transmission line basic presentation

8/15/2019 Transmission Line Basic presentation

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A PresentationA Presentation

onon

Transmission line BasicsTransmission line Basics


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WHY A TRANSMISSION LINE?

Transmission lines are constructed basically for transmissionof power from one point to another

Normal connecting points

Interconnection between 2(two) generating stations

Connecting generating station with substations

Interconnection between substations

Interconnection between substation & power sub station Interconnecting power substations

Connection from power substation to consumers


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3

BASIC SCHEMATIC

G!"#TI$! % T"#!'II$! IT"I*+TI$!

Generator

11 KV

GT220 KV

Step down

transformer

Distribution

Power plant Transmission

systemDistribution system

11220 !V

220""11 !V

110#$ !V


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,

POWER SYSTEM !IA"RAM


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-

TRANSMISSION LINE CONCEPT

Power

Plant

Consumer Home


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POWER SYSTEM COMPONENTS

Source:

www.howstufworks.com


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8/1410

CHOICE O# "ENERATION $ TRASMISSION

%OLTA"E

Generation is normally at , or 11 45

tepped up through transformer and transmitted o5er a longdistance to the desired load centers at different 5oltages which

depends on % 6uantum of power to be transmitted

% 7ine length

% Cost of terminal e8uipments % conomy consistent with desired reliability


9/1419

CON!&CTOR SELECTION SCENARIOS

cenario I : Conductor for low 5oltage lines ( , 4;< 11 4;< 33 4;)

are selected from the point of 5iew of c'rrent carr(ing capacit( cenario II : election of conductor for =; > +=; lines where

conductor si?e can not be increased beyond a certain limit in #CTransmission because of factors li4e in)'ctance *+L,- capacitance

*.$+C,- corona $ RI e//ects etc Corona > "I phenomena increasesdirectly with the diameter of conductor *undle conductor<therefore< ha5e to be used for 5oltage le5el for , 4; and beyondfrom Corona > "I consideration *undle conductor can also be used

in lower 5oltage line to increase the 8uantum of power to betransmitted

S0in e//ect of conductor in #C Transmission also limits si?e ofconductor where bundle conductor is more economical (both cost

and power loss) instead of a single large diameter conductor


10/1411

WHAT IS CORONA?

Transmissionline conductors are surrounded by an electric field

Corona discharge is generated when the electric field at the surfaceof the conductor becomes larger than the brea4down strength of thesurrounding air

urface irregularities such as sharp points and water droplets cause

local field concentration< enhancing corona generation Thus< during bad weather< corona discharge is more intense and losses are muchgreater

Corona discharge generates audible noise and 5isible lights The

5isible light and audible noise can be obser5ed simultaneously The 5oltage at which corona begins in called the discharge inception

5oltage Con5ersely< the 5oltage at which corona ceases is calleddischarge e@tinction

Corona produces radio and tele5ision interference


11/14111

CORONA !ISCHAR"E PHOTO

Corona e5ent captured by corona camera on -4; line

Corona Camera


12/14112

CORONA !ISCHAR"E %I!EO


13/14113

TRANSMISSION LINE %OLTA"E AN!

CHOICE O# CON!&CTORS

Normal Transmission1oltage

T(pe o/ con)'ctor Normall( 'se)

, 4; #C" #nt> s8uirrel

11 4; #C" Aeasel

33 4; #C" "acoon.. 4; #C" og

132 4; #C" Banther> ebra

22 4; #C" ebra> 'oose, 4; Twin #C" 'oose > *ersimis> In5ar

/.- 4; 6+# #C" *"I'I>In5ar


14/1411,

TRA!E NAME O# CON!&CTORS

Trade name of conductors are normally 4ept after the names of

5arious animals< birds and insects ome of the common ones are:Code !ame

#ppro@ current carryingcapacity (#mp)

ia ofconductor

(mm)

#ppo@+T

(4g)

#ppro@weight(4g>4m),D ambient ,-D ambient

8uirrel 11- 1/ .33 /11 0-

Gopher 133 123 /0 9-2 1.

Banther -2 ,02 21 912/ 9/.

