CT VT Calculation Al AIN Rev.3(Latest)
Short Description
CT VT Calculation Al AIN Rev.3(Latest)...
Description
.
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical)
33/11kV S/S IN AL AIN AREA INDEX CT / VT PARAMETER CALCULATION Description A.
B.
CT Parameter Calculation
Sheets 3 TO 27
1 33kV Cable Feeder -Directional Over Current & Earth Fault Protection (67,67N)
3 TO 4
2 33kV Cable Feeder -Pilot Wire Protection- (85)
5 TO 5
3 33kV Cable Feeder -Metering
6 TO 7
4 33kV Bus Bar Differential Protection Line Feeder (87B)
8 TO 9
5 33kV Bus Bar Differential Protection Transformer Feeder (87B)
10 TO 10
6 33kV Transformer Feeder -Metering
11 TO 12
7 33/11kV Transformer Differential Protection Calculation (87T)
13 TO 16
8 33kV Transformer Feeder -Directional Over Current Protection (51-51N)
17 TO 18
9 33/11kV Transformer Feeder -Restricted Earth Fault Protection- (64R)
19 TO 21
10 33/11kV Transformer Feeder -Stand By Earth Fault Protection (SBEF)
22 TO 23
11 11kV Cable/Capacitor Bank Feeder -Directional Over Current Protection (51-51N)
24 TO 25
12 11kV Transformer Feeder -Directional Over Current Protection (51-51N)
26 TO 27
VT Parameter Calculation
28 TO 35
1 33kV Line VT - Metering
28 TO 29
2 33kV LINE VT- PROTECTION
30 TO 31
3 33kV Bus VT
32 TO 33
4 11kV Bus VT
34 TO 35
C.
Summary Sheet
36 TO 38
D.
List of catalogue References
39 TO 39
2 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
1 1.1
1.2
1.3
1.4
1.5
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.200 4
33kV Cable Feeder -Directional Over Current & Earth Fault Protection (67,67N) The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap
= = = = = =
CT-F1, CORE-1 600-400/1A 1 A 5 P 20 2 Ohms at 400 A
Assumptions : The Max.3Ph.S.C Current of 33kV Bus
=
31.5 kA
Relays Proposed a Make b Directional Over Current Relay c Directional Earth Fault Relay d Rated Relay secondary current
= = = =
ABB SPAS 348 C REJ 527 1 A
= = = = = = = =
4 sq.mm Cu 5.52 Ohms/km 30 Mtrs 0.030 x 5.52 0.166 Ohms 0.33 Ohms (1x1) x 0.33 VA 0.33 VA
Ipn Isn Rct
Ir
Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL VA Burden of the Lead
Burden of Relay Directional Over Current Relay (SPAS 348 C) Directional Earth Fault Relay (REJ 527) VA Burden of Over Current Relay (SPAS 348 C) VA Burden of Over Current Relay (REJ 527)
3 of 43
= = = = = =
100 mohm 100 mohm (1x1) x 100.00 / 1000 0.10 VA (1x1) x 100.00 / 1000 0.10 VA
400
A tap
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
1.6
1.7
Ref : G1409--RL7440J353 A PREP CHKD APPRD
Burden Details S.No. Device a. Directional Over Current Relay b. Directional Earth Fault Relay c. Lead Burden Total Burden Accuracy Limit Factor of the CT ABB's Requirement Ikmax = In =
RAJIV
SKA / AKS
Burden 0.10 0.10 0.33 0.53
Make SPAS 348 C, ABB REJ 527, ABB
n'
>
Ikmax/In
Highest Fault Current Nominal Primary Current of the CT
=
400 A
Hence as Per ABB (n') must be greater than
Real accuracy Limit Factor
n'
> >
31500 / 400 79
=
nx
KRJ
(PN + PE) (PB + PE)
n PN
=
CT rated Accuracy Limit Factor
=
20
=
15
VA Chosen Value
=
Rated CT Power CT Internal Losses In2 x Rct
=
PE
=
2
Watts
PB
=
Burden at Rated Current
= = =
0.53 20 x (15.0 + 2.0) / (0.53 + 2.0) 134
n'
n' = 1.8
134
>
79 , so the current transformer satisfies the requirement.
