Westinghouse Electric Corporation

Eaton Corporation

Richard E White

Alfred E Maier

Kenneth Martin Fischer

Douglas Charles Marks

Ronald W Crookston

H Richard Beck

Steven Castelein

David Curtis Turner

Roger William Helms

William E Beatty, Jr

William George Eberts

David A Parks

David Edward Little

Arthur D Carothers

Yun-Ko N Chien

Henry Richard Beck

Walter Oliver Jenkins

Andrew James Male

John K Livesey

John G Salvati

Amelia M Stay

The movable contact arms of a circuit breaker are latched in the blow open position to prevent rebound and possible restrike of the arc in response to the very high magnetic repulsion forces generated by a short circuit in the protected electrical system. Each movable contact arm is mounted on a secondary carrier coupled to a main carrier by a spring loaded cam mechanism which allows the movable contact arm to blow open before the main carrier is rotated to the open position by the spring driven circuit breaker operating mechanism. In one embodiment of the invention, the movable contact arm is latched in the blow open position by a latching detent in the cam surface of the cam mechanism. In a preferred embodiment, the secondary carrier is latched by a detent formed by a leaf spring cantilevered from a fixed support. Subsequent rotation of the main carrier by the operating mechanism releases the latch by rotating the secondary carrier clear of the detent formed by the leaf spring.

Circuit breaker with latch preventing rebound of blow open contact arm

A circuit breaker includes a housing; separable contacts moveable between closed and open positions; an operating mechanism, for moving the separable contacts between the closed and open positions, having a first latched position and a second unlatched position corresponding to the open position of the separable contacts, and including a pair of cradles pivotally supported about a pivot axis within the housing to pivot in a first pivotal direction to the first position of the operating mechanism and a second pivotal direction to the second position of the operating mechanism; a handle mechanism for moving the cradles in the first pivotal direction; a latch mechanism for latching the operating mechanism in the first position thereof and for releasing the operating mechanism to the second position thereof, including a latch plate pivotally supported within the housing having two opposing elongated openings, a roller pin cross member generally parallel to the cradle pivot axis supported by the latch plate at each of the openings, and a spring mechanism for biasing the cross member with respect to the cradles; and a trip mechanism cooperating with the latch mechanism for releasing the operating mechanism to the second position thereof. An arcuate reset surface of the cradles independently engages a corresponding end of the cross member when the operating mechanism is moved toward the first position thereof. The cross member engages a linear latch surface of the cradles for latching the operating mechanism in the first position thereof.

Roller latching and release mechanism for electrical switching apparatus

A circuit breaker includes a housing; separable contacts housed by the housing; an operating mechanism, for moving the separable contacts between a closed position and an open position thereof, having a first position and a second position corresponding to the open position; a latching and releasing mechanism for latching the operating mechanism in the first position thereof and for releasing the operating mechanism to the second position thereof; a rotatable trip bar rotatable in a first rotational direction and a second rotational direction for unlatching the latching and releasing mechanism; a sensing mechanism for sensing an electrical condition associated with the separable contacts and for moving the trip bar in the second rotational direction in order to unlatch the latching and releasing mechanism, release the operating mechanism to the second position thereof, and move the separable contacts to the open position thereof; and an adjustable bias spring for biasing the trip bar in the first rotational direction.