ebra /9- /3. 20.2 1331. 1.23'oose 9 03- 31// 1.2- 22

http://www.google.co.in/imgres?imgurl=http://blogs.warwick.ac.uk/images/rosalindhook/2005/06/04/panther.jpg&imgrefurl=http://blogs.warwick.ac.uk/rosalindhook/entry/grey_panther_induction/&h=331&w=482&sz=58&tbnid=usgk7XgE1EoJ::&tbnh=89&tbnw=129&prev=/images%3Fq%3Dpanther%2Bpicture&hl=en&sa=X&oi=image_result&resnum=1&ct=image&cd=1http://www.google.co.in/imgres?imgurl=http://blogs.psychologytoday.com/files/u26/zebra-picture.jpg&imgrefurl=http://blogs.psychologytoday.com/blog/lust-in-paradise/200803/america-zebra-nation&h=427&w=350&sz=19&tbnid=nI3czj1DAq0J::&tbnh=126&tbnw=103&prev=/images%3Fq%3DZebra%2Bpicture&hl=en&sa=X&oi=image_result&resnum=1&ct=image&cd=1http://www.google.co.in/imgres?imgurl=http://www.moose1899.com/Find-8-Moose222.jpg&imgrefurl=http://www.moose1899.com/about%2520our%2520website%2520logo.htm&h=354&w=300&sz=47&tbnid=akqAbbRd9rIJ::&tbnh=121&tbnw=103&prev=/images%3Fq%3DMoose%2Bpicture&hl=en&sa=X&oi=image_result&resnum=2&ct=image&cd=1http://www.google.co.in/imgres?imgurl=http://www.turtletrack.org/Issues04/Co01102004/Art/Gopher.jpg&imgrefurl=http://www.buzz.mn/%3Fq%3Dnode/2645&h=348&w=486&sz=45&tbnid=wuSZEXTWYqoJ::&tbnh=92&tbnw=129&prev=/images%3Fq%3DGopher%2Bpicture&hl=en&sa=X&oi=image_result&resnum=3&ct=image&cd=1http://www.google.co.in/imgres?imgurl=http://www.onlinebangalore.com/life/pets/images/squirrel.jpg&imgrefurl=http://www.onlinebangalore.com/life/pets/squirrel.html&h=253&w=304&sz=11&tbnid=29BUnPucCSwJ::&tbnh=97&tbnw=116&prev=/images%3Fq%3Dsquirrel%2Bpicture&hl=en&sa=X&oi=image_result&resnum=2&ct=image&cd=1


15/1411-

INS&LATE! CABLE %s O%ERHEA! LINE

BARE CON!&CTOR

!ECI!IN" #ACTORS

;oltage le5el

istance

Congestion

Cost consideration

Geographical consideration

#esthetic consideration

"eliability

#5ailable Technology

pecial circumstances


16/1411.

LAYIN" O# TRANSMISSION LIN2

I, Ins'late) ca3les

+nderground

$5erhead on Bylon

upported by *ridge Girder

II, Bare Con)'ctor

irect supports on Insulators

Bylon supports

Laying of Underground cable


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TYPES O# PYLONS

# B$7 (tandard length: /- m> 0- m> 9/- m> 12 m)

Aooden

teel "ail> Channel

Bretressed Concrete ( BC)

"einforced Cement ConcreteWooden Pole

Steel Tubular Pole PS Pole


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TYPES O# PYLONS

* LATTICE STEEL STR&CT&RE (Tower)

'odular welded (self supporting or guyed)

*olted ( built up & self supporting)


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MO!&LAR TOWER ERS


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TYPES O# LATTICE STR&CT&RE

#ccording to support condition

#ccording to number of circuits they carry:

#ccording to tower shapes> base dimension

E #'rt4er classi/ication

#ccording to angle of de5iation


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LATTICE STR&CT&RE CLASSI#ICATION

ACCOR!IN" TO S&PPORT CON!ITION5 elf supporting tower

Guyed tower


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ACCOR!IN" TO NO O# CIRC&IT THEY CARRY ingle circuit tower

ouble circuit tower

'ulti circuit towers



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!ETAILS O# SIN"LE CIRC&IT TOWER

Cross arm at 3 le5els Cross arm at 2 le5els

Cross arm at 1 le5el


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2,

!O&BLE 6 M&LTI CIRC&IT TOWER

!OU"LE IRUIT TOWER

MULTI IRUIT TOWER


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ACCOR!IN" TO CON#I"&RATION

;ertical configuration tower

=ori?ontal configuration tower

elta configuration tower



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#CC$"I!G T$ T$A" =#B> *# I'!I$!

!$T: To be chosen by designer on Techno economical consideration


WI!E "ASE! TOWER

NARROW "ASE!

%&'() *ts

%&'

+$ *ts

#$$ %& NORMAL

TOWER#$$ %& OMPAT

TOWER

400 kV Compact Single pole tower at Delhi &


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400 kV Compact Single pole tower at Delhi &

Noida


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ACCOR!IN" TO AN"LE O# !E%IATION5

*Tangent to+er$ s'spension to+er,

A type tower (2 degree)

Tension to+ers$angle to+ers:

B type tower (1- degree)

C type tower (3 degree)

(#lso used for transposition)

! type tower (. degree)



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TRANSPOSITION TOWER

W4at is transposition to+er an) its con/ig'ration? Transposition tower is normally parallel double circuit

transmission tower to facilitate interchange of transmissionline phase conductor< where the phase conductors occupydifferent structure positions for different portions of the line

length so that transmissionline impedances is balancedFor e@ample< conductor placement on the structures may be"* for onethird of the line length< *" for onethirdof the line length< and *" for the remaining third of theline length

Ctype tower with modified crossarm is generally usedwith ?ero degree de5iation


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WHY TRANSPOSITION?

Bower transmission lines are transposed primarily forimpedance balance so as to eliminate or reducedisturbances in the neighboring communicationcircuits produced by geometric imbalances of power

line Transposition tower are re8uired for a line length

H 2 4ms why

#rrangement of transposition tower is shown below

LINE TRANSPOSITION


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LINE TRANSPOSITION

WITH 7C8 TYPE TOWER

R

'

"

R

'

"

R

'

"

R

'

"

T( T)T*


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SIN"LE %s B&N!LE CON!&CTOR

ingle Conductor : !ormal +se

*undle Conductors:

eciding Factors

Capacity nhancement

Technical reasons ( =andling & rection easiness< Corona> "adioInterference ( "I) consideration

*undle conductor Configuration

Twin *undle

6uad *undle

pecial Burpose *undle (=e@agonal> $ctagonal etc)


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TOWER SI9ES

TOWER HEI"HT IS !ECI!E! BASE! ON

pan : 7onger the span< more is the height 'inimum Ground clearance (#) re8uired to be

maintained

Conductor sag (*) Insulator assembly length (C) to maintain

re8uired electrical

;ertical separation of Cross arms ()

!umber of cross arm and its configuration

Bea4 =eight for fi@ing earth wirecorresponding to shield angle ()

A

"

!

