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33/11kV S/S IN AL AIN AREAINDEX
CT / VT PARAMETER CALCULATION
Description Sheets
A. CT Parameter Calculation 3 TO 27
1 33kV Cable Feeder -Directional Oer Current ! "art# Fault Protection $%7&%7'( 3 TO 4
2 33kV Cable Feeder -Pilot )ire Protection- $*+( + TO +
3 33kV Cable Feeder -,eterin % TO 7
4 33kV u/ ar Differential Protection 0ine Feeder $*7( * TO
+ 33kV u/ ar Differential Protection Tran/former Feeder $*7( 1 TO 1
% 33kV Tran/former Feeder -,eterin 11 TO 12
7 3311kV Tran/former Differential Protection Calculation $*7T( 13 TO 1%
* 33kV Tran/former Feeder -Directional Oer Current Protection $+1-+1'( 17 TO 1*
3311kV Tran/former Feeder -e/tricted "art# Fault Protection- $%4( 1 TO 21
1 3311kV Tran/former Feeder -5tand 6 "art# Fault Protection $5"F( 22 TO 23
11 11kV CableCaacitor ank Feeder -Directional Oer Current Protection $+1-+1'( 24 TO 2+
12 11kV Tran/former Feeder -Directional Oer Current Protection $+1-+1'( 2% TO 27
. VT Parameter Calculation 2* TO 3+
1 33kV 0ine VT - ,eterin 2* TO 2
2 33kV 08'" VT- POT"CT8O' 3 TO 31
3 33kV u/ VT 32 TO 33
4 11kV u/ VT 34 TO 3+
C. 5ummar6 5#eet 3% TO 3*
D. 0i/t of cataloue eference/ 3 TO 3
LARSEN TOU!RO LIMITEDECC Di"ision # EDRC $E%ectric&%'
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C %-41A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > + P 2
5econdar6 )indin e/i/tance ct > 2 O#m/ at 4 A ta
5elected Ta > 4 A
10 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.5 kA
13 Re%&2s Propose*
a ,ake > A
b Directional Oer Current ela6 > 5PA5 34* C
c Directional "art# Fault ela6 > "9 +27
d ated ela6 /econdar6 current 8r > 1 A
1 C&%c+%&tion o4 Le&* !+r*en RLCable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .1%% O#m/
20 > .33 O#m/
VA urden of t#e 0ead > $1?1( ? .33 VA
> .33 VA
15 !+r*en o4 Re%&2
Directional Oer Current ela6 $5PA5 34* C( > 1 mo#m
Directional "art# Fault ela6 $"9 +27( > 1 mo#m
VA urden of Oer Current ela6 $5PA5 34* C( > $1?1( ? 1. 1
> .1 VA
VA urden of Oer Current ela6 $"9 +27( > $1?1( ? 1. 1
> .1 VA
23.4.24
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 4 A
n ?
n > CT rated Accurac6 0imit Factor > 2
> ated CT PoBer > 1+ VA C#o/en Value
> > 2 )att/
> urden at ated Current > .+3
n > 2 ? $1+. E 2.( $.+3 E 2.(
> 134
n > 134 7 & /o t#e current tran/former /ati/fie/ t#e re@uirement.
