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P
a
rt
A
1 .
a)
G ive
five
p ro p e r t ie s
o f s ta t i c
m agn e t ic
f
ie l
d
in t
e n
s i ty
.
W h
a t
a
r e
th
e
d if
fe
ren
t
m
e t
h o
d s
b
y
w h
ic
h i t
c a
n
b
e
c
a l
c u
la t
e d
?
W
rit
e
M
a
xw
ell
s
eq
u a t
io
n r
e la
t in
g t
h i
s
i
n in
te
g ra
l
a n
d
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ffe
ren
t ia
l fo
rm
s .
1
2
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9
P
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b)
I< xp
lain
th e
o
llow
ing :
i) P
o y n t
in g
v ec t
o r a
n d
i t s
s i
gn i f
i can
c e
i i ]
L o
ss ta
n g e
n t o
f d ie
le c tr
ic s
a s
u s e
d
in w
ave
p r
o p a
g a t
io n
i i i) I
n t r i
n s ic
im
p e
d a n
c e o f
a
w
ave
m e
d iu m
1
{c)
W
h a
t i s a
d is
to r t
io n l
e s s
l
i ne?
H o
w to
a c
h ie v
e d i
s to r
t io n
le s s
c o
n d i t
io n
o n
th e
l in e
?
D
eriv
e th
e n
e c e
s sa r
y e q
u a t i
o n s
. 1
2 .
a)
S h o
w th
e e
le c t r
ic a l
c o
n n e
c t io
n
d ia
g ra m
a n d
m
o d
e l
th e
a rm
a tu
re
v
o lta
g e
c o n
tro l
le d
d
.c . m
o to
r
in
a
b lo
c k
d ia
g ra m
form
.
A
ssu
m e
th e
n
e c e
s s a r
y
v a
r iab
le s
a n d
o b
ta i
n
t r an
s fe
r
fu
n c t
io n
fo r
c h
a n g
e
in
p
o s i
t ion
o
f a r
m a
tu re
to
th e c
h a n
g e
in
a rm
a tu
r e v
o lta
ge .
E x
p re s
s
t h e t r
a n s
fe r
fu n c t io
n
in
s ta n
d a r
d
f
o rm
.
1
2
b) F
o r
m e
s y
s te
m
r e p
re s
e n t e
d b y a
b
lo c k
d
ia g
ra m
s
h o w
n b
elow
,
e v a l
u a t
e t
h e
c l
o sed
- loo
p
t r a
n s f
e r fu n
c t io
n .
C a l
c u la
te
d a m
p in
g fa
c to r
. f r
e q u
e n c
y o
f o sc i
l la t i
o n
[if
a n y
, s
te a
d y -s
ta te
e r r o
r i th
e in p
u t
is
u n i
t r
a m p
i
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r
Tc
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c)
3
.
a
)
i)
F
o r
a
s
e
co
n
d -
o r
de
r
sy
s
te
m
, th
e
lo
ca
ti
on
o f
p
o l
e s
1s
k
n
ow
n
to
b
e
-
3
j7
C
a l
cu
la
te
p
e a
k
t i
m
e ,
o
/o
o
v
e r
sh
o
o t
a
n d
ap
p
ro
x i
m
a t
e
se t t l ing
t im e
fo r ±2
range .
i
i) W
ha
t
a r
e
th
e
p r
op
e
r t i
e s
o
f
l i
n e
a r
sy
s
te
m
s
n
o
t
va
li
d
f
o r
n
on
- l
in
ea
r
5
sy
s t
e
m
s?
Ex
p
la
in
e
a
ch
b
rie
fl
y
5
•
i)
D
et
e r
m
in
e
th
e
co
m
p
le
te
s
tab
i
l i t
y
in
fo
rm
a
ti
on
b
y
us
in
g
R
o
u t
h
c
r
i te
r i
a
fo
r a
u
n
i t
y
f
ee
db
a
ck
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lo
se
d
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te
m
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ll
ed
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s
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19
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i i)
F
o r
th
e
sy
s
te
m
s
ho
w
n
in
t
h e
f i
gu
re
b
e l
ow
,
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ra
w
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y
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is
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d
ia
g
ra
m
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m
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rg
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s
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6
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s)
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b )
i} A
s y s t e m
Ls r e p r e s e n t e d
b y t h e
fo l low ing t r a n s f e r
f u n c t i o n m o d e l
G(s) C (s)
= .
s 5 .