E

!

S+ield angle


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WHY EARTH WIRE?

To protect conductor against lightning flasho5ers

To pro5ide a path for fault current

!irect #las4o1er

$ccurs due to shielding failure with lightning on the conductor<flasho5er ta4ing place across the insulator string from conductorto ground

Bac0 #las4o1er

$ccurs due to high tower footing resistance with a high 5oltage atthe grounded tower cross arm compared to conductor< resulting ina flasho5er across the insulator string from ground to conductor


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WHY EARTH WIRE?

'a@imum allowable fault current (I) through earth wire mainlydepends on

#rea of earth wire (#)

'a@imum permissible temperatureTime of short circuit (t)

I 5aries proportional to # and in5erse proportion to s8rt (t)


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3.

SHIEL! AN"LE

arth wire is placed on top of the structure to

pro5ide a shied angle for protection againstlightning o5er power conductors< therecommended angle being 3 degree with the5ertical in case of 5ertical formation of powerconductors

7ocation where iso4eraunic le5els are high< lowerangle of shielding may be adopted

#s cross arm width increases< hori?ontal spacing

of conductor increases To protect the conductorswith specified shield angle< earth wire has to be

placed at a higher ele5ation in such cases Toreduce the tower pea4 height< double pea4 with

double earth wire are used in those cases


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STAN!AR! NORMAL SPAN

#OR %ARIO&S %OLTA"E CLASSES

%OLTA"E SPAN RAN"E *METERS,

11 4; /-1

33 4; 103- ( 913- o5er poles)

.. 4; 2,32

132 4; 3-3.-

22 4; 3230

, 4; 3- ,-

/.- 4; ,,-


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MINIM&M "RO&N! CLEARANCE

%OLTA"E MINIM&M "RO&N! CLEARANCE

IN METERS *IS :;.


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NO O# CROSS ARMS

AN! ITS CON#I"&RATION

3 for single circuit line

. for double circuit line

12 or more for multi circuit lines

Cross arms can be of =ori?ontal > ;ertical or Triangularconfiguration

MINIM&M PHASE TO PHASE


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MINIM&M PHASE TO PHASE

ELECTRICAL CLEARANCE

%OLTA"E MINIM&M PHASE CLEARANCE*APP=, MM * IS :;.


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WHAT IS "ALLOPIN"?

"alloping *)ancing o/ con)'ctor, is ;ery low fre8uency< high

amplitude 1i3rations induced by: =igh 5elocity steady winds on conductors with asymmetrical

ice deposit

Ahen ice on a portion of ice co5ered conductor melts and

suddenly drops off Ahen a floc4 of birds perching together on a conductor

suddenly ta4es off< lea5ing the conductor Jumping in loops

Ot4er +in) in)'ce) 1i3rations are5

#eolian 5ibrations : =igh fre8uency< low amplitude 5ibrationsinduced by low< steady & laminar wind

Aa4e induced 5ibrations: 7ow fre8uency< medium amplitude5ibrations induced by high 5elocity steady winds on bundleconductors


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CON!&CTOR SA"

Conductor sag depends on

Type of conductor

pan length

Aeight of conductor

Conductor tension Sag 7SK L A72 > 0T

A L conductor weight per meter

7L span length ( tower spacing)TL Conductor Tension

!e1elope) Lengt4 7!KL 7M A2 73

2,T2

L, -.an

S ,

- a g

!


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INS&LATOR ASSEMBLY LEN"TH

%oltage Appro>imate Stan)ar) ins'lator assem3l(lengt4- single s'spension string

11 4; 2 mm

33 4; -- mm.. 4; 9.-mm

132 4; 1.3 mm

22 4; 23, mm, 4; 3/, mm

/.- 4; -- mm


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,,

MINIM&M TOWER HEI"HT

MINIM&M TOWER HEI"HT IS "O%ERNE! BY

Minim'm gro'n) clearance *A,

Ma>im'm sag *B,

Ins'lator assem3l( lengt4 * C,

*/or s'spension to+er onl(,

Cross arm spacing

*1ertical con)'ctor separation, * !,

Eart4 +ire pea0 )istance /rom top most

cross arm point * E,

A

"

!

E

!


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CROSS ARM SI9E *WI!TH,

%oltage Minim'm Bo)(clearance * mm,

11 4;

33 4; 33

.. 4; .1

132 4; 1/

22 4; 1./-, 4; 10.

/.- 4;

'inimum electrical clearance of conductor> Jumper from Tower body

(I -.13)

LOA!S ON TOWER


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,.

