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اﻟﺸﺮآﺔ اﻟﺴﻌﻮدﻳﺔ ﻟﻠﻜﻬﺮﺑﺎء
Centeral Region Branch
ﻓﺮع اﻟﻤﻨﻄﻘﺔ
CHEK'D
Y.R
DESCRIPTION
ISSUED FOR BASE DEISGN
Y.R
M.A
APP'D CERT'D
Saudi Electricity Company
A
NO.
DATE
JAN- '12
BY
DAR
CT SIZING CALCULATION
REVISIONS DESIGNED Y.R
BY:DATE:-
JAN - '12 CHECKED Y.R
BY:DATE:-
JAN - '12 OPRG. DEPT
BY DATE:-
JAN - '12
ENG'G. DEPT. BY:DATE:-
CERTIFIED. BY:DATE:THIS DRAWING IS NOT TO BE USED FOR CONSTRUCTION OF FOR ORDERING MATERIALS UNTIL CERTIFIED AND DATED
AS BUILT BY INDEX
132kV CT SIZING CALCULATION FOR
9016 SUBSTATIION RIYADH
1/21/2012
DATE DOCUMENT TITLE
A
PLANT
C269
DOCUMENT NO.
SHEET NO.
CE-267304
1 OF 50
SAUDI ARABIA CONTRACT NO: 11031117/00
DWG.CON. SHT.
REV.
A
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Sr. No
DESCRIPTION
Sht.No
1
COVER SHEET
1
2
INDEX
2
3
CT DATA
3‐9
4
STSTEM DATA
10‐11
5
87T1‐GT(RET670) CT CALCULATION
12‐13
6
87T2‐GT(RET670) CT CALCULATION
14‐15
7
87C1+95C1‐SGT(REC670) CT CALCULATION
16‐17
8
87C2+95C2‐SGT(REB670) CT CALCULATION
18‐19
9
SGT 132kV OC‐EF CT CALCULATION
20‐21
10
87C+95C (REC670)‐132kV REACTOR CT CALCULATION
22‐23
11
87R+95R(REB650)‐REACTOR CT CALCULATION
24‐26
12
50‐51+50BF1(BUILT IN)‐REACTOR CT CALCULATION
27‐28
13
51NR(REF615)‐REACTOR CT CALCULATION
29‐30
14
BS‐BC 50‐51+50BF1+50CBF2 CT CALCULATION
31‐32
15
87B+95B‐DISC(REC670) CT CALCULATION
33‐34
16
87B+95B‐CHK(REC670) CT CALCULATION
35‐36
17
SGT 132kV METERING CT CALCULATION
37‐38
18
METERING‐GT FEEDERS CT CALCULATION
39‐40
19
METERING‐SPARE OG FEEDERS CT CALCULATION
41‐42
20
METERING‐CAPACITOR FEEDERS CALCULATION
43‐44
21
METERING‐SPARE SVC BAY CT CALCULATION
45‐46
22
METERING‐REACTOR FEEDERS CT CALCULATION
47‐48
23
132kV BS‐BC METERING
49‐50
INDEX
CE‐267304
2/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No =D22 ( SPARE SVC BAY )
CT DATA
CT No
Function
Relay Type
CT Primary Adopted CT ( Amp) Tap ( Amp) Secondary
IPCT + DM(LCC) + ALPHA‐A3 3000‐2500‐ Energy + DSM + 2000‐1600‐ IPCT 1200‐1000 Meter + DSM
1
T11 CORE‐3
2
T11 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
3
T11 CORE‐1
MAIN‐1 PROTN (FUTURE)
‐
4
T12 CORE‐1
BCU + FR
5
T12 CORE‐2
87B (DISC ZONE)
REC670
6
T12 CORE‐3
87B (CHK ZONE)
REC670
CT Class
CT Knee Point Voltage
CT CT Knee CT CT CT Magnetizin Point Resistance Magnetizin g Current Resistance Voltage At Selected g Current ( At Selected (Ohms) Adopted Tap (Ohms) mAmp ) Tap Tap
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
3000‐2500‐ 2000‐1600‐ 1200‐1000
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
3000‐2500‐ 2000‐1600‐ 1200‐1000
NA
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
NA
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
NA
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
7MD664 + 3000‐2500‐ FR ( 2000‐1600‐ Hathaway ) 1200‐1000
CE‐267304
3/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No =D17, =D02 ( SPARE CAPACITOR BAYS )
CT DATA
CT Class
CT Knee Point Voltage
CT Primary Adopted CT ( Amp) Tap ( Amp) Secondary
CT Class
CT Knee Point Voltage
Sr. No
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
Sr. No
CT No
Function
Meter Type
1
T13 CORE‐3
2
T13 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
3
T13 CORE‐1
MAIN‐1 PROTN (FUTURE)
‐
4
T14 CORE‐1
BCU+FR
5
T14 CORE‐2
87B (DISC ZONE)
REC670
6
T14 CORE‐3
87B (CHK ZONE)
REC670
IPCT + ALPHA‐A3 2000‐1600‐ DM(LCC) + + DSM + 1200‐1000‐ Energy IPCT 800 Meter +
CT Knee Point Voltage At Adopted CT Knee Point Voltage At Adopted
CT Magnetizin g Current ( mAmp ) CT Magnetizin g Current ( mAmp )
CT CT CT Resistance Magnetizin Resistance Selected g Current (Ohms) Tap (Ohms) At Selected CT CT CT Magnetizin Resistance Resistance At Tap‐2 At Tap‐1 g Current (Ohms) At Selected (Ohms)
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
1750
10‐12.5‐ 16.7‐20‐25
20
5‐4‐3‐2.5
3
2000‐1600‐ 1200‐1000‐ 800
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
‐
10‐12.5‐ 16.7‐20‐25
‐
5‐4‐3‐2.5
‐
2000‐1600‐ 1200‐1000‐ 800
NA
1
X
3500‐2800‐ 2100‐1750‐ 1400
‐
10‐12.5‐ 16.7‐20‐25
‐
5‐4‐3‐2.5
‐
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
1750
10‐12.5‐ 16.7‐20‐25
20
5‐4‐3‐2.5
3
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
7MD664 + 2000‐1600‐ FR ( 1200‐1000‐ Hathaway ) 800
CE‐267304
4/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No=D01, =D03, =D07, =D08, =D11, =D13, =D15, =D19, =D12, =D16, =D18, =D20, =D24 ( SPARE UG & OHL FEEDERS )
CT DATA
CT Class
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
1600‐1200‐ 800‐600
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
7MD664 + 1600‐1200‐ FR ( 800‐600 Hathaway )
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
CT No
Function
1
T3 CORE‐1
Energy Meter + DSM Through IPCT
ALPHA‐A3 1600‐1200‐ + DSM + 800‐600 IPCT
800
2
T3 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
1600‐1200‐ 800‐600
3
T3 CORE‐3
MAIN‐1 PROTN (FUTURE)
‐
4
T4 CORE‐1
BCU + FR
5
T4 CORE‐2
87B (DISC ZONE)
REC670
6
T4 CORE‐3
87B (CHK ZONE)
REC670
Sr. No
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
CT Knee Point Voltage
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CE‐267304
5/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No=D04, =D09, =D10 ( 132/13.8kV GT Bays )
CT DATA
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
1
IPCT + DM(LCC) + DM(LCC) + BCU(LCC) + T5 CORE‐1 BCU(LCC) + DSM + DSM + AMR + PQM AMR + PQM
2
T5 CORE‐2
3
T5 CORE‐3
4
5
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
300
300
1
5P20, 30VA
NA
NA
NA
NA
NA
NA
300
300
1
X
360
360
50
50
1
1
MAIN‐1 PROTN RET670 + (BOX‐1) + HATHAWAY FR
300
300
1
X
360
360
50
50
1
1
T6 CORE‐1
87B (DISC ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
T6 CORE‐2
87B (CHK ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
MAIN‐2 PROTN (BOX‐2)
RET670
CE‐267304
6/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No=D21, =D26 ( 132kV Reactor Bays )
Shunt Reactor Bushing CTs
CT DATA
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
1
DPDM(LCC) +BCU(LCC) + FR + IPCT T7 CORE‐1 + ENERGY METER + DSM
2
T7 CORE‐2 50/51N + FR REF615 + FR
1200‐600‐ 400‐200
200
1
X
2400‐1200‐ 800‐400
400
8.33‐16.7‐ 25‐50
50
6‐3‐2‐1
1
3
T7 CORE‐3 87C + 95C
REC670
1200‐600‐ 400‐200
1200
1
X
2400‐1200‐ 800‐400
2400
8.33‐16.7‐ 25‐50
8.33
6‐3‐2‐1
6
4
T8 CORE‐1
87B (DISC ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
5
T8 CORE‐2
87B (CHK ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
1
LC1‐1
87R+95R
REB650
600‐400‐ 200
200
1
X
NOT AVILABLE
400
NOT AVILABLE
50
NOT AVILABLE
1
2
LC1‐2
87C+95C
REC670
1200‐600‐ 400‐200
1200
1
X
3
NC1‐1
49 ( WIND TEMP )
4
NC2‐1
87R+95R
REB650
600‐400‐ 200
200
1
X
5
NC2‐2
51NR
REF615
400
400
1
5P20, 15VA
DPDM(LCC) +BCU(LCC) + FR + IPCT 1200‐600‐ 400‐200 + ENERGY METER + DSM
200
1
X
2400‐1200‐ 800‐400
400
8.33‐16.7‐ 25‐50
50
6‐3‐2‐1
1
CE‐267304
400
50
1
7/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
1
2 132kV Bay No=D05, =D06, =D14 ( 132kV SIDE SGT BAYS )
CT No
Function
Meter / CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
DPDM(LCC) DPDM(LCC) +BCU(LCC)+ T1 CORE‐1 +BCU(LCC)+ 3000‐1500 ALPHA‐ EM+DSM A3+DSM SGT 132kV SIDE 50/51NS + REF615 + REC670 + 3000 5CBF1 T1 CORE‐2 (REC670) + REB650 50CBF2(REB 650)
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
3000
1
0.2FS5, 30‐ 15VA
NA
NA
NA
NA
NA
NA
3000
1
X
1000
1000
25
25
7
7
3
T1 CORE‐3 87C2+95C2
REB650
3000
3000
1
X
1000
1000
25
25
7
7
4
T1 CORE‐4 87C1+95C1
REC670
3000
3000
1
X
1000
1000
25
25
7
7
5
T2 CORE‐1
SPARE
‐
3000
3000
1
X
1000
1000
25
25
7
7
6
T2 CORE‐2
87B (DISC ZONE)
RET670
4000
4000
1
X
800
800
25
25
6
6
7
T2 CORE‐3
87B (CHK ZONE)
RET670
4000
4000
1
X
800
800
25
25
6
6
1
BCT‐3
87C1+95C1
REC670
3000
3000
1
X
1000
1000
25
25
7
7
2
BCT‐4
87C2+95C2
REB650
3000
3000
1
X
1000
1000
25
25
7
7
SGT Bushing CTs
CT DATA
CE‐267304
8/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No=D130, =D230, =D120, =D220 ( 132kV BUS SECTION & BUS COUPLER BAYS )
CT DATA
Function
CT Class
1
0.2FS5, 30‐ 15VA
NA
NA
NA
NA
NA
NA
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
Sr. No
CT No
1
T9 CORE‐1
DPDM(LCC) DPDM(LCC) 4000‐2000 +BCU(LCC) +BCU(LCC)
2000
2
T9 CORE‐2
87B (DISC ZONE)
RET670
4000
6
T10 CORE‐1
87B (DISC ZONE)
REC670
7
T10 CORE‐2
50/51 + 50N/51N + REF615 + 50BF1+50BF REF615 2
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
CT Knee Point Voltage
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CE‐267304
9/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
System Data
System Fault Level, Ikmax1
40 kAmp
Voltage Level, Vp
132 kV
System X / R Ratio
50
Copper Prperties
Resitivity of Copper at 20 oC, ρ
17.2 nΩm
Temperature Coefficient of Copper, α
0.0039
First Temperature
20 oC
Second Temperature
75 oC
Change in Temperature, ∆t
55 oC
CT Secondary Cct Cable Data For 4mm2 Size
4 mm2
Area of Cross Section, A Length of the Conductor
1000 mm
Resistance per 1000 mm at 20 oC, R20 = ρ x l / A
0.0043 Ω
First Teperature, T1
20 OC
Second Teperature, T2
75 OC
Difference in Temperaturwe, ∆t = T2 ‐ T1
55 OC
Resistance at 75oC, R75 = R20 x ( 1 + α x ∆t )
SYSTEM DATA
CE‐267304
0.00522235 Ω
10/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
CT Secondary Cct Cable Data For 10mm2 Size
10 mm2
Area of Cross Section, A Length of the Conductor
1000 mm
Resistance per 1000 mm at 20 oC, R20 = ρ x l / A
0.00172 Ω
First Teperature, T1
20 OC
Second Teperature, T2
75 OC
Difference in Temperaturwe, ∆t = T2 ‐ T1
55 OC
Resistance at 75oC, R75 = R20 x ( 1 + α x ∆t )
SYSTEM DATA
CE‐267304
0.00208894 Ω
11/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT Data ( GT Bays, =D09, =D04, =D10 ) CT No
T5 CORE‐3 MAIN‐1 PROTN (BOX‐ 1) + FR RET670 + HATHAWAY
Function Relay Type CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
360
Volts
CT Knee Point Voltage At Adopted Tap
360
Volts
CT Magnetizing Current ( mAmp )
50
mAmp
CT Magnetizing Current At Selected Tap
50
mAmp
CT Resistance (Ohms)
1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation 2
Lead Burden Lead Burden CT Cable Route Length ( One Way ) CT Cable Size
3
metre
4
mm2
CT Cable Resistance per metre
Reffer System Data
0.00522235
Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 200
1.04447
Ω
VA Burden of RET670 CT Input
0.02
VA
VA Burden of FR CT Input
0.05
VA(As sumed
Relay Burden
Total VA Burden
=0.02 + 0.05
Rated Secondary Current, In Relay CT Input Resistance = VA / In2 4
200
0.07 1
=0.07 / 1^2
0.07
Amp Ω
CT Stability Criterion
87T1‐GT(RET670)
CE‐267304
12/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS There arae two criterion for estimating the minimum requirement for CT Knee Point Voltage Criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ], Where, Int = transformer rated current, Ipn = CT Primary rated Current, & Isn = CT Secondary rated current Criterion No.2, Vk = 2 x Itf x ( Isn / Ipn ) x [ Rct + 2 x Rlead + Rrelay ], Where, Itf = transformer through fault current The maximum external ( through ) fault current is limited by the %Z of the transformer and given by Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) 132/13.8kV GT MVA Rating
60
MVA
Grid Transformer % Impedance, %Z
10
%
Grid Transformer HV Side Voltage, kV
132
kV
=60 x 10^5/(SQRT(3) x 132 x 10)
2624.32
Amp
=60 x 1000/(SQRT(3) x 132)
262.432
Amp
=30 x 262.432 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.07)
82.901
Volts
=2 x 2624.32 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.07) 1 04447 + 0 07)
55.267 55. 67
Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) Transformer rated current, Itn = MVA (TF) x 1000 / (SQRT(3) x kV ) Knee point voltage as per criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] Knee point voltage as per criterion No.2, Vk x Itf x (Isn/ Ipn) x [ Rct x Rlead Rrelay Vk = 2 x Itf x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] The required knee point = max ( Criterion No.1 , Criterion No.2 ) CT Actual Knee Point Voltage
82.901
Volts
360
Volts
Hence the CT Knee Point Voltage is OK
87T1‐GT(RET670)
CE‐267304
13/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT Data ( GT Bays, =D09, =D04, =D10 ) CT No
T5 CORE‐2 MAIN‐2 PROTN (BOX‐2)
Function Relay Type
RET670
CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
360
Volts
CT Knee Point Voltage At Adopted Tap
360
Volts
CT Magnetizing Current ( mAmp )
50
mAmp
CT Magnetizing Current At Selected Tap
50
mAmp
CT Resistance (Ohms)
1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation 2
Lead Burden Lead Burden CT Cable Route Length ( One Way ) CT Cable Size
3
metre
4
mm2
CT Cable Resistance per metre
Reffer System Data
0.00522235
Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 200
1.04447
Ω
0.02
VA VA
Relay Burden VA Burden of RET670 CT Input VA Burden of FR CT Input
( No FR )
0
Total VA Burden
=0.02 + 0
0.02
Rated Secondary Current, In Relay CT Input Resistance = VA / In2 4
200
1 =0.02 / 1^2
0.02
Amp Ω
CT Stability Criterion
87T2‐GT(RET670)
CE‐267304
14/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS There arae two criterion for estimating the minimum requirement for CT Knee Point Voltage Criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ], Where, Int = transformer rated current, Ipn = CT Primary rated Current, & Isn = CT Secondary rated current Criterion No.2, Vk = 2 x Itf x ( Isn / Ipn ) x [ Rct + 2 x Rlead + Rrelay ], Where, Itf = transformer through fault current The maximum external ( through ) fault current is limited by the %Z of the transformer and given by Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) 132/13.8kV GT MVA Rating
60
MVA
Grid Transformer % Impedance, %Z
10
%
Grid Transformer HV Side Voltage, kV
132
kV
=60 x 10^5/(SQRT(3) x 132 x 10)
2624.32
Amp
=60 x 1000/(SQRT(3) x 132)
262.432
Amp
=30 x 262.432 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.02)
81.589
Volts
=2 x 2624.32 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.02) 1 04447 + 0 02)
54.392 54.39
Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) Transformer rated current, Itn = MVA (TF) x 1000 / (SQRT(3) x kV ) Knee point voltage as per criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] Knee point voltage as per criterion No.2, Vk x Itf x (Isn/ Ipn) x [ Rct x Rlead Rrelay Vk = 2 x Itf x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] The required knee point = max ( Criterion No.1 , Criterion No.2 ) CT Actual Knee Point Voltage
81.589
Volts
360
Volts
Hence the CT Knee Point Voltage is OK
87T2‐GT(RET670)
CE‐267304
15/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
SGT Bays, Bay No =D05, D06, D14 1
CT Data T1 CORE‐ 4 87C1+95C 1
CT No Function Relay Type
2
REC670
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
7
Ω
CT Resistance Selected Tap (Ohms)
7
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 3000
13.333
=13.333 x (7 + 2 x 2.08894)
149.035 Volts
=1.2 x 149.035
178.842 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
179
Volts
1790
Ω
To provide greater stability against through faults, the Voltage setting of 179 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=179 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet
87C1+95C1‐SGT(REC670)
CE‐267304
16/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
4.48
mAmp
0
mAmp
0
mAmp
104.48
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage Iop = Ir + Im + Isupvn + Imet
=100 + 4.48 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 3000
3600
Amp
Required Secondary Operating Current, Iops
=3600 x 10001 / 3000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 104.48
1095.52 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=179x 1000 / 1095.52
163.39
Ohms
=179^2/163.39
196.1
Watts
2
Required Wattage of Shunt Resistor = Vs / Rsh 5
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 3000
750
Amp
Secondary current during minimum load, Ismin
=750 x 1 / 3000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
1790
Ω
Relay Shunt resistance, Rsh
Calculated above
163.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 1000 / 7
142857.1 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1790 x 163.39 x 142857.142857143 / (1790 x 163.39 + 1790 x 149.567 Ω 142857.142857143 + 163.39 x 142857.142857143)
Voltage developed across the CT supervision relay = =0.25 x 149.567 Ismin x R The current through the relay and series resistance =37.39175 / 1790 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87C1+95C1‐SGT(REC670)
CE‐267304
37.39175 Volts 0.021
Amp
38
Volts
17/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
SGT Bays, Bay No =D05, D06, D14 1
CT Data T1 CORE‐ 3 87C2+95C 2
CT No Function Relay Type
2
REB650
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
7
Ω
CT Resistance Selected Tap (Ohms)
7
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 3000
13.333
=13.333 x (7 + 2 x 2.08894)
149.035 Volts
=1.2 x 149.035
178.842 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REB650 + Series Resistance Combination REB650 Current Setting Range
0.02 ‐ 1 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
179
Volts
1790
Ω
To provide greater stability against through faults, the Voltage setting of 179 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=179 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet
87C2+95C2‐SGT(REB650)
CE‐180973
18/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
Where Ir = REB650 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
4.48
mAmp
0
mAmp
0
mAmp
104.48
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 4.48 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 3000
3600
Amp
Required Secondary Operating Current, Iops
=3600 x 10001 / 3000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 104.48
1095.52 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=179x 1000 / 1095.52
163.39
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=179^2/163.39
196.1
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 3000
750
Amp
Secondary current during minimum load, Ismin
=750 x 1 / 3000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
1790
Ω
Relay Shunt resistance, Rsh
Calculated above
163.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 1000 / 7
142857.1 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1790 x 163.39 x 142857.142857143 / (1790 x 163.39 + 1790 x 149.567 Ω 142857.142857143 + 163.39 x 142857.142857143)
Voltage developed across the CT supervision relay = =0.25 x 149.567 Ismin x R The current through the relay and series resistance cct, Ir = Vr / Rs
=37.39175 / 1790
Hence the CT supvn element pickup Voltage
87C2+95C2‐SGT(REB650)
CE‐180973
37.39175 Volts 0.021
Amp
38
Volts
19/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
BAY No =D05, =D06, =D14 1
CT DETAILS CT No
T1 CORE‐2 SGT 132kV SIDE 50/51NS + 5CBF1 (REC670) + 50CBF2(REB650) REF615 + REC670 + REB650
Function
Meter / Relay Type
2
3
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mA
CT Magnetizing Current At Selected Tap
25
mA
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms)
7 7
Ω Ω
METER BURDEN DETAILS 50/51NS Burden
0.1
50CBF1 Burden
0.1
50CBF2 Burden
0.0001
VA(Assumed ) VA(Assumed ) VA
Any Other Device Burden
( No other device )
0
VA
Total Burden
=0.1 + 0.1 + 0.0001 + 0
0.2001
VA
Total Burden Resistance, Rb = VA / In2
=0.2001 / 1^2
0.2001
Ω
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A
4
Lead Resistance per metre, rl
Reffer System Data
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
0.00522235 Ω / metre 1.04447 Ω
CLASS X CONVERSION TP P CLASS The following formula is used to convert class X CT to equivalent P class CT Vk = Fn x In x [ Rct + Sn / In^2 ] / 1.3 OR Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] x In^2 Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] x In^2
SGT 132kV OC‐EF
CE‐267304
20/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Fn Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] / In^2 4
20 = 1.3 x 1000 / (20 x 1 ) ‐ 7) x 1^2)
58 VA
CRITERION FOR METERING CLASS CT ADEQUACY Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
20
Sn = CT Rated VA Burden
58 VA
Sin = In2 x Rct
=1^2 x 7
Sa = In2 x [ Rlead x 2 + Rrelay ]
=1^2 x ( 2 x 1.04447 + 0.2001)
Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
=20 x (7 + 58 ) / (7 + 2.28904)
7 VA 2.28904 VA
139.95
The CT is OK since Fa > Fn
SGT 132kV OC‐EF
CE‐267304
21/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Reactor ( Bay No =D21, =D26) 1
CT Data CT No
T7 CORE‐ 3
Function
87C + 95C
Relay Type
REC670 1200‐600‐ Amp 400‐200
CT Primary ( Amp) Adopted Tap ( Amp)
1200
Amp
CT Secondary
1
Amp
CT Class
X 2400‐ 1200‐800‐ Volts 400
CT Knee Point Voltage CT Knee Point Voltage At Adopted Tap
2400
8.33‐16.7‐ mAmp 25‐50
CT Magnetizing Current ( mAmp ) CT Magnetizing Current At Selected Tap
8.33
mAmp
6‐3‐2‐1 Ω
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms) 2
Volts
6
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 1200
33.333
=33.333 x (6 + 2 x 2.08894)
339.259 Volts
=1.2 x 339.259
407.111 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
408
Volts
4080
Ω
To provide greater stability against through faults, the Voltage setting of 408 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=408 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme
87C+95C (REC670)‐132kV REACTOR
CE‐267304
22/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
1.42
mAmp
0
mAmp
0
mAmp
101.42
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage Iop = Ir + Im + Isupvn + Imet
=100 + 1.42 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 1200
1440
Amp
Required Secondary Operating Current, Iops
=1440 x 10001 / 1200
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 101.42
1098.58 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=408x 1000 / 1098.58
371.39
Ohms
=408^2/371.39
448.22
Watts
2
Required Wattage of Shunt Resistor = Vs / Rsh 5
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 1200
300
Amp
Secondary current during minimum load, Ismin
=300 x 1 / 1200
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
4080
Ω
Relay Shunt resistance, Rsh
Calculated above
371.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 2400 / 6
400000 Ω
=4080 x 371.39 x 400000 / (4080 x 371.39 + 4080 x 400000 + 371.39 x 400000)
340.115 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
Voltage developed across the CT supervision relay = =0.25 x 340.115 Ismin x R The current through the relay and series resistance =85.02875 / 4080 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87C+95C (REC670)‐132kV REACTOR
CE‐267304
85.02875 Volts 0.021
Amp
86
Volts
23/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT Data ( Reactor Bay =D21 & =D26 ) CT No
LC1‐1
Function
87R+95R
Relay Type
REB650
CT Primary ( Amp)
600‐400‐ 200
Amp
200
Amp
CT Secondary
1
Amp
CT Class
X
Adopted Tap ( Amp)
NOT Volts AVILABLE
CT Knee Point Voltage CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current At Selected Tap
50
mAmP
NOT Ω AVILABLE
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm
2
0.00522235 Ω
CT Cable Resistance per metre Total CT Cable Resistance ( One Way ) 3
Volts
NOT mAmP AVILABLE
CT Magnetizing Current ( mAmp )
2
& NC2‐1
=0.00522235 x 400
2.08894
Ω
Reactor Through Fault Current Calculation Reactor MVAR rating
40
MVAR
Reactor Voltage Rating, kV
132
kV
Reactor Through Current, Itr = 1000 x MVA / [ =40 x 1000 / [SQRT(3) x 132] SQRT(3) x kV ] Reactor CT Secondary Through Current, Itrs = =174.955 / 200 Itr / CT Primary Required Voltage Setting, Vsmin = Itrs x [ Rct =0.874775 x [ 1 + 2 x 2.08894] + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=1.2 x 4.53
174.955
Amp
0.874775
Amp
4.53
Volts
5.436
Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REB650 + Series Resistance Combination
87R+95R(REB650)‐REACTOR
CE‐267304
24/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS REB650 Current Setting Range
0.02 ‐ 1
Selected Current Setting, Is = 0.03 x 1000 mAmp
Amp
30
mAmp
11
Volts
To provide greater stability against through faults, the Voltage setting of 11 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=11 / 30 x 1000
366.67
Ω
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REB650 operating current
30
mAmp
1.38
mAmp
CT Supervision Relay ( Built In ) Current
0
mAmp
Imet, Metrosil Current = 0 at setting voltage
0
mAmp
31.38
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