R(s) {s
•
1 (s
2) s 3)
O b t a i n t h e
s t a te s p a c e
m o d e l fo r
t h i s s y s t e m s u c h
th t
t h e s y s te m
m a t r i x
is
i n
d i a g o n a l i z e d
f o r m .
T h e c h o i c e
o f s t a t e
v a r i a b l e s
n e e d s
to b e c l e a r l y
i n d i c a t e d .
5
i i) A s y s t e m i s m o d e l l e d
b y
s t a te s p a c e
m o d e l a s
Y = [ l OJ
E v a l u a t e t h e
s t a t e
t r a n s i t i o n
m a t r i x a n d
t h e
a u t o n o m o u s
r e s p o n s e o f
t h e
s y s t e m
w i t h
i n i t i a l
c o n d i t i o n x O) = {1 2lT- 5
{c)
D r a w
t h e
s c h e m a t ic d i a g ra m
o f
a
2 p h a s e
s e r v o m o t o r
a n d
d r a w
t h e
t o rq u e s p e e d
c h a r a c t e r i s t i c .
W h a t c a r e
i s t a k e n to
o b t a i n l i n e a r
c h a r a c t e r i s t i c ?
D e r i v e t h e l i n e a r i z e d
t r a n s f e r
f u n c t i o n
u n d e r
l o a d c o n d i ti o n .
Part B
4 a)
G i v e
t h e p r o p e r t i e s
o f s u p e r c o n d u c t o rs .
1 0
W h a t a r e
t y p e
I a n d t y p e
II
s u p e r -
c o n d u c t o r s ?
I n d i c a t e th e i r b e h a v i o u r
w i t h
r e s p e c t to a p p l i e d
m a g n e t i c f ie ld .
1 2
D R S R L
RRA/69
4
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b) Expla in t h e H al l
effect
in s e m i
c o n d u c t o r s a n d d e f in e Hal l c o n s t a n t .
W h a t
d o
y o u
m e a n b y n e g a t i v e Hal l
c o n s t a n t ?
c)
E x p l a i n t h e
fo l lowing :
i) C o m p l e x
die lec t r ic
c o n s t a n t
ii) C e r a m i c s a s i n s u l a t i n g
m a t e r i a l s
5 .
a)
N a m e t h e
b a s i c
po la r i za t ion
m e c h a n i s m s
w h i c h
o ccu r i n a
dielect r ic .
A
die lec t r i c
mate r i a l c o n t a i n s 2 x 1 0
1 9
p o l a r
molecu le s f
m
3
, e a c h o f d ipo le m o m e n t
1 · 8 x to -
2 7
C - m .
A s s u m i n g t h a t
al l
t h e
d ipo le s
a r e
a l i g n e d in
t h e d i r ec t ion
s-
o f e lec t r ic fiel = 1 0 x V / m f ind
--
P a n d
E r
b) W i t h r e s p ec t t o m a g n e t ic b e h a v i o u r
give t h e c lass i f ica t ion o f m a g n e t i c
ma te r i a l s . D i s c u s s gene ra l e lec t r i c a n d
m a g n e t i c
charac te r i s t i c s
o f
fe r r i t e s a n d
t he i r appl ica t ions .
c) D esc r ibe
in
de ta i l
t h e
t h e r m a l
b r e a k
d o w n
o f
so l id d ie lec t r i c s u n d e r
app l i ca t i on o f
a l t e r n a t i n g a s wel l
a s
1 2
12
1 0
1 6
di rec t ·
vol tages .
1 0
D R S R L R R A /6 9
5
[
P .T .O.