LOA!S ON TOWER

;"TIC#7 7$# ead weight of Tower ead weight of conductor & arth wire 7i5e weight of wor4ing personal<

hoisting tools & tac4les etc now loading (where5er applicable)

Transient loads =$"I$!T#7 7$#For the purpose of con5enience weconsider all hori?ontal loads in two perpendicular a@es

$ne in Trans5erse direction wrt crossarm $ne in longitudinal direction wrt cross

arm


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ORIENTATION O# TOWER +@r@t CROSS ARM

Su-.en-ion to/er .o-ition-

Line align0ent

Line align0ent

ro-- ar0 orientation 1.lan2

# uspension Tower Longitudinal direction

Longitudinal direction

T r a n - 3

e r - e

d i r e c t i o n


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,0

ORIENTATION O# TOWER +@r@t CROSS ARM

* #ngle Tower

Angle of

de3iation

Angle of

de3iation

"i-ector

Angle To/er Po-ition-

ro-- Ar0 Orientation of Angle to/er 1.lan2


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TRANS%ERSE LOA! ON TOWER

$n account of wind pressure on tower body

$n account of wind pressure on conductor< earth wire &insulator string

$n account of conductor > earth wire pull

Wind load on to/er , wind

pressure 4 .ro5ected area

Wind load on conductor6eart+

/ire , wind pressure 4

.ro5ected area

onductor

TRANS%ERSE LOA! ON TOWER ON A$c O#


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TRANS%ERSE LOA! ON TOWER ON A$c O#

CON!&CTOR $ EARTHWIRE P&LL

7 , angle of !e3iation

T-in 86*

*Tco- 86*

T-in 86*

T

T

T

T

8 , (#$9 : ;


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LON"IT&!INAL LOA! ON TOWER ON ACCO&NT

O# CON!&CTOR$ EARTHWIRE P&LL

Longitudinal direction

Tran-3er-e direction


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LON"IT&!INAL LOA! ON TOWER

# $n account of conductor > arth wire pull

In normal case< 7ongitudinal load due to conductor pull canceleach other e@cept for bro4en wire condition (*AC) where therewill be imbalanced pull on the cross arm

# ! T$A" which are used for termination of a line atswitch yard end are subJected to se5ere pull by conductor whichare strung on one side only

* $n account of unbalanced Tension of conductor > earth wire ontwo sides of towers which may happen due to error during final

tensioning & temperature 5ariation which may cause unbalancetension due to linear e@pansion> contraction when section lengthon either side of the tower are different

C +nder *ro4en wire condition (*AC)


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!ead End To/er

S/itc+ yard gantry

onnection to S/itc+ yard gantry i-done at a later -tage and /it+ -lac%

-.an only

LON"IT&!INAL LOA! ON TOWER


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-,

CONCEPT O# WEI"HT SPAN

Ahat is weight span

It is the span length (length of conductor or earth wire)which contribute to the 5ertical load on tower

Weig+t -.an Weig+t -.an

Weig+t -.an

1left2

Weig+t -.an

1rig+t2

W( W*


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--

WHY NE"ATI%E WEI"HT SPAN OCC&RS ?

$n steeply inclined spans< the low point of sag may fall beyond the

lower support This indicates that the conductor in the uphill span ise@erting a negati5e or upward force on the lower tower The amountof this upward force is e8ual to the weight of the conductor from thelower tower to t4e lo+ point in t4e sag@ I/ 'p+ar) pull of the uphillspan is greater t4an t4e )o+n+ar) loa) o/ t4e ne@t adJacent span<

actual uplift will 3e ca'se)


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-.

NE"ATI%E WEI"HT SPAN

R"

L"

1:2R A

L A

A

"

Total weight span of tower # L 7# % " #

Total weight span of tower * L 7* M " *

THEORETICAL #ORM&LA #OR CALC&LATION


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O# WEI"HT SPAN BETWEEN TOWERS AT

!I##ERENT ELE%ATION

!i-tance of Null .oint or Lo/ .oint of conductor fro0 t+e center of -.an

i- gi3en by t+e for0ula


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THEORETICAL CONCEPT O# O#

NE"ATI%E WEI"HT SPAN

L*

L(

T*

T(

;*

;(

;*

T*

T

/L(

T(

T*

T,T*OS;* , T( co- ;(

T*SIN ;* , /L*

T* OS ;( , T(OS ;(

T*SIN ;*@/L(,T(SIN ;(

/1L(@L*2,T(SIN ;(


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SI"NI#ICANCE O# NE"ATI%E WEI"HT SPAN

!egati5e weight span will mean that conductor> earth wire in

such a location will produce a 5ertically upward load instead of5ertically down in normal cases

;ertically upward load L () weight span @ weight per unitlength of conductor> earth wire

E##ECT O# NE"ATI%E WEI"HT SPAN

ffect of negati5e weight span is that suspension tower can not be used at location with negati5e weight span as it will lift up

the suspension insulators #ngle towers are therefore< to beused for such locations e5en if angle of de5iation is ?ero


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.

CONCEPT O# WIN! SPAN

WHAT IS WIN! SPAN?

