33kv-11kv ct-vt size 16.10.06 (r2) - man
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR.SS
Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR , o 33
Se!%on - + : Sn'e Lne Da'ram
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR " o 33
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR 0 o 33
Se!%on - , : ""#$ Lne
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR 5 o 33
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR o 33
+. Me%ers !onne!%e6
,A
a. Make && &&7. Mdel && &&$. -A #%rden .+ &&d. 8!9. )s.; 1 &&e )e! -A .+ &&
,. CT De%as
CT Ra!i C6R4&1
" A Primar9
1 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 33S5< 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 2+ 3 se$.
". Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M!r CT ! Me!ers m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 6hm &&&&2;
The e!ernal #%rden =
= .+ F .++;= 1.+ -A &&&&3;
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1.+;
= , $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
0. Con!uson :
+
, Summar9 o CT 4arame%ers
CT Ra!i : 0+ A
Class : +Ra!ed #%rden : +5
S5H +
,.+ CTs or - Me%ern'(""#$ s%!8'ear n!omer)
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI R m
RL
Rm F R
L
P#C
P#)
The Cnne$!ed CT 7%rden is 2 hile !he Ra!ed CT 7%rden is 1+ As Ra!ed CT 7%rden JCnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR 7 o 33
+. A44!a%on
Pr!e$!in : ,ir.6/C * 4/5 Pr!e$!in '(/'() * +1/+1);
,. Rea9 Pro4ose6
a. Make Siemens7. Mdel (S'2$. T9pe )%meri$alI ,MTL T9pe
". CT De%as
-l!age Class : 33 k-5re>%en$9 : + @
Shr! !ime ra!ing : 2+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 33k- s.gear
CT Ra!i : Cre&2" A Primar9
1 A Se$ndar9
CT Class: +P AL5: 2
1+ -A
R$! = " 6hm (Assumed)
s$$.ma = 2+ kA
0. Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 Siemens; = .+ &&&&1;Ref. Siemens SP.2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m &&&&2;
CTs in!ernal Resis!an$e "/1 Tap a! (+?C; R$! = " 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D"E0 $A &&&&3;
Cnne$!ed CT 4!ernal #%rden == .+F.++;= .3 $A &&&&";
,., CTs or a!#u4 Pro%e!%on - 77N & 5+5+N (""#$ S%!8'ear In!omer)
pn
sn
Ra!ed#%rden:
Rr -A a! S)
RL
Pi
Rr F RL;
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR 3 o 33
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .';
= .7" $A
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ffi$ien!
5 Ca!ua%on o mnmum re;ure6 <A!!ura!9 Lm% =a!%or< or %8e CT:(refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= maim%m shr!&$ir$%i! $%rren! in Ampere;
= 2+ Amppn = )minal CT primar9 $%rren! in Ampere;= " Amp
= maDhigh&se! pin! / pn;I 2E= maD2+ / ";I 2E= ,.5
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> " &&&&';
' Ca!ua%on o o4era%n' <A!!ura!9 Lm% =a!%or< or %8e CT:
here &= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 2
= Ra!ed resis!ive 7%rden f CT in 6hm;= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;
= .(3= CT se$. dg. resis!an$e in 6hm;
= "
= 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as flls &
=
= 2 D1+F"; / .(3F";E= 2 D10 / ".(3E= .332(
Th%s !he effe$!ive CT AL5
> 3."0 &&&&+;
P#C
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$ Kss$ DR#) F R$!; / R#C F R$!;E
?<ss!
K ' ssc= K
ssc×
( RBC
+ Rct
RBN + R
ct )
K ' ssc1≥max[( I high−set po int
I pn ) , 20]
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR 2 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : "/1 AClass : 5P,
R$! ma.; : " 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is .3" hile !he Re>%ired CT AL5 is '3 i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR + o 33
,." CTs =OR DISTANC/ PROT/CTION - ,+
(""#$ OHL =//D/RS)
+. S9s%em Da%a
1 S9s!em -l!age * 5re>%en$9: 33k-I 3PhI +@I 3 ire RN#; s9s!em
,. CT Da%a: 6a%a as 4er S!8ne6er
a7 CT magne!iing $%rren! = +mA O -k/2
CT primar9 $%rren! " CT Se$. C%rren!=1
CT Class: +P
AL5: KnAL5 2 (Assumed)
Ra!ed #%rden: 1 -A
CT in!. res.: R$! H +." 6hm
". =au% e1e
Sr$e fa%l! $%rren! f= 2+ kA fr 3 Se$.
0. =ee6er Da%a:
a Ca7le !ermina!ed n ! an eis!ing 33k- 6@L
33k- Ca7le par!i$%lars: 1r%n3C3 s>. mmI C%I LP4Q
> .52@.++j 6hm/km
7 33k- 6@L par!i$%lars: PA)T@4R ACSR $nd%$!rQ> .+75@.","j 6hm/km
5. Rea9 Da%a:
(Ref: SIEE!S SIP-200" Chapter-2, page 53)
In!omer-+
T!al Ca7le leng!h = ." kmT!al 6@L = 20.1 km
Ref: C#$su%ta$t %etter EPE-&'-*200"-0"*0+ dt. .0.0"
In!omer-,
T!al Ca7le leng!h = 3.(00 kmT!al 6@L = 21.(3 km
CT Ra!i = "/1 AQ Class I CT in!ernal 7%rden/resis!an$e : R$! = +." 6hm
P#)
mpedan$e $a7
mpedan$e line
S4M4)S make 7SA5,, ,is!an$e Pr!e$!in Rela9
II. Ca!ua%on o one+ =au% Le1e or ""#$ In!omer OHLB Cabe %o MADINAT AL NAHDAH Ss
The eis!ing 33k- n$mer&1 feeder frm 4@AT S/S $nsis! f 6@L feeder and !he prpsed 33k-n$mer&2 feeder frm 4@AT s/s $nsis!s f 33k- Ca7le flled 79 a 33k- 6@L. The apprima!eleng!hs are as flls:
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ++ o 33
(a) Source Impedance Calculations
5r S%r$e mpedan$e fr 2+kA a! L@AT S/s 33k- #%s7ars33k- S9s!em /R ra!i: = , .. Ass%med;
33k- S9s!em L/R ra!i: /R;s/2.p.f; = 2/2p+;= ".7"232+750 mse!
= +0,3.20+2+,0 M$A
.223+35 4u
n 33k- * 1M-A #ase
= .7,+,"55"
= .7,+,"55" 37.+0 O8ms
= .('21 $s(.13; F U..('21 sin(.13;= ."[email protected]+,j O8ms
(b) Line & Cable Impedance Calculations
The 6@L/VW Ca7le impedan$e in 6hm is $al$%la!ed as flls &
.+0F.11U; ."
= ,."/-,@0.0/-,j
= .022 +.72
.1(+F.323U; 20.1
= 5.2,5@2."22"j
= +.2, +.55
.+0F.11U; 3.(00
= .,,[email protected]+732j
= .070, +.72
.1(+F.323U; 21.(3
= 7.70+0 +.55
Xne1 pr!e$!in rea$h envisaged YX1P = G D$a72 F line2 Fline1F$a72E
= ..22"1"1F."1(0U F 3.'(((+F'.'+(0U F +.02+F0.3003U F 2.3'4&2F"."4&2U;= . 0.21'F1'.''(('0U;= 7.,,,0+,3@+".""0,+5,j O8m
33k- S%r$e mpedan$e s;:SCM-A = s>r!3; 33 2+ =
s in p%; = 1/ SCM-A = D1/1"2.0"2E =
s in 6hm; = s in p%; 332/1 = '.002 1&"; 332/1
S%r$e impedan$e s = .('21 ar$!anD/R;sE
S%r$e impedan$e s
s = s $s> F U.s sin>
$a71 =
line1 =
$a72 =
line2 =
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Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
(c) Zone1-end Fault Condition
5r a 3phase fa%l! a! !he end f !he Xne1 rea$h YXfa%l! s
.31F.('12U
1 Amp and 2 f Th%s CT1 and CT2; ill see negligi7l9 l $%rren!. This $ase is !herefre n! $nsidered fr CT siing.
(d) Close-in Fault Condition
(PROPOSED)
(EXISTING)33kV SWITCHGEAR
33/11kV AL NAHDAH PRIMARY SUBSTATION
Zs
JEHAT S/S33kV SOURCE
!kA
"AULTZONE1#END
CABLE
Z$%&'
I/C OHL
*+,Z$%&'1
I/C OHL
NC
CT#
CT#1
TO 1
-/1A.CLPS
-/1A.CLPS
TO 1
CLOSE#IN"AULT
I1
I0I1I
-/1A.CLPS
-/1A.CLPS
CT#1
CT#
I/C OHL*+,Z$%&'1
I/C OHL Z$%&' Z24
CABLE
!kA
33kV SOURCEJEHAT S/S
Zs
33/11kV AL NAHDAH SUBSTATION BUS
(EXISTING)
(PROPOSED)
I1 I
NC
I/C OHL
Z$%&'1
I/C OHL
Z$%&' Z24
CABLE
CLOSE#IN"AULT
!kA
33kV SOURCEJEHAT S/S
Zs
33/11kV AL NAHDAH PRIMARY SUBSTATION
33kV SWITCHGEAR (EXISTING)
(PROPOSED)
TO 1
-/1A.CLPS
-/1A.CLPS
TO 1
CT#1
CT#
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Do!. No.:++,MA
Da%e
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR +0 o 33
5r a 3 phase $lse&in $lse ! CT1; fa%l! YXfa%l! Xf1; =Xs F Xline2F X$a72;
.31F.('12U; F .22"1"1F."1(0U F 3.'(((+F'.'+(0U;
3.0+1'F(.0+''0U3.22, ".3
Xfa%l! Xf2; =Xs F Xline1FX$a71;;
.31F.('12U; F +.02+F0.3003U; F 2.3'4&2F"."4&2U;+.1+"2F1.2"+U++.0"," ".,
T!al fa%l! $%rren! f; frm !he s%r$e Yf = -s9s / Z3 Xf1;1 33[1 / Z3 .0012'''032;
,+"2 ".3
f = -s9s / Z3 Xf2;2 33[1 / Z3 11."323+12113(;
+7 ".,
make 33k- Sgr. ,a!a;& Cn!rl $a7le da!a: "C" s>. mmI C%I 1.1k- grade P-CQ
Ma. Leng!h = 22+m = + m g * re!%rn leng!hs;
Ca7le resis!an$e as per 6man Ca7le Ca!alg%e = +.(0 6hm/km
.,325 O8m#m
& S4M4)S (SA+22 rela9 da!aI refer a!!a$hed shee!s;
Refer a!!a$hed shee!s fr S4M4)S re$mmenda!ins fr sele$!in f Knee Pin! -l!age fr dis!an$e rela9.
