Abstract: A molded case circuit breaker utilizes a thermally responsive trip unit for providing long and short-time overcurrent protection and a magnetically responsive trip unit for instantaneous or short-circuit protection. An electrically and thermally insulative lever interfaces between the thermal element and the circuit breaker trip response bar to linearize the movement of the thermal trip element in response to circuit current.

Abstract: The secondary latch of a molded case circuit breaker latching arrangement is formed from a latching pin assembly with a solid metal latching sphere rotatably mounted at one end thereof. The latching sphere contacts the operating mechanism latching plate to provide a low-friction latching force to the circuit breaker operating mechanism. The latching sphere contacts the latching plate and is continuously lubricated by means of a lubrication reservoir integrally-formed within the latch pin assembly.

Abstract: A molded case circuit breaker of the type containing an electronic trip unit and a combined actuator-accessory unit to articulate the circuit breaker operating mechanism employs an optimum cradle configuration within the circuit breaker operating mechanism. The operating cradle is fabricated from a steel composition that is optimized to promote improved hardness properties. The optimized cradle interacts with the circuit breaker latch assembly to substantially reduce the tripping force required to articulate the operating mechanism.

Abstract: A molded case circuit interrupter of the type employing a thermal-magnetic trip unit to interrupt circuit current utilizes a flexible electrical braid conductor to connect between the thermal-magnetic trip unit and the movable contact arm. A helical spring arranged around the braid conductor at the welded connection with the movable contact arm provides long-term strain relief. A metal phosphate coating on the surface of the circuit breaker operating cradle and latch assembly eliminates polishing while insuring release of the cradle from the cradle-latch interface surfaces.

Abstract: A trip accelerator interfaces the thermal-magnetic trip unit and the operating mechanism within a thermal-magnetic molded case circuit breaker for improved response to overcurrent conditions within an associated electrical distribution circuit. The trip accelerator is in the form of a trip lever rotatably mounted on the operating mechanism side frame and is reset by the operating mechanism upon displacement of the circuit breaker operating handle.

Abstract: Field-installable accessories are used within a thermal-magnetic industrial-rated circuit breaker. On 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.

Abstract: A molded case circuit breaker of the type containing an electronic trip unit and a combined acutator-accessory unit to articulate the circuit breaker operating mechanism employs an optimum cradle configuration within the circuit breaker operating mechanism. The optimized cradle interacts with the circuit breaker latch assembly to substantially reduce the tripping force required to articulate the operating mechanism.

Abstract: A molded case circuit breaker with a visual access slot next to the circuit breaker operating handle allows the conditions of the circuit breaker contacts to be visually ascertained. To prevent inadvertent displacement of the circuit breaker operating handle when the circuit breaker is connected within an electrical distribution circuit, a handle guard is positioned over the circuit breaker operating handle. The handle guard is arranged such that the circuit breaker operating handle is free to reciprocate between the ON, OFF and TRIPPED positions while the operating handle guard is in position.

Abstract: An integrated protection unit is a circuit interrupter which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with mechanical trip and reset interface components. An actuator-accessory unit arranged within the interrupter cover interacts between the actuator-accessory unit and the interrupter operating mechanism to separate the interrupter contacts and interrupt a protected circuit.

Abstract: An integrated protection unit is a circuit interrupter which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with mechanical trip and reset interface components. One such accessory used with the integrated protection unit is a bell alarm for indicating the status of the circuit interrupter contacts.

Abstract: A compact circuit breaker containing an electronic trip unit employs an actuator-accessory unit to articulate the circuit breaker operating mechanism and separate the circuit breaker contacts to interrupt current within a protected circuit. A tolerance compensating spring is attached to the actuator-accessory unit trip armature to precisely set the separation gap between the tip of the armature and the actuator-accessory trip actuator arm.

Abstract: An integrated protection unit is a circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with supplemental trip and reset interface components. The reset mechanism allows the actuator-accessory unit to become reset without interfering with the operation of the integrated protection unit. The trip interface components allow the circuit interrupter to interrupt a protected circuit by operation of the actuator-accessory unit.

Abstract: An integrated protection unit is a circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with mechanical trip and reset interface components. The reset mechanism allows the actuator-accessory unit to become reset without interfering with the operation of the integrated protection unit.

Abstract: A rotatable trip test assembly unit for molded case circuit breakers consists of a unitary plastic part that cooperates with the internal structure of the circuit breaker cover to provide return spring bias to the trip test button. The trip test assembly unit rotates about a pivot and strikes the circuit breaker trip bar to thereby articulate the circuit breaker operating mechanism and separate the circuit breaker contacts. The interaction between a cam-follower on the assembly unit and a cam-shaped piece within the circuit breaker cover automatically returns the trip test button to its initial position upon release.

Abstract: A handle interlock arrangement is attached to the top surface of a manually operable circuit breaker operating handle to prevent the handle from being locked in its "OFF" position when the circuit breaker contacts are actually in their closed condition. A handle cover is hingeably attached to the circuit breaker cover and includes a pair of apertures arranged through the opposite sidewalls of the cover. The location of the apertures relative to the circuit breaker operating handle prevents the insertion of a padlock through the apertures when the circuit breaker operating handle is in its "ON" position.

Abstract: A compact circuit breaker utilizing an electronic trip unit for overcurrent determination contains a compact slot motor and a compact arc chute to minimize and control the arc that occurs when the circuit breaker contacts become separated upon intense overcurrent conditions.

Abstract: A molded case circuit breaker movable contact arm electrically connects with the circuit breaker load terminal without requiring a flexible electrical conducting braid. The contact arm is pivotally arranged within a contact arm support to which the load terminal lug is attached. The contact arm pivot pin is supported on a pair of parallel support posts extending from the contact arm support and a pair of bifurcated shunt plates are positioned on the pivot pin, one on each side of the contact arm to promote good electric transport between the contact arm and the support posts during short circuit conditions without interfering with the rotational movement of the contact arm.

Abstract: A compact current limiting circuit breaker with an electronic trip unit arranged within the circuit breaker cover and current transformers in the circuit breaker case incorporates reinforcement ribs in the cover to provide added strength. The cover also includes line terminal plugs that removably attach to the cover for preventing inadvertent access to the circuit breaker line terminals when the circuit breaker is energized. Protrusions formed on the bottom surface of the circuit breaker cover under the trip unit provide further strength while cooperating with flexible pads on the top of the current transformers to automatically compensate for manufacturing tolerances.

Abstract: An integrated protection unit is a circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with mechanical trip and reset interface components. The reset mechanism allows the actuator-accessory unit to become reset without interferring with the operation of the integrated protection unit.

Abstract: Electronic circuit breaker components are selectively coated with zinc and tin compounds to protect the components from the environment and to promote lubricity. Selected components within the operating mechanism, actuator and crossbar assemblies are coated with zinc phosphate followed by an over-coating of tin phosphate.