It is the span length ( length of conductor & arth wire) which contributeto the trans5erse hori?ontal load on the tower

B( B*

Wind -.an , 1 B( @ B*2 6 *

Wind load on conductor6 Eart+ /ire , /ind .re--ure 4 .ro5ected area

TOWER SPOTTIN"


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TOWER SPOTTIN"

Tower spotting is the process of choosing right type of Tower

along the line routeTB I!;$7;

Choosing Techno economical line route

Fi@ing of #ngle ( de5iation point) to a5oid> minimi?e obstaclesenroute

Ta4ing le5els at intermediate points for drawing of profile between #ngle points ( igital instruments li4e total stations arenow a days used)

rawing of Brofile ( lectronic soft wares are now a days usedusing data from digital instruments

TOWER SPOTTIN"


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.2

Tower spotting is done either manually using sag templatecur5es or through electronic soft ware li4e B7C#

To/er -.otting on .rofile

TOWER SPOTTIN"

SA" TEMPLATE C&R%E


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SA" TEMPLATE C&R%E

Conductor & arth wire when strung between towers normally

ta4es shape of a catenary cur5e Catenary cur5es of conductordrawn at the wor4ing tension forms the sag template cur5e

Blastic sagtemplates are made for the purpose of manualtower spotting and also for random chec4ing of spotting done

through electronic soft ware

TOWER SPOTTIN" !ATA


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.,

TOWER SPOTTIN" !ATA

$nce the technical parameters li4e angle of de5iation< weight

span< wind span etc are tabulated< the ne@t step is to choose thecorrect type of towers at 5arious locations after comparing thefield parameters with the design parameters In case of hilllyterrains< towers with 'ne'al leg e>tension are also used This

is mainly adopted to reduce benching wor4 in a particularlocation The design parameters are contained in a documentcalled Tower spotting ata

&NE&AL LE" E=TENSIONS


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.-

&NE&AL LE" E=TENSIONS

Leg 1 @ CD 0tr E4tn2

Leg ! 1 @ 0tr E4tn2

1"2 !V Badarpur K-lie-riat /ine

/oc# o# 1 /3 4"5 "5 "5 +6

1 @ 0tr E4tn2

1 @ ) 0tr E4tn2


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SAMPLE TOWER SPOTTIN" !ATA


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TOWER SCHE!&LE


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.9

TOWER SCHE!&LE

Loc

No

Angle o/

!e1iation

Weig4t Span Win) Span Recommen)e)

to+er t(peLe/t Rig4t Total Le/t Rig4t Total

"ENERAL I!EA ON WIN! PRESS&RE


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/

"ENERAL I!EA ON WIN! PRESS&RE

Aind pressure is proportional to wind 5elocity

Aind pressure ?onesIndia is di5ided in . ( i@) wind ?ones based on wind speed

;b is based on pea4 gust 5elocity a5eraged o5er a short timeinter5al of about 3 ( Three) seconds

!ote: Aind as per I 02 and Aind ?one as per I 0/-

Aind one *asic wind speed (;b) m>sec

1 33

2 393 ,,

, ,/

- -

. --

WIN! 9ONES O# IN!IA


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/1

WIN! 9ONES O# IN!IA

WIN! 9ONES 6 BASIC WIN! SPEE!S O# NER


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/2

WIN! 9ONES 6 BASIC WIN! SPEE!S O# NER

Name o/ states Win) Done Basic +in) spee) * %3,m$sec

#ssam .>->,>2 -->->,/>39

'eghalaya .>->, -->->,/

#runachal Bradesh ->3 ->,,

!agaland ,>3 ,/>,,

'anipur .>->3 -->->,,

'i?oram . --

Tripura . --


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WIN! 9ONE MI9ORAM


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/,

WIN! 9ONE MI9ORAM

WIN! 9ONE MANIP&R


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/-

WIN! 9ONE MANIP&R

WIN! 9ONE ME"HALAYA


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/.

WIN! 9ONE ME"HALAYA

WIN! 9ONE AR&NACHAL PRA!ESH


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//

WIN! 9ONE AR&NACHAL PRA!ESH

WIN! 9ONE TRIP&RA


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/0

WIN! 9ONE TRIP&RA

WIN! SPEE!


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WIN! SPEE!

METEOROLO"ICAL RE#ERENCE WIN! SPEE! * %R ,

;" is e@treme 5alue of wind speed o5er an a5eraging period of 1( ten) minutes duration

;" L ; b> N

N is ta4en as 13/- to con5ert 3 seconds pea4 gust speed in to 1minutes a5erage

!ESI"N WIN! SPEE! * %),

;d L ;" @ N 1 @ N 2

N 1L "is4 coefficient

N 2 L Terrain "oughness coefficient

SELECTION TABLE #OR 2


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0

SELECTION TABLE #OR 2 .

Aind ones1 2 3 , - .

"eliability 7e5el

7e5el 1 (up to , 4;) 1 1 1 1 1 1

7e5el 2 (abo5e , 4;)Mtriple & 6uad c4t up to ,

4;

10 11 111 112 113 11,

7e5el 3 (Tall "i5er crossing& special tower)

11/ 122 12- 12/ 120 13

SELECTION TABLE #OR 2


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01

Terrain Categor( %al'e o/ 2

Cat .5 @posed terrain with few or no obstructionswith a5erage height of obJects less than 1- m li4eopen sea coast> water stretch< deserts< flat tree lessterrain

10

Cat 5 $pen terrain with well scattered obstructionsha5ing height between 1-m to 1 m li4e normalcountry with 5ery few obstacles

1

Cat < 5 Terrain with numerous closely spaced

obstructions li4e built up & forest area

0-

Note? For line- encountering ill-6 ridge-> K* -+ould be ta%en a- ne4t

+ig+er 3alue


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%AL&E O# !RA" COE##ICIENT C)t


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0,

#OR TOWER

Soli)it( Ratio !rag Coe//icient C)

+p to - 3.