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P
a
rt
e
6
{a )
F
in
d ~ h e
u
r r
e n ~
x
w h
ic
h f l
ow
s
t
h r
o u
g h
i l i
e 3
n
re s
is t
o r
in
t h
e
c
i rc
u i
t o
i
i l i
e
b)
f
igu
re
b
e lo
w
·
12
1 0
.
V
In
i l ie c i rc u i t o f
sw
i t
c h
S
h
a s
be
en
lo
ng
t im
e
;
t h e
f igu re
be low
i n
po
s i t
io
n I
to
r
a
1
l
O
r
·
·
·
·
·
Q
/
~
2
~
I
o o
o
v ~
j
_ c
~
J l
F
T
~ = l
J lF
T
{
i
F
in
d
th e
co
m p
le
te
so
lu
t io
n to
r th
e
c
u r
re n
t
in
t
h e
c
i rc
u i
t w
he
n
i
s
p
u t
t
o
po
s i t
io
n
2 .
{ i
i) H
ow
to
ng
d
oe
s i t
t a
k e
in
s e
co
n d
s
or
~ h e
t r
a n
s i e
n t
t
o d i
s a
p p
e a
r
cu
r r
en
t
to
d
e c
ay
w i
ili
in
)?
i i
i )
D e
te
rm
in
e
th
e
v
o l
tag
e
w
h
ich
a p
p e
a r s
a
c ro
s s
e a
c h
c
ap
ac i
to
r a t
s
te
a d
y
s ta
te
.
12
D
R S
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L
R
R A
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9
6
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c)
A
s i n g le - p h a s e m o t o r t a k e s 5 0
A a t a
p. .
o f
0 ·5 l ag f r o m
a
2 5 0
V, 5 0 H z
su p p ly .
W h a t
m u s t
b e t h e v a l u e o f t h e s h u n t i n g
c a p a c i t o r
to n u s e t h e overa l l p.f .
to
0 · 9
l a g ?
H o w
d o e s
t h e
c a p a c i t o r
a fec t
t h e l i n e a n d m o t o r c u r r e n t s ? 1 2
7 .
a)
A
f ixed
c a p a c i t a n c e ( Xc
= 2 0 o h m s ) 1s
p l a c e d
in pa r a l l e l
w i t h a se r i e s
c o m b i n a t i o n o f r e s is t a n c e R
=
8 o h m s }
a n d
va r i ab le
i n d u c t a n c e XL
o h m s ) ,
h a v i n g negl ig ib le r e s i s t ance . A n
a l t e r n a t i n g
vol tage
o f 1 2 0 v o l t s i s
app l i ed
a c r o s s t h e p a ra l l e l c o m b in a t io n .
S h o w t h a t t h e v a l u e o f X L w h i c h wil l
p r o d u c e
u n i t y p o w e r f a c t o r r e s o n a n c e
i s g iven
b y
X L = X c
±
X ~ R 2
2 v 4
D e t e r m i n e t h e
m i n i m u m
v a l u e
o f t h e
c u r r e n t
d r a w n
f r o m
t h e
supp ly .
1 2
b)
A c i r cu i t h a s
t h e c o n f i g u r a ti o n d e p i c t e d
i n t h e f igure b e lo w
:
e t ) ~
1 4 1
s i n 4 0 0 t
L = O · l H
C = 2 5 J L F
i)
F i n d t h e e q u i v a l e n t
i m p e d a n c e
a p p e a r i n g
to
t h e
r i g h t o f p o i n t s ab
S R l r R R A / 6 9
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i i j
D c t e r r n i n e t h e
v a l u e
o f
n ; a c t a n c e w h i c h make '
s o u r c e
< Urrent i n
p h a s e
w t t h
s o u r c e
vo l t age .
t h e
t h e
t h e
i i i j S h o u l d t h e
r e a c t a n c e
X o f p a r t iiJ
b e i nduc- t ive o r c a p a c i t i v e ?
F i n d t h e
r e q u i r e d v a l u e
o f o r
C.
