Abstract: An operating mechanism is disclosed which is capable of meeting electrical code requirements in the world market. The operating springs controlling the OPEN and CLOSED states of the circuit breaker contacts are charged both before and after the contacts are in their CLOSED conditions. The mechanism is both latched and unlatched by operation of a rotating cradle operator.

Abstract: A molded case circuit breaker having a thermal-magnetic trip unit is provided with a mechanical rating plug to allow a number of circuit breakers of different ampere ratings to be used within a common-sized enclosure. Multiple mechanical rating plugs are stored at the place of distribution to adapt the common enclosure to a specific ampere rating at a substantial savings in time, labor and materials.

Abstract: A molded case circuit breaker controlled by an electronic trip unit is cost-competitive with electromagnetic circuit interruption devices. A novel contact arm assembly and shield arrangement in combination with a contact arm spacer and operating cradle interface reduces the assembly time and the number of operating components to effect significant cost savings.

Abstract: A molded case circuit breaker having a thermal-magnetic trip unit is provided with a mechanical rating plug to allow a number of circuit breakers of different ampere ratings to be used within a common-sized enclosure. The rating plug interacts with a thermal-magnetic trip unit to set the circuit breaker ampere rating.

Abstract: A molded case circuit breaker movable contact arm electrically connects with the circuit breaker load terminal requiring only a small diameter auxiliary electrical braid conductor by pivotally arranging the contact arm within its support. The braid conductor is electrically connected with the movable contact arm and is contained within the contact arm support posts. The contact spring and the terminal screw retainer are formed from a single plate of spring steel. The contact arm support posts are capable of supporting movable contact arms of various thickness.

Abstract: A molded case circuit breaker enclosure and operating components are provided with additional features to enable compliance with a variety of international electrical requirements for sales in the world market. The circuit breaker operating handle is prevented from returning to the OFF position upon contact welding as one example. Another modification includes a reinforcement and rejection pin used with the enclosure case. A further modification includes a shield used with the movable contact arm to prevent the arc gas contaminants from contacting the circuit breaker operating springs.

Abstract: A molded case circuit breaker handle interlock unit is arranged on the top surface of the circuit breaker to lockingly prevent intentional displacement of the circuit breaker operating handle from either the ON or OFF positions. The movable clip on the unit is attached to the circuit breaker handle to prevent tampering.

Abstract: A molded case circuit breaker controlled by an electronic trip unit is cost-competitive with electromagnetic circuit interruption devices. A novel contact arm assembly and shield arrangement in combination with a contact arm spacer and operating cradle interface reduces the assembly time and the number of operating components to effect significant cost savings.

Abstract: A molded case circuit breaker motor operator includes a keying arrangement to prevent energizing the circuit breaker unless the motor associated with the motor operator is in the proper operating mode. The keying arrangement is in the form of a rejection plate that interfaces between the circuit breaker operating handle and the motor operator driver plate.

Abstract: A molded case circuit breaker movable contact arm electrically connects with the circuit breaker load terminal by means of parallel electric paths provided by a looped braid conductor. The contact arm support includes a single support leg for pivotally retaining the movable contact arm on one side. The opposite side of the contact arm is supported on the operating mechanism crossbar. Contact arms of increasing thickness are used to accommodate the higher transport currents required with circuit breakers of increased ampere ratings.

Abstract: A motor operator interface assembly allows a large industrial-rated circuit breaker to be manually operated between its ON and OFF conditions as well as electrically driven by a motor operator. The interface assembly includes a motor driver plate that connects and disconnects the circuit breaker operating handle from the motor operator unit to allow either manual or motor-driven operation. A drive pawl and drive plate insure resetting the circuit breaker.

Abstract: A molded case circuit breaker of the type containing an electronic trip unit to control an operating mechanism for automatically turning the circuit breaker contacts between ON and OFF conditions under overload conditions and a handle operator for same under quiescent conditions is designed for operation with a motor operator unit. The operating mechanism unit is structured to resist the high impact forces translated to the mechanism by the motor operator unit.

Abstract: A compact molded case circuit breaker operating mechanism crossbar assembly allows a unitary crossbar design to be used within a wide range of circuit breaker ampere ratings. A common phenolic crossbar and a metal staple are used for the higher ratings. An L-shaped filler in combination with the crossbar and staple are used to adapt the crossbar to the staple for the lower ratings.

Abstract: A molded case circuit breaker rotary handle operator allows the circuit breaker handle to be locked when the circuit breaker contacts are open. The handle is prevented from being locked in position when the circuit breaker contacts are welded in their closed condition.

Abstract: A modular crossbar arrangement for molded case circuit breakers allows a plurality of contact arm assemblies to be interconnected from a single modular unit. To provide increased acceleration to the movable contact arms a contact arm accelerator lever interfaces with the contact arm and crossbar assembly. To promote further acceleration of the movable contact arms to their closed positions, the movable contact arms in a multi-pole circuit breaker are staggered with respect to their rotational alignment within each pole on the crossbar assembly.

Abstract: A modular crossbar arrangement for molded case circuit breakers allows a plurality of contact arm assemblies to be interconnected from a single modular unit. To provide increased acceleration to the movable contact arms a contact arm accelerator lever interfaces with the contact arm and crossbar assembly. To promote further acceleration of the movable contact arms to their closed positions, the movable contact arms in a multi-pole circuit breaker are staggered with respect to their rotational alignment within each pole on the crossbar assembly.

Abstract: A screw retainer is fabricated from a thin sheet of spring steel and is comprised of three sections: a screw support section, a leg support section and a leg section. The screw support section contains a through-hole for receiving a support screw. The leg support section is bounded by the screw-support section and the leg section. The leg section is angulated with respect to the leg support section and has a degree of spring action that allows it to be compressed so as to allow it and the leg support section to be inserted between the respective lower portions of integrally-formed upstanding support arms of a support base. Once the screw retainer is completely inserted between the respective lower portions of the integrally-formed upstanding support arms, the leg section springs back to its normal position thereby preventing the screw retainer from becoming dislodged from its position.

Abstract: A modular crossbar arrangement for molded case circuit breakers allows a plurality of contact arm assemblies to be interconnected from a single modular unit. To provide increased acceleration to the movable contact arms a contact arm accelerator lever interfaces with the contact arm and crossbar assembly. To promote further acceleration of the movable contact arms to their closed positions, the movable contact arms in a multi-pole circuit breaker are staggered with respect to their rotational alignment within each pole on the crossbar assembly.

Abstract: A multi-pole circuit breaker is formed from a modular array of single-pole circuit breakers. The individual circuit breaker operating handles are ganged together by means of a handle connector placed over the individual circuit breaker operating handles. The handle connector has a U-shaped central part flanked by a pair of C-shaped parts disposed on the outside portions thereof to facilitate switching the individual operating handles in unison.

Abstract: Field-installable accessories are used within a thermal-magnetic industrial-rated circuit breaker. One such accessory in the form of a combined undervoltage release and shunt trip unit is field-installable within the circuit breaker cover. A bell alarm accessory unit can also be inserted within the circuit breaker cover either in combination with or apart from the undervoltage-shunt trip accessory unit.