37.5MVA_Transformer_Differential_Protection

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

CONFIDENTIAL The information contained in this document is not to be communicated either directly or indirectly to any person not authorised to receive it

SETTING CALCULATION FOR RELAYS 37.5 MVA 132kV / 6.9kV Transformer Differential Protection

CUSTOMER PROJECT

: MONNET ISPAT & ENERGY LTD : 132KV Transformer Differential Protection

Prepared By

K. Rajesh Ananth

Date

22.06.2007

Checked By

Nagesh Tilwani

Rev

Rev - 0

AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 1

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

TRANSFORMER DIFFERENTIAL PROTECTION: 1. 132/6.9, 37.5MVA TRANSFORMER DIFFERENTIAL PROTECTION CTR HV: 300/1A CTR LV1: 3500/1A Relay type - P632

Transformer Data : Power: 37.5 MVA HV voltage: 132kV LV1 Voltage: 6.9kV Transformer percentage imp: 12.74 % Transformer vector group: YNyn-o Tap + 10 Steps of 1.25 % (Assumed) 1.1

SUPPORTIVE CALCULATION TO VERIFY BIAS SETTINGS

Id> 0.2 Iref Id>> 10 Iref ( should be 10% more than max inrush current) Id>>>15 Iref m1 0.2 m2 0.8 At normal condition current in HV bias circuit (Winding a) Primary current Current in CT Secondary Required Ratio compensation

= 37.5MVA / (1.732 * 132 kV) = 164.02 A = 164.02 / 300 A = 0.546 In (Will be calculated by relay) = 1 / 0.546 = 1.828 (Will be calculated by relay)

At normal condition current in LV1 bias circuit ( Winding b ) Primary current Current in CT Secondary Required Ratio compensation

= 37.5 MVA / (1.732 * 6.9kV) = 3137.86 A = 3137.86/3500 = 0.89 In (Will be calculated by relay) = 1 / 0.89 AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 2

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

= 1.11 (Will be calculated by relay) At - 10 % tap condition current in HV bias circuit HV Side current Current in CT Secondary With ratio compensation

= 37.5MVA / (1.732 * 118.8 kV) = 182.24A = 182.24 x 1.828 / 300 = 1.11

At + 10 % tap condition current in HV bias circuit HV Side current Current in CT Secondary With ratio compensation

= 37.5 MVA / (1.732 * 145.2 kV) = 149.11 A = 149.11 x 1.828 / 300 = 0.908

Differential Current at Tap Extremities At -10% Tap

Idiff1 = 1.11-1 = 0.11 At +10% Tap Idiff2 = 1-0.908 = 0.092 Bias Current at Tap Extremities Ibias = IRHV + IRLV 2 IRHV – Relay HV Current IRLV – Relay LV Current Ibias1 Ibias2

= 1.11 + 1 2 = 1.055 = 0.908 + 1 2 = 0.954

OPERATING CURRENT IOP At -10% Tap IOP1 = Is + (Bias setting x bias current) = 0.2+(0.2X1.055) = 0.41 AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 3

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

Idiff1 = 0.11 = 26.76% Iop1 0.41 Since the differential current is not greater than 90% of the operating current at -10% tap the relay will operate satisfactorily. OPERATING CURRENT IOP At +10% Tap IOP2 = Is + 0.2 x Ibias2 = 0.2 + 0.2 x 0.954 = 0.39 Idiff2 = 0.092 = 23.58% Iop2 0.39 Since the differential current is not greater than 90% of the operating current at +10% tap the relay will operate satisfactorily. Hence Bias setting of

m1

m2

= 25% (0.25) 1.5 times of Full load current, = 80% for through fault stability

(Note : 1. Out put relays, LED s, Opto inputs front panel etc, need to be configured at site during commissioning. 2. Only differential and over flux protection is enabled since separate relays available for REF and back up over current

2. 400/220 KV ,315 MVA TRANSFORMER, O/C, E/F PROTECTION- HV SIDE Relay type : MiCOM P632 CTR : 300/1 O/C setting HV Full load current = 164.02A Pick up setting = Full load current x 1.1 Drop off ratio

=

164.02x 1.1 0.95 AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 4

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

=

0.63 A

Operating time setting of the relay should be more than the operating time of relays in LV side relays Hence consider an operating time of 1 Sec. Fault current in HV for an LV fault = (164.02 / 0.125) = 1312.16 A 0.14 x tms psm∧0.02-1 Psm = 4.37/0.63 = 6.9 Tms = 0.28 High set = LV short ckt. current seen in HV x 130% = 3137.86 x 6.9 x 1.3 0.125 132

x 1/300

= 5.68 A

GROUP 1 OVERCURRENT I>1 Function IEC S Inverse I>1 Direction Directional Fwd I>1 Current Set 0.63A I>1 TMS 0.28 I>1 tRESET 0s I>2 Function DT I>2 Direction Disabled I>3 Status ENABLED I> 3current set 5.68 A I> 3 Time Delay 0 s I>3 tRESET 0s I>4 Status Disabled AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 5

