Existing ATS logic in our plant for tie closing: U/V Timer of incomer(1.5 sec) + bus dead + health check of other bus + tie in service position -----> tie closing.
Buscoupler/Tie closing logic in auto transfer scheme
Disadvantage I observed in above scheme:
Though incomer tripped on intertrip (tripping downstream breaker on tripping of upstream breaker) tie will take min 1.5 sec to turn on as timer logic is included.
Proposed Scheme: Instead of U/V timer of incomer can i use U/V contact of incomer and breaker off contact for changeover?
incomer undervoltage + incomer off + bus dead + health check of other bus + tie in service position -----> tie closing.
Is there any disadvantage if i change above logic?