Gould Inc.

I-T-E Imperial Corporation

Siemens-Allis, Inc.

Bernard Di Marco

Andrew J Kralik

Keith T Krueger

An improved anti-rebound mechanism for circuit breakers having a blow-off, current-limiting feature is provided. The improvement consists of a ferromagnetic latch which is activated by any massive current surge through the circuit breaker sufficient to cause blow-off current interruption. The latch is caused to be magnetically attracted to, and engage with, a notch on a movable arm of a circuit breaker to maintain the arm in an open position until the circuit breaker is manually reset in a closed position.

Electromagnetically actuated anti-rebound latch

A molded elongated arcuate shield is snap-fitted to a circuit breaker operating handle to achieve a lost motion connection thereto. The operating handle projects through an elongated wall opening in the circuit breaker housing and is movable longitudinally thereof. The shield is disposed between an arcuate interior surface of housing and an arcuate surface of an apron formed integrally with the handle. While the apron above is too short to close the wall opening for all positions of the handle, the apron in cooperation with the shield fully closes the wall opening for all positions of the handle. Latch tabs formed integrally with the shield engage a blocking formation internally of the housing to hold the shield stationary while the handle moves from its On to Trip position. In the former position ON indicia carried by the apron is viewable through an aperture in the shield through which the handle extends, and when the handle is in its Trip position the latched shield blocks the ON indicia from view. Labyrinth-type gas seals are provided adjacent the longitudinal edges of the wall aperture by longitudinally extending ribs formed integrally with the shield and extending into cooperating slots inside the housing wall.

Circuit breaker handle and lost motion connected shield

A multipole circuit breaker is constructed with a single rod pivotally mounting all of the movable contact arms to a common one piece molded insulating carrier. Individual torsion springs engage each of the contact arms to provide contact pressure when the circuit breaker is closed. The construction of the contact arms and carrier are such that under severe overcurrent conditions electrodynamic blowoff forces acting on the contact arms may bring about contact separation that is substantially as great as the contact separation that takes place when the circuit breaker is opened normally by its contact operating mechanism.

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Bellefontaine, OH, United States of America

Bernard Di Marco