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Selected for Directional= Accuracy Class Rated Continuous Thermal Current Rated Short Time Thermal Current
4 of 43
= = = = = =
600-400/1A 400 A 2 Ohms 15 VA 5 P 20 150 % 31.5 kA for 1 Sec
DATE 23.04.200 4
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
2 2.1
2.2
2.3
2.4
2.5
2.6
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.2004
33kV Cable Feeder -Pilot Wire Protection- (85) The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Accuracy Class Secondary Winding Resistance Selected Tap
= = = = = =
CT-F1 CORE-2 600-400/1A 1 A X 2 Ohms at 400 A
Assumptions : The Max.3Ph.S.C Current of 33kV Bus
=
31.5 kA
Relay Proposed a Make b Type d Rated Relay secondary current Ir
= = =
M/S Vatech Reyrolle Ltd. Solkar Rf 1 A
Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL
= = = = = =
4 sq.mm Cu 5.52 Ohms/km 30 Mtrs 0.030 x 5.52 0.166 Ohms 0.33 Ohms
>=
(50/In) + (If/N) x (Rct+2RL)
= =
Rated current of SOLKAR Rf Relay Primary current under maximum steady state through fault conditions Current Transformer Ratio CT Secondary Winding Resistance Single Lead Resistance from CT to Relay
Ipn Isn Rct
Knee Point Voltage Requirement As per Manufactureres Requirement Vk Where In If
400
A tap
Volts
N Rct RL
= = =
Vk
>=
50/1 + 31500 / 400 x (2 + 2x0.166) 234 V
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Class of Accuracy Knee Point Voltage Selected Magnetising Current at Vk/2 Rated Continuous Thermal Current
= = = = >= = 10 for TN= 10 For the time constant of 64 msec Hence the maximum value of the n' form the condition 1 and condition 2 is selected for comparison. n' >= 10 (PN + PE) Rated accuracy Limit Factor n' = n x (PB + PE)
(to be provided by the CT manufacturer) Where n = CT Rated Accuracy Limit Factor PN = Rated VA
=
20
=
10 VA
PE
=
CT Internal Losses In2 x Rct
=
PB
=
Burden at Rated Current n'
n'=
50 >
= = =
Chosen Value
6 Watts 0.35 20 x (10.0 + 6.0) / (0.35 + 6.0) 50
10 , so the current transformer satisfies the requirement.
4.6 Conclusion CT Ratio Selected Line Feeder CT Secondary Resistance Rated VA of the CT Accuracy Class Rated Continuous Thermal Current Rated Short Time Thermal Current
= = = = = =
10 of 43
1200 / 1A 6 Ohms 10 VA 5 P 20 150 % 31.5 kA for
1
Sec
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
5
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.200 4
33kV Bus Bar Differential Protection Transformer Feeder (87B) The CT details Current Transformer Rated Primary Current for CT Rated Secondary Current Rated VA of the CT CT Class Secondary Winding Resistance Rated Continuous Thermal Current Rated Short Time Thermal Current
= = = = = = = =
Note : For Detailed calculation refer clause 4 .
11 of 43
CT-T1-1 CORE-1 1200/1 A 1 A 10 VA 5 P 20 6 Ohms at 150 % 31.5 kA for 1
1200 A tap Sec
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
12 of 43
SKA / AKS
KRJ
DATE 23.04.200 4
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
6 6.1
6.2
6.3
6.4
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
KRJ
23.04.2004
33kV Transformer Feeder -Metering The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap
= = = = = =
Ipn Isn Rct
Assumptions : The Max.3Ph.S.C Current of 33kV Bus Transformer MVA Rating Transformer kV Rating Load Current on 33kV Side Load Current on 11.55kV Side
= = = = =
Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL VA Burden of the Lead
= = = = = = = =
Burden Details S.No. Device a. Bay Control Unit b. Multifunction Meter c. Ammeter Transducer d. Lead Burden
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Selected for Metering Accuracy Class Instrument Security Factor Rated Continuous Thermal Current
CT-T1-1 CORE-2 600-300/1 A 1 A 0.5 S 1.5 Ohms at 300 A
31.5 15 33 / 262.4 749.8
= = = = = 105 , so the current transformer satisfies the requirement.
