue l .
IX . PISTON RINGS
Piston r ings are heavi ly loaded mechanical ly wi th maximum pressure, MIP going upin engines. Ring grooves in cases have been chronre plated to increase wear resistance.
General ly, p iston r ing mater ial is made much harder than mater ial of the l iner to controlhigh wear rate compression r ings exert considerable pressure on the l inerwal l in modernengines (for 900 mm bore engine). Efficient lubricating oil f i lm is essential.
Overhaul ing internal is so long in modern engines, i t is advisable to renew al l the r ingsdur ing overhau l . ,
200
1. Thoroughly rneasure. al l new rings axial ly, radial ly and butt clearance in aring gauge;
2. Check ring prooves for wear giving special attention to uneven wear (in case ofexcessive uneven wear, ring groove to be reconditioned);
3. Roll new ring around !n t fre groove, make sure r ing is not st icking out;4. With rings in place, check with feeler gauge the axial clearanee and make sure
in admissible range.X. STUFFING BOX
It is mounted with a f lange bolted to the bottom of the scavenge air box. Top set of r ingsare sealing rings to prevent scavenge air flowing down the piston rod. Lower set of ringsscraper/case oil off piston rod.
During overhaulino:1. Uppermost scraper r ing and seal ing r ing, seal ing r ings, lower scraper r ings to be
checked for:a. clearance between seal ing r ing section and groove;b. clearance at r ing ends;;d. total cleararrce
2. Check greater spr ing tension.
XI. CRANKSHAFT
Crankshaft of large main propulsion engine are mostly of semi-built type. Some ofmodern engines, namely MAN - B&W have been usirrg welded crankshafts. Moder.ndesign has increased fatigue ltrength considerably by adopting continuous grain ftowrnethod. Welded crankshafts are considerably l ighter reducing the inert ia forcel.
Analysis of stresses on the crankshaft durinE operation are complex, it is better toconsider one unit of the crankshaft. The crank pin is subjected to tensi le and compressivestresses with complete load reversal. Similar nature of stresses are applicable to the webs.The crankshaft is subjected to shear stresses in way of web and journal. This may resuttin sl ipping. The web is subjected to bending due to connecting rod angulari iy. Thecrankshaft is subjected to fatigue.
Durlng Overhaullng1. Crankshaft deflect ion should be taken in a condit ion suggested by makers (De-
f lect ion readings are often over rated.)2. Crankshaft deflecticn should be inspected for cracks in way of fillets, crankpins, pins,
cerrtral portion of webs, slipping in way of journals;3. Pins to be accurately measured tor o'ral i ty, scoring, rubbing marks;4. No repairs to be taken up without owner's knowledge.
XII. CONNECTING ROD
Cross section adopted for connecting rod follows from study of the loads oncon.necting rods and the cost of manufactr:re. Round section connection rods are adoptedfor large engine. ,Connectinq rod is consrdered as a struct, pin-jointed at each end andsubjecled tolateralloading f rom inertia combined with thrust from end loading through pins.These are mqde of forged steel.
201
In operation, connecting rod is swing about the crosshead bearing, the swinging
movement being constrained by the bea.rinJ on ir,, rr"nkpin._The acli.on set up inertia
loads. In slow speed engines, i6uno section-connecting rods of normal length are strong
enough to sustain the coirected gas roading "no
tt'tr ineitia whip loading is not of sufficient
consequence.
May fail from fracture or cracking irr vulnerable areas or may buckle. Failure of
connecting rod in operation .rtrrrrty tit. in slow speed engines. Cases of slight buckling
have been found in same instances where water or oil leaked into cylinder spaces'
XIII . CROSSHEADS
ln targe slow speed engines, the gas pressurs acting on the piston and through lltepiston rod puts a load of a-pproximat6ly 600 tonnes on.the crosshead pins when lhe
ir".iure in tne cytinoer is ai maximum value. Loads of this high value cause soms
deflection. The pin and the bearing has to be kept aligned and modern engine pins are
designed to be r igid"
Crosshead pin to be inspected for scoring and rubbing marks at the bottom half ' to be
checked for ovality. Thoroughly to be inspected for any cracks.
XIV. CAMSHAFT
camshaft is built with number of camshaft sections, joined together by means of
flange couplings using litted bolts and nuts.Each cailrshaft iection has fuel puffip, exhaust valve and indicator drive cam.
Camshaft is carried in underslung shell type bearings. The bearing nuts are hydraulic
tightened. \The coupling .flanges and fuel and exhauiit cams are shrunk onto the shaft by
heating.Dismantling of ftanges is effected by forcing lubricating oilbetween shaft and flange'
Adjustmenlof fuel 6am timing, or adjustqg-nt of camshaft for elongated chaln ls also
done by iorcing lubricating oil between shrink fitted surfaces.Gamshaft rotates at same speed as crankshaft. During reversing, folldwer rollers are
disptaced to alter the pump timing.
XV. CHAIN DRIVE
The camshaft is driven by a chain drive'Chain drive consists of iwo identical chains running over chain wheels fitted on
camshaft and camshaft.Chains are kept tightened by chain tightener placed between the crankshaft and
intermediate wheel-From camshaft, a small chain drive operates cylinder lubricator, distributor and
governor.Long free length of chains are guided by rublrer clad guide bls'
Lubricating oit is supplied by spray p'pes fitted at the guide bdrs and chain wheels'
202
SCAVENGING
Pushinrg o.ut,exhaust gases with the help of fresh air intake so that a fresh charge ofpure air is avai lable-for compression that fol lows.
TYPES
DIREcT SCAVENGING- in the direct scavenging the inlet ports are tocated on ons side ofthe.cylinder opposite the exhaust ports. The fldw 6atn of the scavenging air is from one sideto the other side.