16 Conc%+sion
CT atio 5elected > ,77#77/1A
5elected Ta > 77 A
CT 5econdar6 e/i/tance > 0 Ohsated VA of t#e CT core 5elected for Directional> 15 VA
Accurac6 Cla// > 5 P 07
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
$P'E P
"(
$PE P
"(
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C ated current of 5O0=A f ela6
8f > Primar6 current under ma?imum /tead6
/tate t#rou# fault condition/
' > Current Tran/former atioct > CT 5econdar6 )indin e/i/tance
0 > 5inle 0ead e/i/tance from CT to ela6
Vk > +1 E 31+ 4 ? $2 E 2?.1%%(
234 V
0, Conc%+sion
CT atio 5elected > ,77#77/1A
5elected Ta > 77 A
CT 5econdar6 e/i/tance > 0 Ohs
Cla// of Accurac6 > X
=nee Point Voltae 5elected > 77 V
,aneti/in Current at Vk2 G> 37 A
ated Continuou/ T#ermal Current > 157 8
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 315 kA 4or 1 Sec
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C CT-F1 CO"-3
ated Primar6 Current 8n > %-41A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > .+ 5
5econdar6 )indin e/i/tance ct > 2 O#m/ at 4 A ta
5elected Ta > 4 A
30 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.5 kA
33 C&%c+%&tion o4 Le&* !+r*en RL
Cable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .1%% O#m/
20 > .33 O#m/VA urden of t#e 0ead > $1?1( ? .33 VA
> .33 VA
3 !+r*en Det&i%s
5.'o. Deice urden ,ake
a. a6 Control Hnit .1 A& "F +42
b. ,ultifunction ,eter .% C8CHTO& CV,=
c. Ammeter Tran/ducer 2.2 C"05A& C8
d. 0ead urden .33
Tot&% !+r*en 3.23
35 Conc%+sion
CT atio 5elected > ,77#77/1A
5elected Ta > 77 A
CT 5econdar6 e/i/tance > 0 Ohs
ated VA of t#e CT core 5elected for ,eterin > 17 VA
Accurac6 Cla// > 75 S
8n/trument 5ecurit6 Factor G> 5 &t &%% T&ps
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 12m/& or
for 12m/G>T'G> 3m/
8kma?
81'
T'
$P'E P
"(
$PE P
"(
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C CT-T1-1 CO"-2
ated Primar6 Current 8n > %-31 A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > .+ 5
5econdar6 )indin e/i/tance ct > 1.+ O#m/ at 3 A ta
5elected Ta > 3 A
,0 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.+ kA
Tran/former ,VA atin > 1+ ,VA
Tran/former kV atin > 33 11.++ kV
0oad Current on 33kV 5ide > 2%2.4 A
0oad Current on 11.++kV 5ide > 74.* A
,3 C&%c+%&tion o4 Le&* !+r*en RL
Cable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .1%% O#m/
20 > .33 O#m/
VA urden of t#e 0ead > $1?1( ? .33 VA
> .33 VA
, !+r*en Det&i%s
5.'o. Deice urden ,ake
a. a6 Control Hnit .1 A& "F +42
b. ,ultifunction ,eter .% C8CHTO& CV,=c. Ammeter Tran/ducer 2.2 C"05A& C8
d. 0ead urden .33
Tot&% !+r*en 3.23
,5 Conc%+sion
CT atio 5elected > ,77#377/1 A
5elected Ta > 377 A
CT 5econdar6 e/i/tance > 15 Ohs
ated VA of t#e CT core 5elected for ,eterin > 17 VA
Accurac6 Cla// > 75 S
8n/trument 5ecurit6 Factor G> 5 &t &%% T&ps
ated Continuou/ T#ermal Current > 157 8
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 315 kA 4or 1 Sec
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 33 11.++ kV
,VA atin of t#e Tran/former > 1+ ,VA
Per Hnit 8medance > 1 I
8medance of t#e Tran/former on 33 kV 5ide > .1?$33 ? 33( 1+
> 7.2% o#m/
8medance of t#e Tran/former on 11.++ kV 5ide > .1?$11.++ ? 11.++( 1+
> .* o#m/
T#u/ t#rou# fault current on 33kV 5ide > 33 /@rt$3( $.%E7.2%(
> 2.42 kA
T#u/ t#rou# fault current on 11.++kV 5ide > 11.++ /@rt$3( $.21E.*(
> %.% kA
-, C+rrent Tr&ns4orer Re n ?
)#ere
n > "ffectie accurac6 limit Factor
> Nominal current Related to Protected Obect !
1+ /@rt$3( 33 > 2%2 A
> Nominal current of "# ! 3
n > CT rated Accurac6 0imit Factor > 43 $Calculated eloB(
> ated CT PoBer > 1 VA $5elected Value(
> > 2 )att/
> urden at ated Current > .43
> ,a?imum Primar6 t#rou# fault current> 2.42 kA
For a cla// Current Tran/former& e@uialent alue of CT rated accurac6 cla// factor $n(
n > Hk ? 8n/ec ? 1.3
)#ere
Hk > CT =nee oint Voltae > 4 V $5elected Value(
n > CT rated Accurac6 0imit Factor > 43.3 $Calculated eloB(
n > $4 ? 1?1.3( $1 E 2(
> 43
43 ? $1 E 2( ? 3
$.43 E 2( ? 2%2
n > 24+
For t#e /6/tem under con/ideration > 8kma?8n
8kma? > 2422 2%2> .23
$P'E P
"(? 8
' of CT
$PE P
"(?8
'
8'
8' of CT
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
8kma?
