An innovative method of providing total breaker failure protection

Circuit breaker failure relaying has been generally achieved through the use of a current monitoring relay to determine whether current continues to flow into a fault after a breaker has been instructed to interrupt the circuit. If current continues to flow after a predefined period of time, the circuit breaker is considered to have failed. Steps must then be taken to trip the next set of upstream breakers in the power system to remove the faulted circuit and prevent system damage. However, with industrial power systems, this may be the electric utility's breakers on the feeding transmission line. Regardless, breaker failure schemes must be designed to isolate both the faulted circuit and the failed circuit breaker. This paper discusses a new and innovative method of protecting circuit breakers from the failure described above, plus other failures that go unprotected with conventional schemes, thus providing "total" breaker failure protection.