Interlocking system for switchgear automation in double busbar substation
The tripping of all circuit breakers (CBs) by protective relays is unrestricted.
The opening command for all circuit breakers, except for the busbar coupler circuit breaker, is unrestricted.
An opening command cannot be issued for the busbar coupler circuit breaker under the following circumstances:
Both busbar disconnect switches (DSs) of any feeder are closed.
Any busbar disconnect switch or sectionalizing disconnect switch is in the transition state.
A closing command cannot be given for a circuit breaker when its associated line disconnect switch or busbar disconnect switch is in the transition state.
A line disconnect switch can only be operated when its associated circuit breaker and feeder earthing switch (ES) are open.
A feeder earthing switch can only be operated when its associated line disconnect switch (if applicable) and busbar disconnect switch are open.
A busbar disconnect switch can be operated when its circuit breaker, busbar earthing switch, feeder earthing switch, and the other busbar disconnect switch are all open (except for item 8).
If a busbar disconnect switch is closed, the second busbar disconnect switch can only be operated when the relevant busbar sections are connected through the busbar coupler circuit breaker.
A busbar earthing switch can only be operated when the busbar disconnect switches and the busbar sectionalizing disconnect switch on the associated busbar are open.
A busbar sectionalizing disconnect switch can only be operated when all the busbar disconnect switches and the busbar earthing switch on the same side of this sectionalizing disconnect switch are open.
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