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Accuracy Class Rated Continuous Thermal Current Rated Short Time Thermal Current
= = = = = = =
21 of 43
600-300/1A 300 A 1.5 Ohms 10 VA 5 P 20 150 % 31.5 kA for 1 Sec
DATE 23.04.200 4
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
9
33/11kV Transformer Feeder -Restricted Earth Fault Protection- (64R)
9.1
The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap I magnetising
9.2
9.3
9.4
= = = = = = =
CT-T1-N CORE-1 1000-800/1A 1 A X 7 Ohms at 800 A 30 mA @ Vk/2
Assumptions : The Max.3Ph.S.C Current of 33kV Bus
=
31.5 kA
Relays Proposed a Make b Restricted Earth Fault Relay d Rated Relay secondary current Ir
= = =
ABB SPAJ 115C 1 A
Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL
= = = = = =
4 sq.mm Cu 5.52 Ohms/km 30 Mtrs 0.030 x 5.52 0.17 Ohms 0.33 Ohms
Ipn Isn Rct
9.5 Through fault current calculation KV Rating of the Transformer MVA rating of the transformer Transformer Per unit impedance Short Circuit MVA Hence Maximum through fault current on the secondary side Ikmax 9.6 Knee point voltage calculation The Knee Point Voltage
The setting Voltage
=
800
= 33 / 11.55 kV = 15 MVA = 10 p.u = 15 / 0.10 = 150 MVA = 150000 / (sqrt(3) x 11.55) = 7498.06 A = 7.5 kA
Vk = 2 Us Where Us is the Voltage setting of the Relay Us
KRJ
Ikmax/n x ( Rct + 2 RL)
22 of 43
DATE 23.04.200 4
A tap
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
9.7 Sensitivity Check The Primary operating Current
RAJIV
SKA / AKS
KRJ
DATE 23.04.200 4
Ikmax
=
n Rct RL Us Us
= = = = = = >= >= >= >=
Maximum through fault current for which relay must not operate Current Transformer turns ratio Secondary Resitance ( Ohms) Total resistance of the longest measuring circuit 7498.1 / 800(7 + 0.33) 68.7 75 2Us 2 x 75 150 150
=
400
Set value of Us Hence Knee point voltage
Knee point Voltage selected approx. Adopted Value of Uk
Ref : G1409--RL7440J353 A PREP CHKD APPRD
Uk
n x ( Ir + m * Ie + Iu) CT transformation ratio 800 Ir Relay Operating Current >= m*Ie 45 mA Ie Current Transformer Mag. Current at setting voltage = (30x75) / (400/2) = 11.25 mA m = Number of CT's in the differential current circuit = 4 Nos Iu = Current through varistor at Us = 10 mA (As per Relay Catalogue for SPAJ 115C) (Figure-4, Operating Characterstic of the voltage dependant Resistor) ( Voltage Dependant Resistor Type 5248 831-C) Hence, the primary operating Current = 800 ( 0.045 + 4x0.011 + 0.010) = 80
9.8 Value of stabilising Resistor (Rs) Maximum Possible value of Us Minimum value of start Current Ir Value of stabilising Resistor (Rs)
Iop n
V
= = = = = =
= =
75 V 45 mA
= =
Us/Ir 1666.7
23 of 43
(It is m x Ie as recommended in the catalogue for SPAJ 115C) Ohms Type - (5248 831-C)
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.200 4
The input Impedance of the SPAJ115C relay = 0.1 Ohms Since the input impedance of the relay is negligible in comparison to the value of stabilising resistor, the same is not substracted from the calculated value of Rs above. 9.9
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Selected for Restricted= Earth fault protection Minimum Knee point Voltage Requirement Accuracy Class I magnetising Rated Continuous Thermal Current Rated Short Time Thermal Current
= = =