P'E P
"
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C $from A/ ela6 Cataloue(
$Fiure-1 Pae 33(
n > 24+ & /o t#e current tran/former /ati/fie/ t#e re@uirement.
& 11kV Si*e
A/ er ela6 manufacturer/ Cataloue
n G> n ?
)#eren > "ffectie accurac6 limit Factor
> Nominal current Related to Protected Obect !
1+ /@rt$3( 11.++ > 7+ A
> Nominal current of "# ! *
n > CT rated Accurac6 0imit Factor > 37 $Calculated eloB(
> ated CT PoBer > 1 VA $5elected Value(
> > 4 )att/
> urden at ated Current > .43
> ,a?imum Primar6 t#rou# fault current> %.% kA
For a cla// Current Tran/former& e@uialent alue of CT rated accurac6 cla// factor $n(
n > Hk ? 8n/ec ? 1.3
)#ere
Hk > CT =nee oint Voltae > 4 V $5elected Value(
n > CT rated Accurac6 0imit Factor > 37.1 $Calculated eloB(
n > $4 ? 1?1.3( $1 E 4(
> 37
37 ? $1 E 4( ? *
$.43 E 4( ? 7+
n > 12+
For t#e /6/tem under con/ideration > 8kma?8n
> %+% 7+
> *.*
For 8kma?8n calculated aboe n > *.+ $from A/ ela6 Cataloue(
)#ere $Fiure-1 Pae 33(
8kma? > 125 *.+ & /o t#e current tran/former /ati/fie/ t#e re@uirement.
$P'E P
"(? 8
' of CT
$PE P
"(?8
'
8'
8' of CT
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
8kma?
P'E P
"
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C ,77#377/1 A
CT atio 5elected for 11kV 5ide > 1777#677/1 A
ated VA of t#e CT on 33kV 5ide > 17 VA
ated VA of t#e CT on 11kV 5ide > 17 VA
5elected Ta on 33kV 5ide > 377 A
5elected Ta on 11kV 5ide > 677 A
CT 5econdar6 e/i/tance on 33kV /ide > 0 Ohs
CT 5econdar6 e/i/tance on 11kV /ide > Ohs
Accurac6 Cla// > X
8 maneti/in > 37 A B Vk/0
=nee oint Voltae on 33kV 5ide > 77
=nee oint Voltae on 11kV 5ide > 77
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C %-31A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > + P 2
5econdar6 )indin e/i/tance ct > 1.+ O#m/ at 3 A ta
5elected Ta > 3 A
60 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.5 kA
Tran/former ,VA atin > 1+ ,VA
Tran/former kV atin > 33 11.++ kV
0oad Current on 33kV 5ide > 2%2.4 A
0oad Current on 11.++kV 5ide > 74.* A
63 Re%&2s Propose*
a ,ake > A
b Directional Oer Current and "art# fault ela6 > 5PA9 14Cc ated ela6 /econdar6 current 8r > 1 A
6 C&%c+%&tion o4 Le&* !+r*en RL
Cable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .17 O#m/
20 > .33 O#m/
VA urden of t#e 0ead > $1?1( ? .33 VA
> .33 VA
65 !+r*en Det&i%s5.'o. Deice urden ,ake
a. Directional Oer Current ela6 .1 5PA9 14C
c. 0ead urden .33
Tot&% !+r*en .43
6, Acc+r&c2 Liit )&ctor o4 the CT
A/ e@uirement n > 8kma?8n
> 31+ 3
1+
23.4.24
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C n ?
