Analysis on the false action and operation criteria for the generator circuit breaker failure protection

According to analyzing an accident of generator circuit breaker (GCB) failure protection false action, this essay put forward that the current criteria of GCB failure protection would cause the protection rejecting act. The reason was analyzed that the current criteria of GCB failure protection could not start in single-phase grounding and phase fault of small current grounding system. It was suggested that using current and additional voltage to improve the criteria of GCB failure protection.