1000-800/1A 800 A 7 Ohms 10 VA
= = = = =
400 V X 30 mA @ Vk/2 150 % 31.5 kA for 1 Sec
24 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
10
33/11kV Transformer Feeder -Stand By Earth Fault Protection (SBEF)
10.1
The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap
10.2
10.3
10.4
10.5
Ipn Isn Rct
Assumptions : The Max.3Ph.S.C Current of 33kV Bus Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL VA Burden of the Lead
= = = = = =
CT-T1-N CORE-2 1000-800/1A 1 A 5 P 20 4 Ohms at 800 A
=
31.5 kA
= = = = = = = =
4 sq.mm Cu 5.52 Ohms/km 30 Mtrs 0.030 x 5.52 0.17 Ohms 0.33 Ohms (1x1) x 0.33 VA 0.33 VA
Burden Details S.No. Device a. Stand By Earth Fault Relay B. Lead Burden Total Burden Accuracy Limit Factor of the CT ABB's Requirement Ikmax = In =
Burden 0.10 0.33 0.43
>
Ikmax/In
Highest Fault Current Nominal Primary Current of the CT
=
800 A
> >
31500 / 800 39
=
nx
Real accuracy Limit Factor
n'
(PN + PE) (PB + PE)
n PN
=
CT rated Accuracy Limit Factor
=
20
=
15
VA Chosen Value
=
Rated CT Power CT Internal Losses In2 x Rct
=
PE
=
4
Watts
25 of 43
800
Make ABB, REJ 521
n'
Hence as Per ABB (n') must be greater than
KRJ
DATE 23.04.2004
A tap
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
=
Burden at Rated Current
PB
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV =
26 of 43
0.43
SKA / AKS
KRJ
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV n'
10.6
= =
SKA / AKS
KRJ
20 x (15.0 + 4.0) / (0.43 + 4.0) 86
n' = 86 > 39 , so the current transformer satisfies the requirement. Conclusion CT Ratio Selected = 1000-800/1A Selected Tap = 800 A CT Secondary Resistance = 4 Ohms Rated VA of the CT core Selected for Metering = 10 VA Accuracy Class = 5 P 20 Rated Continuous Thermal Current = 150 % Rated Short Time Thermal Current = 31.5 kA for 1 Sec
27 of 43
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
11
11kV Cable/Capacitor Bank Feeder -Directional Over Current Protection (51-51N)
11.1
The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap
11.2
11.3
11.4
11.5
11.6
= = = = = =
CT-2, 4 CORE-1 600-300/1A 1 A 5 P 20 1.5 Ohms at 300 A
Assumptions : The Max.3Ph.S.C Current of 33kV Bus
=
31.5 kA @
Relays Proposed a Make b Directional Over Current Relay c Directional Earth Fault Relay d Rated Relay secondary current
= = = =
ABB REF 542 Plus REF 542 Plus 1 A
= = = = = = = =
4 sq.mm Cu 5.52 Ohms/km 30 Mtrs 0.030 x 5.52 0.17 Ohms 0.33 Ohms (1x1) x 0.33 VA 0.33 VA
Ipn Isn Rct
Ir
Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL VA Burden of the Lead Burden Details S.No. Device a. Directional Over Current Relay c. Lead Burden Total Burden Accuracy Limit Factor of the CT ABB's Requirement Hence as Per ABB (n') must be greater than
28 of 43
Burden 0.10 0.33 0.43
33
300
kV
Make REF 542 Plus
>= Ikmax/In >= 31500 / 300 >= 105
DATE 23.04.200 4
A tap
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.200 4
For the System under Consideration Real accuracy Limit Factor
n'
=
nx
(PN + PE) (PB + PE)
Where n = PN = PE = PB
=
CT rated Accuracy Limit Factor
=
20
Rated CT Power CT Internal Losses In2 x Rct
=
10
VA (Selected Value)
=
1.5
Watts
Burden at Rated Current
=
0.43 = 20 x (10.0 + 1.5) / (0.43 + 1.5) = 119
n'
n' = 11.7
119 > 105 , so the current transformer satisfies the requirement.