)#ere
n > CT rated Accurac6 0imit Factor > 2
> ated CT PoBer > 1 VA $5elected Value(
> > 1.+ )att/
> urden at ated Current > .43
n > 2 ? $1 E 1.+( $.43 E 1.+(
> 11
n > 11 1+ & /o t#e current tran/former /ati/fie/ t#e re@uirement.
6- Conc%+sion
CT atio 5elected > ,77#377/1A
5elected Ta > 377 A
CT 5econdar6 e/i/tance > 15 Ohsated VA of t#e CT core > 17 VA
Accurac6 Cla// > 5 P 07
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
$P'E P
"(
$PE P
"(
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 5PA9 11+C
d ated ela6 /econdar6 current 8r > 1 A
C&%c+%&tion o4 Le&* !+r*en RLCable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .17 O#m/
20 > .33 O#m/
5 Thro+;h 4&+%t c+rrent c&%c+%&tion
=V atin of t#e Tran/former > 33 11.++ kV
,VA ratin of t#e tran/former > 1+ ,VA
Tran/former Per unit imedance > 1 .u
5#ort Circuit ,VA > 1+ .1> 1+ ,VA
1+ $/@rt$3( ? 11.++(
t#e /econdar6 /ide > 74*.% A
8kma? > 7.+ kA
, :nee point "o%t&;e c&%c+%&tion
T#e =nee Point Voltae Vk > 2 H/
)#ere H/ i/ t#e Voltae /ettin of t#e ela6
T#e /ettin Voltae Us > Ik&@/n @ $ Rct ? 0 RL'
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C ,a?imum t#rou# fault current for B#ic# rela6
mu/t not oerate
n > Current Tran/former turn/ ratio
ct > 5econdar6 e/itance $ O#m/(
0 > Total re/i/tance of t#e lone/t mea/urin circuit
H/ > 74*.1 *$7 E .33(
H/ > %*.7
5et alue of H/ > 7+
2H/
> 2 ? 7+> 1+
=nee oint Voltae /elected Hk > 1+aro?.
Adoted Value of Hk > 4 V
- Sensiti"it2 Check
T#e Primar6 oeratin Current 8o > n ? $ 8r E m J 8e E 8u(
n > CT tran/formation ratio
> 677
8r > ela6 Oeratin Current > mJ8e> 5 A
8e > Current Tran/former ,a. Current at
/ettin oltae
> $3?7+( $42(
> 1105 A
m > 'umber of CT/ in t#e differential current circuit
> Nos
8u > Current t#rou# ari/tor at H/
> 17 A $%s &er Relay "atalogue for SP%' 115"(
$)igure*+, O&erating "-aracterstic of t-e oltage de&endant Resistor(
$ Voltage /e&endant Resistor #y&e 50+ 31*"(
677 $ 775 ? @7711 ? 7717'> *
6 V&%+e o4 st&(i%isin; Resistor $Rs'
,a?imum Po//ible alue of H/ > 7+ V,inimum alue of /tart Current 8r > 4+ mA $8t i/ m ? 8e a/ recommended in
t#e cataloue for 5PA9 11+C(
Value of /tabili/in e/i/tor $/( > H/8r> 1%%%.7 O#m/ T6e - $+24* *31-C(
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C .1 O#m/5ince t#e inut imedance of t#e rela6 i/ neliible in comari/on to t#e alue of /tabili/in re/i/tor&
t#e /ame i/ not /ub/tracted from t#e calculated alue of / aboe.
Conc%+sion
CT atio 5elected > 1777#677/1A
5elected Ta > 677 A
CT 5econdar6 e/i/tance > - Ohs
ated VA of t#e CT core 5elected for e/tricted> 17 VA
"art# fault rotection
,inimum =nee oint Voltae e@uirement > 77 V
Accurac6 Cla// > X
8 maneti/in > 37 A B Vk/0
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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2% of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C urden at ated Current > .43P
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27 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 2 ? $1+. E 4.( $.43 E 4.(
> *%
n > *% 3 & /o t#e current tran/former /ati/fie/ t#e re@uirement.
