Patent number: US4949214A
Abstract: An automatic override circuit is responsive to the magnitude of instantaneous current flow through a monitored conductor to produce an output signal which can actuate a solenoid or a ground fault interrupter to automatically trip a circuit breaker in repsonse to an excursion of current flow which exceeds a predetermined maximum current overhead level. The short circuit protector can automatically override a thermal trip delay and cause the circuit breaker to trip instantly or delay tripping for a prescribed period of short circuit events which exceed the maximum current overload level. In one embodiment, a control signal is generated which actuates a solenoid which is coupled to a thermal magnetic circuit breaker. In an alternative embodiment, the control signal is utilized for automatically triggering a ground fault interrupter. In both embodiments, the power distribution circuit is interrupted in response to a short circuit condition which would otherwise be tolerated during the thermal trip delay of a conventional circuit breaker.
Type: Emergency Protective Circuit
Filed: August 28, 1989
Date of Patent: August 14, 1990
Inventor: George Auther Spencer