Abstract: A selectable rating plug allows a standard molded case circuit breaker design to be used over a wide range of ampere ratings. The rating plug is used to control the thermal load on the thermally responsive trip element within the breaker. Movement of the thermally responsive element articulates the breaker trip mechanism in response to predetermined overload conditions to interrupt circuit current.

Abstract: A compact electric safety switch including a rotatably mounted double contact assembly. Heavy duty compression springs are positioned under the blade assembly for rapid make and break connection between a pair of contact stabs. The series arrangement between the pair of contact stabs generates a corresponding pair of electrical arcs during the make and break occurrence which is less intense and of shorter duration than standard single contact arrangements. The pair of less intense arcs of short duration allow for a corresponding pair of arc chutes of smaller size than standard single arc chute arrangements. The contact stabs that receive the double contact blade are staggered to reduce electromagnetic attraction between the contact and the stabs.

Abstract: A control circuit combined with a magnetically bistable solenoid armature provides a bistable undervoltage release function to a circuit breaker. The solenoid is fabricated from a material having high magnetic remnance and low coercivity. A first signal to the solenoid coil develops a high remnance flux to hold the armature against a spring force. A second signal, of opposite polarity and predetermined voltage, produces an opposing magnetic flux to cancel that retained by the solenoid. The armature then becomes extended under the influence of a charged spring to trip the breaker.

Abstract: A three-piece molded plastic enclosure for disconnect switches consisting of a base, cover, and door individually fabricated by means of an injection molding process. The base has integrally molded extension tabs cooperating with an integrally molded hasp on the door for allowing the enclosure to be padlocked. A two-part hinge wherein part of the hinge is integrally formed with the cover and the remaining part is integrally formed with the door allowing the door to be assembled to the cover in a hinge-like fashion. Electrical components are attached to the interior of the base and the base is secured to the cover by means of a screw. The screw is only accessible from behind the door when the compartment is unlocked. Besides providing a disconnect switch that is tamper-proof behind a locked door, the molded plastic enclosure is water-tight and environmentally secure.

Abstract: Circuit protection and protective relay functions are provided by common circuit elements under the control of a single processor unit. Voltage and current values are obtained on a continuous basis and these values are continuously monitored within the processor to determine the electrical status of a protected power distribution system. Upon the occurrence of an overcurrent or undervoltage condition, the circuit is interrupted by operation of a circuit breaker trip solenoid causing the breaker contacts to open. When the overcurrent or undervoltage condition ceases to exist, the circuit breaker contacts could be closed by operation of a controlled relay. The ROM and RAM storage elements within the processor unit are continuously tested and the circuit breaker contacts are opened upon indication that the ROM or RAM element is nonfunctional.

Abstract: Molded case circuit breakers having rear mounted line connectors are provided with retainer clips and plates to prevent easy removal of the breakers from electric panel box load stab connectors. The breakers can be removed for replacement however, without disassembling the entire electrical panel box.

Abstract: A solid state switch connected across a pair of separable contacts for eliminating arcing across the contacts allows the contacts and the contact driver to be enclosed within an evacuated envelope. The vacuum environment allows the use of an inexpensive, highly conductive contact material, such as copper, without fear of chemical reaction.

Abstract: A molded plastic circuit breaker support for lighting panel boards includes integral guides for robotic insertion of the branch strap conductors as well as integral support means for providing additional support to the main bus conductors. A former plastic cover is positioned over the branch strap conductors for electrical isolation within the panel board enclosure and a formed plastic phase barrier shield is attached to the top of the support for insulating the main bus conductors.

Abstract: A ground fault module is designed for ease of assembly within a ground fault circuit breaker. The module houses the pre-assembled signal processor module, which contains the ground fault circuit interruption logic, along with the mechanical components required for translating the trip initiating response from the signal processor solenoid to the circuit breaker operating mechanism. The ground fault test button and related circuitry are also supported within the ground fault module.

Abstract: A molded case circuit breaker plastic support saddle includes means integrally formed therein for supporting the main bus conductors along with neutral conductors. The neutral conductors are arranged as a pair of conductors parallel with and outboard of the main bus conductors. Interconnection between the neutral conductors is made by a C-shaped insulated metal crossarm contained within a two-part insulating casing. This arrangement of the main bus conductors and neutral conductors allows for robotic assembly in a high speed manufacturing process.

Abstract: A vacuum interrupter whose envelope comprises a cylindrical insulated casing and top and bottom metal end bells that support movable and fixed contact rods. The cylindrical wall portion of the end shields are secured to the cylindrical wall portion of the end bells and are positioned by snap arrangement of mating deformations, preferably protruberations and mating voids.