1 3,2 29

3 2-

, 22

- and abo5e 2

SOLI!ITY RATIO


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0-

SOLI!ITY RATIO

olidity ratio L Brotected area of all members

#rea of frame

!$T: rag coefficient ta4es in to account the shielding effects ofwind on the leeward face but if leeward members are not shielded

by the windward face< proJected area of the leeward members shallalso be considered in the calculation

%AL&ES O# "&ST RESPONSE #ACTOR #OR


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0.

TOWER * "T, AN! INS&LATOR * "I,

WIN! LOA! ON CON!&CTOR


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0/

6 "RO&N! WIRE

Fwc

L Bd @ Cdc

@ 7 @ d @ Gc

Bd L esign wind pressure in !>m2

Cdc L rag coefficient (1 for conductor and 12 for ground wire> earth wire)

7 L Aind span L =alf of sum of adJacent span

d L iameter of conductor> arth wire in meter

Gc

L Gust response factor

%AL&ES O# "&ST RESPONSE #ACTOR "C

#OR CON!&CTOR 6 EARTH WIRE


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00

#OR CON!&CTOR 6 EARTH WIRE

WIN! LOA! ON INS&LATOR STRIN"


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09

WIN! LOA! ON INS&LATOR STRIN"

Fwi

L Bd @ Cdi

@ #i @ GiBd L esign wind pressure in !>m2

Cdi L rag coefficient to be ta4en as 12

#i L - Q proJected area of insulator stringGi L Gust response factor

!ote: !o mas4ing effect will be considered in case of multiple >; insulator strings

TENSION LIMIT O# CON!&CTOR 6 E$WIRE

* R / IS FG P t I$S I .:,


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9

* Re/5 IS FG Part I$Sec I- .:,

Conductor >arth wire tension at e5eryday temperature and withoute@ternal load< should not e@ceed the following:

Condition I

Initial unloaded tension : 3- Q of ultimate tension strength ( +T)Final unloaded tension: 2-Q of +T ( for 5oltage le5el upto 22 4;)

22Q for conductor & 2 Q for arth wire

( for , & 0 4; le5el)


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#ORM&LA #OR CALC&LATIN" CHAN"E IN

TENSION O# CON!&CTOR$ E$WIRE !&E TO


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92

TENSION O# CON!&CTOR$ E$WIRE !&E TO

CHAN"E IN TEMP 6 PRESS&RE *RE#5 IS :;< PART I,

T22

S T2 % (T1 l2

w2

812

U)> 2,T12

VtUWX L l2

w2

822

U > 2,where

T2 L Tension at temp t2 R C in 4g

T1 L Tension at temp t1 R C in 4g

l L pan length in meter AL Aeight per meter

81 L Y( w2 Mw12 )>w w1 L wind load in 4g> m

ZL #

L oung modulus in 4g> cm2#L Cross section area ( m2)

V L Coefficient of linier e@pansion per RC

62 L loading factor

t L (t2 % t1) R C

SA" TENSION CHART


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93

SA" TENSION CHART

Aith change in ambient temperature< tension on conductor and

earth wire shall also change in the following pattern because ofthermal e@pansion> contraction in the following manner

Temperature increases : Tension decreases

Temperature decreases : Tension increases It is therefore important that correct tensions are maintained

during stringing of conductor > earth wire corresponding toambient temperature so that design tension and sags are

maintained during worst loading conditions as alreadye@plained earlier

SA" TENSION CHART


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9,

For this purpose< tension and sags at different ambient

temperatures are calculated corresponding to base wor4ingtension at e5ery day temperature and with no wind & usingformula already discussed earlier

The results are than tabulated in a con5enient way for reference

SA" TENSION CHART

SA" TENSION CHART


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9-

SA" TENSION CHART

METHO! O# MAINTAININ" CORRECT

TENSION AT THE TIME O# STRIN"IN"


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9.

TENSION AT THE TIME O# STRIN"IN"

*y measuring sag

*y measuring tension

TB

tepI : 'easure ambient temp

tep II: Calculate a5erage ruling span of the section using thefollowing formula

tep III : Consult ag Tension chart and note sag and tension5alue corresponding to ambient temp and corresponding

to a5erage ruling spantep I; : elect the span whose length is nearest to the ruling span

& adJust sag or tension so as to attain the re8uired 5alue before final tensioning (clamping on tower)

TOWER LOA!IN" CON!ITIONS


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7oadings shall be determined for the Two loading conditions

Combination I : Corresponding to ma@imum wind at meanannual temperature

Combination II : Corresponding to 2>3 rd ma@imum wind at

the minimum temperature

TOWER LOA!IN" TRANS%ERSE LOA!S


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90

WIN! LOA!S NORMAL CON!ITION BRO2EN WIRE CON!ITION

$n conductors andground wires onfull proJected areas

Corresponding to full windspan of bundledconductors & ground wire

Corresponding to -Q of intactspan and 1Q of bro4en span of bundled conductor> ground wire