17, Conc%+sion
CT atio 5elected > 1777#677/1A
5elected Ta > 677 A
CT 5econdar6 e/i/tance > Ohs
ated VA of t#e CT core 5elected for ,eterin > 17 VA
Accurac6 Cla// > 5 P 07
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
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2* of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C %-31A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > + P 2
5econdar6 )indin e/i/tance ct > 1.+ O#m/ at 3 A ta
5elected Ta > 3 A
110 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.5 kA 33 kV
113 Re%&2s Propose*
a ,ake > A
b Directional Oer Current ela6 > "F +42 Plu/
c Directional "art# Fault ela6 > "F +42 Plu/
d ated ela6 /econdar6 current 8r > 1 A
11 C&%c+%&tion o4 Le&* !+r*en RLCable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 3 ,tr/
5inle 0ead e/i/tance from CT to > .3 ? +.+2
ela6 0 > .17 O#m/
20 > .33 O#m/
VA urden of t#e 0ead > $1?1( ? .33 VA
> .33 VA
115 !+r*en Det&i%s
5.'o. Deice urden ,ake
a. Directional Oer Current ela6 .1 "F +42 Plu/
c. 0ead urden .33Tot&% !+r*en .43
11, Acc+r&c2 Liit )&ctor o4 the CT
A/ e@uirement > 8kma?8n
> 31+ 3
1+
23.4.24
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2 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C n ?
)#ere
n > CT rated Accurac6 0imit Factor > 2
> ated CT PoBer > 1 VA $5elected Value(
> > 1.+ )att/
> urden at ated Current > .43
n > 2 ? $1. E 1.+( $.43 E 1.+(
> 11
n > 11 1+ & /o t#e current tran/former /ati/fie/ t#e re@uirement.
11- Conc%+sion
CT atio 5elected > ,77#377/1A
5elected Ta > 377 A
CT 5econdar6 e/i/tance > 15 Ohsated VA of t#e CT core 5elected for Directional> 17 VA
Oercurrent "art# fault rotection
Accurac6 Cla// > 5 P 07
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
$P'E P
"(
$PE P
"(
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 1-*1A
ated 5econdar6 Current 8/n > 1 A
CT Cla// > + P 2
5econdar6 )indin e/i/tance ct > 4 O#m/ at * A ta
5elected Ta > * A
100 Ass+ptions :
T#e ,a?.3P#.5.C Current of 33kV u/ > 31.5 kA 33 kV
Tran/former ,VA atin > 1+ ,VA
Tran/former kV atin > 33 11.++ kV
0oad Current on 33kV 5ide > 2%2.4 A
0oad Current on 11.++kV 5ide > 74.* A
103 Re%&2s Propose*
a ,ake > A
b Directional Oer Current and "art# fault ela6 > 5PA9 14Cc ated ela6 /econdar6 current 8r > 1 A
10 C&%c+%&tion o4 Le&* !+r*en RL
Cable con/idered for CT connection > 4 /@.mm Cu
AC e/i/tance of t#e cable 7de C > +.+2 O#m/km
0ent# betBeen CT and t#e ela6 > 1 ,tr/
5inle 0ead e/i/tance from CT to > .1 ? +.+2
ela6 0 > .% O#m/
20 > .11 O#m/
VA urden of t#e 0ead > $1?1( ? .11 VA
> .11 VA
105 !+r*en Det&i%s5.'o. Deice urden ,ake
a. Directional Oer Current ela6 .1 5PA9 14C
c. 0ead urden .11
Tot&% !+r*en .21
10, Acc+r&c2 Liit )&ctor o4 the CT
A/ e@uirement > 8kma?8n
> 31+ *
3
23.4.24
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31 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C n ?
)#ere
n > CT rated Accurac6 0imit Factor > 2
> ated CT PoBer > 1 VA $5elected Value(
> > 4 )att/
> urden at ated Current > .21
n > 2 ? $1 E 4.( $.21 E 4.(
> %7
n > %7 3 & /o t#e current tran/former /ati/fie/ t#e re@uirement.