LooP SCAVENGING- in tlrel.oop.scavenging the intake and exhaust Forts are located atone side, the exhaust over the intake ports.inl tlow part oiair is from tnb intat e port acrossto the opposite side and up towards rire cytintler head and thrn make a loop to the exhaustportq above the intake ports"
uNlFLow SCAVENGING- in the uniflow intake ports are f ocated atthe side of the cylinderand exhaust at the cylinder head. The air enters the intake and moves up towards thecylinder head where exhaust valve are instailed"
The Actual process
Consists part ial ly of perfect scavenging, mixing and short-circuit ing.
orinf;iill$il?*ntf:mbustion products is initiallv pushed out of the cytinder without
Gradually ' mixing and sho.rt-circuit ing causes the outf lowing products to be di luted bymore and more fresh air unti l the situatioi is sarne as for perfect mixing.
into iolJ?r1iH1ll3?::::::"sins process is Perfect scavensins which then chanses
Scavenglng Stages
1. Blow down2. Scavenging3. Contain ing of a i r
lmportance of Scavenging
1. Engl lg ef f ic iency depends on scavenging2. Ineffici_ent scavengin.g _gives 6;s power output per weight3' Incomplete scaveigi;g results in in.rr"sed fuel consumption per unit power4' Incomptete scavenging leads to greater piston ring and liner wears.5. Ineff icient scavenging giues higher mean temperatures
203
{
tIIIItJ
--f u
,., .r,
t
LOOP SCAVENGE
I
II0
CROSS SCAVENICJE / 'L INIFL.OW SCAVENGE
*_-._J
II\
. L\.
fIII
III
III
J
,i
1I
tI
' t
iiI
{I
\\I
I
a\
j
ADVANTAGES
Cross Scavenge.Simple*Less Maintenance*Low Cost
Loop Scavenge \'Higher Ef f ic iency
"S imple
.Less Main tenance
. Rel iable
.S imple Cy l inder - cansustain f t igher thermalstresses.
Unif low Scavenge.No short c i rcui t ing'No overmixing.Very high ef f ic iencY
204
DISADVANTAGIiT;
.Slrort Circuit*Lcrwer Eff icierrcy" l-ess BMEP
. Pisto n/ l- iner Distort iondue to TenrP. gradientfrom exhaust toscavenge ports.
- Cran kcase/u ncle rpiston space rnoredirty.
. Exhaust Port c;arb'rt l i -sat ion excessive.
*Uneven Piston r ingwear.
'Less eff iciencY cJtteto overmixing
'More comPlex.Higher cost'More main tenance
Examples of Use
"Sulzer*RD, RND
-M .A .N
.RND-M Sulzer
- B & W"SUIZER-RTA
JJI
II
II
I
II
I
SUPERCHARGING
Process of pushing a higher pressure air charge into the cylinder greater thanatmosphelic pressure, thus increasing power output of the engine.
Advantages Gained
1 . Higher output2. Better combustion3. Less specif ic fuel consrrmption4. lmproved thermal eff iciency5. Less weighvspaco/cost to produce a particutar power6. Lower exhaust temperature
Dlsadvantages
Higher init ial costHigher thermal loading due to higher maximum pressure
1 .2 .
Methods of Supercharging
1. f ndependent ly dr iven compressor2. Engine driven compressor3. Underpiston supercharging4. Exhaust gas turbochargirrg5. Combinat ion of the above
Types of Equipment that can be useeJ
1. Posi t ive d isplacement pump2, Posit ive displacement blower (roots blower)3. Centr i fugal blower (electr ic cJriven)4. Turboblower (exhaust gas driven)
f-rr inciple of Operation
1. Pulse system - fUE2. Constant pressure system * Generator
Valve t iming per iods
scavenge ports open at approxim:tely 35 degrees b.d.c. and close 35 degrees afterb'd.c. The exhaust valve wi l l open ahead ofthc r"ai , ,nge ports to give a blowdown per iodand close at some t ime to leave the correct an ount of air in the cyt i iOer for the combust ionof fuel . The open per iod for the exhaust valve wi l l be about B0 to g0 degrees of crankrotat ion and the .va. lve wi l l open about 45 degrees before b.d.c. l t should be noted thatconsiderable var iat ion may be found in valve t i rn ing f igures for var ious engines.
205
TURBOCHARGINGVery effr;ctive pressure charging. Util izes 20% of waste heat in exhaust gas whichContalns 35V" of fuel heat. lt consist of two parts, the blower and exhaustturbtne slde fitted In one motor shaft.
Advantagas1 . Hrgher plant eff iciency.2. No separate povver source required.3. Power demand low,4. Attempts to cater for overloading condition"5. More efficient thtrn other fortns of supercharging.
Exhaust Turbocharglng
Pulse System
Pulse operation needs:1 . Exhaust pipes short narrow - minimum bends - Losses in pipe minimum. Small
volume flow.2. Exhaust pipes connection to same TC inlet from different units to be arranged
such that no^interference of pulses happen - this may otherwise affect scaveng-ing operatioh.
3. Period between discharge of successive cylinders into a common manifold to bemore than 240o for a 4-stroko and 120o for a 2-stroke engine to avoid interference.
Not more than 3 cylinders firing successively can be exhausted into acommon manifold. Engines with more than 3 cytinders will have more than 1 TCor 1 TC with multi-entry arrangement.
Advantagesa. Highly responsiveb. Good turbocharger accelerat ionc. Good low load and low speed performanced. Scavenging assistance not necessarye. Better scavenging
Dlgadvantagesa. Poor turbine efficiency at high ratingsb. Turbine operation rough and inefficientc. Exhaust piping complex
206
PULSE SYSTEM
TURBOCHARGER OPERATING PROBLEMS' l t l ' ' q 1 ' ' t
SURGING
lf due to any rlason, the air pressure gensrated in tho blower, fatts betow dellverypressure, there rwill be a .sudden breakdown of air delivery, followed immediatety by abackvvard wave rof air throurgh the blowe'r which wilt continub until the delivery resi;tancehas decreased sufficiently for air discharge to be resumed. Thls periodical breakdown ofair delivery is called 'surE;ing', and is manifested as irregular howling noise from theTurbocharger.
Sfages af surglngl . Hummingll. Snortirngl l l . Howling
SYMPTOMS OF SURGING1. Howling Noise2. Rapid surges in scavenge air pressure3. 'Gulping" of air by blower4. Repeated irregular violent thud from air intake to blower.5. Alternate "suck-in" and "puih-out" at blower air intake.