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

I> Blocking 0000 I> Char Angle 30.00 deg V CONTROLLED O/C VCO Status Disabled E/F settings HV Full load current = 164.02 A Earth fault pick up = 30 % of FLI =0.164 Operating time setting of the relay should be more than down stream protection relays Hence consider an operating time of 1Sec. ( Since PSM is more than 20 , Hence calculated TMS at PSM 20) 0.14 x tms psm∧0.02-1 tms = 0.44

GROUP 1 EARTH FAULT 2 IN2> Input Derived IN2>1 Function IEC S Inverse IN2>1 Direction Directional Fwd IN2>1 Current 300.0mA IN2>1 TMS 0.44 IN2>1 tRESET 0s IN2>2 Function DT IN2>2 Direction Disabled N2>2 tRESET 0s IN2>3 Status Disabled IN2>4 Status Disabled IN2> Blocking 0000 IN2> Char Angle -45.00 deg IN2> Pol Zero Sequence AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 6

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

3. 132/6.9 KV ,37.5 MVA TRANSFORMER, O/C, E/F PROTECTION- LV SIDE Relay type : CTR : 3500/1A O/C setting LV Full load current = 3137.86A Pick up setting = Full load current x 1.1 Drop off ratio = =

3137.86x 1.1 0.95 1.03 A

Operating time setting of the relay should be more than the operating time of relays in LV side relays Hence consider an operating time of 1 Sec. Fault current in LV for a HV fault = (3137.86 / 0.125) = 25102.88 A

0.14 x tms psm∧0.02-1 Psm = 7.17/1.03 = 6.9 Tms = 0.28 High set = HV short ckt. current seen in LV x 130% = 164.02 x 132 x 1.3 0.125 6.9

x 1/3500

= 9.32 A

AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 7

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

GROUP 1 OVERCURRENT I>1 Function IEC S Inverse I>1 Direction Directional Fwd I>1 Current Set 1.03A I>1 TMS 0.2 I>1 tRESET 0s I>2 Function DT I>2 Direction Disabled I>3 Status ENABLED I> 3current set 9.32 A I> 3 Time Delay 0 s I>3 tRESET 0s I>4 Status Disabled I> Blocking 0000 I> Char Angle 30.00 deg V CONTROLLED O/C VCO Status Disabled E/F settings LV Full load current = 3137.86 A Earth fault pick up = 30 % of FLI =0.26 Operating time setting of the relay should be more than down stream protection relays Hence consider an operating time of 1Sec. ( Since PSM is more than 20 , Hence calculated TMS at PSM 20) 0.14 x tms psm∧0.02-1 tms = 0.44 GROUP 1 EARTH FAULT 2 IN2> Input Derived IN2>1 Function IEC S Inverse IN2>1 Direction Directional Fwd AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 8

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

IN2>1 Current 300.0mA IN2>1 TMS 0.44 IN2>1 tRESET 0s IN2>2 Function DT IN2>2 Direction Disabled N2>2 tRESET 0s IN2>3 Status Disabled IN2>4 Status Disabled IN2> Blocking 0000 IN2> Char Angle -45.00 deg IN2> Pol Zero Sequence

4. 132/6.9KV , 37.5 MVA TRANSFORMER, LOW IMPEDENCE REF PROTECTION-HV Side CTR Phase Side : 300/1 CTR Neutral Side : 200/1 | Group | Description | Active value -------------+----------------------+---------------------------REF_2 Enable PS1 | Yes REF_2 Operating Mode PS1 | Low Imped. /IP,Max REF_2 Idiff> PS1 | 0.20 Iref REF_2 Idiff>>> PS1 | 15 Iref REF_2 m1 PS1 | 0.20 REF_2 m2 PS1 | 0.80 REF_2 IR,m2 PS1 | 1.5 Iref

Note: Since the Provided Data’s is for Low Impedence REF Protection settings on HV Side are suggested to suit Low Impedence REF

5. 132/6.9KV , 37.5 MVA TRANSFORMER, REF PROTECTION – LV Side Relay type – P632 CTR : 3500/1

R stab calculation AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 9

132KV Transformer Protn

APPLN07/Settings/Monnet Ispat 132KV

Relay setting recommendations

Rev-0

22.06.2007

Fault current at 6.9 kv side neglecting source impedance FLI/%imp = 3137.86 /(12.74/100) IF in secondary : 24629.98/ 3500 = 7.03 A RCT : 15ohm RL : 0.3(Given) Vs = If (Rct+2 Rl) = 7.03 x (15+2x0.3) = 109.66V Rstab = Vs In Since it is a Numerical Relay, the relay burden is Negligible Rstab = Vs In = 1096 ohm (i.e 1.09Kohm) Note: Since this setting is more than the range, it is required to put some series Resistance.

1.09Kohm Note Out put relays an LEDs to be assigned during commissioning as per approved drawing.

AREVA T&D AUTOMATION SUPPORT 19/1 GST Road, Pallavaram, Chennai -600043 Page 10