Th%s !he ma fa%l! $%rren! !hr% CT1 is 2130 A apprima!el9. The CT design knee pin! vl!age shall 7e s%$h !ha!!he CT des n! sa!%ra!e fr !his fa%l! $%rren!
III. CT #nee 4on% !a!ua%ons base6 on Rea9 Manua!%urerEs (SI/M/NS) Re!ommen6a%on
CT in!ernal
Lead resis!an$e:RL = +/1; +.(0 =
Rela9 7%rden: R# = .+
(PROPOSED)
(EXISTING)
33/11kV AL NAHDAH SUBSTATION BUS
Zs
JEHAT S/S33kV SOURCE
!kA
CABLEZ24Z$%&'
I/C OHL
Z$%&'1I/C OHL
CT#
CT#1
-/1A.CLPS
-/1A.CLPS
I0I1I
I1
"AULTCLOSE#IN
I
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR +5 o 33
hereQ
= )minal CT A$$%ra$9 Limi!ing 5a$!r = ,
= A$!%al r pera!ing CT A$$%ra$9 Limi!ing 5a$!r = )minal #%rden f CT= + ass%med $nserva!ivel9 n ler side;== .""25 = .330+ 6hm r .330+-A n 1A CT se$
.330+6hm r .330+ -A n 1A CT Se$ndar9= n!ernal CT #%rden = 5.0 6hm
= 5.0 O8m or 5.0$A on +A CT se!on6ar9
) 7ased n !he a7ve frm%la !he pera!ing r effe$!ive CT a$$%ra$9 limi!ing fa$!r is $al$%la!ed as flls &
=
= D1F+."; / .330+F+.";E 2= +".
Th%s 6pera!ing AL5 > 50.
Th%s A$!%al CT AL5 KAL5; is +"A;
hereQ
= 5a%l! $%rren! fr $lse&in fa%l!s
= ,+"2
= 5a%l! $%rren! a! !he end f Xne1 rea$h
".70 mse$.
a = " * 7 = + val%es fr Ts \ 2 mse$;
" 2130/"; = ,+."2
=
KnAL5
KAL5
P#)
P#C Cnne$!ed #%rden n CT = R# F RL;
Pi
5rm !he a7ve A$!%al AL5 KAL5; $an 7e $al$%la!ed as flls Y
KAL5 DP#) F Pi; / P#C F Pi;E KnAL5
?oAL=
5r S4M4)S (SA+22 dis!an$e pr!e$!in rela9 $mum reured C' A//ura/ &mt$g 1a/t#r is $al$%la!ed asfllsY
) = )minal Primar9 CT $%rren! i.e.Q e>%al ! "A;SCC.ma.$ls
refer $al$%la!ins a7ve;
SCC.ma.Xn
= Arefer $al$%la!ins a7ve;
The s9s!em !ime $ns!an! is Ts =
Th%s KAL5 $an 7e $al$%la!ed fr $lse&in fa%l! $ndi!in; as flls &
Cnsidering an ver dimensining marginI K65 = +GI !he re>%ired KAL5 isKAL5 K65 KAL5min;
K nALF
≥ ( PBC + Pi
PBN + P
i )× K
oALF
K oALF = a × ( I SCC .max .(close−in fault )
I N )
and
K oALF = b×( I SCC .max .(Zone1−end fault )
I N )
K oALF (min)= a ×( I
SCC .max.(close−in fault )
I N )
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR + o 33
= 1.+ 21.30= ,,.0 .#
-k=1.3 pn
-k= + 2130 +." F .330+; 1 ; / 1.3 ";
= ++2
Minim%m re>%ired knee Pin! -l!ageI -kph = 110 -l!
5r 33k- Ca7le/6@L feeder CT $re fr dis!an$e pr!e$!in; shall have !he flling parame!ers Y
Appli$a!in: 33k-I 3PhaseI +@I 3 ireI 2+kA/3se$. s9s!emQ,is!an$e pr!e$!in.
5.0 O8mF
++2 $o%
5rm a7ve i! is ver9 $lear !ha! !he A$!%al CT AL5 =+" refer A; is grea!er !han !he Minim%m re>%ired CT AL5=22."+0+ refer #;I !h%s !he sele$!ed CT is a$$ep!a7le
As per S4M4)S $nversin frm 4C'"" defini!in ! #S303 defini!in; !he re>%ired knee pin! vl!age -k fr!he $nne$!ed 7%rden $an 7e apprima!el9 $al$%la!ed as flls Y
KAL5 7; s$$ maXne1&end fa%l!; R$! F R7; sn
I$. Con!usons Re!ommen6a%ons.
CT ra!i = "/1AQ CT Class = Class Q
n!ernal CT #%rden in 6hm; =Magne!iing $%rren!: mag = + mA O -k/2
Knee Pin! -l!age: $# >
The CTs fr dis!an$e pr!e$!in appli$a!in; ffered 79 33k- Si!$hgear man%fa$!%rer M/s S$hneider have a knee
pin! vl!age = 3 -l!/Ph m%$h grea!er !han !ha! re>%ired110 -l! and !h%s !he same is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR +7 o 33
Se!%on - " : ""#$ Transormer In!omer
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR +3 o 33
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR +2 o 33
+. Rea9 Pro4ose6
a. A)S ). (T7. Make S4M4)S
$. Mdel (VT'121d. T9pe )%meri$alI ,ifferen!ial L mepdan$e !9pe;
,. CT Ra%o
11k- Line Side CTs-l!age Class : 33 k-
5re>%en$9 : + @Shr! !ime ra!ing : 2+ kA fr 3 se$.
M%n!ing: CT m%n!ed in 33k- Si!$hgear CT Ra!i : Cre&3
" A Primar9
1 A Se$ndar9
CT Class: G
CT in!. res.: R$! +." 6hmkP- : -k 3 -l!
4$. C%rren!: mag + mA *2
". S9s%em Inorma%on
S9s!em -l!age -s9s = 33 k-Transfrmer ra!ing = 2 M-ATransfrmer mpedan$e a! Prin$ipal Tap GXp!; = 12.+ GTransfrmer mpedan$e a! nega!ive !leran$e = 1.'2+ G i!h &ve 1+G !leran$e;Transfrmer f%ll lad $%rren! =LC = Traf. Ra!ing / Ds>r!3; -s9sE
= 2M-A / D1.(32 33k-E= "02.2+ A
Cal$%la!in f Maim%m !hr%gh fa%l! $%rren! !f;I ass%ming infini!e per s%r$e
!f = -s9s / Ds>r!3; Xl!E-s9s = 33 k-hereXl! = mpedan$e f !he !ransfrmer a! nega!ive !leran$eXl! = GXl!/1; Dk-7ase;B2 / M-A7ase;E
hereI M-A7ase; = 2 M-Ak-7ase; = 33 k-
@en$e Xl! = 1.'2+/1; D33B2;/2E= .1'2+ 10/2;= .1'2+ +"."+
Th%sI Xl! = +.( 6hm
@en$e !f&ma = -s9s / Ds>r!3; Xl!E= 33 / D1.(32 +.(E= 33/1.11= 320'.20"' Amp
hi$h is = .2"1 CT ra!ed primar9 $%rren!Th%s !f&ma = 320'.20"' Amp
0. Ca!ua%on o ur6en !onne!%e6 %o %8e CT Core
0.+
-A #%rden f !he Rela9 '"R45 Pr = .1 -A a! n=1A &&&&1;Rr = .+ O8m
".+ CTs or ,M$A Transormer Deren%a Pro%e!%on - 37T(""#$ S%!8'ear Ou%'on')
P)
sn
Conne!%e6 Rea9s ur6en (Rr )
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR , o 33
0.,
Referring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C = 2." 6hms/km
Single Lead Leng!h f !he $a7le frm #CT ! CRP = 5 M!r
@en$e 2 a9 lead #%rden = 2 mpd. f !he $a7le +; / 1= 2 0.3 +; / 1
= 03;/1RL = .2" 6hm &&&&2;
@en$e 4!ernal Cnne$!ed #%rden =
(th 206 marg$) = 1.11' 6hm
= +.++ $A &&&&3;
0."