Iop = Ir + Im + Isupvn + Imet
=30 + 1.38 + 0 + 0
It is proposed that, the primary operating current should not be less that 0.1 times the CT primary =0.1 x 200
=0.1 x 200
20
Amp
Required Secondary Operating Current, Iops
=20 x 1000 x / 400
100
mAmp
=100 ‐ 31.38
68.62
mAmp
=11 x 1000 x / 68.62
160.3
Ohms
=11^2 / 160.3
0.75
Watts
174.955
Amp
0.874775
Amp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop Required Value of Shunt Resistor, Rsh = Vs / Ish 2 Required Wattage of Shunt Resistor = Vs / Rsh 6
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. For Reactor, we take the minimum load to be 100% of the rated CT Primary Minimum load = Reactor Rated Load Secondary current during minimum load, Ismin
87R+95R(REB650)‐REACTOR
=174.955 / 200
CE‐267304
25/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance Relay series resistance, Rs
366.67
Ω
Relay Shunt resistance, Rsh
160.3
Ω
8
Ω
7.465
Ω
6.53
Volts
CT magnetizing imedance, Xm = Vk / Im
=400 / 50
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm =366.67 x 160.3 x 8 / ( 366.67 R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x x 160.3 + 366.67 x 8 + 160.3 x Rsh ] 8) Voltage developed across the CT supervision =0.874775 x 7.465 relay = Ismin x R The current through the relay and series resistance cct, Ir = Vr / Rs
=6.53/ 366.67
Hence the CT supvn element pickup Voltage
87R+95R(REB650)‐REACTOR
CE‐267304
0.018
Amp
7
Volts
26/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
2
CT DETAILS ‐ REACTOR ( Bay No =D21, =D26) CT No
T7 CORE‐2
Function
50/51N + FR
Meter / Relay Type
REF615 + FR
CT Primary ( Amp)
1200‐600‐400‐ 200
Amp
Adopted Tap ( Amp)
200
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2400‐1200‐800‐ Volts 400
CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current ( mAmp )
8.33‐16.7‐25‐50 mAmP
CT Magnetizing Current At Selected Tap
50
mAmP
CT Resistance (Ohms)
6‐3‐2‐1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
Reactor OC/EF Relay REF615 Burden
0.02
VA
FR CT Input Burden
0.02
VA
Total Device Burden
0.04
VA
Volts
RELAY BURDEN DETAILS Connected Burden
3
CT LEAD BURDEN Lead Length ( One Way ), L
100 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235 Ω / metre
Total Lead Resistance, RLEAD = rl x L
4
0.522235 Ω
CRITERION FOR OC/EF RELAY REF615 The OC/EF + 50BF relay REF615 is connected to class X CT. Its equivalent P class CT parameters are calculated by the formula, Sn = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn, Where
50‐51+50BF1(BUILT IN)‐REACTOR
CE‐267304
27/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Fn = CT Accuracy Limiting Factor at Rated Burden Sn = CT Rated VA Burden = = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn The Criterion for any P class CT used for OC/EF protection, in general is given by, Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
Sin = CT Internal Burden = In2 x Rct
20 25
1 VA
2 Sa = CT Connected Burden = In x [ Rlead x 2 + Rrelay ]
1.08447 VA
Actual Accuracy Limiting Factor, Fa = Fn x [ Sin + Sn ] / [ Sin + 249.46 Sa ] Maximum Secondary Short Circuit Current, Issc = Maximum 200 Primary ( 40kAmp ) / CT Primary The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is Fa IS OK OK if Fa > IHIGHSET
50‐51+50BF1(BUILT IN)‐REACTOR
CE‐267304
28/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
2
CT DETAILS ( Reactor Bay =D21 & =D26 ) CT No
NC2‐2
Function
51NR
Relay Type
REF615
CT Primary ( Amp)
400
Amp
Adopted Tap ( Amp)
400
Amp
CT Secondary
1
Amp
CT Class
5P20, 15VA
CT Resistance ( Assumed )
2
Ω
Reactor 51NR Relay REF615 Burden
0.02
VA
Total Device Burden
0.02
VA
RELAY BURDEN DETAILS Connected Burden
3
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L 4
=200 x 0.00522235
Ω / metre
1.04447 Ω
CRITERION FOR OC/EF RELAY 7SJ64 The Criterion for any P class CT used for OC protection, in general is given by , Fa = Fn x [ Sin + Sn ] / Fn = CT Accuracy Limiting Factor at Rated Burden Sin = CT Internal Burden = In2 x Rct
20 =1^2 x 2
Sn = CT Rated Burden
15 VA
Sa = CT Connected Burden = In2 x [ Rlead x 2 + =1^2 x ( 1.04447 x 2 + 0.02) Rrelay ] Actual Accuracy Limiting Factor, Fa = Fn x [ Sin =20 x (2 + 15 ) / ( 2 + 2.10894) + Sn ] / [ Sin + Sa ]
51NR(REF615)‐REACTOR
2 VA
CE‐267304
2.10894 VA 82.746
29/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Maximum Neutral Current = Reactor Rated Current The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa > Imax
51NR(REF615)‐REACTOR
CE‐267304
0.874775 Amp
Fa IS OK
30/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT DETAILS ( BUS SECTION =D120, =D220, BUS COUPLER =D130, =D230 ) CT No
T10 CORE‐2 50/51 + 50N/51N + 50BF1+50BF2 REF615 + REF615
Function Meter / Relay Type
2
Two No
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
NA
Volts
CT Magnetizing Current ( mAmp )
25
mAmP
CT Magnetizing Current At Selected Tap
NA
mAmP
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
NA
Ω
Bus Section OC + 50BF1 Relay REF615 Burden
0.02
VA
Bus Section EF + 50BF2 Relay REF615 Burden
0.02
VA
0.04
VA
RELAY BURDEN DETAILS Connected Burden
Total Device Burden 3
=0.02 + 0.02
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L 4
0.00522235 =0.00522235 x 200
Ω / metre
1.04447 Ω
CRITERION FOR OC/EF RELAY 7SJ64 The OC + 50BF1 & EF + 50BF2 relays REF615 are connected to class X CT. Its equivalent P class CT parameters are calculated by the formula, Sn = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn
BS‐BC 50‐51+50BF1+50CBF2
CE‐267304
31/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Fn = CT Accuracy Limiting Factor at Rated Burden
20
Sn = CT Rated VA Burden = = [ 1.3 x Vk ‐ Fn x In x Rct = ( 1.3 x 800 ‐ 20 x 1 x ] x In / Fn 6) x 1 / 20
46
The Criterion for any P class CT used for OC/EF protection, in general is given by, Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] 2 Sin = CT Internal Burden = In x Rct
=1^2 x 6
Sa = CT Connected Burden = In2 x [ Rlead x 2 + Rrelay ] Actual Accuracy Limiting Factor Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Maximum Secondary Short Circuit Current, Issc = Maximum Primary ( 40kAmp ) / CT Primary
=1^2 x ( 1.04447 x 2 + 0.04) =20 x ( 6 + 46 ) / ( 6 + 2.12894) =40 x 1000 / 4000
The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa > IHIGHSET
BS‐BC 50‐51+50BF1+50CBF2
CE‐267304
6 VA 2.12894 VA 127.94 10
Fa IS OK
32/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Busbar Discriminative Zones 1
CT Data CT No
T2 CORE‐ 2
Function
87B (DISC ZONE)
Relay Type
RET670
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
800
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
6
Ω
Note: This CT data is related to SGT bays 132kV side CTs. Note that same data is applicable to busbar protection CTs of all bays 2
CT Knee Point Voltage Calculation CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=40 x 1000 / 4000
10
Amp
=10 x (6 + 2 x 2.08894)
101.779 Volts
=1.2 x 101.779
122.135 Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
123
Volts
1230
Ω
To provide greater stability against through faults, the Voltage setting of 123 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=123 x 1000 / 100
Shunt Resistor Calculation
87B+95B‐DISC(REC670)
CE‐267304
33/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
3.84
mAmp
0
mAmp
0
mAmp
103.84
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 3.84 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 4000
4800
Amp
Required Secondary Operating Current, Iops
=4800 x 10001 / 4000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 103.84
1096.16 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=123x 1000 / 1096.16
112.21
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=123^2/112.21
134.83
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take Minimum load = 0.25 x CT Primary
=0.25 x 4000
1000
Amp
Secondary current during minimum load, Ismin
=1000 x 1 / 4000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT Relay series resistance, Rs
Calculated above
1230
Ω
Relay Shunt resistance, Rsh
Calculated above
112.21
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 800 / 6
133333.3 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)
Voltage developed across the CT supervision relay = =0.25 x 102.75 Ismin x R The current through the relay and series resistance =25.6875 / 1230 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87B+95B‐DISC(REC670)
CE‐267304
102.75
Ω
25.6875 Volts 0.021
Amp
26
Volts
34/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Busbar Check Zone 1
CT Data T2 CORE‐ 3 87B (CHK ZONE)
CT No Function Relay Type
RET670
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
800
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
6
Ω
Note: This CT data is related to SGT bays 132kV side CTs. Note that same data is applicable to busbar protection CTs of all bays 2
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=40 x 1000 / 4000
10
Amp
=10 x (6 + 2 x 2.08894)
101.779 Volts
=1.2 x 101.779
122.135 Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
123
Volts
1230
Ω
To provide greater stability against through faults, the Voltage setting of 123 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=123 x 1000 / 100
Shunt Resistor Calculation
87B+95B‐CHK(REC670)
CE‐267304
35/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
3.84
mAmp
0
mAmp
0
mAmp
103.84
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 3.84 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 4000
4800
Amp
Required Secondary Operating Current, Iops
=4800 x 10001 / 4000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 103.84
1096.16 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=123x 1000 / 1096.16
112.21
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=123^2/112.21
134.83
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take Minimum load = 0.25 x CT Primary
=0.25 x 4000
1000
Amp
Secondary current during minimum load, Ismin
=1000 x 1 / 4000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT Relay series resistance, Rs
Calculated above
1230
Ω
Relay Shunt resistance, Rsh
Calculated above
112.21
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 800 / 6
133333.3 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)
Voltage developed across the CT supervision relay = =0.25 x 102.75 Ismin x R The current through the relay and series resistance =25.6875 / 1230 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87B+95B‐CHK(REC670)
CE‐267304
102.75
Ω
25.6875 Volts 0.021
Amp
26
Volts
36/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
BAY No =D05, =D06, =D14 1
CT DETAILS CT No
T1 CORE‐1 DPDM(LCC)+B CU(LCC)+EM+ DSM DPDM(LCC)+B CU(LCC)+ALPH A‐A3+DSM
Function
Meter Type
2
3
CT Primary ( Amp)
3000‐1500
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
0.2FS5, 30‐ 15VA
CT Resistance, Rct ( Assumed )
7.5
Ω (Assumed )
DPDM (LCC ) Burden
0.1
VA(Assumed)
Bay Control Unit Burden
0.1
VA(Assumed)
Energy Meter Alpha‐A3 Burden
0.0001
VA
DSM Burden
0.1
VA(Assumed)
METER BURDEN DETAILS
Total Burden Total Burden
=0.1 + 0.1 + 0.0001 + 0.1 0 1 + 0 1 + 0 0001 + 0 1
0 3001 0.3001
VA
Total Burden Resistance, Rb = VA / In2
=0.3001 / 1^2
0.3001
Ω
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A
4
Lead Resistance per metre, rl
Reffer System Data
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
0.00522235 Ω / metre 1.04447 Ω
CRITERION FOR METERING CLASS CT ADEQUACY Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
5
Sn = CT Rated VA Burden
30 VA
Sin = In2 x Rct
=1^2 x 7.5
Sa = In2 x [ Rlead x 2 + Rrelay ]
=1^2 x ( 2 x 1.04447 + 0.3001)
CT Accuracy Limiting Factor at Rated Burden, Fn Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
SGT 132kV METERING
7.5 VA 2.38904 VA 5
=5 x (7.5 + 30 ) / (7.5 + 2.38904)
CE‐267304
18.96
37/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Maximum Secondary Short Circuit Current, Issc = Maximum Primary ( 40kAmp ) / CT Primary
=40 x 1000 x 1 / 3000
13.333 Amp
The meter security will be checked based on the actual accuracy limiting factor, if Fa < Issc, otherwise, it will be based on the maximum secondary short circuit current.
