CT & PT Calculations-480V Swgr-Arar
Short Description
Ct and PT calculations...
Description
TCE CONSULTING ENGINEERS LIMITED 30421007-3CL00007-P0B
SHEET i OF i CT & PT CALCULATION FOR 480V SWITCHGEAR SIZING REPORT
SAUDI ELECTRICITY COMPANY EASTERN OPERATING AREA Dammam, Saudi Arabia GENERATION EXPANSION OF ARAR POWER PLANT (CONTRACT NO : 30421007/00)
DESIGN BASIS FOR CT & PT CALCULATION FOR 480V SWITCHGEAR
DOCUMENT NO : 30421007-3CL-0000-P0B APRIL 2005
ENGINEERING CONSULTANT TCE CONSULTING ENGINEERS LIMITED 73/1, ST.MARK'S ROAD BANGALORE 560001 INDIA
CONTRACTOR: AL-TOUKHI COMPANY FOR INDUSTRY & TRADING P.O.BOX 497, RIYADH 11411, KINGDOM OF SAUDI ARABIA TEL.00966-1-14633660 : FAX.00966-1-4631150
P0B 03.05.2005
DG
SJH
REV NO. DATE
PREPARED BY
CHECKED BY
276447609.xls SECTION :cover sheet
CLEARED BY
APPROVED BY
SHEET 1 OF 9
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH 7/14/2015
Project : Generation expansion at ARAR P/P
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
Rev. No.
CALCULATIONS FOR CT & PT PARAMETERS IN ARAR GENERATION EXPANSION PROJECT REFERENCE DATA 1) Short Cicruit Study 2) General Site Layout - Dwg No KA-667182 3) SEC -EOA's Specification : PTS-1022 4) Main One line diagram(480V Swgr) dwg no KA667484 5) 480V Aux One line Diagram KT-808221
2 of 9
P0B
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Project : Generation expansion at ARAR P/P Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
7/14/2015
Rev. No.
480V Switchgear Incomer CT sizing 1) Calculation of parameters for SAT Neutral side CT used for Earth Fault 51G protection. BCT-HY.C1 Station Auxiliary Transformer Rating
=
3 MVA , ONAN 4.16/0.480kV, Dyn11, Z=8% at ONAN rating
Therefore full load currrent on 480V Side
= = =
(MVAx 1000)/(1.732 x kV) 3 x 1000 / 1.732 x 3608.55 Amps
CT ratio chosen
=
0.48
4000/1 A
Relay Used : SPAJ110C Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation The actual fault as per short cirucit study is 45.7kA. Considering 20% margin it is Kx = 54.84/ 2000 =
27.42
Rct
=
14
Rb
=
54.84 KA
Rrelay + 2Rl
The CT burdens of numerical relays are below 0.1VA and can therefore be neglected Considering 6 sq.mm copper conductor cable between CT and relay, resistance of 6 sq.mm copper cable = 3.5 Ohms / km Maximum cable length = 50 Cable Lead Resistance for the loop Rl
Rb
=
0.350
=
0.350
M =
(from site plan) 2
x
3.5
x
Ohms
Knee point voltage Ek
= 27 x (14 + 0.35) = 393 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 472 Ek
=
CT Class = Therefore CT chosen CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class CT Cable to be used
475
V
PX
>= =
4000/1 A 475 V 14 ohms PX 6 sq.mm copper cable
2) Calculation of CT parameters for ( 51& 51N) on LV side of SAT CT-101F.C1
3 of 9
0.05
P0B
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Project : Generation expansion at ARAR P/P Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
7/14/2015
Rev. No.
CT Ratio Selection : SAT Rating
=
Full Load current on 0.48kV side
= =
CT ratio selected on 480V side is
3.0
MVA
(MVAx 1000)/(1.732 x kV) 3608.44 A =
4000 /1 Amp
Relay Used : SPAJ140C Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation The actual fault as per short cirucit study is 45.7KA. Considering 20% margin it is Kx = 54.84/ 2000 =
27.42
Rct
=
14
Rb
=
54.84 KA
Rrelay + 2Rl
The CT burdens of numerical relays are below 0.1VA and can therefore be neglected Considering 6 sq.mm copper conductor cable between CT and relay, resistance of 6 sq.mm copper cable = 3.5 Ohms / km Maximum cable length = 50 Cable Lead Resistance for the loop Rl
Rb
=
0.350
=
0.350
M =
(from site plan) 2
x
3.5
x
0.05
Ohms
Knee point voltage Ek
= 27 x (14 + 0.35) = 393 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 472 Ek
=
CT Class = Therefore CT chosen
475
V
PX
CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class CT Cable to be used
>= =
4000 /1 Amp 475 V 14 ohms PX 6 sq.mm copper cable
3) SAT LV side metering CT CT-101F.C1 Meters
0.05 0.05
Total CT VA burden selected is
As per ION metering catalogue
30VA
Voltage developed across CT at rated current(1A) =
1 x (Rct + 30) V
4 of 9
P0B
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Project : Generation expansion at ARAR P/P Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
7/14/2015
Rev. No.