CTs in!. res. "/1 Tap a! (+?C R$! = 5.0 6hms &&&&";
5. Ca!ua%on o 1arous CT 4arame%ers
5.+ Ca!ua%on o CT #nee 4on% 1o%a'e $#(mn) re;uremen%Traf. maim%m !hr% fa%l! $%rren! n CT primar9
fspri; = 320'.3 Amp 6n CT Primar9 side
@en$e fsse$; = fspri; / "/1; 6n CT Se$ndar9 side= 320'.3/D"/1;E= .2"1 Amp
Mn. rea9 se%%n' 1o%a'e ($s%ab) = fsse$; R$! F R7;= .2"1 +."F1.11';= .2"1 '.+1';
-s!a7min; = +3.'03' -l!Sa9 Sele$!ed Se!!ing vl!age : -s = 5 $o% (th 206 se/urt marg$)
Mnmum ?nee 4on% 1o%a'e $#(mn) = 2 -s -l!= 2 '+
$#(mn) > +" $o% &&&&+;
5., Ca!ua%on o Ma'ne%sn' Curren% re;uremen%The rela9 se!!ing $%rren! $rrespnding ! !he rela9 se!!ing vl!ageI as per S4M4)S $a!alg%e &Rela9 se!!ing $%rren! in$l%ding varis!r; r = .2 ARela9 se!!ing vl!age sele$!ed -r = -s = '+ -). f spill parallel; pa!hs n = " ns.Sele$!ed CTs Magne!iing Chara$!eris!i$s : 33k- Line Side CTs;Magne!iing $%rren! O -k/2 mag = .+ A O -k/2 in -l!; = 1+Magne!iing $%rren! O -s = '+- mag1 = .,+7 A sin$e #@ $%rve is linear %p! -k;
The mag1 fr 7!h side CTs is same. The rela9 pera!ing $hara$!eris!i$s shall 7e $he$ked fr !hese CTs.#ased n !he a7veI !he rela9 pera!ing $%rren! $an n 7e $al$%la!ed as flls &
p = r F n mag1;= .2 F 3.21(= .35 A
6n CT primar9I p prim; = p pn/sn;"0. A
hi$h is = p prim; / 5LC; 1= 3" / 3"0.01; 1= 2.7, G r + o =LC rou'89.
5." Ca!ua%on o /%erna Seres S%absn' Ress%an!eRela9 mpedan$e
The rela9 impedan$e $an 7e $al$%la!ed as flls &rela9 se!!ing $%rren! r = .2 A (ths s a f7ed 8a%ue)
rela9 se!!ing vl!age -r = '+ -l!rela9 7%rden Pr = .1!h%s rela9 impedan$e Rr = Pr / rB2
Lea6 ur6en (RL)
RL
R7
CT ur6en (R!%)
-A (f#r Is$ 9 A)
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR.SS
Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,+ o 33
= 2+ 6hm
Rr > ,5 O8m
4!ernal S!a7ilising Resis!an$eThe re>%ired e!ernal series resis!an$e val%e $an 7e $al$%la!ed as flls &
Rs! = -r / r; & Rr = '+ / .2; & 2+
= 3. 6hm
Rs% > ". O8m &&&&';
T!al rela9 $ir$%i! 7ran$h impedan$e = Rs! F Rr = ",5. O8m
. Con!usons & Summar9
1. Cn$l%sin5rm +; a7veI minim%m re>%ired CT knee pin! vl!age = 13 -l!
2. S%mmar9 f CT parame!ers
6n Traf. Line SideCT Ra!i : 0 + A
Class : G
R$! ma.; : 5.0 O8m
-k min.; : " $o%
mag O -k/2; : 5 mA
3. S!a7ilising Resis!r Re>%iremen! " O8m
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,, o 33
+. Me%ers !onne!%e6
,A
a. Make && &&7. Mdel && &&$. -A #%rden .+ &&d. 8!9. )s.; 1 &&e )e! -A .+ &&
,. CT De%as
CT Ra!i Cre&1
" A Primar9
1 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 33S5< 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 2+ 3 se$.
". Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M!r CT ! Me!ers m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 6hm &&&&2;
The e!ernal #%rden =
= .+ F .++;= 1.+ -A &&&&3;
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1.+;
= , $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
0. Con!uson :
+
, Summar9 o CT 4arame%ers
CT Ra!i : 0+ A
Class : +Ra!ed #%rden : +5
S5H +
"., CTs or - ,M$A Transormer Me%ern'(""#$ s%!8'ear Ou%'on')
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI R m
RL
Rm F R
L
P#C
P#)
The Cnne$!ed CT 7%rden is 2 hile !he Ra!ed CT 7%rden is 1+ As Ra!ed CT 7%rden JCnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR.SS
Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ," o 33
+. A44!a%on
Pr!e$!in : 6/C * 4/5 Pr!e$!in +/+) * +1/+1);
,. Rea9 Pro4ose6
a. Make Siemens7. Mdel (S'21$. T9pe )%meri$alI ,MTL T9pe
". CT De%as
-l!age Class : 33 k-5re>%en$9 : + @
Shr! !ime ra!ing : 2+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 33k- s.gear
CT Ra!i : Cre&3" A Primar9
1 A Se$ndar9
CT Class: +P AL5: ,
1+ -A
R$! = " 6hms$$.ma = 2+ kA
0. Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 Siemens; = .+ &&&&1;Ref. Siemens SP.2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m &&&&2;
CTs in!ernal Resis!an$e "/1 Tap a! (+?C; R$! = " 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D"E0 $A &&&&3;
Cnne$!ed CT 4!ernal #%rden == .+F.++;= .3 $A &&&&";
"." CTs or , M$A Transormer a!#u4 Pro%e!%on - 55N & 5+5+N(""#$ S%!8'ear Ou%'on')
pn
sn
Ra!ed#%rden:
Rr -A a! S)
RL
Pi
Rr F RL;
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,0 o 33
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .';
= .7" $A
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ffi$ien!
5 Ca!ua%on o mnmum re;ure6 <A!!ura!9 Lm% =a!%or< or %8e CT:(refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= maim%m shr!&$ir$%i! $%rren! in Ampere;
= 2+ Amppn = )minal CT primar9 $%rren! in Ampere;= " Amp
= maDhigh&se! pin! / pn;I 2E= maD2+ / ";I 2E= ,.5
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> " &&&&';
' Ca!ua%on o o4era%n' <A!!ura!9 Lm% =a!%or< or %8e CT:
here &= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 2
= Ra!ed resis!ive 7%rden f CT in 6hm;= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;
= .(3= CT se$. dg. resis!an$e in 6hm;
= "
= 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as flls &
=
= 2 D1+F"; / .(3F";E= 2 D10 / ".(3E= .332(
Th%s !he effe$!ive CT AL5
> 3."0 &&&&+;
P#C
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$ Kss$ DR#) F R$!; / R#C F R$!;E
?<ss!
K ' ssc= K
ssc×
( RBC
+ Rct
RBN + R
ct )
K ' ssc1≥max[( I high−set po int
I pn ) , 20]
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR.SS
Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,5 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : "/1Class : 5P,
R$! ma.; : " 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is .3" hile !he Re>%ired CT AL5 is '3 i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR , o 33
+. A44!a%on
Pr!e$!in : 6/C * 4/5 Pr!e$!in +1/+1);
,. Rea9 Pro4ose6
a. Make Siemens7. Mdel (S'21$. T9pe )%meri$alI ,MTL T9pe
". CT De%as
-l!age Class : 33 k-5re>%en$9 : + @
Shr! !ime ra!ing : 2+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 33k- s.gear
CT Ra!i : Cre&212 A Primar9
1 A Se$ndar9
CT Class: +P AL5: 1
1+ -A
R$! = " 6hms$$.ma = 2+ kA
0. Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 Siemens; = .+ &&&&1;Ref. Siemens SP.2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m &&&&2;
CTs in!ernal Resis!an$e 12/1 Tap a! (+?C; R$! = " 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D"E0 $A &&&&3;
Cnne$!ed CT 4!ernal #%rden == .+F.++;= .3 $A &&&&";
".0 CTs or us !ou4er a!#u4 Pro%e!%on - 5+5+N (""#$ S%!8'ear)
pn
sn
Ra!ed#%rden:
Rr -A a! S)
RL
Pi
Rr F RL;
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,7 o 33
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .';
= .7" $A
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ffi$ien!
5 Ca!ua%on o mnmum re;ure6 <A!!ura!9 Lm% =a!%or< or %8e CT:(refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= maim%m shr!&$ir$%i! $%rren! in Ampere;
= 2+ Amppn = )minal CT primar9 $%rren! in Ampere;= 12 Amp
= maDhigh&se! pin! / pn;I 2E= maD2+ / 12;I 2E= ,.3
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> ,+ &&&&';
' Ca!ua%on o o4era%n' <A!!ura!9 Lm% =a!%or< or %8e CT:
here &= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 1
= Ra!ed resis!ive 7%rden f CT in 6hm;= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;
= .(3= CT se$. dg. resis!an$e in 6hm;
= "
= 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as flls &
=
= 1 D1+F"; / .(3F";E= 1 D10 / ".(3E= ".1'013
Th%s !he effe$!ive CT AL5
> 0.+7 &&&&+;
P#C
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$ Kss$ DR#) F R$!; / R#C F R$!;E
?<ss!
