Operation sequence for main bus grounding in MV GIS switchgear according to IEEE

Sequence for grounding of main bus section A:

It is assumed that the tie CB is in the energized condition:

1. Open all disconnect switches on “A” bus and verify by viewing.
2. Block closing of disconnect switches.
3. Open tie circuit breaker[Figure(a)].
4. Open bus B disconnect switch of bus tie CB [Figure(b)]. Verify by viewing.
5. Close the bus B grounding switch [Figure(b)] (possible only if all disconnect switches on “A” bus feeders are in open position). Verify by viewing.
6. Close the tie CB.
7. Lock tie CB in closed position according to manufacturer’s O&M manual.
8. The A bus is grounded.

Sequence for grounding of main bus section B:

1. Open all disconnect switches on “B” bus. Verify this by viewing.
2. Block closing of disconnect switches.
3. Open the tie circuit breaker.
4. Open bus “A” disconnect switch of the bus tie circuit breaker [Figure(a)]. Verify by viewing.
5. Close the bus “A” grounding switch [Figure(a)] (possible only if all disconnect switches on “B” bus feeders are in open position). Verify by viewing.
6. Close the tie CB.
7. Lock tie CB in closed position according to manufacturer’s O&M manual.
8. The B bus is grounded.

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