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: A molded case circuit breaker employs a multiple latch assembly for maintaining the circuit breaker operating mechanism in a closed condition. The multiple latch assembly includes three separate latch levers mounted on a common latch support frame. The multiple latch arrangement substantially reduces the amount of tripping force required to articulate the circuit breaker operating mechanism.

Abstract: A molded case circuit breaker includes an operating handle yoke that contacts the cradle operator and drives the operating mechanism springs over-center when the circuit breaker operating handle is moved from its RESET to its ON position. The contact between the handle yoke and cradle operator accelerates the over-centering of the powerful operating mechanism springs.

Abstract: A positive trip indication spring is used with circuit breakers that provide colored trip indication through a visual access opening in the circuit breaker cover to ensure that the trip indicia on the circuit breaker operating handle align with the visual access opening upon the occurrence of a trip condition. The trip indication spring cooperates with the powerful circuit breaker operating mechanism springs to provide additional bias to the circuit breaker operating handle to move the operating handle to its fully "TRIPPED" position.

Abstract: A compact circuit breaker containing an electronic trip unit for interrupting overcurrent conditions within a protected circuit is made operable over a wide operating current range by means of current transformers having multiple turn primary windings. The primary windings are selected to provide a constant ampere-turns ratio to the current transformers without changing the size of the secondary winding or the volume of the transformer core.

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 bi-stable interlock arrangement allows two circuit interruption devices such as electric circuit breakers and electric disconnect switches to be interlocked such that only one such device can be turned ON at one time. The interlock is used with main and auxiliary power sources to ensure that only one source of electrical power is activated at one time.

Abstract: A molded case circuit breaker having a pair of movable contact arms arranged within a single pole utilizes a shunt clip between the movable contact arms to insure electrical continuity between the contact arms and the support base during intense short circuit interruption. A compression spring-driven camming arrangement insures good electrical connection between the circuit breaker contacts under steady quiescent operating conditions while preventing reclosing of the contacts during short circuit interruption.

Abstract: A molded case circuit breaker movable contact arm electrically connects with the circuit breaker load terminal requiring only a small diameter auxiliary electrical conducting braid by pivotally arranging the contact arm within its support. The contact arm is nickel-plated prior to attachment of the contact to insure high current circuit interruption withtout damage to the contact or the contact arm.

Abstract: A circuit breaker containing an electronic trip unit utilizes a digital keypad and display to enter and display the trip parameters. The trip parameters are determined by means of a setpoint value that is incremented by means of an algorithm whenever the trip parameters are changed.

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: An electric circuit breaker enclosure includes a pultruded glass-filled plastic inset for added strength to the line and load terminal straps. The line and load terminal straps are fastened to the inset on the side and receive the corresponding line and load terminal cables on an opposite side thereof. The inset allows connection within a high-rated electrical power distribution circuit without damage to the circuit breaker case upon short circuit interruption.

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 fixed and movable contacts become separated upon intense overcurrent conditions. The fixed contact is arranged on a fixed contact arm that includes an arc runner for rapidly directing the arc into the arc chute.

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 fixed and movable contacts become separated upon intense overcurrent conditions. The fixed contact is arranged on a fixed contact arm that includes an arc runner for rapidly directing the arc into the arc chute. The arc chute includes a keying arrangement which cooperates with slots formed within the circuit breaker case interior sidewalls to orient the arc plates relative to the arc runner.

Abstract: A digital circuit interrupter includes a microprocessor programmed for tailored overcurrent protection to industrial power systems containing a plurality of electric motors as well as motor protective relays. A communication link permits the overcurrent set points to be selectively set within the microprocessor memory from a remote location. The tailored overcurrent motor trip parameters are then derived by means of a logarithmic interpolation algorithm which resides in the microprocessor memory.

Abstract: A molded case circuit breaker enclosure cooperates with the current-limiting line strap to prevent the egress of ionized gases. The gases are generated by a high temperature arc which occurs when the contacts are separated under short circuit conditions.

Abstract: A combination panelboard-switchboard housing accepts plug-on connection with a plurality of modular electric switch-circuit breaker enclosures. The modular enclosure accepts circuit breakers or electric switches which can be field-installed with minor alteration to the enclosure. The modular switch enclosure further accepts a wide range of ampere ratings within a standard enclosure size. A mechanical latch arrangement on the bottom of the modular enclosure prevents the modular enclosure from being removed from the panelboard-switchboard housing. Controlled temperatures are achieved within the housing by optimized circulating air flow.

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.