CT Sizing Calculations

‫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


‐

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 Bay No =D17, =D02 ( SPARE CAPACITOR BAYS )

CT DATA

CT Class


CT Primary Adopted CT ( Amp) Tap ( Amp) Secondary

CT Class


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


‐

3

T13 CORE‐1


‐

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 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


‐

1600‐1200‐ 800‐600

3

T3 CORE‐3


‐

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



CE‐267304

5/50


Sr. No

132kV Bay No=D04, =D09, =D10 ( 132/13.8kV GT Bays )

CT DATA

CT No

Function


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



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


Sr. No

132kV Bay No=D21, =D26 ( 132kV Reactor Bays )

Shunt Reactor Bushing CTs

CT DATA

CT No

Function


CT Class



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


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



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 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




CE‐267304

9/50


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


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


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


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


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


360

Volts


360

Volts


50

mAmp


50

mAmp


1

Ω


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


Reffer System Data

0.00522235

Ω


=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


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


1000

Volts


1000

Volts


25

mAmp


25

mAmp


7

Ω


7

Ω

CT Knee Point Voltage Calculation CT Cable Route Length ( One Way ) CT Cable Size

400

metre

4

mm2


Reffer CT Data

0.005222 Ω


=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


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


SGT Bays, Bay No =D05, D06, D14 1

CT Data T1 CORE‐ 3 87C2+95C 2


2

REB650

CT Primary ( Amp)

3000

Amp

Adopted Tap ( Amp)

3000

Amp

CT Secondary

1

Amp

CT Class

X


1000

Volts


1000

Volts


25

mAmp


25

mAmp


7

Ω


7

Ω


400

metre

4

mm2


Reffer CT Data

0.005222 Ω


=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


Amp


Voltage Setting Of REB650 + Series Resistance Combination REB650 Current Setting Range

0.02 ‐ 1 Amp


100

mAmp

179

Volts

1790

Ω


=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


Where Ir = REB650 operating current

100

mAmp


4.48

mAmp

0

mAmp

0

mAmp

104.48

mAmp



Imet, Metrosil Current = 0 at setting voltage

5

Iop = Ir + Im + Isupvn + Imet

=100 + 4.48 + 0 + 0


=1.2 x 3000

3600

Amp


=3600 x 10001 / 3000

1200

mAmp


=1200 ‐ 104.48

1095.52 mAmp


=179x 1000 / 1095.52

163.39

Ohms

Required Wattage of Shunt Resistor = Vs2 / Rsh

=179^2/163.39

196.1

Watts


=0.25 x 3000

750

Amp


=750 x 1 / 3000

0.25

Amp



Calculated above

1790

Ω


Calculated above

163.39

Ω


=1000 x 1000 / 7

142857.1 Ω


=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


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


1000

Volts


1000

Volts


25

mA


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


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 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


Reffer CT Data

0.005222 Ω


=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


Amp



0.01 to 25 Amp


100

mAmp

408

Volts

4080

Ω


=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


Iop = Ir + Im + Isupvn + Imet Where Ir = REC670 operating current

100

mAmp


1.42

mAmp

0

mAmp

0

mAmp

101.42

mAmp



Imet, Metrosil Current = 0 at setting voltage Iop = Ir + Im + Isupvn + Imet

=100 + 1.42 + 0 + 0


=1.2 x 1200

1440

Amp


=1440 x 10001 / 1200

1200

mAmp


=1200 ‐ 101.42

1098.58 mAmp


=408x 1000 / 1098.58

371.39

Ohms

=408^2/371.39

448.22

Watts

2

Required Wattage of Shunt Resistor = Vs / Rsh 5


=0.25 x 1200

300

Amp


=300 x 1 / 1200

0.25

Amp



Calculated above

4080

Ω


Calculated above

371.39

Ω


=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



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


50

mAmP

NOT Ω AVILABLE

CT Resistance (Ohms) CT Resistance Selected Tap (Ohms)

