Research on Anti-accident Measures of Starting Current Setting for Trip/closing Self-holding Relay

In view of frequent trip accidents of 220 kV bus coupling and main transformer circuit breaker for unknown causes in the substation after tests and analysis,it is found that the minimum starting current of trip/closing self-holding relay is insufficient so that it can easily cause a mistrip of breaker if abnormal circumstances occur in the substation such as DC grounding,AC intrusion into DC system etc.This paper analyzes the adjustment method of action current of trip/closing self-holding relay.