Gauses1 . Dirty rair filter2. Power imbalance between cylinders3. Engine racing4. Faulty injection5. Fouled/damaged Turbine6. Fouled Air Cooler7. Overpressure at Scav" manifoldB. Mismatch of Engine/TC.
Remedy/Control \
1 . Proper matching2. Larger dia scav. manifold3. Reduce speed and ease pressure
&,Ncjca'v r Pee s 'suaeS'-<r, ru,
TURBO CHARGING SYSTEM
207
TURBOCHARGER SUHGING
surging can be divided into two main categories
l. Restrictions in the airlgas system;l l . Var iat ions in cyl inder load.
-
CHECK THE FOLLOWING1' Fuel oi l system such as f i l tors, fuel punrp, f uel in jector , fuel t iming, air in fuel ,fuel v iscosi ty, load distr ibut ion, etc"2' Exhaust System' Bacf<, pressure. valve operring & tinring, pressure f luctuation, etc.3' Turbocharger, Foulscl or damageO iurUine or compressor side, foulect f i tter"4'
,:tr#iff,f,ti"*"1'#,';,L?i:Jii"oorcr, cfr.t<*.i u."uense ports, hish scavense5" Governor. Huntir.rg
o. what are the nreanrngs, furrctrons or ure joi lowrng terms?
ff#f"fl"5lT."TrTl; is the volunte swept or traver by the piston rrom top dead center
compression Eatto - the ratio of the piston displacement plus the cfearance volumeto the clearance volume.
Flash polnt - the temperature at wlrich flarnmable l iquic wil l give off sufficient vaporto support a f lash flame but wil l not support continuous combustion.
:if l{J:, !{ ' :{+- the weislrt of a .solid or t iquici as conrpared with an equat votume
calorlflc value - the highest amount of heat that can be produce from a given quantityof fuel by compfete combustion is called heat or caforif ic value.vlscoslty - is the internal fr iction or resistance to f low of a l iquid at certain temperature.volumetrlc efflctency - the ratio of the weight of the air which is trapped in the cylinderat the beginning of the compression stroke and the weight of air coutd be containedin the cylinder under conditions of atniosprreric pressure.counter welghts - fitted to the crankshaft of the engine in order to balance the revotvingweight of the crankpins, webs, and the lower portion-or tne connecting rod thereby reducivibration.
Jacklng gear - i9.an arrangement of gears used to rotate the engine crankshaft" consistof warm gear which e,'rgages a gear-toothed frywheelshims - are pieces of metal or other materiaf use for plating or equal spacing betweentwo connecte'J metal parts l ike the unginu frarne, bearings ancj motor basement.Pyrometer - is a mil l ivolt calibrated in temperature units, attached through a selectorswitch to each individuar cyrinder exhaust inermo;o;;i;. '
208
Thermocouple - is mad e of 2 rods of different metals that are wetded together at oneend, when heated at the welclecJ junction, an electromotive force is produced betweenthe terminals.
lsochronous - governing keeps an engine running at a constant speed regardtessof load. This gives perfect speect regulation and nJ spoed drop.
Speed Droop - is a decrease in the speerl of an engine from no toad to full load conditions.Sensltlvlty - is the change in engine speed before the governor makes its correctivechange to the fuel control. f t is usually expressed as a percent of the normal or averagespeed of the engine.
' -
Stablllty - is the ability of a governor to settle down to a steady after a change of load.
Huntlng - is the unstable operation of a governor. Jt wiff not maintain a steady speedcaused by overoorrection.
Deadbeaf - is the inabil i ty to change the speed when a new load requires such a change.
Oll Mlst Detector - fitted in the main engine crankcase, that give a more reliable andquicker warning of oil mist formation, whith connected pipe l i ie samfte air from eachcrankcase compartment. The rJetector wil l give an alarm at a mist concentration of 2-5% of the inflammable quarrtity, for safety precaution, have ample time to stop the enginebefore igni t ion of the mist can tal<e place.
O' When maklng an order or Inqulry for englne parts, what are the essenilal dataIn order to supply you the correct parts for the Indlv lduat englnes?
VVhen order lng englne spare parts you should state the fol lowlng:
1 . Sh ip 's name2. Classi f icat ion3. Type of erlgines and numbers of cyri irders4. Engine numbers5. Main eng ine bu i lders6. Nanre of parts requirecl7. Plate no. of engine partsB. l tem no. of engine parts9. Quant i ty required.
Q. In modern maln propulslon engines, what are t l re mafor parts of the englneneed proper maintenance and attent lon?Modern crosshead type mair , propulsion engines are highly ratecl , super long stroks
and bearing extremely Poon qual i ty residual f uel . Fol lowing components of engine r i i l neeOproper maintenance and attent ion:
1. cyl inder l iner top part subjected to severe mechanical and thermat stresses;2. Frames and guides are subjectecJ to high side thrust because of super long
stroke arranqement.
209
3. Bedplate cross girders and at junction welds between longitudinal and crossg irde rs;
4. Holding down arrangements;5. Exhaust valves, air springs and hydraulic actuating arrangements;6. Piston crown and top of side walls subjected to severe thermal stresses;7. Crosshead bearings and guideshoes are heavi ly loaded;8. Crankshafts are welded tyoe, special attention to t i l lets, webs and crank pins.
NOTE: No repairs special ly invclv ing welding, hot work to be carr ied out on majorengine components such as bedplate, f rames,crankshafts etc without owne/s knowledgeunder any circumstances.
O. What are the desirable character ist ics of a good fuel oi l (Dieset)?
1. A nrax imum heat va lue.2. A rnaximum of water, sediment, sulphur, sand, and other impuri t ios.3. A f lu idi ty such that i t can be pumped without heat ing i t too much.4. The oi l shoul.J not be too slow-burning, so as to cause delayed igni t ion in tho
cyl inder.5.
'The oi l should burn completely without leaving any car lcon residue in the form of
ash or soot.
Q. What factors would you say control led combust ion in a dieset englne?
Proper amount of air; proper amount of fuel; proper mixture of fuel and air andproper temperature of Fuel and Air for ignit ion.