= =
1 x (14 + 30) 44V
Isf selected is 5 Therefore during fault voltage across CT = 5 x (Rct + 30) V = 185 V When the connected burden is 0.05 the voltage developed is = y x (14 + 0.05) y
=
Where y is magnified Isf)
13
Therefore CT chosen
4000 /1 A. 30 VA CL.0.5 ISF = =
2000 /1 Amp 250 V 7 ohms PX 6 sq.mm copper cable
7) Calculation of parameters for UAT LV side Overall Unit Differential Protection 87OA. CT-201F.C3 Refer CT calculation for GT and UAT bay 8) Calculation of parameters for 480V VT for Incomers & Bus VT PT201 Refer Calculation for GT and UAT bay 9) Incomer metering CT CT-201F.C2 & CT-202F.C2 Refer Calculation for GT and UAT bay Station Switchgear & Unit Switchgear Outgoing feeders 10) 800A Feeder(Typ)- 50/51, 50N/51N CT ratio selected
=
800 /1 Amp
Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation
6 of 9
P0B
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Project : Generation expansion at ARAR P/P Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
7/14/2015
Kx
=
20
Rct
=
3
Rev. No.
Rb = Rrelay + 2Rl The CT burdens of numerical relays are below 0.1VA and can therefore be neglected Rl is neglible as they are internally wired. Knee point voltage Ek
= 20 x 3 = 60 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 72 Ek
=
100
CT Class = Therefore CT chosen
V
PX
CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class
>= =
800 /1 Amp 100 V 3 ohms PX
11) 1000A Feeder(Typ)- 50/51, 50N/51N CT ratio selected
=
1000 /1 Amp
Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation Kx
=
20
Rct
=
3.5
Rb = Rrelay + 2Rl The CT burdens of numerical relays are below 0.1VA and can therefore be neglected Rl is neglible as they are internally wired. Knee point voltage Ek
= 20 x 3.50 = 70 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 84 Ek
=
CT Class = Therefore CT chosen CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class
100
V
PX
>= =
1000 /1 Amp 100 V 3.5 ohms PX
7 of 9
P0B
By
TCE CONSULTING ENGINEERS LIMITED
DG
Date Chd. Date
7/14/2015
Project : Generation expansion at ARAR P/P Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
7/14/2015
Rev. No.
12) 2000A Feeder(Typ)- 50/51, 50N/51N CT ratio selected
=
2000 /1 Amp
Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation Kx
=
20
Rct
=
7
Rb = Rrelay + 2Rl The CT burdens of numerical relays are below 0.1VA and can therefore be neglected Rl is neglible as they are internally wired. Knee point voltage Ek
= 20 x 7 = 140 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 168 Ek
=
175
CT Class = Therefore CT chosen
V
PX
CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class
>= =
2000 /1 Amp 175 V 7 ohms PX
13 ) CT parameters for Station switchgear Bus coupler protection , 51 CT1.1 CT ratio selected
=
4000 /1 Amp
Knee Point Voltage Formulae The rated knee point voltage
Ek
=
Kx (Rct+Rb) x Isn
( IEC 60044-1 Amend, Page 17)
where Kx Rct Isn Rb
= Dimensioning facor = Maximum resistance of secondary winding = Rated secondary current = Rated resistive burden = Rrelay + 2Rl Rl = Cable resistance between CT & Relay Knee Point Voltage calculation Kx
=
20
Rct
=
14
Rb = Rrelay + 2Rl The CT burdens of numerical relays are below 0.1VA and can therefore be neglected
8 of 9
P0B
By Date Chd. Date
TCE CONSULTING ENGINEERS LIMITED
DG 7/14/2015
Doc. No.30421007-3CL-00007
Client : Saudi Electricity Company
SJH 7/14/2015
Project : Generation expansion at ARAR P/P
Subject : CT & PT Calculation for 480V Swgr Contract No.- 30421007
Rev. No.
Rl is neglible as they are internally wired. Knee point voltage Ek
= 20 x 14 = 280 Considering a margin of 20% on Ek as per PTS-1022, Appendix-V, Page 20 of 46 = 336 Ek
=
CT Class = Therefore CT chosen CT RATIO Knee Point Voltage CT Wdg. Res. Rct CT Class
350
V
PX
>= =
4000 /1 Amp 350 V 14 ohms PX
9 of 9
P0B
View more...
Comments