K ' ssc= K
ssc×
( RBC
+ Rct
RBN + R
ct )
K ' ssc1≥max[( I high−set po int
I pn ) , 20]
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,3 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : 12/1Class : +P1
R$! ma.; : " 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is ".1( hile !he Re>%ired CT AL5 is 21 i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ,2 o 33
+. Me%ers !onne!%e6
,A Amme!er
a. Make && &&7. Mdel && &&$. -A #%rden .+ &&d. 8!9. )s.; 1 &&e )e! -A .+ &&
,. CT De%as
CT Ra!i
12 A Primar9
1 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 33S5H 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 2+ 3 se$.
". Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M!r CT ! Me!ers m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 6hm &&&&2;
The e!ernal #%rden =
= .+ F .++;= 1.+ -A &&&&3;
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1.+;
= , $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
0. Con!uson :
+
, Summar9 o CT 4arame%ers
CT Ra!i : +,+ A
Class : +Ra!ed #%rden : +5
S5H +
".5 CTs or - us!ou4er Me%ern'(""#$ s%!8'ear)
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI R m
RL
Rm F R
L
P#C
P#)
The Cnne$!ed CT 7%rden is 2 hile !he Ra!ed CT 7%rden is 1+ As Ra!ed CT 7%rden JCnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR " o 33
Se!%on - 0 :"" #$ PT
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR "+ o 33
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR ", o 33
+. A44!a%on
Me!ering and pr!e$!in
,. PT Ra%o & De%as
Ra!i Cl Vni! Cnne$!in L$a!in
33/Z3 - S!ar Primar9
11/Z3 Cl: 1. - S!ar Se$ndar9
11/3 Cl: 3P - 6pen del!a Se$ndar9
". Lea6 ur6en
Referring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/kmRea$!an$e f 2.+s>mm Ca7le a! (?C .111 6hms/km@en$e mpedan$e f 2.+S>mm Ca7le : S8RTD0.3B2;F.111B2;E
= S8RTD'."0F.12321E= S8RTD'.+2321E= 2." 6hms/km
Single Lead Leng!h f !he -T $a7le frm 33k- Sgr ! 33k-Pr!e$!in / Cn!rl / Me!ering Panel = 5 M!r
@en$e 2 a9 Lead impedan$e f !he $a7le = D2 mpd. f !he $a7le + / 1E= D2 0.3'' + / 1E= .03''= .2" 6hms &&&&1;
0. $A ur6en or Pro%e!%on $T Core
0.+ De%as o Rea9s bur6en !onne!%e6 %o $T !ore
Sno Rea9 Ma#e Mo6e
1 S4M4)S (S'211 .2 1 .'
2 S4M4)S (S' .1 1 .3
#%rden .0 ""1."1
Cnne$!ed 3ph #%rden = .0 -A &&&&2;Cnne$!ed Rela9s Resis!an$e = ""1."1 6hmsLead Resis!an$e f $a7le = .03'' 6hms@en$e !!al Resis!an$e in -T $ir$%i! = ""2."12 6hm Ph&);
C%rren! !hr%gh !he -T Cir$%i! = .112+ Amps@en$e Lead $a7les 3Ph -A #%rden = .1'("3 -A &&&&3;
@en$e !!al 7%rden n -T $re = 2; F 3;= .01'("3 -A
i!h 2G ,esign Margin re>%ired -A #%rden = 1.22""+2 -A
Sele$!ed -A #%rden f -T Cre = + -A * @en$e s%ffi$ien!
0.+ PT or In!omer ne ee6ers PT(""#$ S%!8'ear)
-P)
-S)
-S)
$AP8 ur6enn $T Cr!u%
Juan%%9(No)
Ne% " P8 $Abur6en on$T Core
O8m!Im4e6an!e1aue (O8m)
(P8-N)
'(/'() & #a$k%p dire$!inal
Pr!e$!in
)e%!raldispla$emen!
rela9
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR "0 o 33
5. $A ur6en or Man Me%ern' $T Core
5.+ De%as o Me%er bur6en !onne!%e6 %o $T !ore
Sno Me%er Ma#e Mo6e
1 -l!me!er . . 1 1 32 . . .+ 1 1.+
3 . . .+ 1 1.+
" . . .13" 1 ."3
+ . . .13" 1 ."3
#%rden '.'''( '(1.32
Cnne$!ed 3ph #%rden = '.'''''( -A &&&&";Cnne$!ed Me!ering Resis!an$e = '(1.32 6hms
Lead Resis!an$e f $a7le = .03'' 6hms@en$e !!al Resis!an$e in -T $ir$%i! = '(2.2+ 6hm Ph&);
C%rren! !hr%gh !he -T Cir$%i! = .0""(1'310 Amps@en$e Lead $a7les 3Ph -A #%rden = .2"0221 -A &&&&+;
@en$e !!al 7%rden n -T $re = "; F +;= '.320'("( -A
i!h 2G ,esign Margin re>%ired -A #%rden = (.230+'2'"0( -A
Sele$!ed -A #%rden f -T Cre = + -A * @en$e s%ffi$ien!
. Re!ommen6e6 ""#$ S%!8'ear PT De%as or ""#$ In!omers
A44!a%on Conne!%on Cass $A ur6en
33/]311/3 6pen ,el!a 3P 1
11/Z3 S!ar 1. 1
$AP8 ur6enn $T Cr!u%
Juan%%9(No)
Ne% " P8 $Abur6en on$T Core
O8m!Im4e6an!e1aue (O8m)
(P8-N)
-l!age!ransd%$er 5re>%en$9!ransd%$er
MTransd%$er
M-ARTransd%$er
Prmar91o%a'e ($
PN)
Se!on6ar91o%a'e ($
SN)
Pr!e$!inCre
Me!eringCre
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR "5 o 33
+. A44!a%on
Me!ering and pr!e$!in
,. PT Ra%o & De%as
Ra!i Cl Vni! Cnne$!in L$a!in33/Z3 - S!ar Primar9
11/Z3 Cl: 1. - S!ar Se$ndar9
11/Z3 Cl: 1. - S!ar Se$ndar9
3.0 Lead Burden
(R'0'55%&6 78 T4$' # 9+ 80 O:& C4$' C7$86;' 085 PVC %&s;$7'< LT/C8&758$ 24$'s)
R's%s7&2' 80 *!s=:: C4$' 7 >?C @*3 O:s/k:
R'27&2' 80 *!s=:: C4$' 7 >?C *111 O:s/k:
H'&2' I:'<&2' 80 *!S=:: C4$' SRT(@*3E)(*111E)F
SRT+9*-@*131F
SRT+9*!31F
9.30066 O:s/k:
S%&6$' L'< L'&67 80 7' VT 24$' 058: 33kV SG65
78 33kV P587'27%8& P&'$ / C8&758$ &'$ 50 M75
H'&2' G L'< %:'<&2' 80 7' 24$' , I:<* 80 7' 24$' , ! / 1F
, @*399 , ! / 1F
*@399
0.930066 O:s ####(1)
4.0 VA Burden for Protection VT Core
As 80 &8G &8 587'27%8& 5'$ %s '&%s6'< %& B;s PR P587'27%8& C85'* H8G''5. 085 0;7;5' ;s' 7' VA B;5<'& 80 7'
s:' %s 28s'& sS'$'27'< VA B;5<'& 80 VT C85' 100 VA
5.0 VA Burden for Metering VT Core
5.1 Detail of Meter !urden connected to VT core
"lno Meter Ma#e Model
1 V8$7:'7'5 J* J* 1 9
J* J* *! 1 1*!
3 J* J* *! 1 1*!
- MW T5&s<;2'5 J* J* *13- 1 *-3
! J* J* *13- 1 *-3
B;5<'& @*+999> -->*>->
C8&&'27'< 3 B;5<'& @*+99999> VA ####()
C8&&'27'< M'7'5%&6 R's%s7&2' -->*>-> O:s
L'< R's%s7&2' 80 24$' *@399 O:s
H'&2' 787$ R's%s7&2' %& VT 2%52;%7 --+*9>> O: (P#N)
C;55'&7 758;6 7' VT C%52;%7 *1-1!-9-31 A:s
H'&2' L'< 24$'Ks 3P VA B;5<'& *!!@!99 VA ####(3)
0., us PT(""#$ S%!8'ear)
-P)
-S)
-S)
VA$P% Burden
in VT Circuit
&uantit'
()o*
)et 3 P%
VA !urden
on VT Core
+%,ic
-,edance
/alue (+%,*
(P%)*
"5'=;'&275&s<;2'5
V8$76'75&s<;2'5
MVART5&s<;2'5
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Do!.: ""#$ Curren%$o%a'e Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.,
Da%e: 2.++.,
Ppd.: AKRChkd: AKSM/SRKR " o 33
H'&2' 787$ 4;5<'& 8& VT 285' () (3)
@*93@9@@3 VA
W%7 D's%6& M56%& 5'=;%5'< VA B;5<'& 1*+>9>93>! VA
S'$'27'< VA B;5<'& 80 VT C85' 100 VA H'&2' s;00%2%'&7
6.0 eco,,ended PT Detail for 33#V Bu PT in 33#V "2itc%gear
Alication Connection Cla VA Burden
S75 3P 1
O'& D'$7 1* 1
Pri,ar'
/oltage (VP)
*
"econdar'
/oltage (V")
*
P587'27%8&C85'
33/√3
11/√3
M'7'5%&6C85'
11/3
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e "7 o 33
Se!%on - 5 : ++#$ Transormer In!omer
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e "3 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
DDo!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e "2 o 33
+. Me%ers !onne!%e6
,A
a. Make && &&7. Mdel && &&$. -A #%rden .+ &&d. 8!9. )s.; 1 &&e )e! -A .+ &&
,. CT De%as
CT Ra!i Cre&"
12 A Primar9
1 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 11S5H 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 1.+ 3 se$.
". Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M!r CT ! Me!ers m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3 / 1E= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 6hm &&&&2;
The e!ernal #%rden =
= .+ F .++;= 1.+ -A &&&&3;
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1.+;
= , $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
0. Con!uson :
+
, Summar9 o CT 4arame%ers
CT Ra!i : +,+ A
Class : +Ra!ed #%rden : +5
S5H +
5.+ CTs or - Me%ern'(, M$A Transormer ee6er n ++#$ s%!8'ear)
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI R m
RL
Rm F R
L
P#C
P#)
The Cnne$!ed CT 7%rden is 2 hile !he Ra!ed CT 7%rden is 1+ As Ra!ed CT 7%rden JCnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0 o 33
+. Rea9 Pro4ose6
a. Make Siemens
7. Mdel (S'21$. T9pe )%meri$alI,ir. 6C * 45 ,MTL T9pe
, CT De%as
-l!age Class : 11 k-5re>%en$9 : + @
Shr! !ime ra!ing : 1.+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 11k- Si!$hgear C%7i$le.CT Ra!i : Cre & 3
12 A Primar9
1 A Se$ndar9CT Class: +P
AL5 1
1+ -A
R$! = 5 6hms$$.ma = 1.+ kA
" Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 (S'21; = .1Ref Ch.+I Pg. "1 :SP 2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m
CTs in!ernal Resis!an$e12/1 Tap a! (+?C; R$! = + 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D+E5 $A
The e!ernal Ra!ed #%rden =
= .1F.++;= .53 $A
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .'+;
= .72 $A
5., CTs or a!#u4 Pro%e!%on - 75+(,M$A Transormer ee6er n ++#$ s.'ear)
pn
sn
Ra!ed#%rden:
Rr -A a!
S)
RL
Pi
RrF R
L;
P#C
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0+ o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0, o 33
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ff
5 Ca!ua%on o CT <Re;ure6 A!!ura!9 Lm%n' =a!%or< (refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &
= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren
= maim%m shr!&$ir$%i! $%rren! in Ampere;= 1+ Amp
pn = )minal CT primar9 $%rren! in Ampere;= 12 Amp
= maDhigh&se! pin! / pn;I 2E
= maD1+ / 12;I 2E= ,.
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> ,
Ca!ua%on o CT <O4era%n' A!!ura!9 Lm%n' =a!%or<
here &
= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 1+
= Ra!ed resis!ive 7%rden f CT in 6hm;
= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;= .(0
= CT se$. dg. resis!an$e in 6hm;
= += 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as fl
=
= 1+ D1+F+; / .(0F+;E= 1+ D2 / +.(0E= +1.13"(
Th%s !he 6pera!ing CT AL5> 5+.3,
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$
Kss$
DR#)
F R$!; / R
#C F R
$!;E
?<ss!
K ' ssc= K
ssc×
(
RBC + Rct
RBN +
Rct
)
K ' ssc1≥max[( I
high−set po int
I pn ) , 20]
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0" o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : 12/1 AClass : +P1
R$! ma.; : 5 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is +1.2 hile !he Re>%ired CT AL5 is 2 i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 00 o 33
&&&&1; Siemens
/ 1E
&&&&2;
&&&&3;
&&&&";
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 05 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0 o 33
i$ien!
! fa$!r
&&&&';
ls &
&&&&+;
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 07 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 03 o 33
+. Rea9 Pro4ose6
a. A)S ). '"R457. Make S4M4)S
$. Mdel (S'22d. T9pe )%meri$alI R45 @igh mepdan$e !9pe;
,. CT Ra%o
11k- Line Side CTs-l!age Class : 11 k-
5re>%en$9 : + @Shr! !ime ra!ing : 1.+ kA fr 3 se$.
M%n!ing: CT m%n!ed in 11k- Si!$hgear CT Ra!i : Cre&2
12 A Primar9
1 A Se$ndar9
CT Class: G
CT in!. res.: R$! ' 6hmkP- : -k 2 -l!
4$. C%rren!: mag " mA *2
1+M-A Traf. @- )e%!ral Side CT-l!age Class : 11 k-
5re>%en$9 : + @Shr! !ime ra!ing : 1.+ kA fr 3 se$.
M%n!ing: CT m%n!ed in 11k- Side Traf. #%shingCT Ra!i : Cre & 2
12 A Primar9
1 A Se$ndar9
CT Class: GR$! ' 6hm (same as that f#r %$e sde C's)
-k 2 -l! (same as that f#r %$e sde C's)
mag " mA *2
". S9s%em Inorma%on
S9s!em -l!age -s9s = 11 k-Transfrmer ra!ing = 2 M-ATransfrmer mpedan$e a! Prin$ipal Tap GXp!; = 12.+ GTransfrmer mpedan$e a! nega!ive !leran$e = 1.'2+ G (th -8e 56 t#%era$/e)
Transfrmer f%ll lad $%rren! =LC = Traf. Ra!ing / Ds>r!3; -s9sE= 2M-A / D1.(32 11k-E= +02.7" A
Cal$%la!in f Maim%m !hr%gh fa%l! $%rren! !f;I ass%ming infini!e per s%r$e
!f = -s9s / Ds>r!3; Xl!E-s9s = 11 k-hereXl! = mpedan$e f !he !ransfrmer a! nega!ive !leran$eXl! = GXl!/1; Dk-7ase;B2 / M-A7ase;E
hereI M-A7ase; = 2 M-Ak-7ase; = 11 k-@en$e Xl! = 1.'2+/1; D11B2;/2E
= .1'2+ 121/2;= .1'2+ '.+
Th%sI Xl! = .'" 6hm
5." CTs or Transormer Res%r!%e6 /ar%8 =au% Pro%e!%on - 0R/=(,M$A Transormer n ++#$ S%!8'ear)
P)
sn
P)
sn
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 02 o 33
@en$e !f&ma = -s9s / Ds>r!3; Xl!E= 11 / D1.(32 .'"E= 11/1.10= 0023.2((+ Amp
hi$h is = .2'0 CT ra!ed primar9 $%rren!Th%s !f&ma = 0023.2((+ Amp
0. Ca!ua%on o ur6en !onne!%e6 %o %8e CT Core
0.+
-A #%rden f !he Rela9 '"R45 Pr = .1 -A a! n=1A &&&&1;Rr = .+ O8m
0.,
Referring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C = 2." 6hms/km
Single Lead Leng!h f !he $a7le frm #CT ! CRP = 5 M!r
@en$e 2 a9 lead #%rden = 2 mpd. f !he $a7le +; / 1= 2 0.3 +; / 1
= 03;/1RL = .2" 6hm &&&&2;
@en$e 4!ernal Cnne$!ed #%rden =(th 206 marg$) = 1.11' 6hm
= +.++ $A &&&&3;
0."
CTs in!. res. 12/1 Tap a! (+?C R$! = 6hms &&&&";
5. Ca!ua%on o 1arous CT 4arame%ers
5.+ Ca!ua%on o CT #nee 4on% 1o%a'e $#(mn) re;uremen%
Traf. maim%m !hr% fa%l! $%rren! n CT primar9fspri; = 0023.2 Amp 6n CT Primar9 side
@en$e fsse$; = fspri; / 12/1; 6n CT Se$ndar9 side= 0023.2/D12/1;E= .2( Amp
Mn. rea9 se%%n' 1o%a'e ($s%ab) = fsse$; R$! F R7;= .2( 'F1.11';= .2( (.11';
-s!a7min; = +."032 -l!Sa9 Sele$!ed Se!!ing vl!age : -s = 7+ $o% (th 206 se/urt marg$)
Mnmum ?nee 4on% 1o%a'e $#(mn) = 2 -s -l!= 2 (1$#(mn) > +0, $o% &&&&+;
5., Ca!ua%on o Ma'ne%sn' Curren% re;uremen%The rela9 se!!ing $%rren! $rrespnding ! !he rela9 se!!ing vl!ageI as per S4M4)S $a!alg%e &Rela9 se!!ing $%rren! in$l%ding varis!r; r = .2 ARela9 se!!ing vl!age sele$!ed -r = -s = (1 -). f spill parallel; pa!hs n = 0 ns.Sele$!ed CTs Magne!iing Chara$!eris!i$s : 11k- Line Side CTs;Magne!iing $%rren! O -k/2 mag = ." A O -k/2 in -l!; = 1Magne!iing $%rren! O -s = (1- mag1 = .,30 A sin$e #@ $%rve is linear %p! -k;Sele$!ed CTs Magne!iing Chara$!eris!i$s : Xigag Traf. 11k- @- side ne%!ral #CT;Magne!iing $%rren! O -k/2 mag = ." A O -k/2 in -l!; = 1
Magne!iing $%rren! O -s = (1- mag1 = .,30 A sin$e #@ $%rve is linear %p! -k;
Conne!%e6 Rea9s ur6en (Rr )
Lea6 ur6en (RL)
RL
R7
CT ur6en (R!%)
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5 o 33
The mag1 fr 7!h side CTs is same. The rela9 pera!ing $hara$!eris!i$s shall 7e $he$ked fr !hese CTs.#ased n !he a7veI !he rela9 pera!ing $%rren! $an n 7e $al$%la!ed as flls &
p = r F n mag1;= .2 F ".2"= .+"0 A
6n CT primar9I p prim; = p pn/sn;+." A
hi$h is = p prim; / 5LC; 1
= 1'.32 / 1"0.(3; 1= +5.,3 G r + o =LC rou'89.