10- Conc%+sion
CT atio 5elected > 1777#677/1A
5elected Ta > 677 A
CT 5econdar6 e/i/tance > Ohsated VA of t#e CT core 5elected for Directional> 17 VA
Oercurrent "art# fault rotection
Accurac6 Cla// > 5 P 07
ated Continuou/ T#ermal Current > 157 8
ated 5#ort Time T#ermal Current > 315 kA 4or 1 Sec
$P'E P
"(
$PE P
"(
P'
P"
CT 8nternal 0o//e/ 8n2? ct
P
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C PT-F1& CO"-1
Voltae atin > 33/3 / 110/3
VA atin > 100 VA
Core-1 > Cl :1
10 VT !+r*en C&%c+%&tion
!+r*en on Core#1
Voltae atin of t#e VT > 11 V
VA atin of t#e VT > 1 VA
Current 5ulied b6 VT at ma?imum VA atin > $1 ? /@rt$3( ( $11(
1.+7+ A
$a( 0ead urden on Core-1
Cable
From To
1 VT 56nc#roni/in Circuit 4C ? 2.+ *.*7 2 ? 3 1.32
Cu. Conductor %
$b( Ot#er urden/ on Core-1
5.'o. Deice urden $VA( ,ake T6e
1 T&rri4 Meterin;
'ot Alicable
0 !&ck+p Meterin;
Voltmeter + - -
3 Protection Re%&2s'ot Alicable
S2nchronis&tion
a. C#eck 56nc#roni/ation ela6 .2+ A 5PAH14 C
b. 56nc#ro/coe % A
c. Double Fre@uenc6 ,eter 1.2 A
d. Double Volt ,eter + A
e. 'o Voltae ela6 1.2 A
5 Le&* !+r*en
a. 0ead urden under 5.'o-1 aboe 1.32
Tot&% !+r*en 1-
8VT
5.'o
Cable 5iKein [email protected](
Cablee/i/tance
$( in$O#m/km(
2 )a6Cable0ent#
$0( in $m(
Total 0ead0o// $VA(>$8
VT2??01(
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33 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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34 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C PT-F1& CO"-2
Voltae atin > 33/3 / 110/3
VA atin > 50 VA
Core-2 > Cl :3P
00 VT !+r*en C&%c+%&tion
!+r*en on Core#0
Voltae atin of T#e VT > 11 V
VA atin of t#e VT > + VA
Current 5ulied b6 VT at ma?imum VA atin > $+ ? /@rt$3( ( $11(
.7*7 A
$a( 0ead urden on Core-1
Cable
From To
1 VT 5PA5 34*C ela6 4C ? 2.+ *.*7 2 ? 3 .33
Cu. Conductor %
$b( Ot#er urden/ on Core-2
5.'o. Deice urden $VA( ,ake T6e
1 T&rri4 Meterin;
'ot Alicable
0 !&ck+p Meterin;
'ot Alicable
3 Protection Re%&2s/irectional O2" and art- )ault Relay .+ A 5PA5 34* C
S2nchronis&tion
'ot Alicable
5 Le&* !+r*en
a. 0ead urden under 5.'o-1 aboe .33
Tot&% !+r*en 763
8VT
5.'o
Cable 5iKein [email protected](
Cablee/i/tance
$( in$O#m/km(
2 )a6Cable0ent#
$0( in $m(
Total 0ead0o// $VA(>$8
VT2??01(
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3+ of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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3% of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C PT-H5-1& CO"-1
Voltae atin > 33/3 / 110/3
VA atin > 100 VA
Core-1 > Cl :1
