Abstract: An electric circuit breaker having fast short circuit response along with reduced arc energy is provided by means of a current limiting contact arm arrangement. The contact arm is arranged to pivot independently of the circuit breaker operating mechanism under the influence of magnetic repulsion forces. A contact spring configuration controls the rate at which the contacts separate, thereby limiting the energy of the arc created upon contact separation.

Abstract: High speed trip facility is provided within a molded case circuit breaker used within industrial applications. The movable contact arm is pivotally arranged to open independently of the trip unit-driven operating mechanism. A "latch kicker" arrangement interfaces between the mechanism trip bar and the circuit breaker intermediate latch whereby rotation of the trip bar causes the latch kicker to immediately displace the intermediate latch from the circuit breaker cradle thereby allowing the interrupter mechanism to untoggle the mechanism and open the breaker contacts.

Abstract: A thermal magnetic circuit interrupter with instantaneous short circuit current response utilizes a hook-shaped contact arm pivotally mounted on the operating mechanism at the end of the contact arm most distant from the contact. A saddle-type torsion spring proximate the pivot end of the contact arm provides adequate contact pressure while allowing the contact to immediately respond to magnetic forces generated under short circuit conditions. The immediate separation of the contacts reduces the current let-through the operating mechanisms while the tripping mechanism operates to trip the breaker.

Abstract: A movable contact arm for circuit breakers allows the contact opening characteristics to be determined over an entire range of breaker ratings. The contact arm is provided with a camming surface with the contact closure spring arranged as a cam follower. Under short circuit conditions, the contact repulsion force is sufficient to overcome the bias provided by the contact closure spring and to drive the cam follower along the camming surface so that the resulting spring torque rapidly changes from a high initial torque on the contact arm to zero torque in a very short period of time. The contact arm is linked with the contact operating mechanism to open upon current overload in response to the trip mechanism.

Abstract: A secondary disconnect plug is arranged on the sidewall of a circuit breaker compartment for mating with a complimentary receptacle attached to the sidewall of a track-mounted circuit breaker for allowing auxiliary electrical functions to be maintained when the circuit breaker is partially withdrawn from the compartment to a test position. The disconnect plug is floatingly attached to the compartment sidewall and contains a centering and aligning mechanism to provide a wide range of tolerance when the circuit breaker is moved in and out of the compartment.

Abstract: An adapter assembly is provided for use with circuit breakers having automatic charge and employing undervoltage release accessory. The adapter is inserted between the undervoltage release tripping mechanism and the circuit breaker operating mechanism to prevent the circuit breaker from tripping from a charged position when the circuit breaker contacts are open. The adapter assembly interferes with the undervoltage tripping lever when the circuit breaker contacts are open to prevent the undervoltage release tripping mechanism from tripping the breaker under conditions of undervoltage or power outage, thus providing a true stored energy device regardless of undervoltage conditions.

Abstract: A pivotally mounted primary latch lever carries a latch pin for latchingly engaging a cradle to sustain it in a reset position against the bias of the breaker mechanism operating springs. An intermediate latch lever, pivotally mounted to the primary latch lever, is formed with a pair of latch shoulders for respective latching engagement with a pair of latch pins associated with a pivotally mounted secondary latch lever. The geometry of the latch assembly parts and their various latching engagements are such that an exceptionally light trip initiating force on the secondary latch lever is effective in releasing the cradle from its reset position.

Abstract: In an industrial circuit breaker having a spring-powered movable contact operating mechanism and a spring-powered charging mechanism, each having the facility of storing a charge rendering the circuit breaker capable of being closed, condition indicator apparatus includes a first indicator for indicating whether the breaker movable contacts are open or closed and a second indicator for indicating whether or not a charge is stored in either the operating mechanism or the charging mechanism.

Abstract: Compound hook apparatus for intercepting and holding circuit breaker contacts in a hooked open position against the closing force of charged operating mechanism springs includes a primary hook releasably latching an intermediate hook in a hooking position to fixedly dispose a pin in intercepting relation with a hook cam carried by a breaker movable contact assembly. The primary hook is articulated to unlatch the intermediate hook, freeing the latter to thereby release the movable contacts from their hooked open position.

Abstract: A normally open close switch and a normally open arming switch are connected in series with a closing solenoid operatively coupled with hook apparatus for releaseably holding breaker movable contacts in a hooked open position against the closing force of a charged breaker operating mechanism. An arm actuates the arming switch in response to the movable contacts assuming their hooked open position, such that subsequent actuation of the close switch effects closing solenoid activation of the hook apparatus to release the movable contacts from their hooked open position. A holding solenoid, wired in shunt with the arming switch, prevents the arm from reactuating the arming switch in the event of sustained actuation of the close switch.

