scope:

This guide is intended to help the relay engineer understand the application considerations when applying breaker failure protection (BFP) to power circuit breakers. The discussion is limited to those instances where the breaker does not clear the fault after a protective relay has issued a command to open (trip) the circuit breaker. Failure to close, failure while closed, and failure while open are not discussed. The intent of this guide is not to give the reader methods of protecting a power circuit breaker from failing; rather, it is to give the reader a guide in how to detect that a breaker has failed to clear a fault, and how to electrically isolate the fault after the breaker has failed to clear the fault.