30 VT !+r*en C&%c+%&tion
!+r*en on Core#1
Voltae atin of T#e VT > 11 V
VA atin of t#e VT > 1 VA
Current 5ulied b6 VT at ma?imum VA atin > $1 ? /@rt$3( ( $11(
1.+7+ A
$a( 0ead urden on Core-1
Cable
From To
1 VT 56nc#roni/in Circuit 4C ? 2.+ *.*7 2 ? 3 1.32
Cu. Conductor %
$b( Ot#er urden/ on Core-1
5.'o. Deice urden $VA( ,ake T6e
1 T&rri4 Meterin;
'ot Alicable
0 !&ck+p Meterin;
'ot Alicable
3 Protection Re%&2s'ot Alicable
S2nchronis&tion
a. C#eck 56nc#roni/ation ela6 .2+ A 5PAH14 C
b. 56nc#ro/coe % A
c. Double Fre@uenc6 ,eter 1.2 A
d. Double Volt ,eter + A
e. 'o Voltae ela6 1.2 A
5 Le&* !+r*en
a. 0ead urden under 5.'o-1 aboe 1.32
Tot&% !+r*en 1-
8VT
5.'o
Cable 5iKein [email protected](
Cablee/i/tance
$( in$O#m/km(
2 )a6Cable0ent#
$0( in $m(
Total 0ead0o// $VA(>$8
VT2??01(
7/24/2019 CT VT Calculation Al AIN Rev.3(Latest)
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37 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
7/24/2019 CT VT Calculation Al AIN Rev.3(Latest)
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3* of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C 11/3 / 110/3
VA atin > 100 VA
Core-1 > Cl :1
0 VT !+r*en C&%c+%&tion
!+r*en on Core#1
Voltae atin of T#e VT > 11 V
VA atin of t#e VT > 1 VA
Current 5ulied b6 VT at ma?imum VA atin > $1 ? /@rt$3( ( $11(
1.+7+ A
$a( 0ead urden on Core-1
Cable
From To
1 VT 56nc#roni/in Circuit 4C ? 2.+ *.*7 2 ? 3 1.32
Cu. Conductor %
$b( Ot#er urden/ on Core-1
5.'o. Deice urden $VA( ,ake T6e
1 T&rri4 Meterin;
'ot Alicable
0 !&ck+p Meterin;
'ot Alicable
3 Protection Re%&2s
Voltmeter + - - S2nchronis&tion
a. C#eck 56nc#roni/ation ela6 .2+ A 5PAH14 C
b. 56nc#ro/coe % A
c. Double Fre@uenc6 ,eter 1.2 A
d. Double Volt ,eter + A
e. 'o Voltae ela6 1.2 A
5 Le&* !+r*en
a. 0ead urden under 5.'o-1 aboe 1.32
Tot&% !+r*en 1-
8VT
5.'o
Cable 5iKein [email protected](
Cablee/i/tance
$( in$O#m/km(
2 )a6Cable0ent#
$0( in $m(
Total 0ead0o// $VA(>$8
VT2??01(
7/24/2019 CT VT Calculation Al AIN Rev.3(Latest)
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3 of 43
LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
PO9"CT : 3311kV 55 8' A0 A8' A"A ef : ;14--074493+3 A
P"P C
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
Re"ision A D&te 03
SNo Description CT No C%&ss !+r*en Ukp Rct Re%&2
$A/A' $VA' $V' $Oh'
1. CT-F1& CO"-1 %-41A + P 2 1+ - 2 5PA
2. CT-F1 CO"-2 %-41A - 4 2 5o
3. 33kV Cable Feeder -,eterin CT-F1 CO"-3 %-41A .+ 5 1 - 2
4. CT-F1 CO"-4 12 1A + P 2 1 - % A&
+. CT-T1-1 CO"-1 121 A + P 2 1 - % A&
%. CT-T1-1 CO"-2 %-31 A .+ 5 1 - 1.+
7.