Abstract: A circuit breaker trip latch assembly includes a primary latch having a latching member releasably latching a cradle in its reset position against the bias of charged operating mechanism springs. The primary latch and either one of the first and second secondary latches commonly engage a latch pin carried by the free end of a pivotally mounted, elongated intermediate latch. The geometry of this common engagement is such as to greatly reduce the force of the charged mechanism springs ultimately absorbed by the first secondary latch as the cradle is relatched and the second, trip initiating, secondary latch while the breaker is closed.

Abstract: A spring powered charging mechanism is operatively coupled with a spring powered, circuit breaker contact operating mechanism such that charging of the operating mechanism springs is powered exclusively by the charging mechanism springs as they discharge. The charging mechanism includes a prop controlled by the condition of the operating mechanism to releaseably sustain the charging springs in a fully charged condition, while the operating mechanism includes a hook to releaseably sustain the breaker contacts open against the urgence of fully charged operating mechanism springs. Consequently, the circuit breaker is capable of executing multiple contact opening and closing operations without recharging.

Abstract: A handle operator slide and a motor operator slide are individually coupled with a charging mechanism to independently charge charging springs thereof. The charging mechanism is operative to charge the springs of a contact operating mechanism as the charging springs discharge. The charging mechanism includes a prop controlled by the condition of the operating mechanism to releasably sustain the charging springs in a fully charged condition, while the operating mechanism includes a hook to releasably sustain the breaker contacts open against the urgence of fully charged operating mechanism springs. Consequently, the circuit breaker is capable of executing multiple contact opening and closing operations without recharging the charging springs by either the handle or the motor via their respective slides.

Abstract: A circuit breaker is provided with a hook operating to hold the breaker movable contacts open against the bias of charged mechanism springs. The hook is selectively actuated by a closing solenoid to release the contacts for abrupt closure under the urgence of the mechanism springs. An indicator is appropriately positioned under the joint control of the breaker mechanism and movable contacts to identify OFF, charged and ON breaker conditions and to, in turn, control an actuating lever for a switch operating in an external charged signalling and closing solenoid circuit.

Abstract: A circuit breaker is provided with a hook operating to hold the breaker movable contacts open against the bias of charged mechanism springs. The hook is selectively actuated to release the contacts for abrupt closure under the urgence of the mechanism springs. An indicator is appropriately positioned under the joint control of the breaker mechanism and movable contacts to display the existing breaker condition.

Abstract: An arc chute for circuit interrupting devices comprises a series of identical arc plates, each having a pair of opposed, laterally extending tangs which fit through slots in insulative sideplates. The tangs are undercut to provide notches in which the sideplates are engaged when the arc plates are bodily shifted to locked positions with the tangs latched in the sideplate slots. An insulative backplate captured in slides in the sideplates engages the arc plates to sustain their locked positions.

Abstract: An accessory apparatus package for electric circuit breakers includes a pivotal lever for latching a spring powered trip slide in a reset position. Either of two shunt trip solenoids acts on this lever to unlatch the slide, which springs to an actuated position, initiating tripping of the breaker. A UVR solenoid can also act on this lever to unlatch the slide. A powerful reset spring, controlled by the breaker operating mechanism, discharges as the breaker trips to return the slide to its reset position and, in the process, causes the lever and the solenoid plungers to be reset. All parts are operatively mounted by a common support affixed to the breaker.

Abstract: A door interlock includes first and second, normally intercoupled plates mounted to a circuit breaker for sliding movement between respective first and second positions. The first plate includes an aperture through which a circuit breaker trip pushbutton normally extends, thereby sustaining the plates in their first positions where the second plate serves as a catch for the door of the breaker enclosure. Upon depression of the trip pushbutton, the breaker is tripped and the plates may be conjunctively slid to their second positions where the first plate sustains the depressed condition of the pushbutton to ensure that the breaker is open, while the second plate clears the enclosure door such that it can be opened. If desired, the intercoupling between the plates may be defeated, such that the second plate can be slid to its second position independently of the first plate, and the door may be opened while the circuit breaker is closed.

Abstract: In a circuit breaker undervoltage release device, a spring powered trip slide is held in a latched position by a latch lever while the plunger of a solenoid is magnetically held in a seated position against the bias of a calibrated return spring. In the event of an undervoltage condition, the spring retracts the plunger, causing the latch lever to release the trip slide, which then moves to trip the breaker. Opening movement of the breaker mechanism first actuates a reset lever to load a reset spring and then returns the slide to its latched position. As the latch lever regains latching control of the slide, the reset spring discharges to snap the plunger to its seated position.

Abstract: A circuit breaker includes an operating mechanism having powerful mechanism springs to achieve the requisite contact pressures for high current carrying capacity. A single crank of a rotary handle through a relatively small arc of 120.degree. resets the operating mechanism via a reciprocating slide and a latching mechanism, while loading the mechanism springs. Return of the handle to its original position shifts the line of action of the springs such as to abruptly straighten a toggle and achieve rapid closure of the circuit breaker contacts. The latching mechanism is equipped with plural circuit breaker tripping capabilities, together with a lockout and bell alarm switch accessory.