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Selected for Directional= Overcurrent Earth fault protection Accuracy Class Rated Short Time Thermal Current
29 of 43
= = =
= =
600-300/1A 300 A 1.5 Ohms 10 VA 5 P 20 31.5 kA for 1 Sec
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
12
11kV Transformer Feeder -Directional Over Current Protection (51-51N)
12.1
The CT details Current Transformer Rated Primary Current Rated Secondary Current CT Class Secondary Winding Resistance Selected Tap
12.2
12.3
12.4
12.5
12.6
Ipn Isn Rct
Assumptions : The Max.3Ph.S.C Current of 33kV Bus Transformer MVA Rating Transformer kV Rating Load Current on 33kV Side Load Current on 11.55kV Side
= = = = = =
CT-T1-2, CORE-4 1000-800/1A 1 A 5 P 20 4 Ohms at 800 A
= = = = =
31.5 kA @ 33 kV 15 MVA 33 / 11.55 kV 262.4 A 749.8 A
Relays Proposed a Make = b Directional Over Current and Earth fault Relay = c Rated Relay secondary current Ir = Calculation of Lead Burden RL Cable considered for CT connection AC Resistance of the cable @ 70deg C Length between CT and the Relay Single Lead Resistance from CT to Relay RL 2RL VA Burden of the Lead
= = = = = = = =
Burden Details S.No. Device a. Directional Over Current Relay c. Lead Burden Total Burden Accuracy Limit Factor of the CT ABB's Requirement Hence as Per ABB (n') must be greater than
30 of 43
KRJ
ABB SPAJ 140C 1 A
4 sq.mm Cu 5.52 Ohms/km 10 Mtrs 0.010 x 5.52 0.06 Ohms 0.11 Ohms (1x1) x 0.11 VA 0.11 VA Burden 0.10 0.11 0.21
Make SPAJ 140C
>= Ikmax/In >= 31500 / 800 >= 39
800
DATE 23.04.200 4
A tap
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
CT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
For the System under Consideration Real accuracy Limit Factor
n'
=
nx
(PN + PE) (PB + PE)
Where n = PN = PE = PB
=
CT rated Accuracy Limit Factor
=
20
Rated CT Power CT Internal Losses In2 x Rct
=
10
VA (Selected Value)
=
4
Watts
Burden at Rated Current
=
0.21 = 20 x (10 + 4.0) / (0.21 + 4.0) = 67
n'
n' = 12.7
67
>
39 , so the current transformer satisfies the requirement.
Conclusion CT Ratio Selected Selected Tap CT Secondary Resistance Rated VA of the CT core Selected for Directional= Overcurrent Earth fault protection Accuracy Class Rated Continuous Thermal Current Rated Short Time Thermal Current
31 of 43
= = =
1000-800/1A 800 A 4 Ohms 10 VA
= = =
5 P 20 150 % 31.5 kA for 1 Sec
DATE 23.04.200 4
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
DATE
KRJ
23.04.2004
1 33kV Line VT - Metering 1.1 VT Details VT Voltage Rating VA Rating Core-1
= = = =
PT-F1, CORE-1 VA Cl :1
1.2 VT Burden Calculation Burden on Core-1 Voltage Rating of the VT = VA Rating of the VT = Current Supplied by VT at maximum VA Rating = IVT (a) Lead Burden on Core-1 Cable
S. No
1
110 V 100 VA (100 x sqrt(3) ) / (110) 1.575
Cable Size in (Sq.mm)
From
To
VT
Synchronising Circuit
4C
x
2.5
A Cable 2 Way Resistance Cable Total Lead (R) in Length Loss (VA)= (Ohms/km) (L) in (m) (IVT2xRxL/1000) 8.87
