Abstract: The gap distance separating the contacts of a low-voltage circuit breaker in the tripped position is increased by utilizing resilient stop means which is located at the bottom wall of the breaker housing rather than at the top wall (or on the handle of the breaker) in accordance with prior art practice. The movable contact arm is pivotally mounted and structured to strike the stop means as the contacts are separated and being blown open during short circuit conditions and, after the circuit breaker is tripped, the collapsed toggle assembly of the operating mechanism shifts the movable contact arm away from the stop means and allows the arm to move an additional distance away from the fixed contact and thus increase the gap distance between the opened contacts.

Abstract: A circuit breaker having an integral handle cover assembly for manual operation of the circuit breaker. The handle assembly comprises a cap segment and a base segment. The base segment removably engages with the operating mechanism of the circuit breaker with the cap segment positioned exterior to the circuit breaker cover and engaged with the base segment such that the handle assembly is attached to the cover while being movable in the opening thereof during the opening and closing of the circuit breaker allowing the cover to be removed from the circuit breaker without the detachment of the handle assembly from the cover.

Abstract: A current limiting circuit interrupter comprises a molded case, separable contacts disposed in the case, the contact arms supporting one of the contacts, an operating mechanism connected to the contact arm to move the arm between open and closed positions, and a slotted magnetic drive device generating electrodynamic force on the contact arm during extreme overcurrent conditions to rapidly separate the contacts. The magnetic drive device includes a molded housing forming a slot having insulated walls disposed about the contact arm, and a stack of U-shaped laminations of magnetic material fitted into the housing. The space between opposing walls of the housing is slightly less than the thickness of the lamination stack so that the laminations may be snugly press-fitted into the housing. The housing is then secured to the case in such a manner that the laminations are captured and securely positioned without the need for rivets or other fastening means extending through the lamination stack.

Abstract: A molded case circuit breaker having thermal and magnetic trip means. A moving contact support structure is disposed about the magnetic trip means so as to cause current flowing through the circuit breaker contacts to pass twice through the magnetic circuit of the magnetic trip means. The moving contact support structure includes resistance material operable upon overcurrent conditions through the contacts to aid in heating the thermal trip means. An operating mechanism includes an operating spring in compression which acts as one leg of a toggle linkage and stores energy to operate the contacts with a snap action.

Abstract: A multi-pole circuit breaker with adjustable thermal trip unit characterized by a circuit breaker mechanism having a plurality of pole units, means releasable when released from a latched position to effect simultaneous opening of the circuit breaker contacts, a multi-pole trip device including trip means for each of said pole units, each of said trip means being constructed to operate upon the occurrence of certain current conditions to effect release of said releasable means, and each pole unit comprising a bimetal element responsive to current flow to effect heating thereof.