400kv Busbar Protection

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SETTING CALCULATION FOR BUSBAR PROTECTION RELAYS 400KV BUSBAR PROTECTIONS CUSTOMER

:M/s HVPNL LTD

PROJECT

:400/220/66/33KV S/S AT FARIDABAD (NAWADA)

GRID

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400KV BUSBAR PROTECTION 1. SUBSTATION INFORMATION Settings and configuration of the P741 Numerical bus bar protection scheme is arrived based on the substation information provided by ALTOM SYSTEMS/HVPNL as detailed below. CTR - Primary of all feeders

2000

CTR - Secondary of all feeders

1

CT knee Point for all feeders

2000 V

CT resistance for all feeders

15 Ohms

Maximum Load level in a feeder

3000 A

Minimum load current in a feeder

245 A

Minimum Short circuit level (ASSUMED)

6 kA

Maximum Short circuit level

40 kA

Maximum loading of 1 bar (ASSUMED)

3000 A

Number of independent bars

Two Main System

Maximum breaking time of CB

100 m sec (assumed 40msec breaker op. time + arcing time)

2. SETTING CRIETERIA OF MiCOM P741 – CENTRAL UNIT

6 values have to be entered in MiCOM P741 central unit Note: All values in CU is for base current of 2000A. 1.ID>1 (from 0.01 to 0.5 A (secondary value)) During normal operation the differential current in the scheme should be zero or negligible. Any abnormality is detected via a given threshold ID>1. This element is using for CT supervision. Recommended setting should be more than 2 % of maximum CT ratio and less than “Minimum Loaded feeder Current”. Recommended setting is 40 A. (NOTE : IF THE SPILL CURRENT IS MORE THAN 90A  SHALL BE ADJUSTED AT SITE ACCORDINGLY) 2. Slope k1 setting range is from 0% to 50%. Recommended setting is 0% , as the minimum loading current is very less and CTs are of  same ratio & similar magnetising characteristics.

FOR M/S. HVPNL - NAWADA  400KV BUSBAR PROTECTION, Rev-0

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M/S. ALSTOM T&D INDIA LTD, 19/1, G.S.T.ROAD, PALLAVARAM, CHENNAI - 600043.

3. Slope k2 setting range is from 20% to 90%, and recommendation is 65% , as the CTs are of same ratio & similar magnetizing characteristics and to provide stability for through faults. A trip is only permitted if this differential current exceeds the set slope of the bias characteristic. Recommended value for normal application is 65%. 4. Slope KCZ setting range is from 0% to 90%, it should be less than Icc min (1 bar) / (((Independent bar - 1) x IloadMax (1 bar)) + Icc min (1 bar)). Recommended setting is 30%. 5.ID>2 (from 0.5 to 30 A (secondary value)) as low as possible The main differential current element of MiCOM P741 will only be able to operate if the differential current reaches a threshold ID>2. In general, this setting will be adjusted above highest normal full load current in order to avoid mal operation even max loaded feeder CT fails. Normally recommended setting is more than 110 -180% of max load level. We shall choose ID>2, more than max loading considering (high instantaneous loading) and less than 50% of minimum short circuit level. Recommended setting is 2000*1.2= 2400 A 6.ID>1 Alarm Timer (from 100ms to 600 s) shall be greater than the longest protection time (such as line, over current, etc…) Recommended time delay is 5 secs. GROUP 1 DIFF BUSBAR PROT GROUP 1 Diff Phase Fault GROUP 1 CZ Parameters Phase Slope kcz IDCZ>2 Current GROUP 1 Zone Parameters Phase Slope k2 ID>2 Current GROUP 1 Common

30.00% 2400 65.00% 2400

Phase Slope k1

0.00%

ID>1 Current

40.00 Amp

ID>1 Alarm Timer

5.00 sec

Diff Earth Fault

Disable

P741 Central unit blocking modes: GROUP1 Busbar Option: CZ circ flt mode Zx circ flt mode Circ flt reset time Circ flt block mode Cz PU error Zx PU error PU error timer PU error reset time

Alarms Latched Alarms Latched 60 secs Block / phase. Alarms Latched Alarms Latched 5 secs 60 secs

FOR M/S. HVPNL - NAWADA  400KV BUSBAR PROTECTION, Rev-0

Amp

Page 3 of 6

Amp

M/S. ALSTOM T&D INDIA LTD, 19/1, G.S.T.ROAD, PALLAVARAM, CHENNAI - 600043.

3.SETTING CRITERIA OF MICOM P743 – PERIPHERAL UNITS CT & VT RATIOS: For all feeders Phase CT Primary Phase CT Sec'y

2000 1 Amp

Amp

RBPh / RBN Power Parameters:For all feeders

 --------(TO BE ENTERED AT SITE)

Standard Input

British Standard

Knee Voltage Vk

2000 V

RCT Sec'y

15 Ohms

Eff. Burden Ohm

----------(TO BE ENTERED AT SITE)

NOTE: RBPh/RBn, Vk, Rct & Effective Burden values are very important to detect /confirm the CT Saturation condition. 4. CB Fail Protection: 50 LBB CB Fail: For all feeders I< (under current)

Recommended setting is 20% of CTR. The setting is 400 A.