Cu. Conductor (b) Other Burdens on Core-1 S.No. Device 1 Tarrif Metering Not Applicable 2 Backup Metering Voltmeter 3 Protection Relays Not Applicable 4 Synchronisation a. Check Synchronisation Relay b. Synchroscope c. Double Frequency Meter d. Double Volt Meter e. No Voltage Relay 5 Lead Burden a. Lead Burden under S.No-1 above Total Burden
2 x 30
1.320
60
Burden (VA)
Make
Type
5
-
-
0.25 6 1.2 5 1.2
ABB ABB ABB ABB ABB
SPAU140 C
1.32 19.97
32 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
1.3 Conclusion Actual Burden of the Line-1 VT Core-1 Selected Parameters VA rating Selected Accuracy Class of Core-1
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
:
19.97
VA
: :
100.0 Cl :1
VA
33 of 43
KRJ
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.2004
2 33kV LINE VT- PROTECTION 2.1 VT Details VT Voltage Rating VA Rating Core-2
= = = =
PT-F1, CORE-2 VA Cl :3P
2.2 VT Burden Calculation Burden on Core-2 Voltage Rating of The VT = VA Rating of the VT = Current Supplied by VT at maximum VA Rating = IVT (a) Lead Burden on Core-1 Cable
S. No
1
110 V 50 VA (50 x sqrt(3) ) / (110) 0.787
Cable Size in (Sq.mm)
From
To
VT
SPAS 348C Relay
4C
x
2.5
A Cable 2 Way Resistance Cable Total Lead (R) in Length Loss (VA)= (Ohms/km) (L) in (m) (IVT2xRxL/1000) 8.87
Cu. Conductor (b) Other Burdens on Core-2 S.No. Device 1 Tarrif Metering Not Applicable 2 Backup Metering Not Applicable 3 Protection Relays Directional O/C and Earth Fault Relay 4 Synchronisation Not Applicable 5 Lead Burden a. Lead Burden under S.No-1 above Total Burden
2 x 30
0.330
60
Burden (VA)
Make
Type
0.5
ABB
SPAS 348 C
0.33 0.83
34 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
2.3 Conclusion Actual Burden of the Line-1 VT Core-2 Selected Parameters VA rating Selected Accuracy Class of Core-2
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV : : :
35 of 43
0.83
SKA / AKS VA
50.0 VA Cl :3P
KRJ
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
KRJ
DATE 23.04.2004
3 33kV Bus VT 3.1 VT Details VT Voltage Rating VA Rating Core-1
= = = =
PT-BUS-1, CORE-1 VA Cl :1
3.2 VT Burden Calculation Burden on Core-1 Voltage Rating of The VT = VA Rating of the VT = Current Supplied by VT at maximum VA Rating = IVT (a) Lead Burden on Core-1 Cable
S. No
1
110 V 100 VA (100 x sqrt(3) ) / (110) 1.575
Cable Size in (Sq.mm)
From
To
VT
Synchronising Circuit
4C
x
2.5
A Cable 2 Way Resistance Cable Total Lead (R) in Length Loss (VA)= (Ohms/km) (L) in (m) (IVT2xRxL/1000) 8.87
Cu. Conductor (b) Other Burdens on Core-1 S.No. Device 1 Tarrif Metering Not Applicable 2 Backup Metering Not Applicable 3 Protection Relays Not Applicable 4 Synchronisation a. Check Synchronisation Relay b. Synchroscope c. Double Frequency Meter d. Double Volt Meter e. No Voltage Relay 5 Lead Burden a. Lead Burden under S.No-1 above Total Burden
2 x 30
1.320
60
Burden (VA)
Make
Type
0.25 6 1.2 5 1.2
ABB ABB ABB ABB ABB
SPAU140 C
1.32 14.97
36 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
3.3 Conclusion Actual Burden of the Line-1 VT Core-1 Selected Parameters VA rating Selected Accuracy Class of Core-1