{ iu j C o m p u t < · t h e effec· t ive
v a l u e o f
t h e
sou1
noe c u r r e n t
for t h e
c o n d i t i o n
d e s c r i b e d in
p a r t
i i). 1 2
c) F i n d ABCD p a r a m e t e r s fo r t h e
two· ·por t
8 . a)
n e t w o r k s h o w n in t h e f igu re b e l o w
12
Part D
E.;xplain, w i t h a diagrru :n , h o w W i e n ·s
b r i d g e
c a n
b e
u s e d
for
e x p e r i m e n t a l
d e t e r m i n a t i o n o f f r e q u e n c y D e r i v e
t h e
e x p r e s s i o n
for f r e q u e n c y in t e r m s
o f
b r i d g e p a r a m e t e r s . 1
D R S R L R R A / 69 8
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b)
T h e p o w e r fac to r
o f a
c i r cu i t 1s
d e t e r m i n e d b y c o s < > = f VI
w h e r e
1s
t h e p o w e r
in
w a t t , V t h e vo l t age i n
vo l t
a n d
i s
t h e c u r r e n t i n
a m p e r e .
T h e
re la t ive
e r r o r s i n
p o w e r ,
c u r r e n t a n d
vo l t age
a r e re spec t ive ly
± 0 · 5°/o,
1
o o
a n d
+lo/o.
C a l c u l a t e
t h e re la t ive e r r o r
in
p o w e r
fac tor . Also c a l c u l a t e
t h e u n c e r ta i n t y in
p o w e r f ac to r i t h e
e r r o r s w e r e spec i f i ed
a s u n c e r t a i n t i e s .
c)
A n
elec t r ic
ut i l i ty
su p p l i e s
p o w e r
to
M W
l o a d
a t
p o w e r f a c t o r p.f.} 0 · 8 5
a n d
a t
11 kV. T h e u t i l i ty
w a n t s
to m e a s u r e
t h e
vol tage ,
c u r r e n t a n d p o w e r
f a c to r
c o n t i n u o u s l y
u s i n g 2 5 0
V
v o l tm e te r ,
1 0
A
a m m e t e r a n d 2 5 0
V ,
1 0
A
p o w e r
f a c to r m e t e r .
D r a w
c i r cu i t
d i a g r a m
o f
t h e s c h e m e .
D i s c u s s ,
w h y
t h e
p.f .
m e t e r d o e s
n o t
c o m e
b a c k to z e r o r e a d i n g l ike
v o l t m e t e r
a n d a m m e t e r
a f t e r
d i s c o n n e c t i n g t h e
1 0
s u p p l y to i t . 1 0
9 .
a) D e s c r i b e t h e pr inc ip le
o f
f r e q u e n c y
m e a s u re m e n t u s in g
dig i ta l
t e c h n i q u e .
D r a w
i t s
b l o c k d i a g r a m .
T h e u n k n o w n
i n p u t s i g n a l
o f 2 V
s q u a r e w a v e i s
o f
3 ·5 k Hz . D e t e r m i n e t h e d i s p l a y
ind ica t ion i f
t h e
g a t e
e n a b l e
t i m e
1s
i) 0 ·1 s e c o n d ,
i i) s e c o n d a n d
{iii)
1 0
s e c o n d s . 1 0
D R S R L R R A /6 9
9
I
P.T.O.
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f j
S u g g e s t nega t ive
t e m p e r a t u r e
coeffictent: dev ice for
t h e
m e a s u r e m e n t
o f
t e m p e r a t u r e 0
C - 1 5 0
~ C .
D e sc r ib e
t h e
r e , ; i s t ance - t cmpera tu re
c h a r a c
t e r i s t ic .
vol tage--current
charac te r i s t i c
a n d
cu r r en t - t i m e
charac te r i s t i c
o f
t h e r m i s t o r s . D r a w a c i rcu i t for
m e a s u r e m e n t
o f
t e m p e r a t u r e
u s i n g
t he rmi s to r . The o u t p u t r e l a t ion
for
a
ther r r l i s tor
t r a n s d u c e r
i s
g iven b y
l l t L . l . l
R
R o e T 1o
F o r T
· · 3 0 0 K. I} = 3 4 2 0 , R
' ·
1
k.Q
a n d
R
2
k " l , ca l cu l a t e T.
