Abstract: A crossbar assembly is formed from an elongated metal bar. A pair of contact arm carriers are slid onto the metal bar and welded in place. Molded electrically insulated sleeves are sliding received at each of the crossbar. The insulated sleeves can be either molded directly on the crossbar or molded separately, in which case, the sleeves are glued with epoxy and pinned to the crossbar to prevent axial movement of the sleeves with respect to the crossbar. The insulated sleeves are formed with a pair of plates disposed at each end. A pair of oppositely disposed slots formed in the plates is used to receive the ends of a cam roll pin assembly. Since the crossbar in accordance with the present invention does not require wrapping with insulating paper, the possibility of dielectric failure due to cracking of the insulating paper is eliminated.

Abstract: A molded case circuit breaker is provided with a quick change current transformer assembly. The current transformer is used to sense overcurrent conditions and apply a signal to an electronic trip unit to trip the circuit breaker. The quick change assembly includes an insulated removable plate located adjacent an open cavity in the housing in which the current transformer is located. The current transformer is donut-type disposed about a load-side conductor located in a cavity in the housing rigidly fastened to the circuit breaker frame. In order to replace a current transformer, the insulated backplate is removed. Next the load-side conductor is unfastened and removed from the circuit breaker housing. The current transformer is then removed from the circuit breaker housing. In order to install a new current transformer, the steps are reversed. A force transmitting spacer is disposed adjacent a bight portion of a shunt, connected between a pivotally mounted contact arm and a load-side conductor.

Abstract: A molded case circuit breaker is provided with a quick change current transformer assembly. The current transformer is used to sense overcurrent conditions and apply a signal to an electronic trip unit to trip the circuit breaker. The quick change assembly includes an insulated removable plate located adjacent an open cavity in the housing in which the current transformer is located. The current transformer is donut-type disposed about a load-side conductor located in a cavity in the housing rigidly fastened to the circuit breaker frame. In order to replace a current transformer, the insulated back-plate is removed. Next the load-side conductor is unfastened and removed from the circuit breaker housing. The current transformer is then removed from the circuit breaker housing. In order to install a new current transformer, the steps are reversed.

Abstract: A circuit breaker apparatus characterized by a molded case containing a circuit breaker structure for opening and closing a circuit which structure comprises a releasable lever operable between latched and unlatched positions corresponding to open and closed circuit conditions, latch means including a latch lever for the releasable lever, interconnected toggle connected to the latch lever and that are biased to the unlatched position of the lever, and a movable trip bar responsive to predetermined overcurrents and having a projection contacting the toggle links for holding the links in the unbiased position.

Abstract: A circuit breaker with a force generate shunt characterized by a circuit breaker structure between spaced conductors with a fixed contact on one conductor and a movable contact on a contact arm that is movable between open and closed positions. A flexible shunt connected between the arm and the other conductor which shunt includes folded-over shunt portions that generate repulsion magnetic forces for pressing the closed contacts together and for expediting the contact arm open.

Abstract: An electric circuit breaker with blow open contact arm characterized by a pair of separable contacts one of which is mounted on a contact arm that is rotatably mounted on mounting bracket. The contacts maintain a repulsion magnetic force which operates to separate the contacts when a predetermined current overload occurs. A trip mechanism is connected to the mounting bracket or automatic opening of the contacts in response to a predetermined current overload condition. The contact arm comprising a cam and the mounting bracket comprising a cooperable cam follower whereby the contact arm is movable to an open contact independently of the mounting bracket.

Abstract: A mechanical interlock for a pair of vertically mounted circuit breakers, each circuit breaker having a trip latch mechanism for opening the circuit breaker and a mechanical contact position indicator for indicating the open or closed position of the circuit breaker with the interlock extending between the trip latch mechanism and contact position indicator mechanism of each circuit breaker. The interlock allowing only one circuit breaker to be closed at any time.

Abstract: A molded case circuit breaker apparatus is taught with an operating mechanism which is triggered in response to the movement of a trip bar. The trip bar in turn is responsive to current flowing in the main terminals of the circuit breaker apparatus. The trip bar is responsive to electrothermal conditions as a gradual overload increases. It is also responsive to a short circuit condition due to a magnetic reaction between an armature and an electromagnet. The armature is flexibly attached to the trip bar for flexible movement in one direction and non-flexible movement in the other direction so that a short circuit may be accommodated by a relatively small air gap by non-flexible movement of the armature and the trip bar to cause a tripping operation.

Abstract: An electric control system characterized by a pair of spaced circuit breakers and a mechanical interlock therebetween, each circuit breaker having a pair of stationary and movable contacts and a trip bar for opening the contacts, and the interlock extending between the movable contact means of each movable contact of one circuit breaker and the trip bar of the other circuit breaker.

Abstract: A circuit breaker including stationary contact means and a movable contact operable between open and closed positions with respect to the stationary contact means. A contact holder engages the movable contact, and means are utilized for effecting movement of the movable contact between the open and closed positions. Indicator means indicate the position of the movable contact with respect to the stationary contact, and may also function to reset an automatic tripping mechanism.

Abstract: A multi-pole circuit breaker characterized by a circuit breaker structure including a releasable arm for opening a circuit through the breaker, a bimetal element for each pole which is responsive to an overload current condition to effect release of the releasable arm, a latch bracket and a trip bar coaxially mounted and having an adjustment screw to vary the position of the trip bar in relation to the bimetal to change thermal rating of the circuit breaker.