$n Tower $n 1- times the proJected

areas of members on thewindward face of towers

$n 1- times the proJected areas

of members on the windwardface of towers

$n insulator strings1) uspension

2) Tension

1 4g

3 4g

1 4g

3 4g

TOWER LOA!IN" TRANS%ERSE LOA!S


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99

!E%IATION

LOA!S

NORMAL

CON!ITIONS

BRO2EN WIRE

CON!ITIONS

Trans5erse componentstension of bundledconductors and groundwire

a) uspension tower Trans5erse components

corresponding to -Q ofthe tension of bundled

conductors or 1Q of thetension of ground wire

b) Tension tower

Trans5erse componentcorresponding to 1Q ofthe tension of bundledconductor> ground wire

TOWER LOA!IN" %ERTICAL LOA!S


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1

!&E TO

CON!&CTOR

NORMAL

CON!ITIONS

BRO2EN WIRE

CON!ITIONS

uspensiontower

8ual to the ma@imum>minimum weight span of bundled conductors

.Q of ma@imum>minimum weight span of bundled conductors

Tension Tower 8ual to ma@imum weightspan of bundledconductors ( downward orupward)

.Q of ma@imum weightspan of bundledconductors ( downward orupward)

TOWER LOA!IN" %ERTICAL LOA!S


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11

!&E TO"RO&N! WIRE

NORMALCON!ITIONS

BRO2EN WIRECON!ITIONS

uspension tower 8ual to the ma@imum>minimum weight span ofGround wire

.Q of ma@imum>minimum weight span ofGround wire

Tension Tower 8ual to ma@imumweight span of Groundwire ( downward orupward)

.Q of ma@imum weightspan of Ground wire( downward or upward)

ue to Insulator &conductor#ccessories

8ual to the weight ofInsulator strings< spacers<dampers etc

8ual to the weight of Insulatorstrings< spacers< dampers etc

TOWER LOA!IN" LON"IT&!INAL LOA!S


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12

!&E TO POWER

CON!&CTOR

NORMAL

CON!ITIONS

BRO2EN WIRE CON!ITIONS

uspension Towers !I7 - Q of the tension of bundledconductors

Tension Towers 8ual to the tension of bundled power

conductors for deadend towers only

8ual to the components of tensionof the bundled power conductors

corresponding to the rele5ant anglesof de5iation

ue to Groundwire

!ormal conditions *ro4en wire conditions

uspension Towers !I7 8ual to the tension of Ground wire

Tension Towers 8ual to the tension ofGround wire fordeadend towers only

8ual to the components of tensionof the Ground wire corresponding tothe rele5ant angles of de5iation

TOWER LOA!IN" ERECTION LOA!S


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13

NORMALCON!ITIONS

BRO2EN WIRECON!ITIONS

'an with Tools !I7 8ual to the tension ofGround wire

7oads due to liftingtac4les< line car etc(to be considered atconductor cross armand lifting points)

8ual to thetension ofGround wire fordeadend towersonly

8ual to the componentsof tension of the Groundwire corresponding tothe rele5ant angles ofde5iation

!ote: The design of towers shall be based on loading combinationand condition which is more stringent for the particular member

#O&N!ATION LOA!IN"S


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1,

Calculated from Tower 7oadings

Typical Tower 7oading tree is indicated below

#O&N!ATION LOA!IN"S


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1-

7oads transmitted to Foundation through tower legs

Two types of loads act on foundation

# ;"TIC#7 ( M )* =ori?ontal or side thrust

&N!ER %ERTICAL LOA!


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1.

&N!ER HORI9ONTAL LOA!

A@ O%ERT&RNIN"


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1/

O%ERT&RNIN"

&N!ER HORI9ONTAL LOA!B@ SLI!IN"


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10

SLI!IN"

%ERTICAL LOA! ON #O&N!ATION


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19

&L/ &LM&L/&LM

FSTFST

L

WIN!

FORE

LOA! ON #O&N!ATION


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11

On acco'nt o/ gra1it( /orce *+eig4t, on to+er

If A L Total gra5ity force ( weight)

Then 5ertical load (;7) on account of A on each leg<

;7w L A>, which acts downward (down thrust)

On acco'nt HoriDontal /orces *trans1erse $ longit')inal , on to+er

Ahich produces turning moment at the base of tower

!et 'oment 'T L [ F= @ h

Ahere F= L =ori?ontal force at a particular height

h L corresponding height from foundation top

LOA! ON #O&N!ATION


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111

@ternal 'oment ' produces restoring moment in the form of upward &downward thrust at leg> foundation

"estoring 'oment

'" L 2(upward> downward thrust in each leg @ leg to leg dist)

ie '" L 2 ;7' @ 7

For stability: !et turning moment L !et "estoring moment

ie 'T L '" \ ie 'T L 2;7' @ 7 \ ie ;7' L 'T>27

!et down thrust on 2 legs on one side L M( ;7A M ;7')

!et upward thrust on 2 legs on other side L ( ;7' % ;7A) !ormally ;7' HH;7A and therefore there is net upward thrust on 2 legs

of a tower which also acts on the foundation and this is called uplift onfoundation