5
Maximum anticipated current in the meter, ImMAX Maximum Short duration withstand Currents
13.333 Amp
DPDM ( LCC )
20
BCU ( LCC )
20
Energy Meter
40
DSM
40
Minimum Short Duration Current
20
The meter will be safe, since ImMAX < Minimum Short Duration Current
SGT 132kV METERING
CE‐267304
38/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS GRID TRANSFORMER FEEDERS =D09, =D04, =D10 1
2
CT DETAILS CT No
T5 CORE‐1
Function
IPCT + DM(LCC) + BCU(LCC) + DSM + AMR + PQM
Relay Type
DM(LCC) + BCU(LCC) + DSM + AMR + PQM
CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
5P20, 30VA
CT Knee Point Voltage
NA
Volts
CT Knee Point Voltage At Adopted Tap
NA
Volts
CT Magnetizing Current ( mAmp )
NA
mAmp
CT M CT Magnetizing Current At Selected Tap ti i C t At S l t d T
NA
mAmp A
CT Resistance (Ohms)
NA
Ω
CT Resistance Selected Tap (Ohms)
NA
Ω
0.05
VA
LCC Digital Meter Burden
0.05
VA (Assum ed)
Alpha Meter CT Burden per phase
0.0001
VA
DSM CT Input Burden per phase
0.0001
ACCS Burden
0.05
DEVICE BURDEN DETAILS Bay Control Unit 7SMD664 Burden
Total Device Burden 3
=0.05 + 0.05 + 0.0001 + 0.0001 + 0.05
0.1502
VA (Assum ed) VA (Assum ed) VA
CT LEAD BURDEN Lead Length ( One Way ), L
METERING‐GT FEEDERS
200 metre
CE‐267304
39/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
Ω / metre
1.04447 Ω
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden Lead Burden = In2 x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1502 + 1.04447
1.19467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.2
METERING‐GT FEEDERS
CE‐267304
40/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT DETAILS ( BAY No =D19, =D17, =D15, =D13, =D11, =D07, =D03, =D01, =D02, =D08, =D12, =D16, D18, =D20, D22, =D24 CT No
T3 CORE‐1 Energy Meter + DSM Through IPCT ALPHA‐A3 + DSM + IPCT 1600‐1200‐800‐ Amp 600
Function Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
800
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2800‐2100‐ 1400‐1050
Volts
CT Knee Point Voltage At Adopted Tap
1400
Volts
CT Magnetizing Current ( mAmp )
12.5‐16.7‐25‐ 33.3
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
4‐3‐2‐1.5
Ω
CT Resistance Selected Tap (Ohms)
2
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐SPARE OG FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
41/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden Lead Burden = In2 x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐SPARE OG FEEDERS
CE‐267304
42/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT DETAILS ( BAY No =D17, =D02 ) CT No
T13 CORE‐3
Function
IPCT + DM(LCC) + Energy Meter + DSM ALPHA‐A3 + DSM + IPCT 2000‐1600‐ 1200‐1000‐800
Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
1000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
3500‐2800‐ Volts 2100‐1750‐1400
CT Knee Point Voltage At Adopted Tap
1750
CT Magnetizing Current ( mAmp )
10‐12.5‐16.7‐20‐ mAmp 25
CT Magnetizing Current At Selected Tap
20
mAmp
CT Resistance (Ohms)
5‐4‐3‐2.5
Ω
CT Resistance Selected Tap (Ohms)
3
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
Volts
DEVICE BURDEN DETAILS
Total Device Burden 3
Amp
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐CAPACITOR FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
43/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐CAPACITOR FEEDERS
CE‐267304
44/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT DETAILS ( BAY No =D22 ) CT No
T11 CORE‐3
Function
IPCT + DM(LCC) + Energy Meter + DSM ALPHA‐A3 + DSM + IPCT 3000‐2500‐ 2000‐1600‐ 1200‐1000
Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
1000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
4200‐3500‐ 2800‐2240‐ 1680‐1400
Volts
CT Knee Point Voltage At Adopted Tap
1400
Volts
CT Magnetizing Current ( mAmp )
8.33‐10‐12.5‐ 15.6‐20.8‐25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6‐5‐3.2‐2.4‐2 6 5 3.2 2.4 2
Ω
CT Resistance Selected Tap (Ohms)
2
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
Amp
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐SPARE SVC BAY
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
45/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐SPARE SVC BAY
CE‐267304
46/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS REACTOR FEEDERS =D21, =D26 1
CT DETAILS CT No
T7 CORE‐1 DPDM(LCC)+BCU (LCC) + FR + IPCT + ENERGY METER + DSM DPDM(LCC)+BCU (LCC) + FR + IPCT + ENERGY METER + DSM 1200‐600‐400‐ Amp 200
Function
Relay Type
CT Primary ( Amp)
2
Adopted Tap ( Amp)
200
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2400‐1200‐800‐ Volts 400
CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current ( mAmp )
8.33‐16.7‐25‐50 mAmp
CT Magnetizing Current At Selected Tap g g p
50
mAmp p
CT Resistance (Ohms)
6‐3‐2‐1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
Volts
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐REACTOR FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
47/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐REACTOR FEEDERS
CE‐267304
48/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS 1
CT DETAILS CT No
T9 CORE‐1 DPDM(LCC)+BC U(LCC) DPDM(LCC)+BC U(LCC)
Function Meter Type CT Primary ( Amp)
4000‐2000
Amp
Adopted Tap ( Amp)
2000
Amp
CT Secondary
1
Amp
CT Class
0.2FS5, 30‐15VA
CT Resistance, Rct ( Assumed ) 2
3.5
Ω (Assum ed )
0.1
milli Ohm
0.0001
VA
METER BURDEN DETAILS Connected Burden is the Energy Meter Alpha‐A3RAQ Alpha Meter CT Resistance per phase 2
Meter Burden at CT Secondary Rated Current = In x Rmeter 3
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L 4
=0.00522235 x 200
Ω / metre
1.04447 Ω
CRITERION FOR METERING CLASS CT ADEQUACY The Criterion for any P class CT used for OC/EF protection, in general is given by Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
5
Sn = CT Rated VA Burden
15 VA
2 Sin = CT Internal Burden = In x Rct
=1^2 x 3.5
3.5 VA
2
Sa = CT Connected Burden = In x [ Rlead x 2 + Rrelay =1^2 x ( 1.04447 x 2 + 0.0001) ] CT Accuracy Limiting Factor at Rated Burden, Fn Actual Accuracy Limiting Factor Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
132kV BS‐BC METERING
5 =5 x ( 3.5 + 15) / ( 3.5 + 2.08904)
CE‐267304
2.08904 VA
16.55
49/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
Maximum Secondary Short Circuit Current Issc = Maximum Primary ( 40kAmp ) / CT Primary The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa < Issc Maximum Continuous Current for the meter Maximum Short Duration Current = 200% of Max Continuous Current The meter will be safe, since Fa < Maximum Short Duration Current
132kV BS‐BC METERING
CE‐267304
=40 x 1000 / 2000
20
Fa IS OK 20 Amp 40 Amp
50/50
Centeral Region Branch
ﻓﺮع اﻟﻤﻨﻄﻘﺔ
CHEK'D
Y.R
DESCRIPTION
ISSUED FOR BASE DEISGN
Y.R
M.A
APP'D CERT'D
Saudi Electricity Company
A
NO.
DATE
JAN- '12
BY
DAR
CT SIZING CALCULATION
REVISIONS DESIGNED Y.R
BY:DATE:-
JAN - '12 CHECKED Y.R
BY:DATE:-
JAN - '12 OPRG. DEPT
BY DATE:-
JAN - '12
ENG'G. DEPT. BY:DATE:-
CERTIFIED. BY:DATE:THIS DRAWING IS NOT TO BE USED FOR CONSTRUCTION OF FOR ORDERING MATERIALS UNTIL CERTIFIED AND DATED
AS BUILT BY INDEX
132kV CT SIZING CALCULATION FOR
9016 SUBSTATIION RIYADH
1/21/2012
DATE DOCUMENT TITLE
A
PLANT
C269
DOCUMENT NO.
SHEET NO.
CE-267304
1 OF 50
SAUDI ARABIA CONTRACT NO: 11031117/00
DWG.CON. SHT.
REV.