O. Dlscuss ways of c leaning lube oi i in a diesel en,glne dr lven st1lpf
settling method - used of gravity tankcenffifuging - used of centrifugal purifiersfiltering method - used of fi ltering material
Q. What are the effect of early and late fuel injection?
Early fuel injection causes oil to ignite too soon causing a back pressure on the pistonand a resultant loss of power. Pre-ignition may cause damage to cylinder and cylinderheads or even bent rod. Late ignition causes srnoky exhaust, losses of power andincomplete combustion. Incomplete combustion resutts in carbon accumulation whichaffect piston rings and valve stems. Will carbonizer also a silencer and tmay caused fire
Cl. What ls the cause of "detonation" or "f uel knock" In a dlesel englne cyl lnder?
During the ignition delay period injection of the fuel is contained so that there is agreater amount of fuel in the cylinder prior to ignition. When ignition does takes place thewhole accumulation burns violently. This rapid burning results in an extremely highpressure in the cylinder accompanied by pressur€ waves" This rapid increase of pressureand vibrating pressure waves results in a noise knovrn as fuel knodk.
, 1 , l ' "I
' i ,
1 .2 .3.
ByByBy
210
Q. lf your eriglne shows a very black and smoky exhaust, where would ytrouble?
Find out if the engine is overloaded, check the exhaust pyrometer at.cylinders carry arl equal amount of the load and adjust fuel- valves and spra,accordingfy. Check fuel oil for cleanliness and water. Check fuel pumps and irrel l ines ,-entrapped air. Check scavenging air on a two-cycle engine. Check injection air on injectionengines. A poor grade of fuel oil may atso cauie smo'ky exhaust.
O. Descrlbe an open cool lng system?
The circulating pump take suction from the sea and circulate satt water through theengine and then overboard the engine being cooled directly by salt water.
Cl. Descrlbe a closed cool lng system?
. Tf,t engine is beirrg cooled by fresh water from the storage tank which is circulatedthrouglt the engine by a fresh w'ater pump. This water is cooled-by a heat exchanger usingsea water as cooling medium.
ADVANTAGES:
1. No danger of scale formation2. No danger of galvanic action due to sea water3. Better efficiency since. the engine can be operated at higher temperature.4. These is better control of engine temperature
Q' .WqulO You shut off the cooling water lmmediately after stopping a dieselerrglne? Explaln.
No. The reason for keeping the cooling water circulating after the engine is stoppedis to prevent the.lubricating oil from being euaporated from cylinde, wals anO piston iingr.In case the engine is coofed directly bylalt water, there would be formation of scale onaccount of excessive heat after the engine is stopped.
Q. . Wlth respect to facket cootlng water of a dlesel engine; whlch ls advlsable;witha hlgher temperature or lower temperature? lf so, wnir
With higher temperature because diesel engine is a compression ignition engine andit is susceptible to frequent change of temperature on mechanical parts frim higherio towertemperature thereby to prevent stresses.
O. Why ls ol l used Instead of water for cool ing pistons of a diesel englnes?
lf water is used and leak occured it would leak into the crankcase emulsifying the oiland spoiling its lubricating properties thus burninE out bearings and causing great damageto the engine.
\r.;a.
Iix
211
O' Why should the lube oi l purnp be run before start ing and after stopping a dieseleng ine?
Before start ing to ensure a cornplete oi l f i l rn orr al t bear ings in stopping a diesel engine,the lube oi l pump shoulcl run unt i l the di f ference in temperi t r re bepveen the in let anc1 outtetis f rom 20 to 50. This al lows the bearing to cool evenly.
O' How many degrees is the intal(e valve open? How many degrees l t lsc losed?
lntake valve opens a few degrees bef ore top dead center arounc 5 degreos before topdoad center (TDC) And closes at around 5 degrees af ter BDO. Durat ion of opening is 190degrees and c los ing durat ion is 170 degrees"
o' What is usual fuel valve t iming for l r ig l r speecl diesel engine using l ight fuel?
Fuel valve t iming is usual ly starteci or open at lZdegrees before top dead center. Thisavoragg.
0' what are the usual angles between the cranks of 2 stroke cycte and 4 strokecyc le hav ing 3 ,4 , and 6 cy l inders?
2 cycre 4 cycre3 cy l inders- 1200 1200
4 cy l inders-g0o 1B0o6 cy l inders-600 12Oo
o' what is the valve t iming of the air start ing varve of two cycle diesel engine?
Air starting valve must open to acjnrit starting air to the cytinder at f ive (5) cJegrees aftertop dead center (TDc) and closes approxirnitely g0 dogr""r"
o ' state the t iming of the di f ferent valve of 4 cycle diesel engine in terms of crankangle in relerence to top dead center and bottom dead centers.
In two stroke cycle engine, intake valve opens 48 degreres before bottom dead centerand closes 48 degrees after bottom dead center duratioriof 96 degrees at open posit ion.The exhaust valve opens at 92.5 degrees aFier top dead center andiloses at 44.sdogreesafter bottom dead center. Exhaust valve is opened for a durat ion of 1s7 degrees in thecrank angle. In ject ion valve opens at 17.5 degrees before TDc.
o. Descr ibe at reast three rnethods of dr iv ing camshaft?
a) By a train of gear, which dr ive the camshaft gear onintermediate gears and a driven gear on the crankshaft.
b) By a chain which is driven from Jgrnr on the crankslraftgear.
212
the crankshaft of an
and driven camshaft
c) By gear and a vertical shaft tfrere is.a level gear on both the camshaft gear, andcrankshaft and a slraft has a pinion guuion each and is place between thecamshaft and camshaft gear.
cl. Name the types'of wristpin anc,r describe each
1' SEoURED WRISTPIN - this type has the wristpin secured tighgy in the bossesof the piston casting. A screw'ed do*ef is useld to secure thi pin.
2' FLOATING WRISTPIN - in this typ.e wristpin is free to move in both eye of theconnecting rod and the bosses'of the pirton casting. A spring clip retainer isplaced in grooves in each end of the piston oour in orcler to prevent the pin fromscraping the cylinder wall.
cl " Descrlbe the varlous methods used to introduce water or oif into diesef engineplstons for cooling purpose.
1' The packed and unpacked telescgplc pipe - In this type the moving member ofthe telescope assembly is attached cfird.iiv to ine unddrside of the piston and thestationary member to ihe engine housing oi riame.