1
c)
D r a w t h e
l ine d i a g r a m
o f
d a t a
acqu i s i t i on s y s t e m f rom p r o ces s p lan t t o
c o m p u t e r s y s t e m . E x p l a i n t h e f unc t ion
o f
e a c h
c o m p o n e n t .
W h a t
d o y o u
u n d e r s t a n d b y s m a r t t r a n s d u c e r ?
D i s c u s s
i t
in
brief .
l .O. a) A paral le l -pLate c a p a c i to r w i th
pla te a r e a
o f 1 0 c m
2
a n d
p la t e
s e p a r a t i o n o f
6
m m
h a s a vo l t age
SOsin( l
0
3
t)
vol t
app l i ed
to
i t s
p la t e s .
Dt. · termine t h e
d i s p l a c e m e n t
c u r r e n t ,
a s s u m i n g
£
=
2t.
0
b)
S t a t e
A m p e r e ' s
c i r cu i t
l aw.
A
ho l low
c o n d u c n n g cy l inde r
h a s
i n n e r r a d i u s a
a n d
o u t e r
r a d i u s b, a n d
ca r r i e s
a
c u r r e n t f a l o n g t h e pos i t ive z -d i rec t ion .
·
1
1
F i n d e v e ry w h e re . 1
D R S R L R R A / 6 9
1 0
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c) F o r
a l o s s l e s s
two-wi re t r a n s m i s s i o n
l ine
s h o w th t
i)
t h e p h a s e ve loc i ty
u c
k;
L
{ii)
t h e c h a r a c t e r is t ic i m p e d a n c e
1 2 0
h 1 d
0 c o s -
JE; 2a
1 0
D R S R L R R A /6 9
BS 14*
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-
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~
~
7
0
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u
ld
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e
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q
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a l l .
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ue
s
t: i
o
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s
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o
ry
T
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i
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o
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r
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le
c
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r
om
S
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n
s
A
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n
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.
h
e
n
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n
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f
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n
a
rk
s
c
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r r
ie
d
b
y
e
a
c
h
q
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e
s t
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n
i
s
in
d i
c
a
L
ed
t
t h
e
e n
d
o
t h
e
qu
e
s t
_ i
on
.
A
n
sL
V
e
rs
m
u
s
t b
e U
J
ri
t t
en
o
n
l
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in
E
N
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.
A
ss
u
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e
s u
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ta
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le
d
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ta
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e
c
e s
s
a r
y
a
n
d
i
n
d
ic
a
te
th e
sa>ne
c le a r ly .
.
A
(
a
)
U
n l e
.
·
~
o
t
:h
er
LV
i
se
i
n
d i
c
a t
e
d
s
y
m
bo
l
s
n
d
n
o
ta
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io
n
s
ha
v
e
t
h
e
ir
u s
u
a
l
T
ne
a
n
in
g
q
T
he
p
u
rp
o
se
o
f
p
r
ov
id
i
n g
d
um
m
y
c
o i
ls
I n
t h
e
a
rn
1 .
a t
u r
e
o
f
D
C
m
a
c
h
in
e
i s
t
o
j )
I
n
c r
e a
s
e v
o l
ta
g
e
in
d
u c
e
d
i i
)
de
c
re
a s
e
t
h
e
a
rm
a t
u r
e
re
s i
s t
a
n c
e
i
i i
)
p
ro
v
id
e
m
e
c
h a
n
ic
a
l ba
l
a n
c
e
fo
r
t h
e
ro
to
r
iv
)
re
d
u c
e
t
h
e
c
op
p
e
r
Jo
s
s
R
S
R
L
R
R
B
I
C
o
n t
d
.I
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f f1?
f
~ I
(b) I f an
i n d u c t i o n m o t o r
i s
ope ra t . i ng
at 6 0 t ; ~ o l
i t s
s y n c h r o n o u s s p e e d , t h e m a x i m u m e f f ic iency
u n d e r i d e a l conditionos ( theore t i ca l ly
poss ib l e )
is
( i ) 100 >
( ii)
40 '
:.•
(iii}
5 0 £ ~
( i v )
6QC;b
(c) C u r r e n t .