Trip bar with adjustable latch load for electrical switching apparatus

A molded case circuit breaker having current limiting capabilities optimized for relatively smaller frame sizes. More specifically, one aspect of the invention relates to a two-piece carrier assembly for carrying the main and arcing contact arms which allows the main and arcing contacts to be blown open during short circuit conditions. The two-piece carrier assembly includes an inner carrier and an outer carrier pivotally connected together. The contact arms are carried by the inner carrier. When sufficient magnetic repulsion forces are exerted on the contacts due to a short circuit condition, the inner carrier pivots relative to the outer carrier to allow the contact arms to blow open. In order to control the amount of force required for blow open, a compression spring loaded cam assembly is provided. Another important aspect of the invention relates to a contact spring housing which relocates the contact springs away from the separable contacts to protect the springs from damage, for example, from heat due to contact separation. In order to improve the interruption time of the circuit breaker for relatively large overcurrents, such as a short circuit, a reverse current loop is provided which generates sufficient magnetic repulsion forces to blow open the separable contacts in a relatively short period of time. Within the restraints of the physical dimension of a relatively smaller breaker frame size, additional features have also been incorporated. More specifically, an improved rating plug assembly is provided with a one-piece plunger, relatively easier to manufacture than known designs which utilize two-piece plungers. Another aspect of the invention relates to an auxiliary cam plate for controlling the motion of the crossbar at the remote end in a four pole circuit breaker. The cam plate compensates for bending of the crossbar to improve the contact force in the remote pole. Lastly, a molded interphase barrier forms a gas barrier within the circuit breaker and maintains its position during assembly relatively better than known interphase barriers.

Molded case current limiting circuit breaker

A positive off mechanism for a circuit breaker includes a pair of positive off levers slideable in slots in the side plates and extendable into the path of the operating handle to prevent movement of the handle to the off position when the contacts are welded closed. The positive off levers are actuated by positive off links pivotally mounted to the side plates and coupled to the positive off levers by 'dog bone' connections. The positive off links in turn are actuated by the toggle mechanism of the circuit breaker which collapses to open the contacts during normal circuit breaker operation, but which remains erect when the contacts are welded closed.

Circuit breaker with positive off protection

A molded case circuit breaker having current limiting capabilities is dimensionally optimized for relatively smaller frame size circuit breakers. The handle yoke is supported with rollers thereby allowing the crossbar to be disposed in the space normally utilized for the handle yoke pivot axis. A clinch joint arcer assembly with a plurality of arcing contact arms, each pivotally connected by a clinch joint to a pivotally mounted main contact arm permits additional main contact arms to be provided in the same space normally occupied by the arcing contact arms alone. Additionally, arcing contact spring housings protect the arcing contact springs from deterioration due to corrosive ionizing gases generated during interruption. A positive off link assembly prevents the operating handle from being placed on an OFF position when the main contacts are welded together and transfers the force applied to the operating handle to the upper link to allow the weld to be broken. Lastly, a reversible barrier in one of the sidewalls allows in one position circuit breaker auxiliaries, located in the outside pole compartments, to communicate with the operating mechanism and the operating handle. For circuit breakers without auxiliaries, the barrier acts as an interphase gas barrier.

A molded case circuit breaker is provided. Key blocks with a key shaped projection along one side are received in key shaped grooves in the sidewalls of the base. The kay shaped projections and the key shaped grooves may be formed as a dovetail connection. These key blocks provide support for the sidewalls from forces resulting from relatively high overcurrent conditions, such as a short circuit condition. In addition to supporting the sidewalls, the key blocks also form a barrier between the main contacts and other components in the circuit breaker to reduce the amount of arc products allowed to interact with the other components in the circuit breaker. The key block also form a stop surface for capturing the arc chutes to prevent movement of the arc chutes along the longitudinal axis of the circuit breaker. Lastly, the key blocks also hold the insulation barrier on the line conductor in place, thus obviating the need to use adhesives.

Key blocks for circuit breaker

A molded case circuit breaker is provided with a two piece cradle assembly having a cradle portion and a heat-treated portion. The heat-treated portion forms the latch and reset surfaces. The cradle portion is integrally formed from a pair of spaced apart cradle-shaped arms joined together by a connecting portion. The heat treated portion is securely fastened to the connecting portion to form the two piece cradle assembly. A hold down slidably carries a handle barrier with respect to the cover and closes a centrally located aperture in the cover for all handle positions. The handle barrier prevents arc products resulting from a separation of the main contacts from escaping through the centrally located aperture in the cover. Stops are provided in one or both directions to prevent misalignment of the handle barrier with respect to the operating handle. A cover interlock is also provided to prevent the cover from being removed when the circuit breaker is in an 'on' position. The cover interlock can either be molded separately or integrallly molded with the handle barrier hold down.

Growing community of inventors

Brighton Township, Beaver County, PA, United States of America

Richard E White