A
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Sr. No
DESCRIPTION
Sht.No
1
COVER SHEET
1
2
INDEX
2
3
CT DATA
3‐9
4
STSTEM DATA
10‐11
5
87T1‐GT(RET670) CT CALCULATION
12‐13
6
87T2‐GT(RET670) CT CALCULATION
14‐15
7
87C1+95C1‐SGT(REC670) CT CALCULATION
16‐17
8
87C2+95C2‐SGT(REB670) CT CALCULATION
18‐19
9
SGT 132kV OC‐EF CT CALCULATION
20‐21
10
87C+95C (REC670)‐132kV REACTOR CT CALCULATION
22‐23
11
87R+95R(REB650)‐REACTOR CT CALCULATION
24‐26
12
50‐51+50BF1(BUILT IN)‐REACTOR CT CALCULATION
27‐28
13
51NR(REF615)‐REACTOR CT CALCULATION
29‐30
14
BS‐BC 50‐51+50BF1+50CBF2 CT CALCULATION
31‐32
15
87B+95B‐DISC(REC670) CT CALCULATION
33‐34
16
87B+95B‐CHK(REC670) CT CALCULATION
35‐36
17
SGT 132kV METERING CT CALCULATION
37‐38
18
METERING‐GT FEEDERS CT CALCULATION
39‐40
19
METERING‐SPARE OG FEEDERS CT CALCULATION
41‐42
20
METERING‐CAPACITOR FEEDERS CALCULATION
43‐44
21
METERING‐SPARE SVC BAY CT CALCULATION
45‐46
22
METERING‐REACTOR FEEDERS CT CALCULATION
47‐48
23
132kV BS‐BC METERING
49‐50
INDEX
CE‐267304
2/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No =D22 ( SPARE SVC BAY )
CT DATA
CT No
Function
Relay Type
CT Primary Adopted CT ( Amp) Tap ( Amp) Secondary
IPCT + DM(LCC) + ALPHA‐A3 3000‐2500‐ Energy + DSM + 2000‐1600‐ IPCT 1200‐1000 Meter + DSM
1
T11 CORE‐3
2
T11 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
3
T11 CORE‐1
MAIN‐1 PROTN (FUTURE)
‐
4
T12 CORE‐1
BCU + FR
5
T12 CORE‐2
87B (DISC ZONE)
REC670
6
T12 CORE‐3
87B (CHK ZONE)
REC670
CT Class
CT Knee Point Voltage
CT CT Knee CT CT CT Magnetizin Point Resistance Magnetizin g Current Resistance Voltage At Selected g Current ( At Selected (Ohms) Adopted Tap (Ohms) mAmp ) Tap Tap
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
3000‐2500‐ 2000‐1600‐ 1200‐1000
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
3000‐2500‐ 2000‐1600‐ 1200‐1000
NA
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
NA
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
NA
1000
1
X
4200‐3500‐ 2800‐2240‐ 1680‐1400
1400
8.33‐10‐ 12.5‐15.6‐ 20.8‐25
25
6‐5‐3.2‐2.4‐ 2
2
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
7MD664 + 3000‐2500‐ FR ( 2000‐1600‐ Hathaway ) 1200‐1000
CE‐267304
3/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No =D17, =D02 ( SPARE CAPACITOR BAYS )
CT DATA
CT Class
CT Knee Point Voltage
CT Primary Adopted CT ( Amp) Tap ( Amp) Secondary
CT Class
CT Knee Point Voltage
Sr. No
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
Sr. No
CT No
Function
Meter Type
1
T13 CORE‐3
2
T13 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
3
T13 CORE‐1
MAIN‐1 PROTN (FUTURE)
‐
4
T14 CORE‐1
BCU+FR
5
T14 CORE‐2
87B (DISC ZONE)
REC670
6
T14 CORE‐3
87B (CHK ZONE)
REC670
IPCT + ALPHA‐A3 2000‐1600‐ DM(LCC) + + DSM + 1200‐1000‐ Energy IPCT 800 Meter +
CT Knee Point Voltage At Adopted CT Knee Point Voltage At Adopted
CT Magnetizin g Current ( mAmp ) CT Magnetizin g Current ( mAmp )
CT CT CT Resistance Magnetizin Resistance Selected g Current (Ohms) Tap (Ohms) At Selected CT CT CT Magnetizin Resistance Resistance At Tap‐2 At Tap‐1 g Current (Ohms) At Selected (Ohms)
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
1750
10‐12.5‐ 16.7‐20‐25
20
5‐4‐3‐2.5
3
2000‐1600‐ 1200‐1000‐ 800
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
‐
10‐12.5‐ 16.7‐20‐25
‐
5‐4‐3‐2.5
‐
2000‐1600‐ 1200‐1000‐ 800
NA
1
X
3500‐2800‐ 2100‐1750‐ 1400
‐
10‐12.5‐ 16.7‐20‐25
‐
5‐4‐3‐2.5
‐
1000
1
X
3500‐2800‐ 2100‐1750‐ 1400
1750
10‐12.5‐ 16.7‐20‐25
20
5‐4‐3‐2.5
3
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
7MD664 + 2000‐1600‐ FR ( 1200‐1000‐ Hathaway ) 800
CE‐267304
4/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No=D01, =D03, =D07, =D08, =D11, =D13, =D15, =D19, =D12, =D16, =D18, =D20, =D24 ( SPARE UG & OHL FEEDERS )
CT DATA
CT Class
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
1600‐1200‐ 800‐600
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
7MD664 + 1600‐1200‐ FR ( 800‐600 Hathaway )
800
1
X
2800‐2100‐ 1400‐1050
1400
12.5‐16.7‐ 25‐33.3
25
4‐3‐2‐1.5
2
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
CT No
Function
1
T3 CORE‐1
Energy Meter + DSM Through IPCT
ALPHA‐A3 1600‐1200‐ + DSM + 800‐600 IPCT
800
2
T3 CORE‐2
MAIN‐2 PROTN (FUTURE)
‐
1600‐1200‐ 800‐600
3
T3 CORE‐3
MAIN‐1 PROTN (FUTURE)
‐
4
T4 CORE‐1
BCU + FR
5
T4 CORE‐2
87B (DISC ZONE)
REC670
6
T4 CORE‐3
87B (CHK ZONE)
REC670
Sr. No
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
CT Knee Point Voltage
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CE‐267304
5/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No=D04, =D09, =D10 ( 132/13.8kV GT Bays )
CT DATA
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
1
IPCT + DM(LCC) + DM(LCC) + BCU(LCC) + T5 CORE‐1 BCU(LCC) + DSM + DSM + AMR + PQM AMR + PQM
2
T5 CORE‐2
3
T5 CORE‐3
4
5
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
300
300
1
5P20, 30VA
NA
NA
NA
NA
NA
NA
300
300
1
X
360
360
50
50
1
1
MAIN‐1 PROTN RET670 + (BOX‐1) + HATHAWAY FR
300
300
1
X
360
360
50
50
1
1
T6 CORE‐1
87B (DISC ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
T6 CORE‐2
87B (CHK ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
MAIN‐2 PROTN (BOX‐2)
RET670
CE‐267304
6/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
132kV Bay No=D21, =D26 ( 132kV Reactor Bays )
Shunt Reactor Bushing CTs
CT DATA
CT No
Function
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
1
DPDM(LCC) +BCU(LCC) + FR + IPCT T7 CORE‐1 + ENERGY METER + DSM
2
T7 CORE‐2 50/51N + FR REF615 + FR
1200‐600‐ 400‐200
200
1
X
2400‐1200‐ 800‐400
400
8.33‐16.7‐ 25‐50
50
6‐3‐2‐1
1
3
T7 CORE‐3 87C + 95C
REC670
1200‐600‐ 400‐200
1200
1
X
2400‐1200‐ 800‐400
2400
8.33‐16.7‐ 25‐50
8.33
6‐3‐2‐1
6
4
T8 CORE‐1
87B (DISC ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
5
T8 CORE‐2
87B (CHK ZONE)
REC670
4000
4000
1
X
800
NA
25
NA
6
NA
1
LC1‐1
87R+95R
REB650
600‐400‐ 200
200
1
X
NOT AVILABLE
400
NOT AVILABLE
50
NOT AVILABLE
1
2
LC1‐2
87C+95C
REC670
1200‐600‐ 400‐200
1200
1
X
3
NC1‐1
49 ( WIND TEMP )
4
NC2‐1
87R+95R
REB650
600‐400‐ 200
200
1
X
5
NC2‐2
51NR
REF615
400
400
1
5P20, 15VA
DPDM(LCC) +BCU(LCC) + FR + IPCT 1200‐600‐ 400‐200 + ENERGY METER + DSM
200
1
X
2400‐1200‐ 800‐400
400
8.33‐16.7‐ 25‐50
50
6‐3‐2‐1
1
CE‐267304
400
50
1
7/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Sr. No
1
2 132kV Bay No=D05, =D06, =D14 ( 132kV SIDE SGT BAYS )
CT No
Function
Meter / CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
DPDM(LCC) DPDM(LCC) +BCU(LCC)+ T1 CORE‐1 +BCU(LCC)+ 3000‐1500 ALPHA‐ EM+DSM A3+DSM SGT 132kV SIDE 50/51NS + REF615 + REC670 + 3000 5CBF1 T1 CORE‐2 (REC670) + REB650 50CBF2(REB 650)
CT Class
CT Knee Point Voltage
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
3000
1
0.2FS5, 30‐ 15VA
NA
NA
NA
NA
NA
NA
3000
1
X
1000
1000
25
25
7
7
3
T1 CORE‐3 87C2+95C2
REB650
3000
3000
1
X
1000
1000
25
25
7
7
4
T1 CORE‐4 87C1+95C1
REC670
3000
3000
1
X
1000
1000
25
25
7
7
5
T2 CORE‐1
SPARE
‐
3000
3000
1
X
1000
1000
25
25
7
7
6
T2 CORE‐2
87B (DISC ZONE)
RET670
4000
4000
1
X
800
800
25
25
6
6
7
T2 CORE‐3
87B (CHK ZONE)
RET670
4000
4000
1
X
800
800
25
25
6
6
1
BCT‐3
87C1+95C1
REC670
3000
3000
1
X
1000
1000
25
25
7
7
2
BCT‐4
87C2+95C2
REB650
3000
3000
1
X
1000
1000
25
25
7
7
SGT Bushing CTs
CT DATA
CE‐267304
8/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Bay No=D130, =D230, =D120, =D220 ( 132kV BUS SECTION & BUS COUPLER BAYS )
CT DATA
Function
CT Class
1
0.2FS5, 30‐ 15VA
NA
NA
NA
NA
NA
NA
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
4000
4000
1
X
800
NA
25
NA
6
NA
Sr. No
CT No
1
T9 CORE‐1
DPDM(LCC) DPDM(LCC) 4000‐2000 +BCU(LCC) +BCU(LCC)
2000
2
T9 CORE‐2
87B (DISC ZONE)
RET670
4000
6
T10 CORE‐1
87B (DISC ZONE)
REC670
7
T10 CORE‐2
50/51 + 50N/51N + REF615 + 50BF1+50BF REF615 2
CT CT CT CT Knee CT Resistance Magnetizin Magnetizin Point Resistance Selected Voltage At g Current ( g Current (Ohms) Tap (Ohms) mAmp ) At Selected Adopted
CT Knee Point Voltage
CT Primary Adopted CT Relay Type ( Amp) Tap ( Amp) Secondary
CE‐267304
9/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
System Data
System Fault Level, Ikmax1
40 kAmp
Voltage Level, Vp
132 kV
System X / R Ratio
50
Copper Prperties
Resitivity of Copper at 20 oC, ρ
17.2 nΩm
Temperature Coefficient of Copper, α
0.0039
First Temperature
20 oC
Second Temperature
75 oC
Change in Temperature, ∆t
55 oC
CT Secondary Cct Cable Data For 4mm2 Size
4 mm2
Area of Cross Section, A Length of the Conductor
1000 mm
Resistance per 1000 mm at 20 oC, R20 = ρ x l / A
0.0043 Ω
First Teperature, T1
20 OC
Second Teperature, T2
75 OC
Difference in Temperaturwe, ∆t = T2 ‐ T1
55 OC
Resistance at 75oC, R75 = R20 x ( 1 + α x ∆t )
SYSTEM DATA
CE‐267304
0.00522235 Ω
10/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
CT Secondary Cct Cable Data For 10mm2 Size
10 mm2
Area of Cross Section, A Length of the Conductor
1000 mm
Resistance per 1000 mm at 20 oC, R20 = ρ x l / A
0.00172 Ω
First Teperature, T1
20 OC
Second Teperature, T2
75 OC
Difference in Temperaturwe, ∆t = T2 ‐ T1
55 OC
Resistance at 75oC, R75 = R20 x ( 1 + α x ∆t )
SYSTEM DATA
CE‐267304
0.00208894 Ω
11/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT Data ( GT Bays, =D09, =D04, =D10 ) CT No
T5 CORE‐3 MAIN‐1 PROTN (BOX‐ 1) + FR RET670 + HATHAWAY
Function Relay Type CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
360
Volts
CT Knee Point Voltage At Adopted Tap
360
Volts
CT Magnetizing Current ( mAmp )
50
mAmp
CT Magnetizing Current At Selected Tap
50
mAmp
CT Resistance (Ohms)
1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation 2
Lead Burden Lead Burden CT Cable Route Length ( One Way ) CT Cable Size
3
metre
4
mm2
CT Cable Resistance per metre
Reffer System Data
0.00522235
Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 200
1.04447
Ω
VA Burden of RET670 CT Input
0.02
VA
VA Burden of FR CT Input
0.05
VA(As sumed
Relay Burden
Total VA Burden
=0.02 + 0.05
Rated Secondary Current, In Relay CT Input Resistance = VA / In2 4
200
0.07 1
=0.07 / 1^2
0.07
Amp Ω
CT Stability Criterion
87T1‐GT(RET670)
CE‐267304
12/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS There arae two criterion for estimating the minimum requirement for CT Knee Point Voltage Criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ], Where, Int = transformer rated current, Ipn = CT Primary rated Current, & Isn = CT Secondary rated current Criterion No.2, Vk = 2 x Itf x ( Isn / Ipn ) x [ Rct + 2 x Rlead + Rrelay ], Where, Itf = transformer through fault current The maximum external ( through ) fault current is limited by the %Z of the transformer and given by Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) 132/13.8kV GT MVA Rating
60
MVA
Grid Transformer % Impedance, %Z
10
%
Grid Transformer HV Side Voltage, kV
132
kV
=60 x 10^5/(SQRT(3) x 132 x 10)
2624.32
Amp
=60 x 1000/(SQRT(3) x 132)
262.432
Amp
=30 x 262.432 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.07)
82.901
Volts
=2 x 2624.32 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.07) 1 04447 + 0 07)
55.267 55. 67
Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) Transformer rated current, Itn = MVA (TF) x 1000 / (SQRT(3) x kV ) Knee point voltage as per criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] Knee point voltage as per criterion No.2, Vk x Itf x (Isn/ Ipn) x [ Rct x Rlead Rrelay Vk = 2 x Itf x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] The required knee point = max ( Criterion No.1 , Criterion No.2 ) CT Actual Knee Point Voltage
82.901
Volts
360
Volts
Hence the CT Knee Point Voltage is OK
87T1‐GT(RET670)
CE‐267304
13/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT Data ( GT Bays, =D09, =D04, =D10 ) CT No
T5 CORE‐2 MAIN‐2 PROTN (BOX‐2)
Function Relay Type
RET670
CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
360
Volts
CT Knee Point Voltage At Adopted Tap
360
Volts
CT Magnetizing Current ( mAmp )
50
mAmp
CT Magnetizing Current At Selected Tap
50
mAmp
CT Resistance (Ohms)
1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation 2
Lead Burden Lead Burden CT Cable Route Length ( One Way ) CT Cable Size
3
metre
4
mm2
CT Cable Resistance per metre
Reffer System Data
0.00522235
Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 200
1.04447
Ω
0.02
VA VA
Relay Burden VA Burden of RET670 CT Input VA Burden of FR CT Input
( No FR )
0
Total VA Burden
=0.02 + 0
0.02
Rated Secondary Current, In Relay CT Input Resistance = VA / In2 4
200
1 =0.02 / 1^2
0.02
Amp Ω
CT Stability Criterion
87T2‐GT(RET670)
CE‐267304