Retrip timer TBF1/tBF3: A re-trip can be applied after a time tBF1/tBF3. Here we are issuing the retrip command after 50ms of main trip. CBF timer TBF2/tBF4: When both the local trip & retrip have failed, the countdown continues with a second timer adjusted to have a value of tBF2/tBF4. Recommended setting is “maximum breaking time of CB” + 100 msec. Recommended tBF2 & 4 setting is 200msec. GROUP 1 CB FAIL Control By I< Current Set for all feeders I> Status GROUP 1 Internal Trip CB Fail Timer 1 CB Fail Timer 2 GROUP 1 External Trip CB Fail Timer 3 CB Fail Timer 4 5. Dead Zone Protection: Dead Zone setting for all feeders:

I< 400 Disabled 50ms 200.0ms 50ms 200.0ms

Dead zone tripping is provided to sense the fault in-between CT and breaker when breaker is open. Dead zone setting shall be more than maximum loading & less than 80 % of the minimum fault current. Time delay of 50 m secs shall be given to avoid mal operation during arcing period, CB scattering during fault, where CB Open has been realised by PU. I>DZ Current setting I> DZ time delay

FOR M/S. HVPNL - NAWADA  400KV BUSBAR PROTECTION, Rev-0

2400 50 m sec

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Amp

M/S. ALSTOM T&D INDIA LTD, 19/1, G.S.T.ROAD, PALLAVARAM, CHENNAI - 600043.

Group 1 Io supervision : Internal CT / AD converter of PU can be monitored by comparing the measured 3Io and derived neutral (IN =IR + IY + IB). Error co efficient shall be kept at 40% in order to detect internal CT (PU) failure. 40% Error factor KCE 5 secs Alarm delay 6A. SETTING SUMMARY FOR CENTRAL UNIT – P741 Group1 DIFF BUSBAR PROT Range/Options available Description Minimum Maximum Phase slope KCZ 0% 90%

 Adopted Settings 30%

Remarks Check zone slope

IDCZ>2 current

50A

30.0kA

2400

Check zone threshold

Phase slope K2

20%

90%

65%

Main zone slope

ID>2 current

50A

30.0kA

2400

Main zone threshold

ID>1 current

10A

500A

90A 

Circuitry fault pickup

Phase slope K1

0%

50%

0%

Circuitry fault slope

100ms

600 s

5 secs

Maximum

Adopted Settings

ID>1 Alarm timer

Circuitry fault alarm delay

Group1 Busbar Option Range/Options available

Description

Minimum

Remarks

CZ circ flt mode

Blocking latched, Alarms latched, self reset, Alarms Resetting mode  Alarms latched & no block, Alarms SR & no block circuitry fault

Zx circ flt mode

Blocking latched, Alarms latched, self reset, Alarms Resetting mode of main  Alarms latched & no block, Alarms SR & no block  zones circuitry fault 600 s

of

CZ

Circuitry t reset

5s

Circ block mode

Blocking/ phase , 3 phase block 

CZ PU Error mode

Blocking latched, Alarms latched, self reset, Alarms Resetting mode  Alarms latched & no block, Alarms SR & no block  during CZ error

of

PU

Zx PU Error mode

Blocking latched, Alarms latched, self reset, Alarms Resetting mode of  Alarms latched & no block, Alarms SR & no block  during main zone error

PU

60 s Blocking / phase

Circuitry fault reset time Blocking modes on circuitry fault

PU Error timer

2s

600 s

5secs

Alarm delay of PU error

PU Error reset

5s

600 s

60secs

Reset time of PU error

6B. SETTING SUMMARY FOR PHERIPHAL UNIT – P743 Range/Options available Description Minimum Maximum

 Adopted Settings

Remarks

CT, VT Ratios: Phase CT Primary

FOR M/S. HVPNL - NAWADA  400KV BUSBAR PROTECTION, Rev-0

1A

30.0 kA

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2000 A for all CT Primary Rating feeders

M/S. ALSTOM T&D INDIA LTD, 19/1, G.S.T.ROAD, PALLAVARAM, CHENNAI - 600043.

Phase CT Secondary

1A

5A

1A 

CT Secondary Rating

RBph/RBN

0.5

10

**

Ratio of Phase & neutral CT leads resistance

Standard Input

British Standard / IEC

British Standard

CT Standard

2000 V for all CT Knee point Voltage feeders

Knee Voltage Vk

20 V

5000 V

RCT Sec

0.1 Ω

50 Ω

Effective Burden ohm

0.1 Ω

200 Ω

**

Minimum

Maximum

Adopted Settings

I> DZ Current Set

60 A

4800 A

2400

I> DZ Time Delay

0 sec

100 sec

50 msec

15 Ohms forall CT sec resistance feeders Effective burden of lead

Group1 Dead Zone Protection: Description

Range/Options available

Enable/Disable

Disable

Range/Options available

Adopted Settings

IN> DZ Current Set

Remarks

Group1 CB Fail: Description

Minimum

Maximum

I