c h o p p i n g p h e n o m e n o n 1s
a s s o c i a t e d w i t h
( i ) o v e r c u r r e n t r e l a y s
--ii)
s y n c h r o n o u s
g e n e r a t o r
( i i i ) i n d u c t i o n m o t o r
(iv) p o w e r tr a n s fO r m e r
(d) O v e r reach ing · a n d
u u n d e r
r e a c h in g ' '
a r e
e x p e r i e n c e d i n
( i ) f r e q u e n c y r e l a y s
( i i )
o v e r c u r r e n t r e l a y s
( i i i )
d i s t a n c e r e l ay s
( iv)
u n d e r vol tage
r e l a y s
(e} In
a
fu l l w a v e
r ec t i f i e r
c i r cu i t w i t h
c e n t r e - t a p
t ran>
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8/16/2019 IES Conventional Electrical Engineering 2011
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A m o n g D T L , R T L , E C L a n d
C M O S
logic fami l ies ,
E C L h a s t h e propaga t ion de lay a n d p o we r
d is s ipa t ion /ga te respec t ive ly a s
i)
l ow
h igh
ii)
low low
iii)
high , low
iv)
h igh ,
h igh
g) W h i c h o n e o f
t h e fo l lowing
h a s t h e
h i g h e s t
pr io r i ty
?
( i)
RST
7·5
( i i)
RST
5·5
iii)
TRAP
( iv )
H O L D
(h) In P A M , t h e c a r r i e r wave cons i s t s o f a per iodic
tra in o f
rectangular
p u l s e s
a n d
t h e carrier
f requency
i s
equa l to
i ) t h e b a n d w i d t h o f t h e m o d u la t i n g s ig n a l
i i ) t h e
s a m p l i n g
r a t e
o f t h e m o d u la t i n g s ig n a l
( i i i ) a t l eas t
t e n t imes
g r e a t e r t h a n
t h e
b a n d w i d t h
o f t h e mo d u la t i n g s igna l
iv) twice
t he b a n d w i d t h o f t h e m o d u l a t i n g
s igna l
( i ) T h e
m a i n
d r aw b ack o f a p h a se contro l o f 1-phase
controlled rectif ier
circuit i s
i ) i t req u i res m o re gate cu rren t
( i i ) radio f requency in terference
i i i )
more
power loss
iv) eff ic iency i s
less
[Con td . ]
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cj) T h e i m p o r t a n t
f e a t u r e s o f r o t o r O N · - O F F cont.rnl
I . B
a :
b
are
(i)
( .
lL
iii_}
iy)
fa:1t r e s p o n s e ~ 1SffiOoth v a r i a t i o n s i n ospecd
b e t t e r p o w e r fac tor a t
low s p e e d s
a n d w i d e
r a n g e
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S E C T I O N
(a)
E xp la in
N o
vol tage re lease NVR) a n d O v e r load
re lease OLR) coils
provided in
a D C m o t o r
starter
(b) 400
V s h u n t m o t o r d r a w s 3
whi l e
su p p l y i n g
t h e
r a t e d load
a t
a
speed
o f 120 rad / s . T h e
a r m a t u r e
r e s i s t ance
is
1·0
o h m a n d t h e f ie ld
w i n d i n g r e s i s t a n c e
i s
250
ohms . De te rm ine t h e
external res i s tance that m u s t b e inser ted in
ser i e s wit h t h e armat u re circuit so t h a t armatu re
c u r r e n t
does no t exceed
150
o f i t s r a t ed
va lue
w h e n
t he
m o t o r is
plugged .