14/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS There arae two criterion for estimating the minimum requirement for CT Knee Point Voltage Criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ], Where, Int = transformer rated current, Ipn = CT Primary rated Current, & Isn = CT Secondary rated current Criterion No.2, Vk = 2 x Itf x ( Isn / Ipn ) x [ Rct + 2 x Rlead + Rrelay ], Where, Itf = transformer through fault current The maximum external ( through ) fault current is limited by the %Z of the transformer and given by Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) 132/13.8kV GT MVA Rating
60
MVA
Grid Transformer % Impedance, %Z
10
%
Grid Transformer HV Side Voltage, kV
132
kV
=60 x 10^5/(SQRT(3) x 132 x 10)
2624.32
Amp
=60 x 1000/(SQRT(3) x 132)
262.432
Amp
=30 x 262.432 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.02)
81.589
Volts
=2 x 2624.32 x 1 / 300 x ( 1 + 2 x 1.04447 + 0.02) 1 04447 + 0 02)
54.392 54.39
Itf = MVA (TF) x 1000 x 100 / (SQRT(3) x kV x %Z) Transformer rated current, Itn = MVA (TF) x 1000 / (SQRT(3) x kV ) Knee point voltage as per criterion No.1, Vk = 30 x Int x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] Knee point voltage as per criterion No.2, Vk x Itf x (Isn/ Ipn) x [ Rct x Rlead Rrelay Vk = 2 x Itf x (Isn/ Ipn) x [ Rct + 2 x Rlead + Rrelay ] The required knee point = max ( Criterion No.1 , Criterion No.2 ) CT Actual Knee Point Voltage
81.589
Volts
360
Volts
Hence the CT Knee Point Voltage is OK
87T2‐GT(RET670)
CE‐267304
15/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
SGT Bays, Bay No =D05, D06, D14 1
CT Data T1 CORE‐ 4 87C1+95C 1
CT No Function Relay Type
2
REC670
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
7
Ω
CT Resistance Selected Tap (Ohms)
7
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 3000
13.333
=13.333 x (7 + 2 x 2.08894)
149.035 Volts
=1.2 x 149.035
178.842 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
179
Volts
1790
Ω
To provide greater stability against through faults, the Voltage setting of 179 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=179 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet
87C1+95C1‐SGT(REC670)
CE‐267304
16/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
4.48
mAmp
0
mAmp
0
mAmp
104.48
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage Iop = Ir + Im + Isupvn + Imet
=100 + 4.48 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 3000
3600
Amp
Required Secondary Operating Current, Iops
=3600 x 10001 / 3000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 104.48
1095.52 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=179x 1000 / 1095.52
163.39
Ohms
=179^2/163.39
196.1
Watts
2
Required Wattage of Shunt Resistor = Vs / Rsh 5
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 3000
750
Amp
Secondary current during minimum load, Ismin
=750 x 1 / 3000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
1790
Ω
Relay Shunt resistance, Rsh
Calculated above
163.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 1000 / 7
142857.1 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1790 x 163.39 x 142857.142857143 / (1790 x 163.39 + 1790 x 149.567 Ω 142857.142857143 + 163.39 x 142857.142857143)
Voltage developed across the CT supervision relay = =0.25 x 149.567 Ismin x R The current through the relay and series resistance =37.39175 / 1790 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87C1+95C1‐SGT(REC670)
CE‐267304
37.39175 Volts 0.021
Amp
38
Volts
17/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
SGT Bays, Bay No =D05, D06, D14 1
CT Data T1 CORE‐ 3 87C2+95C 2
CT No Function Relay Type
2
REB650
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
7
Ω
CT Resistance Selected Tap (Ohms)
7
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 3000
13.333
=13.333 x (7 + 2 x 2.08894)
149.035 Volts
=1.2 x 149.035
178.842 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REB650 + Series Resistance Combination REB650 Current Setting Range
0.02 ‐ 1 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
179
Volts
1790
Ω
To provide greater stability against through faults, the Voltage setting of 179 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=179 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet
87C2+95C2‐SGT(REB650)
CE‐180973
18/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
Where Ir = REB650 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
4.48
mAmp
0
mAmp
0
mAmp
104.48
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 4.48 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 3000
3600
Amp
Required Secondary Operating Current, Iops
=3600 x 10001 / 3000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 104.48
1095.52 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=179x 1000 / 1095.52
163.39
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=179^2/163.39
196.1
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 3000
750
Amp
Secondary current during minimum load, Ismin
=750 x 1 / 3000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
1790
Ω
Relay Shunt resistance, Rsh
Calculated above
163.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 1000 / 7
142857.1 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1790 x 163.39 x 142857.142857143 / (1790 x 163.39 + 1790 x 149.567 Ω 142857.142857143 + 163.39 x 142857.142857143)
Voltage developed across the CT supervision relay = =0.25 x 149.567 Ismin x R The current through the relay and series resistance cct, Ir = Vr / Rs
=37.39175 / 1790
Hence the CT supvn element pickup Voltage
87C2+95C2‐SGT(REB650)
CE‐180973
37.39175 Volts 0.021
Amp
38
Volts
19/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
BAY No =D05, =D06, =D14 1
CT DETAILS CT No
T1 CORE‐2 SGT 132kV SIDE 50/51NS + 5CBF1 (REC670) + 50CBF2(REB650) REF615 + REC670 + REB650
Function
Meter / Relay Type
2
3
CT Primary ( Amp)
3000
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
1000
Volts
CT Knee Point Voltage At Adopted Tap
1000
Volts
CT Magnetizing Current ( mAmp )
25
mA
CT Magnetizing Current At Selected Tap
25
mA
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms)
7 7
Ω Ω
METER BURDEN DETAILS 50/51NS Burden
0.1
50CBF1 Burden
0.1
50CBF2 Burden
0.0001
VA(Assumed ) VA(Assumed ) VA
Any Other Device Burden
( No other device )
0
VA
Total Burden
=0.1 + 0.1 + 0.0001 + 0
0.2001
VA
Total Burden Resistance, Rb = VA / In2
=0.2001 / 1^2
0.2001
Ω
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A
4
Lead Resistance per metre, rl
Reffer System Data
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
0.00522235 Ω / metre 1.04447 Ω
CLASS X CONVERSION TP P CLASS The following formula is used to convert class X CT to equivalent P class CT Vk = Fn x In x [ Rct + Sn / In^2 ] / 1.3 OR Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] x In^2 Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] x In^2
SGT 132kV OC‐EF
CE‐267304
20/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Fn Sn = [ 1.3 x Vk / ( Fn x In ) ‐ Rct ] / In^2 4
20 = 1.3 x 1000 / (20 x 1 ) ‐ 7) x 1^2)
58 VA
CRITERION FOR METERING CLASS CT ADEQUACY Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
20
Sn = CT Rated VA Burden
58 VA
Sin = In2 x Rct
=1^2 x 7
Sa = In2 x [ Rlead x 2 + Rrelay ]
=1^2 x ( 2 x 1.04447 + 0.2001)
Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
=20 x (7 + 58 ) / (7 + 2.28904)
7 VA 2.28904 VA
139.95
The CT is OK since Fa > Fn
SGT 132kV OC‐EF
CE‐267304
21/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Reactor ( Bay No =D21, =D26) 1
CT Data CT No
T7 CORE‐ 3
Function
87C + 95C
Relay Type
REC670 1200‐600‐ Amp 400‐200
CT Primary ( Amp) Adopted Tap ( Amp)
1200
Amp
CT Secondary
1
Amp
CT Class
X 2400‐ 1200‐800‐ Volts 400
CT Knee Point Voltage CT Knee Point Voltage At Adopted Tap
2400
8.33‐16.7‐ mAmp 25‐50
CT Magnetizing Current ( mAmp ) CT Magnetizing Current At Selected Tap
8.33
mAmp
6‐3‐2‐1 Ω
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms) 2
Volts
6
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
=40 x 1000 / 1200
33.333
=33.333 x (6 + 2 x 2.08894)
339.259 Volts
=1.2 x 339.259
407.111 Volts
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
Amp
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
408
Volts
4080
Ω
To provide greater stability against through faults, the Voltage setting of 408 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=408 x 1000 / 100
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme
87C+95C (REC670)‐132kV REACTOR
CE‐267304
22/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
1.42
mAmp
0
mAmp
0
mAmp
101.42
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage Iop = Ir + Im + Isupvn + Imet
=100 + 1.42 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 1200
1440
Amp
Required Secondary Operating Current, Iops
=1440 x 10001 / 1200
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 101.42
1098.58 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=408x 1000 / 1098.58
371.39
Ohms
=408^2/371.39
448.22
Watts
2
Required Wattage of Shunt Resistor = Vs / Rsh 5
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take the minimum load to be 40% of the rated CT Primary Minimum load = 0.25 x CT Primary
=0.25 x 1200
300
Amp
Secondary current during minimum load, Ismin
=300 x 1 / 1200
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance
Relay series resistance, Rs
Calculated above
4080
Ω
Relay Shunt resistance, Rsh
Calculated above
371.39
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 2400 / 6
400000 Ω
=4080 x 371.39 x 400000 / (4080 x 371.39 + 4080 x 400000 + 371.39 x 400000)
340.115 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
Voltage developed across the CT supervision relay = =0.25 x 340.115 Ismin x R The current through the relay and series resistance =85.02875 / 4080 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87C+95C (REC670)‐132kV REACTOR
CE‐267304
85.02875 Volts 0.021
Amp
86
Volts
23/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT Data ( Reactor Bay =D21 & =D26 ) CT No
LC1‐1
Function
87R+95R
Relay Type
REB650
CT Primary ( Amp)
600‐400‐ 200
Amp
200
Amp
CT Secondary
1
Amp
CT Class
X
Adopted Tap ( Amp)
NOT Volts AVILABLE
CT Knee Point Voltage CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current At Selected Tap
50
mAmP
NOT Ω AVILABLE
CT Resistance (Ohms) CT Resistance Selected Tap (Ohms)
1
Ω
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm
2
0.00522235 Ω
CT Cable Resistance per metre Total CT Cable Resistance ( One Way ) 3
Volts
NOT mAmP AVILABLE
CT Magnetizing Current ( mAmp )
2
& NC2‐1
=0.00522235 x 400
2.08894
Ω
Reactor Through Fault Current Calculation Reactor MVAR rating
40
MVAR
Reactor Voltage Rating, kV
132
kV
Reactor Through Current, Itr = 1000 x MVA / [ =40 x 1000 / [SQRT(3) x 132] SQRT(3) x kV ] Reactor CT Secondary Through Current, Itrs = =174.955 / 200 Itr / CT Primary Required Voltage Setting, Vsmin = Itrs x [ Rct =0.874775 x [ 1 + 2 x 2.08894] + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=1.2 x 4.53
174.955
Amp
0.874775
Amp
4.53
Volts
5.436
Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REB650 + Series Resistance Combination
87R+95R(REB650)‐REACTOR
CE‐267304
24/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS REB650 Current Setting Range
0.02 ‐ 1
Selected Current Setting, Is = 0.03 x 1000 mAmp
Amp
30
mAmp
11
Volts
To provide greater stability against through faults, the Voltage setting of 11 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=11 / 30 x 1000
366.67
Ω
Shunt Resistor Calculation To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REB650 operating current
30
mAmp
1.38
mAmp
CT Supervision Relay ( Built In ) Current
0
mAmp
Imet, Metrosil Current = 0 at setting voltage
0
mAmp
31.38
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
Iop = Ir + Im + Isupvn + Imet
=30 + 1.38 + 0 + 0
It is proposed that, the primary operating current should not be less that 0.1 times the CT primary =0.1 x 200
=0.1 x 200
20
Amp
Required Secondary Operating Current, Iops
=20 x 1000 x / 400
100
mAmp
=100 ‐ 31.38
68.62
mAmp
=11 x 1000 x / 68.62
160.3
Ohms
=11^2 / 160.3
0.75
Watts
174.955
Amp
0.874775
Amp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop Required Value of Shunt Resistor, Rsh = Vs / Ish 2 Required Wattage of Shunt Resistor = Vs / Rsh 6
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. For Reactor, we take the minimum load to be 100% of the rated CT Primary Minimum load = Reactor Rated Load Secondary current during minimum load, Ismin
87R+95R(REB650)‐REACTOR
=174.955 / 200
CE‐267304
25/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT magnetizing impedance Relay series resistance, Rs
366.67
Ω
Relay Shunt resistance, Rsh
160.3
Ω
8
Ω
7.465
Ω
6.53
Volts
CT magnetizing imedance, Xm = Vk / Im