1

Ω


400

metre

4

mm

2

0.00522235 Ω

CT Cable Resistance per metre Total CT Cable Resistance ( One Way ) 3

Volts

NOT mAmP AVILABLE


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


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


Amp

30

mAmp

11

Volts


=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


0

mAmp

31.38

mAmp



=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


=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


=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


160.3

Ω

8

Ω

7.465

Ω

6.53

Volts


=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


CE‐267304

0.018

Amp

7

Volts

26/50


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


2400‐1200‐800‐ Volts 400


400


8.33‐16.7‐25‐50 mAmP


50

mAmP


6‐3‐2‐1

Ω


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


100 metre 4 mm2

Lead Size, A Lead Resistance per metre, rl

0.00522235 Ω / metre


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


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


3


200 metre 4 mm2


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


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


800

Volts


NA

Volts


25

mAmP


NA

mAmP


6

Ω


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


Total Device Burden 3

=0.02 + 0.02


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


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 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


800

Volts


800

Volts


25

mAmp


25

mAmp


6

Ω


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


Reffer CT Data

0.005222 Ω


=0.00522235 x 400

2.08894 Ω


=40 x 1000 / 4000

10

Amp

=10 x (6 + 2 x 2.08894)

101.779 Volts

=1.2 x 101.779

122.135 Volts



0.01 to 25 Amp


100

mAmp

123

Volts

1230

Ω


=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


3.84

mAmp

0

mAmp

0

mAmp

103.84

mAmp




5


=100 + 3.84 + 0 + 0


=1.2 x 4000

4800

Amp


=4800 x 10001 / 4000

1200

mAmp


=1200 ‐ 103.84

1096.16 mAmp


=123x 1000 / 1096.16

112.21

Ohms


=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


=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


Calculated above

112.21

Ω


=1000 x 800 / 6

133333.3 Ω


=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)


87B+95B‐DISC(REC670)

CE‐267304

102.75

Ω

25.6875 Volts 0.021

Amp

26

Volts

34/50


132kV Busbar Check Zone 1

CT Data T2 CORE‐ 3 87B (CHK ZONE)


RET670

CT Primary ( Amp)

4000

Amp

Adopted Tap ( Amp)

4000

Amp

CT Secondary

1

Amp

CT Class

X


800

Volts


800

Volts


25

mAmp


25

mAmp


6

Ω


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


Reffer CT Data

0.005222 Ω


=0.00522235 x 400

2.08894 Ω


=40 x 1000 / 4000

10

Amp

=10 x (6 + 2 x 2.08894)

101.779 Volts

=1.2 x 101.779

122.135 Volts



0.01 to 25 Amp


100

mAmp

123

Volts

1230

Ω


=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


3.84

mAmp

0

mAmp

0

mAmp

103.84

mAmp




5


=100 + 3.84 + 0 + 0


=1.2 x 4000

4800

Amp


=4800 x 10001 / 4000

1200

mAmp


=1200 ‐ 103.84

1096.16 mAmp


=123x 1000 / 1096.16

112.21

Ohms


=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


=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


Calculated above

112.21

Ω


=1000 x 800 / 6

133333.3 Ω


=1230 x 112.21 x 133333.33 / (1230 x 112.21 + 1230 x 133333.33 + 112.21 x 133333.33)


87B+95B‐CHK(REC670)