2' The swing-joint type - This typc' is being used on crosshead engines. The inletand outfet pipes from the piiion are tixdd and lead to the crosshead then to theouter end of thre bracket boltecJ to the crosshead where conne.tion is made to themoving member of the telesssric assernbly.cl ' Name three methods of start ing a dieser engine.
1' Electric motor requiring that electric energy be reidily avaifable.2' Auxiliary gas engine may be attached diriltrvjo dieset engine.3' Hand starting foi small "engiri;s
ano .o*piurred air previousry stored for thepUfpOSg O f S ta f t i ng . - - " " ' r - ' Ysvvv c ' t t P r rTYruL
cl' Explaln why the malrr fournat bearlng caps on 4 stroke cyete engrne arq madeof heavler constructlon than those'oJ thd hM; sirot<e cycfe englne?The main jour:nat caps of 4 stroke ctcle engines are rnade of heavier constructionbecause during the latter part of the exrrouiiutrokdthere is an upward thrust on the bearingcaps due to the inertia and centrifugat iorc.e of rnoving parts" ln the 2 stroke cycle thisupward force is overcome by the coirprn*.i.n of the rir h the cylinder.
what arre the method or reversrng 4 cycre and 2 cycte engrne?4 cyclo engines - can be reverg-9d by changing the timing through the insertionof a set of reversing cam. The iamshatt iJ moved In-such a- mannerthat aset of cams slide under the valves so that so th.at the firing of any cylinderis 180 degrees to its former positlon with the ahead cam.2 cycle engines - reversing method is to rotate the cranrtshaft 30-40 degreeg thusputting the opposite flank of the carn under the fuel valves or pump similarto stephenson rink motion rrsocl irr stearn unfi,..on.
213
O. Descrlbe the path of the fuel oll from the storage tank to the englne cyllnder?
The fuel is taken from the storage tank by means of oil transter pumb to settl ingtank where oil is preheated and settled, passed through a centrifugal purifier for efficientcleaning and deliver it to the service tank in operation, the oil is led to one of the twoelectrically driven suppty pumps, which deliver the oil under pressure through a flowmeter, then to fuelcirculating pumps passes it through the oil heater - viscosity regulator- fi lters then supplied to individual fuel pumps each cylinder to the fuel injector valvesfor combustion process.
O. Trace the path of lube oll system 2 cycle dlesel englne.
Lube oil Pump draws the oil from the sumptank through suction fi lters, forces itthrough the lube oil cooler, passing auto backwashing filter, before it deliver it to theengine where it is divided into two branches: lt supply to main part where oil is sentto the piston cooling manifold, where it is distributed between piston cooling and bearinglubrication. From the crosshead bearings, the oil flows through bores in the connectingrods, to the crankpin bearings. The remaining oil goes to lubrication of the rnain bearings,engine base and sump tank"
Camshaft lube oil system is separated from rnain lube oil system which is alsofitted a tank - suction fi lters - coolers to the main engine c;jlm drive systent, then backto the tank passing rnagnetic fi lters.
Q. Trace tne path of coollng water system 2 cycle diesel englne.
The fresh cooling water is circulated through the cooler by means of fresh (Jacket)water pumps where the water enters the engine through the bottom of each cylinderjacket and upward to th: cylinder head and exhaust valve if fitted; controlled bythermostatically regutating valve, such proportion that the ternperature of the outlet waterfrom the main engine ls maintained at specified normal temp. set point l ike 80 degreescentigrade in order to avoici cylinderwear and condensation ot sulfuric acid on the cylinderwalls" To prevent air accumulation to the system, a venting tank is fitted on outlet pipingand expansir,,n tank for make up the difference in tfre water volumer at changes oftemperature or leaking.
O. Descrlbe cyllnder lubrlcatlon system of a dlesel englne.
The lubricator are usually supplied with cil from a day tank, through gravity whichequipped with a built in float, strainers and stop valves. The oil is pumped,into the cylinderby lubricator pump via non return valve, passing a number cf lubricating orifice duringthe ripwird sirofs. tne oll feed rate or dosago should in accordance with the enginebuilders recommendation and should be increased during stariing, maneuvering and largechanges in engine load.
White on lrigh speed diesel engine, cylinder is lubricated by bearing oil thrown fromthe crankpin, which is splash metlrod of lubrication found on a trunk type diesel engine.
214
Q. What are the preparations for startlng up englnes after Installatlon, longerstandstl l l or malor overhaul?
a) Crankcase should be cleaned well and all internal parts wiped off if necessary.Use rags, not cotton waste. Adjust and secure all internal bolts. Be aware that anyloose cotter pirf, bolt, screw or nut may have serious consequences, especiallywhen these cannot be adjusted during operation.
STARTING AIR:b) Starting air bottle pipes should be blown free of any mud, dirt or water.c) Check pressure of starting air bottles. lt should be between 25 and 30 kp/cm2.d) Gre.rase roller bearing in stai't ing air relay.
LUBE OILe) Before filling the lube oil, check oil sump, canals and pipes carefulty. Remove
any mud and rust. When wiping off use rags.0 After longer standstill poriods drain any water and mud from oit sump"g) With the pneunratic lube oil primer pump, oil is pumped through the engine
at the same time as the engine is turned. Check driving gear. See thai oilis forced thlough to all the lube points connected to the main lube oil system"
h) Check, and if necessary, cleran the tube oil tilter" Check valve gear lube oiltank before filling it up. Remove any mud and rust"
i) lf the valve gear lube oil has become mixed with fuel oil after a longer standstill(during overhaul of the fuel oil system), the oil should be changed.
FUEL OIL :i) Before fi l l ing fuel oil, check tanks and pipes carefully. Remove any mud and rust.k) After longer standstil l periods drain any water and mud from oil tanks. Check oil
level.l) Disconnect fuel oil pipes from filters and let the oil flow through until free of dirt
from tank and pipirrg. Check, and if necessary change after etements.m) Bleed all air from fuel r:il system. When bleeding the fuel oil system, the fuel
oil primer pump can be used. One must avoid to dilute the valve gear lubeoil when the fuel.,.injection pumps are bled.
