Abstract: Collector clips arranged on a circuit breaker trip unit printed circuit board allow removable connection between the trip unit circuit and the circuit within a field-installable rating plug as well as other auxiliary electrical devices. The connector clips are oriented to the rating plug and the trip unit to prevent cold flow of the solder at the junction between the ends of the connector clips and the receiving holes formed within the trip unit circuit board.

Abstract: A molded case circuit breaker containing a digital trip unit is field-tested for both electronically-induced as well as mechanically-induced test conditions by means of a portable test kit unit. The test kit circuit components are contained within a miniature test plug that temporarily connects with the circuit breaker trip unit by insertion within the rating plug receptacle formed within the circuit breaker cover. A compact power supply plug is received within the test plug to provide operating power to the circuit breaker trip unit components and associated accessories.

Abstract: Electric bus bar insulating coatings are calibrated to withstand long term outdoor exposure without failure. Manufacturing samples of the coating material are evaluated at the coating manufacturing site prior to shipment to the bus bar manufacturer. Bus bar samples coated with the material are suspended within a heated water bath and subjected to several hundred volt-amperes. The thickness of the coating is predetermined to provide accurate qualifying data for each coating sample within a reasonable time frame. Coating compositions that qualify are then applied to electric bus bar conductors by the bus bar manufacturer.

Abstract: A bell alarm unit is attached to the actuator-accessory unit of a molded case circuit breaker. The bell alarm unit consists of a microswitch, printed wire board connector and external wire conductors integrally encapsulated within a plastic composition to provide strain relief to the electrical connections between the printed wire board and the external wire conductors.

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 current limiting circuit breaker having a pair of separable contacts closely spaced for electrodynamic repulsion upon the occurrence of a short circuit overload condition utilizes an arc chute to cool and extinguish the arc that occurs when the contacts become separated. The arc chute contains a plurality of metal arc plates supported by side plates which also assist in cooling and extinguishing the arc. The side plates are formed from a suspension of wollastonite fibers within a melamine resin matrix. The wollastonite provides good mechanical strength and temperature-resistance properties while the melamine provides a continuous source of arc-quenching gaseous molecular compounds.

Abstract: An electronic circuit interrupter digital display and keypad device includes a display to view circuit breaker settings combined with a keypad to select settings and values to be displayed. The display and keypad device connects to an electronic trip unit within the circuit interrupter by means of a tamper-free seal to prevent the circuit interrupter set points from being changed without authorization. Alternatively, a password-operated control switch provides a similar function.

Abstract: A thermally efficient joint for electrical power distribution busway electrically connects between adjacent busway sections. Each busway joint includes a modular assembly containing spaced metallic splice plates separated by corresponding insulating plates. The module is sandwiched between a pair of joint covers by means of an insulated thru-bolt. The spacing between the splice joint for receiving corresponding busway stabs is accurately set by an apertured depression stamped within each of the splice plates.

Abstract: A current limiting circuit breaker having a pair of separable contacts closely spaced for electrodynamic repulsion upon the occurrence of a short circuit overload condition utilizes an arc chute to cool and extinguish the arc that occurs when the contacts become separated. The arc chute contains a plurality of metal arc plates supported by side plates which also assist in cooling and extinguishing the arc. The side plates are formed from a three-layer configuration wherein the two outer layers have excellent arc extinguishing properties while the inner layer has good mechanical support strength.

Abstract: A change of state circuit breaker contact material provides a low contact resistance at a low closing force by reducing current density through a pair of circuit breaker contacts. The use of a meltable metal alloy within the contact structure forces the current through a wider area of conduction whenever the temperature increases to melt correspondingly larger quantities of the metal alloy. The reduced contact hardness results in a substantial decrease in the force required to hold the contacts together, thereby allowing the contacts to open more quickly.