Patent ID: 8552728

Claim:
A method of determining sluggish operation of a circuit breaker, the circuit breaker including an actuator, the method comprising the steps of: providing an electronic trip unit for the circuit breaker; setting a threshold tripping duration in the electronic trip unit; determining an existence of an abnormal current condition by the electronic trip unit; sending a trip signal to the actuator by the electronic trip unit due to the abnormal current condition; tripping the circuit breaker by the actuator; monitoring, by the electronic trip unit during the tripping, at least one of a change of a level of electrical current flowing through the circuit breaker, a change of a level of voltage present at the circuit breaker, and a contact state change of a circuit breaker auxiliary contact; determining, by the electronic trip unit, a tripping duration of the circuit breaker from a timing of sending the trip signal to the actuator and a timing of the at least one of the change of the level of electrical current, the change of the level of voltage, and the contact state change of the circuit breaker auxiliary contact, wherein the tripping duration corresponds to a length of time required for the circuit breaker to be tripped and open, and further wherein the tripping duration is a time difference between the timing of sending the trip signal to the actuator and the timing of the at least one of the change of the level of electrical current, the change of the level of voltage, and the contact state change of the circuit breaker auxiliary contact, such that said time difference is an elapsed time for the actuator to trip the circuit breaker and the circuit breaker to open, and the elapsed time excludes a time required for the electronic trip unit to recognize the abnormal current condition; comparing, by the electronic trip unit, the tripping duration to the threshold tripping duration to determine a sluggish operation of the circuit breaker.