STARTING OF ENGINE:a) Open the fuel valve and,the cooling water valve. Close indicator valve.b) Remove the turning ba/ from the flywheel.c) When the above mentioned instructions are carried out, open the main valve on
the starting air bottle and admit air to the cylinders. As soon as the engine hasstarted, the main valve should be closed.
d) lmmediately after starting, check all manometers, for temperatures and pressures.
PREPARATION FOR STAFITING UP AFTER SHORTER STAND STILL PERIODS:a) lf the engine has been out of operation for some time, it should be carefully
checked before starting. Priming the fuel oil system should not be necessary,provided nothing has happeneC that would admit air to the system.
b) Prime the lub. oil system, when turning the engine slowly, to admit oil to all theIub. points.
215
ATTENTION DU RII 'JG OPEF1ATION :a) Check the engine speed, prcssures and tern;:eratures at regular intervals.b) After each start, check that the starting air pressure is above the lower limit, i.o.
1Skp,'cm2. lf the pressure is lower, the starting air bottles have to be charged.c) At intervals drain the starting air bottle for condensation.d) Tho lube oi l pressure in t lre main system afte r f i l ter should normally be 2.5 - 3.0
kp/cm2. For the valve goar lub. oil system 0.5 icp/cm2 minin'ium.e) The lube oi l temperaturo at outlet from eng;ine should normally be 600C.f) J 'he cool ing water pressure should nornral ly be 1.0 - 2.5 kp/cm2.g) The cooling water temperature at ot.rtlet fronr engine must uot exceed 800C.
Normal outlet temperature is 70'C. cle;lencl ,on engine instruction.h) '[he
ctrarge air temperature rnust rrot exceed 600C after cooler. When the chargeair temperature increilses, tlre exlraust gas temperature will also increase.Check the charge air temperature at full load.
i) lnstruction for turboclrarger and intercooler, separate service manual.I lnstruction for Woodward Governor see separate servico manual,.k) Measuring of pressure in cylincler by taking power diagram.
Occasionally measure cylinder pressure of arll cylinders to exanrine if there are anyfaults with the fuol injection or the combustion. Moasure cornpression and combustionpressure every time the chain, camshaft or fuel injection pumps have been idismantled orchanged"
STOPPING ENGINEa) Shorter interruptions of operation.
Run the engine on no load at idle speed unti l the temperature are stabi l ized. Stopthe engine. Fuel oi l and cool ing water valves are closed,. i f needed.
lf danger for frost, all the water in tho engine and thb pipes has to be drained.Faults obeerved during operation must be repaired.
b) Longer interruption of operation.
Run the engine on no load at idle speed rrnt i l temperatures are stabi l ized.Stop the engine.The start ing air pipes must be blown through.The indicator valves must be opened.Starting air bottles are drained for condensed water.The fuel oi l and the cool ing water valves have to be closed.l f danger for frost, al l the water in the engine and pipes has to be drained.Water and mud are drained off the fuel oi l and the lube oi l tank. The lube oi l must
be changed i f necessary.l f the engine wil l be out of operation for a few vreeks or more, i t must be cleaned
and all polished parts must be lubricated with an anti-corrosive oil.
216
1. STARTING DTFFICULTIES AND TROUBLE SHOOTING:
A. The engine does not turn when starting air appried.
Possfble causes:1 . Air pressure too low.2. One or more starting air valve have stuck.3. The starting vatve leaking in cytincler
B. The engine does not ignite or firirrg
Clogged fuel nozzles.Pilot vafve shut.Starting distributor valve shut
1. Air in the fuel system.2- The fuel oil f irter or the fu;r pipes are brocked.3. lncorrect adjustment of the fuel injection pumps.4. Clogged fuel nozzles.5. Fuel By-pass open,6. Booster fuel pump faiture.7. Air ccmpression pressure too low
Possible causes:Water in the fuel oi l .The compression pressure is too row causect r-ry:
a. Woll or broken piston r ings.b. Leaking valves in cyl inder-cover.c' Leaking gaskets between the cylincJer covers and the cylinder liners.d' Todthick gaskets between the tyl incJer l iners ind the cyl inder block.
2. THE ENGINE STOPS
1. Air in the fuel o i l system.2. Faults in the fuel supply.3. Water in the fuel oi l-4. Clogged pipe l ines or fuet oit f i l ter.
t " t
r \ v | ' | | l { \ ) \ ) l ' l a E ; t \
3. ( ENGTNE RpM DRops )\1)---En g ine-isor6--rt o ad ed. i
f ln j_ect ion pumps are workingt i r regular ly. Air in fuel system.
3' A piston oI ,a bear ing has a brer i l l<cJown cjue to insuff ic ient tubr icat ion ordir t in lubeo i l .
PqSsible causesi l_: . . One cyl inder " fal ls oLtt , , .'2. \ Leakage betuveen t l re cyl incJer l incr and the piston.3: Leakage in top gasket.4 ' . Clogged f ' - rel o i l f i l ter .5- The inlet and/or the exhaust valye$ are leaking. { /6. The valve clearances are too smal l7 . ' F i l te r fo r tu rbo-charger is c logged.
4.5.6.
217
4. THE ENGINE KNOCKS
1. Injsction is too early, due to incorrect pre-injection angle.2. Faults in injection valves.3. A piston becomes too hot and seize.4. The gudgeon pin or big end bearing have too big cleanances.5. Too big piston clearance. Worm cyl inder l iner.6. Overloading7. Poor fuel/air atomization
5. ABNORMAL EXHAUST GAS
A. Too high exhaust gas tentperature from one cylinder:
1 . Too high admission on fuel inject ion punrp.2. Injection is too late.3. lnject ion valve has too low opening pressure.4. Partial clogged fuel nozzle.5. Inject ion valve leaks.
Possible causes1. Valve clearances too big.2. Clogged exhaust system.
B. Too low exhaust gas temperature from one cylinder:
1 . Too low admission on fuel inject ion pump.2. Injection is too early.3. Inject ion valve has too high opening pressure.4. Clogged nozzle holes.5. Water leakage in the cylinder.
C. Too high exha\tst gas temperature tn all the cytlnders:
1 . Engine is overloaded.2" Inject ion is too late.3. Too high temperature of charging air.4. Charge air pressure is too low.5. Clogged charge air fi lter.6. Ologged exhaust gas system.