=400 / 50
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm =366.67 x 160.3 x 8 / ( 366.67 R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x x 160.3 + 366.67 x 8 + 160.3 x Rsh ] 8) Voltage developed across the CT supervision =0.874775 x 7.465 relay = Ismin x R The current through the relay and series resistance cct, Ir = Vr / Rs
=6.53/ 366.67
Hence the CT supvn element pickup Voltage
87R+95R(REB650)‐REACTOR
CE‐267304
0.018
Amp
7
Volts
26/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
2
CT DETAILS ‐ REACTOR ( Bay No =D21, =D26) CT No
T7 CORE‐2
Function
50/51N + FR
Meter / Relay Type
REF615 + FR
CT Primary ( Amp)
1200‐600‐400‐ 200
Amp
Adopted Tap ( Amp)
200
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2400‐1200‐800‐ Volts 400
CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current ( mAmp )
8.33‐16.7‐25‐50 mAmP
CT Magnetizing Current At Selected Tap
50
mAmP
CT Resistance (Ohms)
6‐3‐2‐1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
Reactor OC/EF Relay REF615 Burden
0.02
VA
FR CT Input Burden
0.02
VA
Total Device Burden
0.04
VA
Volts
RELAY BURDEN DETAILS Connected Burden
3
CT LEAD BURDEN Lead Length ( One Way ), L
100 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235 Ω / metre
Total Lead Resistance, RLEAD = rl x L
4
0.522235 Ω
CRITERION FOR OC/EF RELAY REF615 The OC/EF + 50BF relay REF615 is connected to class X CT. Its equivalent P class CT parameters are calculated by the formula, Sn = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn, Where
50‐51+50BF1(BUILT IN)‐REACTOR
CE‐267304
27/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Fn = CT Accuracy Limiting Factor at Rated Burden Sn = CT Rated VA Burden = = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn The Criterion for any P class CT used for OC/EF protection, in general is given by, Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
Sin = CT Internal Burden = In2 x Rct
20 25
1 VA
2 Sa = CT Connected Burden = In x [ Rlead x 2 + Rrelay ]
1.08447 VA
Actual Accuracy Limiting Factor, Fa = Fn x [ Sin + Sn ] / [ Sin + 249.46 Sa ] Maximum Secondary Short Circuit Current, Issc = Maximum 200 Primary ( 40kAmp ) / CT Primary The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is Fa IS OK OK if Fa > IHIGHSET
50‐51+50BF1(BUILT IN)‐REACTOR
CE‐267304
28/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
2
CT DETAILS ( Reactor Bay =D21 & =D26 ) CT No
NC2‐2
Function
51NR
Relay Type
REF615
CT Primary ( Amp)
400
Amp
Adopted Tap ( Amp)
400
Amp
CT Secondary
1
Amp
CT Class
5P20, 15VA
CT Resistance ( Assumed )
2
Ω
Reactor 51NR Relay REF615 Burden
0.02
VA
Total Device Burden
0.02
VA
RELAY BURDEN DETAILS Connected Burden
3
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L 4
=200 x 0.00522235
Ω / metre
1.04447 Ω
CRITERION FOR OC/EF RELAY 7SJ64 The Criterion for any P class CT used for OC protection, in general is given by , Fa = Fn x [ Sin + Sn ] / Fn = CT Accuracy Limiting Factor at Rated Burden Sin = CT Internal Burden = In2 x Rct
20 =1^2 x 2
Sn = CT Rated Burden
15 VA
Sa = CT Connected Burden = In2 x [ Rlead x 2 + =1^2 x ( 1.04447 x 2 + 0.02) Rrelay ] Actual Accuracy Limiting Factor, Fa = Fn x [ Sin =20 x (2 + 15 ) / ( 2 + 2.10894) + Sn ] / [ Sin + Sa ]
51NR(REF615)‐REACTOR
2 VA
CE‐267304
2.10894 VA 82.746
29/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Maximum Neutral Current = Reactor Rated Current The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa > Imax
51NR(REF615)‐REACTOR
CE‐267304
0.874775 Amp
Fa IS OK
30/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT DETAILS ( BUS SECTION =D120, =D220, BUS COUPLER =D130, =D230 ) CT No
T10 CORE‐2 50/51 + 50N/51N + 50BF1+50BF2 REF615 + REF615
Function Meter / Relay Type
2
Two No
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
NA
Volts
CT Magnetizing Current ( mAmp )
25
mAmP
CT Magnetizing Current At Selected Tap
NA
mAmP
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
NA
Ω
Bus Section OC + 50BF1 Relay REF615 Burden
0.02
VA
Bus Section EF + 50BF2 Relay REF615 Burden
0.02
VA
0.04
VA
RELAY BURDEN DETAILS Connected Burden
Total Device Burden 3
=0.02 + 0.02
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L 4
0.00522235 =0.00522235 x 200
Ω / metre
1.04447 Ω
CRITERION FOR OC/EF RELAY 7SJ64 The OC + 50BF1 & EF + 50BF2 relays REF615 are connected to class X CT. Its equivalent P class CT parameters are calculated by the formula, Sn = [ 1.3 x Vk ‐ Fn x In x Rct ] x In / Fn
BS‐BC 50‐51+50BF1+50CBF2
CE‐267304
31/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
Fn = CT Accuracy Limiting Factor at Rated Burden
20
Sn = CT Rated VA Burden = = [ 1.3 x Vk ‐ Fn x In x Rct = ( 1.3 x 800 ‐ 20 x 1 x ] x In / Fn 6) x 1 / 20
46
The Criterion for any P class CT used for OC/EF protection, in general is given by, Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] 2 Sin = CT Internal Burden = In x Rct
=1^2 x 6
Sa = CT Connected Burden = In2 x [ Rlead x 2 + Rrelay ] Actual Accuracy Limiting Factor Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Maximum Secondary Short Circuit Current, Issc = Maximum Primary ( 40kAmp ) / CT Primary
=1^2 x ( 1.04447 x 2 + 0.04) =20 x ( 6 + 46 ) / ( 6 + 2.12894) =40 x 1000 / 4000
The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa > IHIGHSET
BS‐BC 50‐51+50BF1+50CBF2
CE‐267304
6 VA 2.12894 VA 127.94 10
Fa IS OK
32/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Busbar Discriminative Zones 1
CT Data CT No
T2 CORE‐ 2
Function
87B (DISC ZONE)
Relay Type
RET670
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
800
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
6
Ω
Note: This CT data is related to SGT bays 132kV side CTs. Note that same data is applicable to busbar protection CTs of all bays 2
CT Knee Point Voltage Calculation CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=40 x 1000 / 4000
10
Amp
=10 x (6 + 2 x 2.08894)
101.779 Volts
=1.2 x 101.779
122.135 Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
123
Volts
1230
Ω
To provide greater stability against through faults, the Voltage setting of 123 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=123 x 1000 / 100
Shunt Resistor Calculation
87B+95B‐DISC(REC670)
CE‐267304
33/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
3.84
mAmp
0
mAmp
0
mAmp
103.84
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 3.84 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 4000
4800
Amp
Required Secondary Operating Current, Iops
=4800 x 10001 / 4000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 103.84
1096.16 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=123x 1000 / 1096.16
112.21
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=123^2/112.21
134.83
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take Minimum load = 0.25 x CT Primary
=0.25 x 4000
1000
Amp
Secondary current during minimum load, Ismin
=1000 x 1 / 4000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT Relay series resistance, Rs
Calculated above
1230
Ω
Relay Shunt resistance, Rsh
Calculated above
112.21
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 800 / 6
133333.3 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)
Voltage developed across the CT supervision relay = =0.25 x 102.75 Ismin x R The current through the relay and series resistance =25.6875 / 1230 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87B+95B‐DISC(REC670)
CE‐267304
102.75
Ω
25.6875 Volts 0.021
Amp
26
Volts
34/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
132kV Busbar Check Zone 1
CT Data T2 CORE‐ 3 87B (CHK ZONE)
CT No Function Relay Type
RET670
CT Primary ( Amp)
4000
Amp
Adopted Tap ( Amp)
4000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
800
Volts
CT Knee Point Voltage At Adopted Tap
800
Volts
CT Magnetizing Current ( mAmp )
25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6
Ω
CT Resistance Selected Tap (Ohms)
6
Ω
Note: This CT data is related to SGT bays 132kV side CTs. Note that same data is applicable to busbar protection CTs of all bays 2
CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Route Length ( One Way ) CT Cable Size
400
metre
4
mm2
CT Cable Resistance per metre
Reffer CT Data
0.005222 Ω
Total CT Cable Resistance ( One Way )
=0.00522235 x 400
2.08894 Ω
Maximum Secondary Through Fault Current, Ifs = Issc / Ipn Required Voltage Setting, Vsmin = Ifs x [ Rct + 2 x Rlead ] Adopted Voltage Setting = 1.2 x Vsmin
=40 x 1000 / 4000
10
Amp
=10 x (6 + 2 x 2.08894)
101.779 Volts
=1.2 x 101.779
122.135 Volts
The CT is OK since Vk > 1.2 x Vs 3
Voltage Setting Of REC670 + Series Resistance Combination REC670 Current Setting Range = 0.01 x In to 25 x In
0.01 to 25 Amp
Selected Current Setting, Is = 0.1 x 1000 mAmp
100
mAmp
123
Volts
1230
Ω
To provide greater stability against through faults, the Voltage setting of 123 is proposed Hence Relay Setting Voltage, Vs The required series resistor value, Rs = Vs / Is 4
=123 x 1000 / 100
Shunt Resistor Calculation
87B+95B‐CHK(REC670)
CE‐267304
35/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS To calculate the shunt resistor value, we have to calculate the minimum operating current of the differential scheme Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current
100
mAmp
Im = Magnetizing Current For CTs at Setting Voltage
3.84
mAmp
0
mAmp
0
mAmp
103.84
mAmp
CT Supervision Relay Current
CT SUPVN Built In Function
Imet, Metrosil Current = 0 at setting voltage
5
Iop = Ir + Im + Isupvn + Imet
=100 + 3.84 + 0 + 0
As per SEC‐COA practice, the primary operating current should not be less that 1.2 times the CT primary =1.2 x 3000
=1.2 x 4000
4800
Amp
Required Secondary Operating Current, Iops
=4800 x 10001 / 4000
1200
mAmp
Current Through The Shunt Resistor, Ish = Iops ‐ Iop
=1200 ‐ 103.84
1096.16 mAmp
Required Value of Shunt Resistor, Rsh = Vs / Ish
=123x 1000 / 1096.16
112.21
Ohms
Required Wattage of Shunt Resistor = Vs2 / Rsh
=123^2/112.21
134.83
Watts
CT Supervision Settings CT Supervision Element should operate when of of the CTs is open and there is minimum load on that feeder. We can take Minimum load = 0.25 x CT Primary
=0.25 x 4000
1000
Amp
Secondary current during minimum load, Ismin
=1000 x 1 / 4000
0.25
Amp
The resultant resistance of the CT circuit during CT open conditions will be equal to the parallel combination of the shunt resistance, relay series resistance, and the CT Relay series resistance, Rs
Calculated above
1230
Ω
Relay Shunt resistance, Rsh
Calculated above
112.21
Ω
CT magnetizing imedance, Xm = Vk / Im
=1000 x 800 / 6
133333.3 Ω
The resultant resistance 1 / R = 1 / Rs + 1 / Rsh + 1 / Xm R = Rs x Rsh x Xm / [ Rs x Xm + Rs x Xm + Rs x Rsh ]
=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)
Voltage developed across the CT supervision relay = =0.25 x 102.75 Ismin x R The current through the relay and series resistance =25.6875 / 1230 cct, Ir = Vr / Rs Hence the CT supvn element pickup Voltage
87B+95B‐CHK(REC670)
CE‐267304
102.75
Ω
25.6875 Volts 0.021
Amp
26
Volts
36/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
BAY No =D05, =D06, =D14 1
CT DETAILS CT No
T1 CORE‐1 DPDM(LCC)+B CU(LCC)+EM+ DSM DPDM(LCC)+B CU(LCC)+ALPH A‐A3+DSM
Function
Meter Type
2
3
CT Primary ( Amp)
3000‐1500
Amp
Adopted Tap ( Amp)
3000
Amp
CT Secondary
1
Amp
CT Class
0.2FS5, 30‐ 15VA
CT Resistance, Rct ( Assumed )
7.5
Ω (Assumed )
DPDM (LCC ) Burden
0.1
VA(Assumed)
Bay Control Unit Burden
0.1
VA(Assumed)
Energy Meter Alpha‐A3 Burden
0.0001
VA
DSM Burden
0.1
VA(Assumed)
METER BURDEN DETAILS
Total Burden Total Burden
=0.1 + 0.1 + 0.0001 + 0.1 0 1 + 0 1 + 0 0001 + 0 1
0 3001 0.3001
VA
Total Burden Resistance, Rb = VA / In2
=0.3001 / 1^2
0.3001
Ω
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A
4
Lead Resistance per metre, rl
Reffer System Data
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
0.00522235 Ω / metre 1.04447 Ω
CRITERION FOR METERING CLASS CT ADEQUACY Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
5
Sn = CT Rated VA Burden
30 VA
Sin = In2 x Rct
=1^2 x 7.5
Sa = In2 x [ Rlead x 2 + Rrelay ]
=1^2 x ( 2 x 1.04447 + 0.3001)
CT Accuracy Limiting Factor at Rated Burden, Fn Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
SGT 132kV METERING
7.5 VA 2.38904 VA 5
=5 x (7.5 + 30 ) / (7.5 + 2.38904)
CE‐267304
18.96
37/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS Maximum Secondary Short Circuit Current, Issc = Maximum Primary ( 40kAmp ) / CT Primary
=40 x 1000 x 1 / 3000
13.333 Amp
The meter security will be checked based on the actual accuracy limiting factor, if Fa < Issc, otherwise, it will be based on the maximum secondary short circuit current.