CE‐267304

102.75

Ω

25.6875 Volts 0.021

Amp

26

Volts

36/50


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


200 metre 4 mm2

Lead Size, A

4

Lead Resistance per metre, rl

Reffer System Data


=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


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


NA

Volts


NA

Volts


NA

mAmp

CT M CT Magnetizing Current At Selected Tap ti i C t At S l t d T

NA

mAmp A


NA

Ω


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


=0.05 + 0.05 + 0.0001 + 0.0001 + 0.05

0.1502

VA (Assum ed) VA (Assum ed) VA


METERING‐GT FEEDERS

200 metre

CE‐267304

39/50

132kV SIDE CT SIZING CALCULATIONS FOR 9016 SS 4 mm2


0.00522235


=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


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


2800‐2100‐ 1400‐1050

Volts


1400

Volts


12.5‐16.7‐25‐ 33.3

mAmp


25

mAmp


4‐3‐2‐1.5

Ω


2

Ω

Bay Control Unit 7SMD664 Burden

0.05

VA


0.05


0.0001

VA (Assum VA


0.0001

VA (Assum

0.1002

VA

DEVICE BURDEN DETAILS


=0.05 + 0.05 + 0.0001 + 0.0001


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



IPCT Burden > Lead Burden + Device burden Lead Burden = In2 x 2 x RLEAD

=1^2 x 1.04447

1.04447 VA


=0.1002 + 1.04447

1.14467 VA


10 VA

Ratio

1:1

Class

0.5

METERING‐SPARE OG FEEDERS

CE‐267304

42/50


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


3500‐2800‐ Volts 2100‐1750‐1400


1750


10‐12.5‐16.7‐20‐ mAmp 25


20

mAmp


5‐4‐3‐2.5

Ω


3

Ω


0.05

VA


0.05


0.0001

VA (Assum VA


0.0001

VA (Assum

0.1002

VA

Volts



Amp

=0.05 + 0.05 + 0.0001 + 0.0001


200 metre 4 mm2


METERING‐CAPACITOR FEEDERS

0.00522235 =0.00522235 x 200

CE‐267304

Ω / metre

1.04447 Ω

43/50



IPCT Burden > Lead Burden + Device burden 2 Lead Burden = In x 2 x RLEAD

=1^2 x 1.04447

1.04447 VA


=0.1002 + 1.04447

1.14467 VA


10 VA

Ratio

1:1

Class

0.5

METERING‐CAPACITOR FEEDERS

CE‐267304

44/50


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


4200‐3500‐ 2800‐2240‐ 1680‐1400

Volts


1400

Volts


8.33‐10‐12.5‐ 15.6‐20.8‐25

mAmp


25

mAmp


6‐5‐3.2‐2.4‐2 6 5 3.2 2.4 2

Ω


2

Ω


0.05

VA


0.05


0.0001

VA (Assum VA


0.0001

VA (Assum

0.1002

VA



Amp

=0.05 + 0.05 + 0.0001 + 0.0001


200 metre 4 mm2


METERING‐SPARE SVC BAY

0.00522235 =0.00522235 x 200

CE‐267304

Ω / metre

1.04447 Ω

45/50




=1^2 x 1.04447

1.04447 VA


=0.1002 + 1.04447

1.14467 VA


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


2400‐1200‐800‐ Volts 400


400


8.33‐16.7‐25‐50 mAmp

CT Magnetizing Current At Selected Tap g g p

50

mAmp p


6‐3‐2‐1

Ω


1

Ω


0.05

VA


0.05


0.0001

VA (Assum VA


0.0001

VA (Assum

0.1002

VA



Volts

=0.05 + 0.05 + 0.0001 + 0.0001


200 metre 4 mm2


METERING‐REACTOR FEEDERS

0.00522235 =0.00522235 x 200

CE‐267304

Ω / metre

1.04447 Ω

47/50




=1^2 x 1.04447

1.04447 VA


=0.1002 + 1.04447

1.14467 VA


10 VA

Ratio

1:1

Class

0.5

METERING‐REACTOR FEEDERS

CE‐267304

48/50


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


200 metre 4 mm2


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


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 ]


5 =5 x ( 3.5 + 15) / ( 3.5 + 2.08904)

CE‐267304

2.08904 VA

16.55

49/50


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


CE‐267304

=40 x 1000 / 2000

20

Fa IS OK 20 Amp 40 Amp

50/50

CT Sizing Calculations

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