D. Black exhe.ust gas.
1 . Engine is overloaded.2. Some cylinders are overloaded.3. lnlet or exhaust gas outlet valve is leaking.4. Faults in the fuel injection pumps or valves.5. lgnition timing iauliy.6. Fuel Temperature too high.
218
E.
F.
6.
A.
Posslble causes1. Bad fuef oi l .2. Piston rings have stuck.3. lnjection is too late.4' Exhaust maniford or exhaust pipes are crogged.
BIulsh exhaust gas.
1. Too mrrch rube oir in one or more cyrinders,Whlte smoky exhaust gas.
1. Engine is too cold.2. Water in cylinder.3' one or more cyfinder rot gotting enough fuer.4. Too fow compression pressure.
LUBE OIL PRESSURE DROPS
Maln sysfem
1. Too littre rube oir i ' circufation. The pump sucks air.2. The lube oil fi lters are cloggeJ.
l: it#,ffJiJffiti'Jrt;.tt"e pipes inside the ensine. Loose main bearins borts.
:. Oil temperature is io high. Oil cooter is dirty.6' The oil relief valve on the bedframe or the l"rrty varve on the pump is sticking.Valve gear sysfem.
1 . Too f it i le lube oif in tank.? Drain pipes to tank are ctogged.3. Lube oit is di lute{with fuet oit .{t. The lube oil fi lter l 's clogged.
Posslbte causes1 . The lube oit pipe is clogged.2' The oil rehef valve in tl ie fi lter or the safety vatve on the pump is sticking.
OVERFIEATED BEARINGS
I 9logqi.ng that prevents the oit suppty.2. Dirty fi lters.3. Too low lube oi l presure.4. Too narrow ctearances.f . Too high lube oi l temperature.6. The oil cooler is dirty.
B.
7l .
219
8.
A.
INSUFFICIENT COOLING
The cooling water temperature on one cytintler increaies.
1, Clogged coo l ing water pipes.2. Cyhnder is overioaded.
Increase of cooting water tenrperature on ail cyrinders.
Errg ine is over loaded.Cooler is c logged.Air in cool ing wa.er system.
B.
1 "2"3 .
OPERqTION PROBLEM AND HAZARDS IN ENGINE"Prevention is betterthan cure." Problems and accirlentsiustdo nottake placewithoutreason' they are caused' ln .case a problern h.as already takei pt??", yi-i nued to think whyit has taken place, but your immediat"liit< thoutd be to t,tke quick necessan/ sn"ps so thatthe plant does not deteriorate any further. For eriipii,'ii u pirton runs hot - do somethingquickly so that it does not run not any ioro. Now itart th,inking why did it run hot at alt atfirst place.
EMERGENCY PROCEDURE WHEN PISTON RUNNING FIOT1" Reduceengine speed immediatery (dead srow)2" Cut out fuel to the cylinder troubf ei.
-
I 9rpply max.imum quantity of the coorant to the piston.4. Increase cylinder lubrication.5' Higher cyl inder cool ing temperature, do not stop the engine immediately and al lowgradual cooring. r{ englne stop, turns by turning'gr"iCRANKCASE EXPLOSIONS
Initiated by a "hotspot" in the crankcase which generated the vapour. As the ,'fuel:air,,ratio reaches explosive limits, the sante "hot spot" piovides 1he source of heat. lt could be:fli$,triuman
being and machinery in the absgnce of correct positive steps to prevent
Safety Featuresa. Crankcase mist detectorb. Crankcase relief doorsc. Strong Crankcase chamber
sfeps to be taken tmmediately in case of an exprosion.a. ltop engine immediaietyb" Put turning gear "on" & itart turning the engine to prevent seizureq. frcp lubricating oit and cooling pumps ond' Do not open crinkcase door fo-r'at least 112 hour until the engine cools downe. lnvestigate the cause and remedy t
220
AIR STARTING LINE EXPLOSION
The fuel comes from the air compressor lubrication through bottle and into the line inthe form of oil layer' lf air is present, source of heat in the form of hot gases from leaky airstarting valve' suddOnly opened trigh fi*.rre air in the line from air botile resuft inexplosion.
Safety Devicef . Relief valvell. Bursting Cartridges
Precautlondry Measure1 Keep air bottfes free of oir by regufar draining2. Maintain starting line cfean3. Maintain air starting valves
SCAVENGING FIRE
Causes
1 .2.3.
of flre In the scavenglng alr box.
lgnition of carbon deposits in scavenge air by means of prolonged btow-byslow combustion. in the cyrinder oue to incorrect atomizationBlow-back through scavenge air ports due to incorrect adjusted exhaust camdisc or back pressure
Warnlngs of Scavenge Flre
1. Increased in exhaust temperature of effected cyrinder2. Turbo charger may surge3. smoke from the turbo ihrrgers air inret f irter4. Hotter $cavenging air box c€sing.
Measures to be taken \
1 ' Reduce speed to srow and ask bridge for permission to step.? Stop the auxil iary btower if f i t ted"3 Stop the fuet oil suppty.4' Put the scavenging air box fire extinguishing steam equipment into func'on.5'
llffitinguish the tire, removo dry deposit ind studge rrbm iir tn. scavenge
6' F':fl:lHinspect
respective piston rod and cytinder tiner, their surfaces afignment
221
STEAM TURBINES
O. What ls a steam turblne? I
A steam turbine is a heat engine in wlrich the potontial energy of a steam is changedhto useful work into two distinct steps:
1. The available energy is convertsd into snergy of moticn, kinetio energy, by steamexpansion in a nozzle or suitable passage, from which the steam emerges at ahigh velocity.
2. This kinetic energy is converted into mechanical energy CIr useful work bydirecting the steam jet against blades mounted on a revolving rotor, or by thereaction of the jet itself in the expanding passage if the passage revolves.
STEAM TURBINE - consist of motor wheel with blades secured to the shaft. A highveloclty fet of superheated steam is directly to the nozzles in impulse turbine or bystatlonary blades in reaction turbine, against the blade row to produce , rotationalmoUon of the shaft which ls connected to reduce reduction gear leading to propeller.It ls mounted by apparatus and steam seals in order to prevent leakage of highpressure steam to the atmosphere and air into the low pressure side.