)rmall9 R45 se!!ing is 7e!een 1&'G 5LC is en%gh fr sa!isfa$!r9 pera!in.
5." Ca!ua%on o /%erna Seres S%absn' Ress%an!eRela9 mpedan$eThe rela9 impedan$e $an 7e $al$%la!ed as flls &rela9 se!!ing $%rren! r = .2 A (ths s a f7ed 8a%ue)
rela9 se!!ing vl!age -r = (1 -l!rela9 7%rden Pr = .1!h%s rela9 impedan$e Rr = Pr / rB2
= 2+ 6hm
Rr > ,5 O8m
4!ernal S!a7ilising Resis!an$eThe re>%ired e!ernal series resis!an$e val%e $an 7e $al$%la!ed as flls &
Rs! = -r / r; & Rr = (1 / .2; & 2+= 33. 6hm
Rs% > "". O8m &&&&';
T!al rela9 $ir$%i! 7ran$h impedan$e = Rs! F Rr = "55. O8m
5.0 C8e!#s or Re;uremen% o $ars%or (non-near s8un% ress%or) & Ca!ua%on o Parame%ers As per S4M4)S CT Siing re$mmenda!in fr R45 & @igh mpedan$e Appli$a!inIMaim%m vl!age fr in!ernal fa%l! -pk = 2 s>r!D2-kmin; -fs&-kmin;;E
-fs ≥ Ma. !here!i$al vl!age a$rss !he rela9 $ir$%i! in $ase f in!ernal fa%l!≥ D!f&ma / pn/sn;E R$! F R7 F Rs! F Rr;≥ D0023.2((+ / 12/1; E ' F 1.11' F 33 F 2+;
Th%sI -fs ≥ ,20+5 $o%
@en$e -pk = 57."2", $o% J 2k-I hen$e varis!r R48VR4,.
. Con!usons & Summar91. Cn$l%sin
5rm +; a7veI minim%m re>%ired CT knee pin! vl!age = 1"2 -l!
2. S%mmar9 f CT parame!ers
6n Traf. Line SideCT Ra!i : +, + A
Class : G
R$! ma.; : O8m
-k min.; : , $o%
mag O -k/2; : 0 mA
6n Traf. )e%!ral SideCT Ra!i : +, + A
Class : G
R$! ma.; : O8m
-k min.; : , $o%
mag O -k/2; : 0 mA
3. S!a7ilising Resis!r Re>%iremen! "" O8m
". -aris!r nn&linear sh%n! resis!r; Re>%ired : Kes
-A (f#r Is$ 9 A)
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5+ o 33
+. Rea9 Pro4ose6
a. A)S ). (T7. Make S4M4)S
$. Mdel (VT'121d. T9pe )%meri$alI ,ifferen!ial L mepdan$e !9pe;
,. CT Ra%o
11k- Line Side CTs-l!age Class : 11 k-
5re>%en$9 : + @Shr! !ime ra!ing : 1.+ kA fr 3 se$.
M%n!ing: CT m%n!ed in 11k- Si!$hgear CT Ra!i : Cre&1
12 A Primar9
1 A Se$ndar9
CT Class: GCT in!. res.: R$! ( 6hmkP- : -k 2+ -l!
4$. C%rren!: mag " mA *2
". S9s%em Inorma%on
S9s!em -l!age -s9s = 11 k-Transfrmer ra!ing = 2 M-ATransfrmer mpedan$e a! Prin$ipal Tap GXp!; = 12.+ GTransfrmer mpedan$e a! nega!ive !leran$e = 1.'2+ G i!h &ve 1+G !leran$e;Transfrmer f%ll lad $%rren! =LC = Traf. Ra!ing / Ds>r!3; -s9sE
= 2M-A / D1.(32 11k-E
= +02.7" A
Cal$%la!in f Maim%m !hr%gh fa%l! $%rren! !f;I ass%ming infini!e per s%r$e
!f = -s9s / Ds>r!3; Xl!E-s9s = 11 k-hereXl! = mpedan$e f !he !ransfrmer a! nega!ive !leran$eXl! = GXl!/1; Dk-7ase;B2 / M-A7ase;E
hereI M-A7ase; = 2 M-Ak-7ase; = 11 k-@en$e Xl! = 1.'2+/1; D11B2;/2E
= .1'2+ 121/2;= .1'2+ '.+
Th%sI Xl! = .'" 6hm
@en$e !f&ma = -s9s / Ds>r!3; Xl!E= 11 / D1.(32 .'"E= 11/1.10= 0023.2((+ Amp
hi$h is = .2'0 CT ra!ed primar9 $%rren!Th%s !f&ma = 0023.2((+ Amp
5.0 CTs or ,M$A Transormer Deren%a Pro%e!%on - 37T(""#$ S%!8'ear Ou%'on')
P)
sn
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5, o 33
0. Ca!ua%on o ur6en !onne!%e6 %o %8e CT Core
0.+
-A #%rden f !he Rela9 '"R45 Pr = .1 -A a! n=1A &&&&1;Rr = .+ O8m
0.,
Referring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C = 2." 6hms/km
Single Lead Leng!h f !he $a7le frm #CT ! CRP = 5 M!r
@en$e 2 a9 lead #%rden = 2 mpd. f !he $a7le +; / 1= 2 0.3 +; / 1= 03;/1
RL = .2" 6hm &&&&2;
@en$e 4!ernal Cnne$!ed #%rden =(th 206 marg$) = 1.11' 6hm
= +.++ $A &&&&3;
0."
CTs in!. res. 12/1 Tap a! (+?C R$! = 7 6hms &&&&";
5. Ca!ua%on o 1arous CT 4arame%ers
5.+ Ca!ua%on o CT #nee 4on% 1o%a'e $#(mn) re;uremen%
Traf. maim%m !hr% fa%l! $%rren! n CT primar9fspri; = 0023.2 Amp 6n CT Primar9 side
@en$e fsse$; = fspri; / 12/1; 6n CT Se$ndar9 side= 0023.2/D12/1;E= .2( Amp
Mn. rea9 se%%n' 1o%a'e ($s%ab) = fsse$; R$! F R7;= .2( (F1.11';= .2( .11';
-s!a7min; = '(.11032 -l!Sa9 Sele$!ed Se!!ing vl!age : -s = 3+ $o% (th 206 se/urt marg$)
Mnmum ?nee 4on% 1o%a'e $#(mn) = 2 -s -l!= 2 1
$#(mn) > +, $o% &&&&+;
5., Ca!ua%on o Ma'ne%sn' Curren% re;uremen%The rela9 se!!ing $%rren! $rrespnding ! !he rela9 se!!ing vl!ageI as per S4M4)S $a!alg%e &Rela9 se!!ing $%rren! in$l%ding varis!r; r = .2 A
Rela9 se!!ing vl!age sele$!ed -r = -s = 1 -). f spill parallel; pa!hs n = " ns.Sele$!ed CTs Magne!iing Chara$!eris!i$s : 11k- Line Side CTs;Magne!iing $%rren! O -k/2 mag = ." A O -k/2 in -l!; = 12+Magne!iing $%rren! O -s = 1- mag1 = .,52 A sin$e #@ $%rve is linear %p! -k;
The mag1 fr 7!h side CTs is same. The rela9 pera!ing $hara$!eris!i$s shall 7e $he$ked fr !hese CTs.#ased n !he a7veI !he rela9 pera!ing $%rren! $an n 7e $al$%la!ed as flls &
p = r F n mag1;= .2 F 3.2+0= .23 A
6n CT primar9I p prim; = p pn/sn;++7." A
hi$h is = p prim; / 5LC; 1
= 11(.312 / 1"0.(3; 1= ++.+3 G r +, o =LC rou'89.
5." Ca!ua%on o /%erna Seres S%absn' Ress%an!eRela9 mpedan$e
Conne!%e6 Rea9s ur6en (Rr )
Lea6 ur6en (RL)
RL
R7
CT ur6en (R!%)
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5" o 33
The rela9 impedan$e $an 7e $al$%la!ed as flls &rela9 se!!ing $%rren! r = .2 A (ths s a f7ed 8a%ue)
rela9 se!!ing vl!age -r = 1 -l!rela9 7%rden Pr = .1!h%s rela9 impedan$e Rr = Pr / rB2
= 2+ 6hm
Rr > ,5 O8m
4!ernal S!a7ilising Resis!an$eThe re>%ired e!ernal series resis!an$e val%e $an 7e $al$%la!ed as flls &
Rs! = -r / r; & Rr = 1 / .2; & 2+= 3. 6hm
Rs% > "3. O8m &&&&';
T!al rela9 $ir$%i! 7ran$h impedan$e = Rs! F Rr = 05. O8m
. Con!usons & Summar9
1. Cn$l%sin5rm +; a7veI minim%m re>%ired CT knee pin! vl!age = 1'2 -l!
2. S%mmar9 f CT parame!ers6n Traf. Line Side
CT Ra!i : +, + A
Class : G
R$! ma.; : 7 O8m
-k min.; : ,5 $o%
mag O -k/2; : 0 mA
3. S!a7ilising Resis!r Re>%iremen! "3 O8m
-A (f#r Is$ 9 A)
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 50 o 33
Se!%on - : ++#$ Transormer Ou%'on'
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 55 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5 o 33
+. Rea9 Pro4ose6
a. Make Siemens
7. Mdel (S'21$. T9pe )%meri$alI ,MTL T9pe
, CT De%as
-l!age Class : 11 k-5re>%en$9 : + @
Shr! !ime ra!ing : 1.+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 11k- Si!$hgear C%7i$le.CT Ra!i : Cre & 1
" A Primar9
1 A Se$ndar9CT Class: +P
AL5 1
1+ -A
R$! = 5 6hms$$.ma = 1.+ kA
" Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 (S'21; = .1Ref Ch.+I Pg. "1 :SP 2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m
CTs in!ernal Resis!an$e"/1 Tap a! (+?C; R$! = + 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D+E5 $A
The e!ernal Ra!ed #%rden =
= .1F.++;= .53 $A
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .'+;
= .72 $A
.+ CTs or a!#u4 Pro%e!%on - 55+(Ou%'on' & Ca4a!%or ee6er n ++#$ s.'ear)
pn
sn
Ra!ed#%rden:
Rr -A a!