F i n d
t h e
b r a k i n g
to rque a t t he i n s t an t o f plugging.
c) 6600 V/400 V/110 V Sta r /S ta r /Me s h connec t ed
t h r e e -pha s e t r a ns fo rm e r h a s a m a gne t i z ing
c u r r e n t
of · 5·5
a n d b a l a n c e d
t h r e e -pha s e
loads o f 1000 kVA a t 0·8
l ag
on secondary
a n d
200 kVA, 0·5 l ead ing power f ac to r l oad on t he
tert iary
F i n d t h e
primary current
a n d p o wer
factor . Neglec t losses .
l-fow will t he breakdown s l i p
a n d
b r e a k d o w n
torque
e
affected w h e n t h e
rotor res i s tance
i s
i n c r e a s e d ?
b)
4-pole, 5 0
Hz ,
3 -phase
induct ion
m o t o r
del ivers
a s ha f t
t o rque o f 110 N - m
a t full load
a n d
r u n n i n g t 9 5 0
rpm. Ca lcu la te
i )
rot-or
c o p p e r
loss ii) power i npu t to t he rotor . T h e m e c h a n i c a l
l o s ses accoun t for 100 W.
1
1
2
10
1
[Contd.J
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1c:
A n indwn. r ia l load o f 4 0 0 0
k W i s s u p p l i e d a t
11 kV, t h e po" ' ' ' r fac tor b e i n g 0 · 8 agl{ing. A
s y n c h r o n o u ~ XlOt.o.r r e q u i r e d
to
o::.P-t:t
a n
add i t i ona l load
of· 1-500
H P
<
I
103 ·25
k
W ; u n d
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4.
5.
S E C T I O N
(a ) S t a r t i n g
f rom
fundaTnentals
derive
t h e
eq u at ion s for s en d in g en d vo l t age a n d s e n d i n g
end
current
for
a
long transmiss ion
line_
U s e
the
d i s t r i b u t ed
p a ra fu e t e r fo rm o f
r e p r e s e n t a t i o n
o f
t h e l ong l ine . Ob t a i n t h e A , B , C , D p a r a m e t e r s
o f
t h e
l ine .
(b)
A
sy n c h r o n o u s g en e r a to r
1s
r a t e d 2 0 M V
A ,
13 ·8 kV. t h a s X
1
= 0·25 p.u . , X
2
=
0·35
p .u .
a n d X
0·10
p .u .
T h e n e u t r a l 1s sol id ly
g r o u n d e d . T h e m a c h i n e i s on no l o a d a n d is
o p e r a t i n g a t r a t e d vol tage
w h e n
a D - L - G f a u l t
occurs a t i t s t e rmina l s . F i n d t h e s u b t r a n s i e n t
c u r r e n t
in
al l
t h e
p h as e s
a n d t h e
f au l t (a l l
in
a m p s )
a n d
t h e l ine- to - l ine vo l tages in
al l
t h e
18
p h a s e s
( in kV).
2
{c )
a )
S k e t c h typica l
sw in g c u r v e s for a
s y n c h ro n o u s
m a c h i n e ( i ) sh o w in g t h a t t h e m a c h i n e is s t a b l e
a f t e r
a
d i s tu rbance
(ii)
s h o w i n g
t h a t
t h e
m a c h i n e is u n s t a b l e
af te r
a d i s tu rbance .
A
r i n g
f eede r wi th five sec t ions
a n d
fed a t one
po in t is to b e pro tec ted u s i n g Direc t iona ) ove r
c u r r e n t (DOC) R e l a y s a n d
O v e r
c u r r e n t (OC)
R e la y s w i t h su i t ab le t i m e ; , Tading. E x p l a i n t h e
w o r k i n g o f t h e sc h e m e . S h o w t h e
loca t ion
o f
D.O.C s
a n d
O.C s
a n d
t h e i r
t i m e
o f
ope ra t ion .
A s s u m e a t im e g ra d i n g o f 5 rns b e t w e e n t h e
r e lays . T h e fa s t e s t
re l ay needs
5 m s for t to
operate
15
0 RSR L RRB
7
[Con td
.]