O. What are the two basic types of steam tu rbines with respect to the actlo n of theobam flow Inslde the turbine casing, operating principle?
1. Reactlon turblne
a. Consist of one row of moving blades arrd one row of stationary blades.b. Pressure drops as steam passes through the rows of stationary,blade and
moving blades.c. Steam velocity increases in passage through stationary blades and de*
creases in moving blades.d. Sleed of reaction Olades varies directly equal to the speed of steam.e. lt consist of several numbers of stages of moving and stationary than
impulse turbine thereby occupying more cargo space.f. lt is mostly used on low pressure, low velocity, and large volume steam
on power plant.g. Most fitted low pressure turbine are cross compound unit.
2. fmpulse turblne
a. Steam expands in the nozzles',vith a decrease in pressure, but an increasein velocity before it strikes the motor blading.
b, The first stage on impulse turbine often permitted to take more than equaNshare of the available pressure drop, thereby its advantages are:
222
1. casing ls subjected to lower strikrng pressure.2. rotational losses is lowered due to decreased steam3. fitted with high pressure seal.
density.
Sped of impulse blades rated varies as one hatf of the steam speed.ll permit use of partial admisslon of steam, on steam chest fitted wlth nozrleto increase efficient operation.lmpulse blade are generally attached directly to the wheels, made In longerfengrth attached.lmpulse blading is heavier and stronger than reaction turbine.
Gl. What are the normal operating procedure In startlng a Turblne Unlt?
. In.starting any turbine unit with which he is not famitiar, the engineer shoutd thoroughlysludy the manufacture/s recommended procedure. The procedure given below is geiei-alized and may differ in minor details from that furnished by any paiicular manufacturst:
1. Start up the lubricating oil pump. Check gravity tank'to see if oil supply issufficient. See that oil pressure is estabtished on bearings and that oil is iislingthrough sight glasses leading to reduction gear housing. lt ttre oil tempeiature lsless than, say, 65i it must bo passed through the heater until its temperaturereaches g0 to 1000F.
2. open turbine-casing and throttle-valve drains.3. The turbine is then iacked over for at least one hour by using the turning geat.
Check with the bridge so that the deck officer on watch can in-vestigate m-o6ringlines and whether or not the propeller is clear.
4. Start .the circulating and condentsate pumps. Open the recirculating valvslrom feed tank to condenser so that condensate pump is assured a waler supply.
5. Check'level of water in boilers. lf the level is as it shoutd be, open tne nidinsteam stop valve"
6. Sfart the second-stage air ejectorand bring vacuum up to approximately l5inches of mercury.lf control vatve is actuatecjgoverning mechanism.Put steam onbealing gtands.Remoue jacking gear.Open throttle valve wide enough to start the rotor turning immediatety; thenthrottle down until the turbine is turning over slowly. On gear-driveninstallations, steam should be first admitted to the astern etementCheck'the emergencynovernor mechanrsm. Trip the turbins out, reset, andreadmit steam to turn rotor slowly.Listen tfor unusual noises.On electric drive, keep rotor turning ovbr siowly. Qn geat drive, atternaterotation of turbine slowly, ahead and astern.Start up first-stage air ejectors and bring vacuum to normal.Circufats sufficient cooling water through oil cooler to maintain temperatureof oil entering boarings between | 10 to 120'FStand,by to maneuver. Observe pressure and temperatures to see that theyremain normal.
17. When runderway, close recirculating valve and turbine drains.Precaution. Proper warming up of the turbine is extremely important.
c.d.
e .
f .
7. lry oil pressure, open valve that admits oit to
Admit steam to steam seal regulator.
1 1 .
8.9 .
1 0 .
12.1 3 .
1 4 .1 5 .
1 6 .
223
Cl. Explain how you would secure your turbine instaltation after your voyage?
Steps to secure turbine installation after voyage:a' Start auxiliary condensate system and tia;rsfer auxiliary exhaust and make upfeed to the auxi l iary condenser.b' Use hand tr ipping device to slrutt steam off main turbine then ctose thrott le
and bulkhead stop ralve.c. secure the main air ejector and main condensate pump.d. shutt off gland seal stearn and open turbine drain.e' Rotate main turbine w.ith turning gear until it coot off and then securs turning gear
and the rnain lubricating pump.f ' When main condenser has coot off , secure main circutat ing punrp.
O. What ls meant, functlon of the followlng mountlngs, fltt lngs on steam turbtneunlt?
Turbine rotor -consist of shaft, spindle rings or wheels and bladingr The shaft isa stesl forglng wlth Integral thrust collar. WhJels are, secured to the shaft and bladesdovetailed into the wheels. Fitted also dummy piston and gland sealing secure onhigh and low pressu,.e end of the shaft.
Turblne caslng - made in two halves housing that encloses the rotor; for lowpressure made of cast iron, and steel for high temperature. lt has a space forreceiving steam sealing glands and extraction connection. The t*oln]r[*li ti.,"casing are bolted together with a metal to metal contact but required graphite beforeassembly.
Throttle valves - provide hand control throttling of steam to increase speed andtrip quick closing varve either by hand o,' ur"iOency governor.
Steam stralner - fitted between main turbine stop valve and entrance of admissionvalve to prevent scale or rust that cause erosion or breaking of turbine blade fromsteam lines.
Gland Steam Sea/s - to preventalso eliminating air leakage into
escaping of stearr from high pressure errd andthe low pressure end whife on standstill.
Beductlon gears - it reduce the high speed turnirrg of a ttrrbine to the low efficientspeed of a pfirpeller. lt consist of thrust bearing collar, main reduction gear, andpinion gears secured to the shaft. Double reduction gears mosly user in cross -compound turbine either nested, articutated type.
Steam extractlon - consist of flanged connection from turbine casing, used forexternal purposes for feed water heating, evaporator steam suppty, ships heating,thereby increasing over all plant efficiency by reducing the amount of cooling surfaceneed to the condenser, atso act as reducing valve to lower pressu?e and temperatureused in auxiliary heatings.
224