Abstract: The root mean square value of sensed current within a protected circuit is used to determine the occurrence of an overcurrent condition. A frequency multiplying circuit produces a pulse stream having a frequency proportional to the square of the amplitude of an analog signal representation of the circuit current. A root mean square value over a prescribed interval is developed from the squared current value. The RMS value is processed within an integrated circuit trip unit to determine an overcurrent condition and to operate a pair of separable contacts to interrupt the circuit current.

Abstract: A magnetic contact driver is arranged to drive a bridging contact out of electrical connection with a pair of fixed contacts to interrupt the current therethrough. The magnetic driver comprises a conductor winding embedded within notches in a plurality of metal laminations and an armature arranged transverse to the metal laminations. An auxiliary contact driver arrangement consisting of a pair of spaced electrical conductors arranged on the opposite side of the bridging contact is simultaneously energized for electrodynamic repulsion at the instant the magnetic driver winding becomes energized.

Abstract: A pair of main contacts and a pair of arcing contacts are electrically and mechanically interconnected within a current limiting circuit interrupter. A common operator biases the main contacts in a closed contact condition, while simultaneously biasing the arcing contacts to an open condition. A contact driver operating to open the main contacts simultaneously closes the arcing contacts causing circuit current to pass through both the main and arcing contacts. Further displacement of the moving contacts completely directs the circuit current through the arcing contacts for electromagnetic repulsion and arcing within a magnetic structure.

Abstract: Miniaturized current sensing transformers are electrically and mechanically attached to the printed wiring board carrying the electronic trip unit circuit within molded case circuit breakers. Electrical contacts extending from the current sensing transformers project through openings in the wiring board to springingly engage metal posts extending from the printed wiring board surface. Notched posts mounted on the current sensing transformers, co-extensive with the contacts, snappingly engage the sides of the printed wiring board for good mechanical support and to maintain alignment between the current transformers on the printed wiring board.

Abstract: Synchronous circuit interruption is provided by operation of a diversion circuit for diverting most of the circuit current away from a pair of series-connected electrical contacts over to a solid state current interrupter prior to energizing a contact operator to separate the contacts to interrupt the remaining circuit current. To ensure arcless contact separation, the contact operator is arranged electrically in series with the solid state current interrupter which ultimately dissipates the system energy within a voltage dependent element. The arrangement of the contact operator circuit in series with the solid state current interrupter synchronizes the operation of the contact operator to ensure that the contacts are separated immediately after the circuit current has become diverted.

Abstract: A composite line strap is used with molded case circuit breakers to support the circuit breaker stationary contact and to retain the circuit breaker line terminal screw. The fixed contact is welded to the line strap within the breaker at a first end and the line terminal screw is attached to the opposite end of the line strap by a through-hole in a spring-steel retainer which extends partially within the circuit breaker. The line terminal screw is tightly held within the through-hole of the retainer at the first end and the retainer itself is trapped between the bottom of the circuit breaker case and the line strap at the opposite end of the line strap.

Abstract: A removable rating plug connectable with electronic trip molded case circuit breakers allows a common rating plug design to be used over a wide range of industrial rated circuit breakers. The burden resistors carried by the rating plug set the breaker ampere rating in combination with a current transformer tap selection. Electrical connection is made between the rating plug and the trip unit circuit board by a plurality of conductive stabs attached to the plug for insertion within spring connectors arranged on the circuit board. The stabs are keyed to ensure electrical connection with reference ground before, during, and after electrical connection is made with the rating plug burden resistors to protect the current sensing transformers from dangerous overvoltage conditions. Additionally, trip test facility and rating plug integrity indication are provided by test connectors on the rating plug in combination with test circuit implementation on the trip unit circuit board.

Abstract: A varistor quenched arc chute for current limiting circuit interrupters utilizes the combination of a plurality of stacked metal plates for attracting the arc that forms upon separation of the current limiting contacts with interspersed varistor elements for dissipating the system stored energy. The number of metal plates and the clamping voltage of the varistors is adjusted for optimum arc de-ionization. After arc extinction, the metal plates serve as cooling fins for the varistors.

Abstract: A main circuit breaker adapter is provided in modular form for attachment to a main lug load center or panelboard to convert to a main circuit breaker load center or panelboard. The main breaker is attached to a thermoplastic unitary support having means for mechanically and electrically connecting to one end of a molded plastic circuit breaker support saddle.