5
Maximum anticipated current in the meter, ImMAX Maximum Short duration withstand Currents
13.333 Amp
DPDM ( LCC )
20
BCU ( LCC )
20
Energy Meter
40
DSM
40
Minimum Short Duration Current
20
The meter will be safe, since ImMAX < Minimum Short Duration Current
SGT 132kV METERING
CE‐267304
38/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS GRID TRANSFORMER FEEDERS =D09, =D04, =D10 1
2
CT DETAILS CT No
T5 CORE‐1
Function
IPCT + DM(LCC) + BCU(LCC) + DSM + AMR + PQM
Relay Type
DM(LCC) + BCU(LCC) + DSM + AMR + PQM
CT Primary ( Amp)
300
Amp
Adopted Tap ( Amp)
300
Amp
CT Secondary
1
Amp
CT Class
5P20, 30VA
CT Knee Point Voltage
NA
Volts
CT Knee Point Voltage At Adopted Tap
NA
Volts
CT Magnetizing Current ( mAmp )
NA
mAmp
CT M CT Magnetizing Current At Selected Tap ti i C t At S l t d T
NA
mAmp A
CT Resistance (Ohms)
NA
Ω
CT Resistance Selected Tap (Ohms)
NA
Ω
0.05
VA
LCC Digital Meter Burden
0.05
VA (Assum ed)
Alpha Meter CT Burden per phase
0.0001
VA
DSM CT Input Burden per phase
0.0001
ACCS Burden
0.05
DEVICE BURDEN DETAILS Bay Control Unit 7SMD664 Burden
Total Device Burden 3
=0.05 + 0.05 + 0.0001 + 0.0001 + 0.05
0.1502
VA (Assum ed) VA (Assum ed) VA
CT LEAD BURDEN Lead Length ( One Way ), L
METERING‐GT FEEDERS
200 metre
CE‐267304
39/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L
=0.00522235 x 200
Ω / metre
1.04447 Ω
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden Lead Burden = In2 x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1502 + 1.04447
1.19467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.2
METERING‐GT FEEDERS
CE‐267304
40/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
1
CT DETAILS ( BAY No =D19, =D17, =D15, =D13, =D11, =D07, =D03, =D01, =D02, =D08, =D12, =D16, D18, =D20, D22, =D24 CT No
T3 CORE‐1 Energy Meter + DSM Through IPCT ALPHA‐A3 + DSM + IPCT 1600‐1200‐800‐ Amp 600
Function Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
800
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2800‐2100‐ 1400‐1050
Volts
CT Knee Point Voltage At Adopted Tap
1400
Volts
CT Magnetizing Current ( mAmp )
12.5‐16.7‐25‐ 33.3
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
4‐3‐2‐1.5
Ω
CT Resistance Selected Tap (Ohms)
2
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐SPARE OG FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
41/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden Lead Burden = In2 x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐SPARE OG FEEDERS
CE‐267304
42/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT DETAILS ( BAY No =D17, =D02 ) CT No
T13 CORE‐3
Function
IPCT + DM(LCC) + Energy Meter + DSM ALPHA‐A3 + DSM + IPCT 2000‐1600‐ 1200‐1000‐800
Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
1000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
3500‐2800‐ Volts 2100‐1750‐1400
CT Knee Point Voltage At Adopted Tap
1750
CT Magnetizing Current ( mAmp )
10‐12.5‐16.7‐20‐ mAmp 25
CT Magnetizing Current At Selected Tap
20
mAmp
CT Resistance (Ohms)
5‐4‐3‐2.5
Ω
CT Resistance Selected Tap (Ohms)
3
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
Volts
DEVICE BURDEN DETAILS
Total Device Burden 3
Amp
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐CAPACITOR FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
43/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐CAPACITOR FEEDERS
CE‐267304
44/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 1
CT DETAILS ( BAY No =D22 ) CT No
T11 CORE‐3
Function
IPCT + DM(LCC) + Energy Meter + DSM ALPHA‐A3 + DSM + IPCT 3000‐2500‐ 2000‐1600‐ 1200‐1000
Relay Type CT Primary ( Amp)
2
Adopted Tap ( Amp)
1000
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
4200‐3500‐ 2800‐2240‐ 1680‐1400
Volts
CT Knee Point Voltage At Adopted Tap
1400
Volts
CT Magnetizing Current ( mAmp )
8.33‐10‐12.5‐ 15.6‐20.8‐25
mAmp
CT Magnetizing Current At Selected Tap
25
mAmp
CT Resistance (Ohms)
6‐5‐3.2‐2.4‐2 6 5 3.2 2.4 2
Ω
CT Resistance Selected Tap (Ohms)
2
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
Amp
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐SPARE SVC BAY
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
45/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐SPARE SVC BAY
CE‐267304
46/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS REACTOR FEEDERS =D21, =D26 1
CT DETAILS CT No
T7 CORE‐1 DPDM(LCC)+BCU (LCC) + FR + IPCT + ENERGY METER + DSM DPDM(LCC)+BCU (LCC) + FR + IPCT + ENERGY METER + DSM 1200‐600‐400‐ Amp 200
Function
Relay Type
CT Primary ( Amp)
2
Adopted Tap ( Amp)
200
Amp
CT Secondary
1
Amp
CT Class
X
CT Knee Point Voltage
2400‐1200‐800‐ Volts 400
CT Knee Point Voltage At Adopted Tap
400
CT Magnetizing Current ( mAmp )
8.33‐16.7‐25‐50 mAmp
CT Magnetizing Current At Selected Tap g g p
50
mAmp p
CT Resistance (Ohms)
6‐3‐2‐1
Ω
CT Resistance Selected Tap (Ohms)
1
Ω
Bay Control Unit 7SMD664 Burden
0.05
VA
LCC Digital Meter Burden
0.05
Alpha Meter CT Burden per phase
0.0001
VA (Assum VA
DSM CT Input Burden per phase
0.0001
VA (Assum
0.1002
VA
DEVICE BURDEN DETAILS
Total Device Burden 3
Volts
=0.05 + 0.05 + 0.0001 + 0.0001
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl Total Lead Resistance, RLEAD = rl x L
METERING‐REACTOR FEEDERS
0.00522235 =0.00522235 x 200
CE‐267304
Ω / metre
1.04447 Ω
47/50
132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS
The available CT for metering is class X. But meters cannot be fed by class X CT, as a general rule. Therefore IPCT is recommended to be used in the start of the metering circuit. The question is now to calculate the suitable IPCT burden
IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD
=1^2 x 1.04447
1.04447 VA
IPCT Burden > Lead Burden + Device burden
=0.1002 + 1.04447
1.14467 VA
Recommended Burden for IPCT
10 VA
Ratio
1:1
Class
0.5
METERING‐REACTOR FEEDERS
CE‐267304
48/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS 1
CT DETAILS CT No
T9 CORE‐1 DPDM(LCC)+BC U(LCC) DPDM(LCC)+BC U(LCC)
Function Meter Type CT Primary ( Amp)
4000‐2000
Amp
Adopted Tap ( Amp)
2000
Amp
CT Secondary
1
Amp
CT Class
0.2FS5, 30‐15VA
CT Resistance, Rct ( Assumed ) 2
3.5
Ω (Assum ed )
0.1
milli Ohm
0.0001
VA
METER BURDEN DETAILS Connected Burden is the Energy Meter Alpha‐A3RAQ Alpha Meter CT Resistance per phase 2
Meter Burden at CT Secondary Rated Current = In x Rmeter 3
CT LEAD BURDEN Lead Length ( One Way ), L
200 metre 4 mm2
Lead Size, A Lead Resistance per metre, rl
0.00522235
Total Lead Resistance, RLEAD = rl x L 4
=0.00522235 x 200
Ω / metre
1.04447 Ω
CRITERION FOR METERING CLASS CT ADEQUACY The Criterion for any P class CT used for OC/EF protection, in general is given by Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ] Fn = CT Accuracy Limiting Factor at Rated Burden
5
Sn = CT Rated VA Burden
15 VA
2 Sin = CT Internal Burden = In x Rct
=1^2 x 3.5
3.5 VA
2
Sa = CT Connected Burden = In x [ Rlead x 2 + Rrelay =1^2 x ( 1.04447 x 2 + 0.0001) ] CT Accuracy Limiting Factor at Rated Burden, Fn Actual Accuracy Limiting Factor Fa = Fn x [ Sin + Sn ] / [ Sin + Sa ]
132kV BS‐BC METERING
5 =5 x ( 3.5 + 15) / ( 3.5 + 2.08904)
CE‐267304
2.08904 VA
16.55
49/50
132kV SIDE CT SIZING CALCULATIONS FOR 9027 SS
Maximum Secondary Short Circuit Current Issc = Maximum Primary ( 40kAmp ) / CT Primary The Actual Accuracy Limiting Factor has to be compared with the maximum secondary short circuit current, and Fa is OK if Fa < Issc Maximum Continuous Current for the meter Maximum Short Duration Current = 200% of Max Continuous Current The meter will be safe, since Fa < Maximum Short Duration Current
132kV BS‐BC METERING
CE‐267304
=40 x 1000 / 2000
20
Fa IS OK 20 Amp 40 Amp
50/50
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