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
:
14.97
VA
: :
100.0 Cl :1
VA
37 of 43
KRJ
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
DATE
KRJ
23.04.2004
4 11kV Bus VT 4.1 VT Details Voltage Rating VA Rating Core-1
VA Cl :1
= = =
4.2 VT Burden Calculation Burden on Core-1 Voltage Rating of The VT = VA Rating of the VT = Current Supplied by VT at maximum VA Rating = IVT
110 V 100 VA (100 x sqrt(3) ) / (110) 1.575
A
(a) Lead Burden on Core-1 Cable
S. No
1
Cable Size in (Sq.mm)
From
To
VT
Synchronising Circuit
4C
x
2.5
Cable 2 Way Resistance Cable Total Lead (R) in Length Loss (VA)= (Ohms/km) (L) in (m) (IVT2xRxL/1000) 8.87
Cu. Conductor (b) Other Burdens on Core-1 S.No. Device 1 Tarrif Metering Not Applicable 2 Backup Metering Not Applicable 3 Protection Relays Voltmeter 4 Synchronisation a. Check Synchronisation Relay b. Synchroscope c. Double Frequency Meter d. Double Volt Meter e. No Voltage Relay 5 Lead Burden a. Lead Burden under S.No-1 above Total Burden
2 x 30
1.320
60
Burden (VA)
Make
Type
5
-
-
0.25 6 1.2 5 1.2
ABB ABB ABB ABB ABB
SPAU140 C
1.32 19.97
38 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) PROJECT
:
33/11kV S/S IN AL AIN AREA
TITLE
:
VT Parameter Calculations
4.3 Conclusion Actual Burden of the 11kV Feeder VT Core-1 Selected Parameters VA rating Selected Accuracy Class of Core-1
Ref : G1409--RL7440J353 A PREP CHKD APPRD RAJIV
SKA / AKS
:
19.97
VA
: :
100.0 Cl :1
VA
39 of 43
KRJ
DATE 23.04.2004
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) Revision : A S.No.
Description
CT No.
Ratio (A/A)
Class
Burden (VA)
Date : 23.04.2004
Ukp (V)
Rct (Ohm)
Relay
1.
33kV Cable Feeder -Directional Over Current & Earth Fault Protection (67,67N)
CT-F1, CORE-1
600-400/1A
5 P 20
15
-
2
SPAS 348 C
2.
33kV Cable Feeder -Pilot Wire Protection- (85)
CT-F1 CORE-2
600-400/1A
X
-
400
2
Solkar Rf
CT-F1 CORE-3
600-400/1A
0.5 S
10
-
2
-
CT-F1 CORE-4
1200 / 1A
5 P 20
10
-
6
ABB, REB 500
CT-T1-1 CORE-1
1200/1 A
5 P 20
10
-
6
ABB, REB 500
CT-T1-1 CORE-2
600-300/1 A
0.5 S
10
-
1.5
-
10
400
2
3. 4. 5. 6.
7.
33kV Cable Feeder -Metering 33kV Bus Bar Differential Protection Line Feeder (87B) 33kV Bus Bar Differential Protection Transformer Feeder (87B) 33kV Transformer Feeder -Metering 33/11kV Transformer Differential Protection Calculation (87T)
CT-T1-1 CORE-3 / CTT1-2 CORE-1
600-300/1 A X 1000-800/1 A
ABB, RET 316*4 10
400
4
8.
33kV Transformer Feeder -Directional Over Current Protection (51-51N)
CT-T1-1,CORE-4
600-300/1A
5 P 20
10
-
1.5
SPAJ 140C
9.
33/11kV Transformer Feeder -Restricted Earth Fault Protection(64R)
CT-T1-N CORE-1
1000-800/1A
X
10
400
7
SPAJ 115C
10.
33/11kV Transformer Feeder -Stand By Earth Fault Protection (SBEF)
CT-T1-N CORE-2
1000-800/1A
5 P 20
10
-
4
ABB, REJ 521
11.
33kV Bus Bar Differential Protection - Bus Section Feeder (87B)
CT-BC1-1 CORE-3 / CTBC1-2 CORE-1
1200/1A
5 P 20
10
-
6
ABB, REB 500
40 of 43
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) Revision : A S.No.
Description
CT No.