S)
RL
Pi
RrF R
L;
P#C
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 57 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 53 o 33
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ff
5 Ca!ua%on o CT <Re;ure6 A!!ura!9 Lm%n' =a!%or< (refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &
= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren
= maim%m shr!&$ir$%i! $%rren! in Ampere;= 1+ Amp
pn = )minal CT primar9 $%rren! in Ampere;= " Amp
= maDhigh&se! pin! / pn;I 2E
= maD1+ / ";I 2E= 0.,5
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> 07
Ca!ua%on o CT <O4era%n' A!!ura!9 Lm%n' =a!%or<
here &
= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 1+
= Ra!ed resis!ive 7%rden f CT in 6hm;
= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;= .(0
= CT se$. dg. resis!an$e in 6hm;
= += 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as fl
=
= 1+ D1+F+; / .(0F+;E= 1+ D2 / +.(0E= +1.13"(
Th%s !he 6pera!ing CT AL5> 5+.3,
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$
Kss$
DR#)
F R$!; / R
#C F R
$!;E
?<ss!
K ' ssc= K
ssc×
(
RBC + Rct
RBN +
Rct
)
K ' ssc1≥max[( I
high−set po int
I pn ) , 20]
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 52 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : "/1Class : +P1
R$! ma.; : 5 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is +1.2 hile !he Re>%ired CT AL5 is "( i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e o 33
&&&&1; Siemens
/ 1E
&&&&2;
&&&&3;
&&&&";
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e + o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e , o 33
i$ien!
! fa$!r
&&&&';
ls &
&&&&+;
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e " o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 0 o 33
+. A44!a%on
Me!ering
,. Me%ers !onne!%e6
,Aa. Make 7. Mdel $. -A #%rden .+d. 8!9. )s.; 1e )e! -A .+
". CT De%as
CT Ra!i Cre&2
" A Primar9
1 A Se$ndar9CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 11
S5 H 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 1.+ 3 se$.
0. Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = 5 M!r CT ! Me!ers m%n!ed in Sgr. L- C%7i$le * 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le + / 1E= 1B2; D2 0.3 + / 1E= 1; .03
= .2" 6hm &&&&2;
The e!ernal #%rden =
= .+ F .03;= 1."3 -A &&&&";
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1."3;
= " $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
5. Con!uson :
., CTs or - Me%ern'(Ou%'on' ee6ers & Ca4a!%or ee6er n ++#$ s.'ear)
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI Rm
RL
Rm F R
L
P#C
P#)
The Cnne$!ed CT 7%rden is 3 hile !he Ra!ed CT 7%rden is 1+ i.e. As Ra!ed CT 7%rden is J Cnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 5 o 33
+. Rea9 Pro4ose6
a. Make Siemens
7. Mdel (S'21$. T9pe )%meri$alI ,MTL T9pe
, CT De%as
-l!age Class : 11 k-5re>%en$9 : + @
Shr! !ime ra!ing : 1.+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 11k- Si!$hgear C%7i$le.CT Ra!i : Cre & 1
12 A Primar9
1 A Se$ndar9CT Class: +P
AL5 1
1+ -A
R$! = 5 6hms$$.ma = 1.+ kA
" Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 (S'21; = .1Ref Ch.+I Pg. "1 :SP 2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3= 1B2; D2 0.3 3 / 1E= 1; .++
= .553 O8m
CTs in!ernal Resis!an$e12/1 Tap a! (+?C; R$! = + 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D+E5 $A
The e!ernal Ra!ed #%rden =
= .1F.++;= .53 $A
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .'+;
= .72 $A
." CTs or a!#u4 Pro%e!%on - 5+5+N(us !ou4er ee6er n ++#$ s.'ear)
pn
sn
Ra!ed#%rden:
Rr -A a!
S)
RL
Pi
RrF R
L;
P#C
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e o 33
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7 o 33
Sele$!ed -A #%rden fr CT $re = +5 $A & is s%ff
5 Ca!ua%on o CT <Re;ure6 A!!ura!9 Lm%n' =a!%or< (refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &
= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren
= maim%m shr!&$ir$%i! $%rren! in Ampere;= 1+ Amp
pn = )minal CT primar9 $%rren! in Ampere;= 12 Amp
= maDhigh&se! pin! / pn;I 2E
= maD1+ / 12;I 2E= ,.
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> ,
Ca!ua%on o CT <O4era%n' A!!ura!9 Lm%n' =a!%or<
here &
= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
= KnAL5= 1+
= Ra!ed resis!ive 7%rden f CT in 6hm;
= 1+
= Cnne$!ed resis!ive 7%rden in 6hm;= .(0
= CT se$. dg. resis!an$e in 6hm;
= += 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as fl
=
= 1+ D1+F+; / .(0F+;E= 1+ D2 / +.(0E= +1.13"(
Th%s !he 6pera!ing CT AL5> 5+.3,
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$
Kss$
DR#)
F R$!; / R
#C F R
$!;E
?<ss!
K ' ssc= K
ssc×
(
RBC + Rct
RBN +
Rct
)
K ' ssc1≥max[( I
high−set po int
I pn ) , 20]
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : 12/1Class : +P1
R$! ma.; : 5 6hmRa!ed #%rden: 1+ -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is +1.2 hile !he Re>%ired CT AL5 is 2 i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 2 o 33
&&&&1; Siemens
/ 1E
&&&&2;
&&&&3;
&&&&";
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7+ o 33
i$ien!
! fa$!r
&&&&';
ls &
&&&&+;
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7, o 33
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7" o 33
+. A44!a%on
Me!ering
,. Me%ers !onne!%e6
a. Make 7. Mdel $. -A #%rden .+d. 8!9. )s.; 1e )e! -A .+
". CT De%as
CT Ra!i Cre&2
12 A Primar91 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 11S5 H 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 1.+ 3 se$.
0. Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;
Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = 5 M!r CT ! Me!ers m%n!ed in Sgr. L- C%7i$le * 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le + / 1E= 1B2; D2 0.3 + / 1E= 1; .03
= .2" 6hm &&&&2;
The e!ernal #%rden =
= .+ F .03;
= 1."3 -A &&&&";
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1."3;
= " $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
5. Con!uson :
.0 CTs or - Me%ern'(us !ou4er ee6er n ++#$ s.'ear)
,A 11k-Sgr.;
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI Rm
RL
Rm F RL
P#C
P#)
The Cnne$!ed CT 7%rden is 3 hile !he Ra!ed CT 7%rden is 1+
i.e. As Ra!ed CT 7%rden is J Cnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 70 o 33
+. Rea9 Pro4ose6
a. Make Siemens
7. Mdel (S'21$. T9pe )%meri$alI ,MTL T9pe
, CT De%as
-l!age Class : 11 k-5re>%en$9 : + @
Shr! !ime ra!ing : 1.+ kA fr 3 se$.M%n!ing: CTs are m%n!ed in 11k- Si!$hgear C%7i$le.CT Ra!i : Cre & 1
5 1 A Primar9
1 1 A Se$ndar9CT Class: +P
AL5 2
+ -A
R$! = , 6hms$$.ma = 2.+ kA
" Ca!ua%on o $A ur6en o %8e CT Core
-A #%rden f !he Rela9 (S'21; = .1Ref Ch.+I Pg. "1 :SP 2';
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = " M%r
CT & Rela9 m%n!ed in 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le 3= 1B2; D2 0.3 3 / 1E= 1; .++= .553 O8m
CTs in!ernal Resis!an$e+/1 Tap a! (+?C; R$! = 2 6hm
CTs in!ernal #%rden = snB2; DR$!E
1B2; D2E, $A
The e!ernal Ra!ed #%rden =
= .1F.++;= .53 $A
.5 CTs or a!#u4 Pro%e!%on - 55+N(5#$A Ou%'on' ee6er n ++#$ s.'ear)
pn
sn
Ra!ed#%rden:
!#te:As per SIEE!S re%a +S"02 re/#mme$dat#$ - Seme$s SIP 3.3- the ma7mum hgh set a25 tmes <I$<. =th C' rat$g I$950A the ma7mum hgh set /urre$t t# h/h the re%a %% se$se s 25 7 51#r fast p/-up tme the the /urr
Rr -A a! S)
RL
Pi
RrF R
L;
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Larsen & Toubro (Oman) LLCProj.: MADINAT AL NAHDAH PH-7 PR-SS
Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 75 o 33
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 7 o 33
@en$e $nne$!ed -A ! CT Cre = 1.2 4!ernal #%rdeni!h design margin f 2G; = 1.2 .'+;
= .72 $A
Sele$!ed -A #%rden fr CT $re = 5 $A & is s%ff
5 Ca!ua%on o CT <Re;ure6 A!!ura!9 Lm%n' =a!%or< (refer SIP-2004, Chapter 2, Pg.53)
Minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &
here &
= minim%m re>%ired s9mme!ri$al shr!&$ir$%i! $%rren
= maim%m shr!&$ir$%i! $%rren! in Ampere;= 2+ Amppn = )minal CT primar9 $%rren! in Ampere;
= + Amp
= maDhigh&se! pin! / pn;I 2E
= maD2+ / +;I 2E= 5.
