Westinghouse Electric Corporation

David L Haggerty

Alfred E Maier

Robert J Tedesco

A circuit breaker with a shock-absorbing mechanism characterized by a movable contact arm operable between open and closed positions of separable contacts, a stop member for stopping movement of the contact arm which member is integral with a housing for the circuit breaker, and a shock-absorbing plate on the member for spreading the energy released when the contact arm collides with the stop member.

Circuit breaker with stop plate for contact arm

A molded case circuit breaker includes a movable upper electrical contact carried by a movable arm having an end portion with an arcuate cam surface formed thereon for engaging an outwardly projecting cam surface of a spring-loaded clip that is disposed in a recess formed in a rotatable cross-bar of an operating mechanism of the circuit breaker. At least one compression spring is retained within the recess between the cross-bar and the spring clip. The spring clip is configured to transfer sufficient biasing force to the end portion of the movable upper electrical contact end to enable the upper electrical contact arm to move in unison with the cross-bar when the circuit breaker is tripped. Upon the occurrence of a high level short circuit or fault current of sufficient magnitude, the upper electrical contact arm and contact rotate independently of the cross-bar and the arcuate cam surface of the arm is moved against the then stationary spring clip cam surface. The outwardly projecting surface of the spring clip and the arcuate cam surface of the end portion of the movable contact arm are configured to provide decreased biasing force as the upper electrical contact rotates to its BLOWN-OPEN position. A detent or groove is formed along the arcuate cam surface of the end portion for receiving an outwardly projecting surface of the spring clip to retain the movable upper electrical contact and arm in a BLOWN-OPEN position, thereby minimizing the possibility of contact restrike.

Growing community of inventors

Pittsburgh, PA, United States of America

David L Haggerty