Interlocking system for switchgear automation in double busbar substation

Tripping by protective relays on all CBs is unrestricted.
The opening command on all CBs, other than the busbar coupler CB is unrestricted.
An opening command cannot be given on the busbar coupler CB when:
- Both busbar DS s are closed in any feeder.
- Any busbar DS or sectionalizing DS is in transit condition.
A closing command cannot be given on a CB when its associated line DS or busbar DS are in the transit condition.
A line DS can only be operated when its associated CB and feeder ES are open.
A feeder ES can only be operated when its associated line DS, if applicable, and busbar DS are open.
A busbar DS can be operated when its CB, busbar earthing switch, feeder ES and the other busbar DS are all open (except item 8).
If a busbar DS is closed, the second busbar DS can only be operated when the busbar sections concerned are coupled through the busbar coupler CB.
A busbar ES can only be operated when the busbar DS s and the busbar sectionalizing DS, on the associated busbar, are open.
A busbar sectionalizing DS can only be operated when all the busbar DSs and the busbar ES located on the same side of this sectionalizing DS, are open.