Th%s !he minim%m re>%ired CT s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r &> 5
Ca!ua%on o CT <O4era%n' A!!ura!9 Lm%n' =a!%or<
here &
= Ra!ed s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r = KnAL5= 2
= Ra!ed resis!ive 7%rden f CT in 6hm;= +
= Cnne$!ed resis!ive 7%rden in 6hm;
= .(0
= CT se$. dg. resis!an$e in 6hm;
= 2
= 4ffe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r
) 7ased n !he a7ve frm%la !he effe$!ive s9mme!ri$al shr!&$ir$%i! $%rren! fa$!r is $al$%la!ed as fl
=
= 2 D+F2; / .(0F2;E= 2 D( / 2.(0E
= +.1(021Th%s !he 6pera!ing CT AL5> 5.+3
P#C
P#)
Ks$$1
high&se! pin!
Kss$1
?s!!+
Kss$
R#)
R#C
R$!
Kss$
Kss$
Kss$
DR#)
F R$!; / R
#C F R
$!;E
?<ss!
K ' ssc= K
ssc× ( RBC + Rct
RBN + R
ct )
K ' ssc1≥max[( I high−set po int
I pn ) , 20]
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 77 o 33
. Con!uson :
1
2 Summar9 o CT 4arame%ers
CT Ra!i : +&1/1Class : +P2
R$! ma.; : , 6hmRa!ed #%rden: + -A
5rm +; * '; a7veI !he 6pera!ing CT AL5 is +.1 hile !he Re>%ired CT AL5 is + i.e. As 6pera!ing CT AL5 J Re>%ired CT AL5 !he sele$!ed CT is ACC4PTA#L4
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 73 o 33
&&&&1; Siemens
/ 1E
&&&&2;
&&&&3;
&&&&";
8a%a;%e s9 250A.
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 72 o 33
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3 o 33
i$ien!
! fa$!r
&&&&';
ls &
&&&&+;
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3+ o 33
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3, o 33
+. A44!a%on
Me!ering
,. Me%ers !onne!%e6
a. Make 7. Mdel $. -A #%rden .+d. 8!9. )s.; 1e )e! -A .+
". CT De%as
CT Ra!i Cre&1
+ 1 A Primar91 1 A Se$ndar9
CT Class: 1. Ra!ed #%rden: 1+ -A -l!age k-;: 11S5 H 1 Ra!ed s9s!em fa%l! $%rren! in kA * !ime in se$.; : 1.+ 3 se$.
0. Ca!ua%on o $A ur6en o %8e CT Core
= .+ -A &&&&1;
Lead #%rdenReferring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;
Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/km
Single Lead Leng!h f !he $a7le frm = 5 M!r CT ! Me!ers m%n!ed in Sgr. L- C%7i$le * 33k- CRP
@en$e 2 a9 Lead #%rden f !he $a7le = snB2; D2 mpd. f !he $a7le + / 1E= 1B2; D2 0.3 + / 1E= 1; .03
= .2" 6hm &&&&2;
The e!ernal #%rden =
= .+ F .03;
= 1."3 -A &&&&";
@en$e $nne$!ed -A ! CT Cre = 1.+ 4!ernal #%rdeni!h design margin f +G; = 1.+ 1."3;
= " $A &&&&+;
@en$e Sele$!ed -A #%rden fr CT $re = +5 $A &&&&';
- s su!en%
5. Con!uson :
. CTs or - Me%ern'(5#$A Ou%'on' ee6er n ++#$ s.'ear)
,A 11k-Sgr.;
P)
S)
S%m f !he -A #%rden f !he Me!ers $nne$!edI Rm
RL
Rm F RL
P#C
P#)
The Cnne$!ed CT 7%rden is 3 hile !he Ra!ed CT 7%rden is 1+
i.e. As Ra!ed CT 7%rden is J Cnne$!ed CT 7%rden !he sele$!ed CT is ACC4PTA#L4
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3" o 33
Se!%on - 7 : PT
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 30 o 33
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
DDo!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 35 o 33
+. A44!a%on
Me!ering and pr!e$!in
,. PT Ra%o & De%as
Ra!i Cl Vni! Cnne$!in L$a!in
11/Z3 - S!ar Primar9
11/Z3 Cl: 1. - S!ar Se$ndar9
11/3 Cl: 3P - 6pen del!a Se$ndar9
". Lea6 ur6en
Referring ! Ta7le & ' f 6man Ca7le Ca!alg%e fr P-C ins%la!ed LT/Cn!rl $a7les;Resis!an$e f 2.+s>mm Ca7le a! (?C : 0.3 6hms/kmRea$!an$e f 2.+s>mm Ca7le a! (?C .111 6hms/km@en$e mpedan$e f 2.+S>mm Ca7le : S8RTD0.3B2;F.111B2;E
= S8RTD'."0F.12321E= S8RTD'.+2321E= 2." 6hms/km
Single Lead Leng!h f !he -T $a7le frm 33k- Sgr ! 33k-Pr!e$!in / Cn!rl / Me!ering Panel = 5 M!r
@en$e 2 a9 Lead impedan$e f !he $a7le = D2 mpd. f !he $a7le + / 1E= D2 0.3'' + / 1E= .03''= .2" 6hms &&&&1;
0. $A ur6en or Pro%e!%on $T Core
0.+ De%as o Rea9s bur6en !onne!%e6 %o $T !ore
Sno Rea9 Ma#e Mo6e
1 S4M4)S (S'211 .2 1 .'
#%rden .' '(22.222
Cnne$!ed 3ph #%rden = .' -A &&&&2;Cnne$!ed Rela9s Resis!an$e = '(22.222 6hms
Lead Resis!an$e f $a7le = .03'' 6hms@en$e !!al Resis!an$e in -T $ir$%i! = '(23.1+2 6hm Ph&);
C%rren! !hr%gh !he -T Cir$%i! = .+"+3(00 Amps@en$e Lead $a7les 3Ph -A #%rden = .2001104&+ -A &&&&3;
@en$e !!al 7%rden n -T $re = 2; F 3;= .'20012 -A
i!h 2G ,esign Margin re>%ired -A #%rden = .(200+0" -A
Sele$!ed -A #%rden f -T Cre = , -A * @en$e s%ffi$ien!
7.+ PT or In!omer ne ee6ers PT(++#$ S%!8'ear)
-P)
-S)
-S)
$AP8 ur6enn $T Cr!u%
Juan%%9(No)
Ne% " P8 $Abur6en on$T Core
O8m!Im4e6an!e1aue (O8m)
(P8-N)
'(/'() & #a$k%p dire$!inal
Pr!e$!in
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Do!.: ++?$ Curren% Transormer S*n' Ca!ua%ons
DDo!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 3 o 33
5. $A ur6en or Man Me%ern' $T Core
5.+ De%as o Me%er bur6en !onne!%e6 %o $T !ore
Sno Me%er Ma#e Mo6e
1 -l!me!er . . 1 1 3
2 . . .+ 1 1.+
3 . . .+ 1 1.+
" . . .13" 1 ."3
+ . . .13" 1 ."3
#%rden '.'''( '(1.32
Cnne$!ed 3ph #%rden = '.'''''( -A &&&&";Cnne$!ed Me!ering Resis!an$e = '(1.32 6hms
Lead Resis!an$e f $a7le = .03'' 6hms@en$e !!al Resis!an$e in -T $ir$%i! = '(2.2+ 6hm Ph&);
C%rren! !hr%gh !he -T Cir$%i! = .0""(1'310 Amps@en$e Lead $a7les 3Ph -A #%rden = .2"0221 -A &&&&+;
@en$e !!al 7%rden n -T $re = "; F +;= '.320'("( -A
i!h 2G ,esign Margin re>%ired -A #%rden = (.230+'2'"0( -A
Sele$!ed -A #%rden f -T Cre = , -A * @en$e s%ffi$ien!
. Re!ommen6e6 ++#$ S%!8'ear PT De%as or ++#$ In!omers
A44!a%on Conne!%on Cass $A ur6en
11/Z311/3 6pen ,el!a 3P 2
11/Z3 S!ar 1. 2
$AP8 ur6enn $T Cr!u%
Juan%%9(No)
Ne% " P8 $Abur6en on$T Core
O8m!Im4e6an!e1aue (O8m)
(P8-N)
-l!age!ransd%$er
5re>%en$9!ransd%$er
MTransd%$er
M-ARTransd%$er
Prmar91o%a'e ($
PN)
Se!on6ar91o%a'e ($
SN)
Pr!e$!inCre
Me!eringCre
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Do!. No.:++,MAN/7A0Re1.+
Da%e:2.++.
Ppd.: AKRChkd: AKSM/SRKR Pa'e 37 o 33
Se!%on - 3 : CATALOB/