Square D Company

Ronald D Borrett

Henry J Zylstra

An electrical circuit to signal a circuit breaker to trip when the circuit breaker is closed and a high level fault occurs or when a low level fault occurs while the breaker is in the process of closing. A mechanical switch tied to the breaker contacts deactivates the low level trip function when the contacts are closed. A high level overcurrent causes a trigger diode to conduct current, energizing an opto-coupler that causes the trip solenoid to trip the breaker. The circuit also causes the breaker to trip if a sustained medium level overcurrent exists.

High level magnetic trip circuit

A circuit breaker having an electronic fault sensing and trip initiating unit which provides increased versatility and ability to coordinate the circuit breaker with other interrupting and protective devices in a wide variety of electrical distribution systems. Electronic circuits and components are provided to vary the ampere rating of the breaker, to adjust current carrying capacity, to provide a long time delay trip, a short time delay trip and an instantaneous trip depending on the amplitude of high fault currents, to provide a ground fault trip, to shorten or lengthen the trip time for short time delay faults and for ground faults, and to provide shunt trip capability. The tripping mechanism is magnetic and mechanical, and includes a plunger movable between a trip and non-trip position controlled by an electronic switch in the electronic circuitry, and a toggle mechanism which is unlatched by the plunger when it moves to the trip position. A bimetal trip mechanism is provided as back-up protection if the ambient temperature not sensed by the electronic circuitry exceeds a pre-determined level.

Growing community of inventors

Cedar Rapids, IA, United States of America

Ronald D Borrett