%-31 A
1 4 2
A&
1-*1 A 1 4 4
*. CT-T1-1&CO"-4 %-31A + P 2 1 - 1.+ 5PA
. CT-T1-' CO"-1 1-*1A 1 4 7 5PA
1. CT-T1-' CO"-2 1-*1A + P 2 1 - 4 A&
11. 121A + P 2 1 - % A&
R&tio
33kV Cable Feeder -DirectionalOer Current ! "art# Fault
Protection $%7&%7'(
33kV Cable Feeder -Pilot )ireProtection- $*+(
33kV u/ ar DifferentialProtection 0ine Feeder $*7(
33kV u/ ar DifferentialProtection Tran/former Feeder
$*7(
33kV Tran/former Feeder-,eterin
3311kV Tran/former DifferentialProtection Calculation $*7T(
CT-T1-1 CO"-3 CT-T1-2 CO"-1
33kV Tran/former Feeder-Directional Oer CurrentProtection $+1-+1'(
3311kV Tran/former Feeder-e/tricted "art# Fault Protection-
$%4(
3311kV Tran/former Feeder-5tand 6 "art# Fault Protection
$5"F(
33kV u/ ar DifferentialProtection - u/ 5ection Feeder
$*7(
CT-C1-1 CO"-3 CT-C1-2 CO"-1
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
Re"ision A D&te 03
SNo Description CT No C%&ss !+r*en Ukp Rct Re%&2
$A/A' $VA' $V' $Oh'
R&tio
12. CT-C1-1 CO"-2 121A .+ 5 1 - 4.+
13. CT-C1-1 CO"-1 121A + P 2 1 - % 5PA
14. CT-T1-2& CO"-4 1-*1A + P 2 1 - 4 5PA
1+. CT-T1-2& CO"-3 1-*1A .+ 5 1 - 4
1%. CT-2& 4 CO"-1 %-31A + P 2 1 - 1.+ "F +
17. CT-2& 4 CO"-2 %-31A .+ 5 1 - 1.+
1*. CT-3 CO"-1 31A + P 2 % - "F +
1. CT-3 CO"-2 31A .+ 5 7.+ -
2. CT-1 CO"-1 1%1A + P 2 1 - * "F +
33kV u/ 5ection Feeder -,eterin
33kV u/ 5ection Feeder -Directional Oercurrent Protection
$+1-+1'(
11kV Tran/former Feeder-Directional Oer Current
Protection $+1-+1'(
11kV Tran/former Feeder-,eterin
11kV CableCaacitor ankFeeder -Directional Oer Current
Protection $+1-+1'(
11kV CableCaacitor ankFeeder - ,eterin
11kV Au?. Tran/former Feeder-Oer Current Protection
11kV Au?. Tran/former Feeder-,eterin
11kV u/ 5ection Feeder- OerCurrent Protection
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LARSEN & TOUBRO LIMITED
ECC Division - EDRC (Electrical)
Re"ision A D&te 037
SNo Description CT No C%&ss !+r*en Ukp Rct Re%&2
$A/A' $VA' $V' $Oh'
R&tio
21. CT-1 CO"-2 1%1A .+ 5 1 - *
SNo VT D&t& VT No R&tio !+r*en Se%ecte* C%&ss
$V/V' $VA' $VA'
1. 33kV 0ine VT - ,eterin PT-F1& CO"-1 33/3 / 110/3 1.7 1 Cl :1
2. 33kV 08'" VT- POT"CT8O' PT-F1& CO"-2 33/3 / 110/3 .*3 + Cl :3P
3. 33kV u/ VT PT-H5-1& CO"-1 33/3 / 110/3 14.7 1 Cl :1
4. 11kV u/ VT Core-1 11/3 / 110/3 1.7 1 Cl :1
Technic&% D&t& 33kV Si*e Technic&% D&t& 11kV Si*e
1. ated Voltae 3% kV ated Voltae 12 kV
2. 5erice Voltae 33 kV 5erice Voltae 11 kV
3. Fre@uenc6 +
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RE)ERENCES
CT / VT PARAMETER CALCULATION
SNo Description
a.
b. 5PA5 34*C ela6 Cataloue for ela6 urden 8nformation
c. "9 +27 ela6 Cataloue for ela6 urden 8nformation
d. 5olkar f ela6 Cataloue for Current Tran/former e@uirement
e. Circuitor CV=m ,ultifunction ,eter Cataloue
f. C"05A C8 Ammeter Tran/ducer
e. " + ela6 Cataloue for urden 8nformation
. A/ e@uirement on Current Tran/former/ for " +
#. "T 31%J4 ela6 Cataloue for urden 8nformation
8. A/ e@uirement on Current Tran/former/ for "T 31% "T 31%J4
L. 5PA9 14 C ela6 Cataloue for urden 8nformation
k. 5PA9 11+ C ela6 Cataloue
l. A/ e@uirement on Current Tran/former/ for 5PA9 11+C
m. "9 +21 ela6 Cataloue for urden 8nformation
n. "F +42 Plu/ ela6 Cataloue for urden 8nformation
LARSEN TOU!RO LIMITEDECC Di"ision # EDRC $E%ectric&%'
A/ Alication uide to Oercurrent ,odule/ and function/ of 5PACO, and"M 5erie/