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b ) i )
A s u r g e
o r
100
k V is i n c i d e n t o n
a
l i ne
h a v i n g
a s u r g e
i m p e d a n c e
o r 4 0 0 ohrns . f t
m e e t s
cable h a v i n g
~ u r g e
i m p e d a n c e nr
4 0 o h m s D e r i v e
exp res s ion for t h e
t . rano;mit ted
vo l t age
a n d
reflect ed
vo l t age
a n d
con1pute
the ir va lu es
i i ) E x p l a i n t h e prac t i ca l i m p o r t a n c e o f t h i s
s i tuat ion
c ) A
3 - p h a s e
d o u b l e c i rcu i t
l ine
I S a r r a n g e d as
s h o w n b e lo w
I 4 m - - j
a
G-----
0
c ·
m
I
y ·
b ~
'
5·5
m
. ~ r
3 Ill
c Q
l
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S E T I O N
a) T h e c i rcu i t
s h o wn
uses a si l icon
transistor
w i th J =
50,
V
BE
= 0-6
V,
V CC = 22-5 V a n d
R c 5-6 K. F in d
t he
va lues o f
t he re s i s to rs RE,
R
1
a n d R
2
so t h a t Q
poin t i s
se t
a t
V
CE
12
V
a n d Ic = 1·5 rnA. Th e s tab i l i ty factor ,
S
m u s t
be
< 3.
I
:?
R c
c
_
2
D R SR L R R B
9
[C o n td . ]
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7.
b ) A n i n p u t
ot·
E · t 5 0 V
i s a p p l i e d
to
t h e c l ipp ing
circuit
T h e o u t p u t current f rom t h e circuit
is
t o
b e
IL 2 0 xnA a n d
t ;he
n e g a t i v e o u t p u t
v o l t a g e
i>
n o t t o e x c e e d
0 · 5
V
n
[ > - - - - , - - - - - = = ~
C a l c u l a t e
t h e v a l u e of R
1
. Spec i fy t h e d i o d e
in
t erms
o f
forward current
power diss ipat ion
and
p e a k
r e v e r t ~ - e
voltage.
A s s u m e
t h e reverse
s a t u r a t io n c u r r e n t
I ~ i s j i A a n d
f o r w a r d vo l t age
o f
diode ,
V f'
0·7 V.
c )
a )
:b
c )
Co n Bt r u c t l og ic c i rcu i t
to
g i v e a n
X
=
A B + A C l A D + C } w i t h o u t a n y
o u t p u t
r e d u c t i o n
in n u m b e r
o f
gates
G i v e
t.he logic circuitti
in
s t e p
b y s t e p .
E x p l a i n
M e m o r y m a p p e d
110.
E x p l a i n
I n t e r r u p t , ;
a n d
S e r i a l
110
o f 8085 .
L i s t
t h e
m a c h i n e cy c le s
o f
8 0 8 5 .
0 RSR l RRB 1 0
[ C o n t
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a )
W i t h
a
explain
s ignaL
S E T I O N
neat c ircuit diagram and w v e f o r m s ~
h o w
enve lope de tec tor de tec t s A M
b)
A s inuso ida l m odu la t ing wave
o f a mp l i t u d e
5 V
a n d f r equency
1
k H z
i s appl ied
to
a
f r equency
modula to r . T h e f r equency
sens i t iv i ty o f
t he
mo d u la to r i s 40
Hz/V. T h e
c a r r i e r
f requency i s
100
kHz .
Calcu la te
i)
f requency devia t ion
ii)
modula t ion
index
iii) i n s t a n t a n e o u s f requency
o f
t h e F M wave .
6
Also wri te t he
express ion
of t he
F M
waveform.
6
c) Cons ider a n F D M s y s t e m us ing
A M S S B
m o d u l a t i o n to t r a n s m i t
24
i n d e p e n d e n t vmce
i npu t s . A s s u m e
a
b a n d w i d t h
o f
4
k H z for
each
votce
input
Determine
the
transmiss ion
bandwid th . C o m p a r e t h e
b a n d w i d t h
w i th t h a t o f
a
s t a n d a r d 8 b i t
P C M w i t h T D M . A s s u m e b i t
dura t ion
is
0·64
7
J. S.
11
LContd. ]
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