#O&N!ATION LOA!IN" WIN! 9ONEII *


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112

* ,

#OR GG 2% !$C TOWER WITH TWIN MOOSE CON!&CTOR

TOWER TYPE COMPRESSION*2g,

&PLI#T *2g, SI!E THR&ST*TRANS, *2g,

SI!E THR&ST*LON", *2g,

# M -9 -3


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113

B@ HORI9ONTAL LOA! ON #O&N!ATION

=ori?ontal forces on tower also produces side thrust onfoundation

ide Thrust F&T L [ F= > ,

arth8ua4e forces


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TOWER #O&N!ATION


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11.

c) # footing with an under cut generally de5elops uplift

resistance of two to three times that of an identical footingwithout undercut +ndercut foundations are normally

pro5ided in fissured & soft roc4 foundations

TOWER #O&N!ATION


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11/

Failure .lane Soil S+ear Stre--

Undercut

Foundation

F$+!#TI$! TB

TOWER #O&N!ATION


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110

F$+!#TI$! TB

BROA! CLASSI#ICATION :

$pen Cast % 'ost commonly used

#ugured under reamed pile (where open e@ca5ation is Broblematic)

Bile foundation

Aell foundation $n pecial 7ocations: "i5er *ed< !earby ri5er< prone to erosion< Aea4 soil

OPEN CAST #O&N!ATION


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119

A&"&RE! &N!ER REAME! PILE

#O&N!ATION


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12

PILE #O&N!ATION


121/141

121

WELL #O&N!ATION


122/141

122

PILE #O&N!ATION


123/141

123

PILE #O&N!ATION CONSTR&CTION

LI#TIN" O# CA"E


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12,

P7/3 8&9DAT7& &ST%9T7&

/owerin, of reinforcement ca,e in pile bore


125/141

12-

, , p

P7/3 8&9DAT7& &ST%9T7&

/owerin, of reinforcement ca,e in pile bore


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12.

, , p

P7/3 8&9DAT7& &ST%9T7&

7nstalled pile


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12/

http://us.f347.mail.yahoo.com/ym/ShowLetter?box=Inbox&MsgId=7316_5371269_958_2182_4736217_0_145619_6254142_4149395225&bodyPart=2&tnef=&YY=76524&y5beta=yes&y5beta=yes&order=down&sort=date&pos=1&view=a&head=b&VScan=1&Idx=29http://us.f347.mail.yahoo.com/ym/ShowLetter?box=Inbox&MsgId=7316_5371269_958_2182_4736217_0_145619_6254142_4149395225&bodyPart=2&tnef=&YY=76524&y5beta=yes&y5beta=yes&order=down&sort=date&pos=1&view=a&head=b&VScan=1&Idx=29


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P7/3 8&9DAT7& &ST%9T7&

3rected tower on pile foundation


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129

WELL #O&N!ATION


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13WELL FOUN!ATION

WELL #O&N!ATION &N!ER CONSTR&CTION


131/141

131

OPEN CAST #O&N!ATION


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132

'ost commonly used< Con5enient & 8uic4 in e@ecution wherethere is no high water table and soil collapse problem

COMMON TYPE O# OPEN CAST #O&N!ATION:

!epen)ing on t(pe o/ materials 'se)

teel Grillage Type foundation

BCC > "CC foundation !epen)ing on e>tent o/ e>ca1ation

Indi5idual footing

Chimney % frustrum type

Chimney % Bad type

*loc4 type

pread type footing

STEEL "RILLA"E TYPE #O&N!ATION


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133

PCC $ RCC #O&N!ATION


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13,

CHIMNEY PA! TYPE #O&N!ATION


135/141

13-

BLOC2 TYPE #O&N!ATION


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13.

SPREA! TYPE #O&N!ATION


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13/

OPEN CAST #O&N!ATION *Cont)@,

!epen)ing on t(pe o/ soil


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130

!epen)ing on t(pe o/ soil

!ormal dry soil foundation ry fissured roc4 (with under cut) "oc4 Foundation (#nchored) *lac4 Cotton soil foundation< commonly 4nown as Aet

*lac4 Cotton (A*C) type !epen)ing on )ept4 o/ +ater ta3le

ry Foundation: Aater table below footing depth Aet Foundation: Aater table 1- ' from ground surface

Bartially ubmerged (B): Aater table between 1- to /- mfrom ground surface

Fully ubmerged (F): Aater table abo5e /- m

WHY CLASSI#ICATION

BASE! ON WATER TABLE?


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139

Aeight of soil and concrete is less when submerged in water because of buoyancy effect and therefore offers lessresistance to uplift then in dry condition

#ngle of internal friction (]) is less for wet soil and

therefore 5olume of frustum of soil abo5e footing pad is lessin wet condition & therefore offers less resistance to uplift

conomy in cost is therefore achie5ed in classifyingfoundations based on water table instead of adopting one

type considering worst condition (F type)

#O&N!ATION %OL&ME


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1,

Comparison of foundation 5olume for different fdn classification:

!ame of 7ine : , 4; >C 'isa *alipara

TOWERTYPE

CONCRETE %OL&ME *C&M,

!RY WET P@S #@S

# 9.0 133 12.9 1-/,

* 2,9, 20-1 3,99 ,29

C 2/0. ,3-31 -3,9 .3.2

3,-. -219 -03- 1330,


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T=#!N $+

transmission line basic presentation

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