GE P742

P74
x/EN AP/Na7
Application Notes
(AP) 6
-10 MiCOM P74
1, P742, P743
AP
2.1.1.3.1 Sub-station features
8 values have to be known:
1. Number of independent bus
2. Minimum load current in a feeder
3. Maximum load current in a feeder
4. Maximum load current in a bus
5. Biggest CT primary winding
6. Minimum phase to phase short-circuit value in a bus
7. Minimum phase to ground short-circuit value in a bus
8. Maximum phase to ground short-circuit value in a bus
2.1.1.3.2 “Idiff_Ibias_SDEF_HighImp” Setting calculation spreadsheet
Enter in the Idiff_Ibias_SDEF spreadsheet the 8 values here above listed and you’ll be able
to choose the 9 values hereafter listed.
2.1.1.3.3 SDEF Busbar Protection
15 values have to be entered:
1. ID>1 (from 5 A to 500 A (primary value)) as high as possible
2. Slope k1 (ID>1) (from 0% to 50%), recommendation is 5%.
3. ID>2 (from 50 A to 50000 A (primary value))
4. Slope k2 (ID>2) (from 20% to 90%), recommendation is 65%.
5. IDCZ>2 (from 50 A to 50000 A (primary value)) as low as possible
6. Slope kCZ (IDCZ>2) (from 0% to 90%), recommendation is 30%.
7. ID>1 Alarm Timer (from 0 to 100 s) shall be greater than the longest protection time
(such as line, overcurrent, etc…)
8. Current IbiasPh> Cur. (from 50 A to 50000 A (primary value)) as low as possible