Ratio (A/A)
Class
Burden (VA)
Date : 23.04.2004
Ukp (V)
Rct (Ohm)
Relay
12.
33kV Bus Section Feeder Metering
CT-BC1-1 CORE-2
1200/1A
0.5 S
10
-
4.5
-
13.
33kV Bus Section Feeder Directional Overcurrent Protection (51-51N)
CT-BC1-1 CORE-1
1200/1A
5 P 20
10
-
6
SPAJ 140C
14.
11kV Transformer Feeder -Directional Over Current Protection (51-51N)
CT-T1-2, CORE-4
1000-800/1A
5 P 20
10
-
4
SPAJ 140C
15.
11kV Transformer Feeder -Metering
CT-T1-2, CORE-3
1000-800/1A
0.5 S
10
-
4
-
16.
11kV Cable/Capacitor Bank Feeder -Directional Over Current Protection (51-51N)
CT-2, 4 CORE-1
600-300/1A
5 P 20
10
-
1.5
REF 542 Plus
17.
11kV Cable/Capacitor Bank Feeder - Metering
CT-2, 4 CORE-2
600-300/1A
0.5 S
10
-
1.5
-
18.
11kV Aux. Transformer FeederOver Current Protection
CT-3 CORE-1
30/1A
5 P 20
6
-
REF 542 Plus
19.
11kV Aux. Transformer FeederMetering
CT-3 CORE-2
30/1A
0.5 S
7.5
-
-
20.
11kV Bus Section Feeder- Over Current Protection
CT-1 CORE-1
1600/1A
5 P 20
10
-
41 of 43
8
REF 542 Plus
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical) Revision : A S.No.
21.
S.No. 1. 2. 3. 4.
1. 2. 3. 4. 5.
Description
11kV Bus Section FeederMetering
VT Data 33kV Line VT - Metering 33kV LINE VT- PROTECTION 33kV Bus VT 11kV Bus VT Technical Data: 33kV Side Rated Voltage Service Voltage Frequency Continuous Thermal Current Short time Current (1 sec.)
CT No.
CT-1 CORE-2
VT No. PT-F1, CORE-1 PT-F1, CORE-2 PT-BUS-1, CORE-1 Core-1
Additional CTs requirements 36 kV 33 kV 50 Hz 150 % 31.5 kA
Ratio (A/A)
Class
1600/1A
Ratio (V/V)
0.5 S
Burden (VA) 19.97 0.83 14.97 19.97
Technical Data: 11kV Side Rated Voltage Service Voltage Frequency Continuous Thermal Current Short time Current (1 sec.)
42 of 43
Burden (VA)
Date : 23.04.2004
Ukp (V)
10
Rct (Ohm)
-
Selected Class (VA) 100 Cl :1 50 Cl :3P 100 Cl :1 100 Cl :1
12 kV 11 kV 50 Hz 150 % 31.5 kA
8
Relay
-
LARSEN & TOUBRO LIMITED ECC Division - EDRC (Electrical)
REFERENCES CT / VT PARAMETER CALCULATION S.No. a.
Description ABB's Application guide to Overcurrent Modules and functions of SPACOM and RE_ Series
b.
SPAS 348C Relay Catalogue for Relay Burden Information
c.
REJ 527 Relay Catalogue for Relay Burden Information
d.
Solkar Rf Relay Catalogue for Current Transformer Requirement
e.
Circuitor CVKm Multifunction Meter Catalogue
f.
CELSA CRI Ammeter Transducer
e.
REB 500 Relay Catalogue for Burden Information
g.
ABB's Requirement on Current Transformers for REB 500
h.
RET 316*4 Relay Catalogue for Burden Information
I.
ABB's Requirement on Current Transformers for RET 316 / RET 316*4
j.
SPAJ 140 C Relay Catalogue for Burden Information
k.
SPAJ 115 C Relay Catalogue
l.
ABB's Requirement on Current Transformers for SPAJ 115C
m.
REJ 521 Relay Catalogue for Burden Information
n.
REF 542 Plus Relay Catalogue for Burden Information
43 of 43
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