Abstract: Molded case circuit breakers having increased short circuit current ratings contain a dual contact blade arm assembly and an arc shield wherein the operating mechanism is shielded from the arc blast which occurs during contact arcing. The arc blast shield consists of a trifurcated barrier interposed between the circuit breaker operating mechanism and the arc chute without interfering with the contact arm motion.

Abstract: A safety shield assembly for insertion within a drawout circuit breaker compartment between the load and line receivers in the compartment and the power stabs on the circuit breaker. The shield assembly utilizes a moveable shield, a pair of spring motors and a pair of actuating probes to operate the shield. One spring motor and one actuating probe are attached on either side of the circuit breaker compartment and both probes must be actuated before the spring motors can draw the moveable shield into an open position to expose the line and load receivers. The probes include a compression spring at its point of contact with the circuit breaker to compensate for overtravel.

Abstract: A shield mechanism for isolating line and load stabs within a 2500-4000 ampere circuit breaker compartment is disclosed having a primary operating arm for operating a lower moveable shield and an upper moveable shield interconnected by a reversing bell crank link. Interconnection between the bell crank link and an intermediate lever is made by means of a lower expansion link. The corresponding downward motion fo the lower expansion link, when the circuit breaker is inserted in the compartment, forces the upper moveable shield to pivot into an open clockwise direction by connection between the upper moveable shield, the bell crank link and an upper expansion link against the force exerted by a return spring. Direct connection between the lower moveable shield and the intermediate lever forces the lower moveable shield into an open counterclockwise direction.

Abstract: At a point on a residential branch circuit downstream from the service entry load center where the termination of the neutral conductor thereof is solidly clamped to ground and the ground conductor is terminated in electrical connection in common with the neutral conductor termination, a transformer is linked with one of the neutral and ground conductors. Downstream from the transformer, a capacitive coupler is connected across the branch circuit neutral and ground conductors. A transmitter of high frequency voltage signals is connected with either the transformer or capacitive coupler and a signal receiver is connected with the other thereof, such as to establish a communications lin between the transmitter and receiver using the branch circuit neutral and ground conductors.

Abstract: A thermal shield is employed with a circuit breaker operating spring to protect the spring from thermal degradation during contact arcing. One embodiment includes an ablative plastic coating on the outer surface of the shield to promote arc quenching.

Abstract: An integrally molded coil assembly extends about the intermediate leg, and is wedged between the outer legs of an E-frame magnet. It has rigid interior walls and top and bottom flange portions. Flexible flange extensions extend from the sides of the flange portions. The extensions are coplanar with the flange portions during the coil winding operations, and are bent in overlapping relationship during assembly of the coil form on the magnet. The flange portions are dimensioned so that the extensions are tightly wedged against the outer legs.

Abstract: Separate bargraph displays controlled by the electronic trip unit of a static trip circuit breaker continuously indicate the magnitude of the highest phase current as a percentage of the log-time delay pickup current setting and the timing out of a long-time delay as a percentage of the applicable long-time trip delay interval for a given phase current in excess of the long-time delay pickup setting.

Abstract: An integrated circuit ground fault signal processor utilizes a power supply having a first, regulated, half-wave rectified supply voltage section and second DC supply voltage section. Operating current for a fault signal amplifier and charging current for a fault signal integrating capacitor are drawn from the second power supply section on a full-cycle basis. Operating current for a trip threshold detector or comparator and a high frequency oscillator circuit is drawn from the first power supply section for operation on an alternate half-cycle basis.

Abstract: A multi-functional mounting module for J and K frame breakers utilizes an accessory post for mounting a plurality of breaker accessories for common actuation by means of a resettable tripping mechanism cooperating with the breaker trip assembly. A slidably mounted cam assembly on the module housing provides for tripping the breaker under predetermined conditions as well as resetting and indicating the breaker operational state.

Abstract: Power line communication over plural residential branch circuits is accommodated by creating a signal coupling inductive impedance in a tie conductor electrically interconnecting the grounded neutral bus, to which the branch circuit neutral conductors are commonly terminated, and a ground bus commonly terminating the branch circuit ground conductors, such as to support voltage signals propagating on the ground conductors with respect to the neutral conductors of the branch circuits. This inductive impedance is created either by a signal coupling transformer linked with the tie conductor and driven by a signal transmitter, with signal receivers capacitively coupled across the branch circuit neutral and ground conductors, or is of a passive nature, with both transmitters and receivers capacitively coupled across the branch circuit ground and neutral conductors.

Abstract: A passive control network for connection between a pair of load output level setting terminals, as on a ballast for a dimmable fluorescent lamp in a lighting system, to provide a required variable impedance, where the magnitude of the impedance establishes the load output level. The passive control network includes an isolation transformer for coupling a periodic waveform at the load input terminals to the variable impedance component, the magnitude of which impedance is reflected through the transformer to provide the load level-setting impedance.

Abstract: Circuits for providing a variable-amplitude D.C. analog control signal to a load, responsive to the time duration of a periodic, variable-pulse-width input signal, while providing isolation between the input signal circuit and the load circuit. Embodiments utilizing either a fly-back transformer or an optoelectronics isolator, are disclosed.

Abstract: A grounding receptacle is provided with a low resistance grounding path. Low resistance is achieved at an interface between grounding contact and a steel grounding strap by including a surface treatment and surface coating of deposited tin metal.

Abstract: A barrier system includes elongated, insulative, high impact resistant isolating barrier members clamped in semi-embracing relation with the horizontal bus runs in an electrical switchboard and the like. These horizontal bus runs are interrupted by bus joints electrically connecting them with riser bus; these joints being isolated by an enclosure comprising an insulative collar and a removable, insulative cover. The barrier members, joint enclosures, and insulative barrier panels and support bases isolating the riser bus all cooperate to afford an essentially impenetrable barrier protecting the buswork and preventing inadvertent human contact therewith.

Abstract: A contactor assembly comprises an arc chute having side walls, an intermediate wall and legs extending from the latter. A stationary electromagnet assembly is supported by a metallic support member, i.e. base plate, whose sidearms are secured to the bottom of the legs. Pole shader rings are nested in the arms of the magnet assembly. Portions of the pole shaders extending transversely from the magnet legs are clamped against platforms on the sidewalls of the arc chute by the spring force exerted by the base plate. An armature is secured to a moveable contact carrier that carries a spring biased contact bridge. The wear allowance of the contact carrier can be readily controlled by machining the platforms to the correct height. This is accomplished prior to installation of the electromagnet assembly by exerting a force directly against the contact bridges to close them against the stationary contacts. The platforms are then machined to a predetermined depth from the pole face of the armature.

Abstract: In an electrical switchboard vertical section, vertically adjacent pairs of cubicle doors are mounted by common hinge blocks located adjacent door corners and releaseably, latchingly retained in their closed positions by common latch blocks located adjacent opposed door corners. Horizontally aligned pairs of hinge and latch blocks additionally serve as mounts for instrument compartments located in the spaces available between vertically adjacent doors; these compartments slidingly accomodating drawout instrument drawers.

Abstract: A copper busbar is created in H-shaped cross-section by assembling a pair of elongated copper bars of rectangular cross-section to one or more conjoining copper webs of U-shaped cross-section. The bars and web legs are pre-punched with series of holes accommodating bolts clamping the bars to the web in parallel spaced relation. The bridging portion of the web is also pre-punched with a series of bolt holes facilitating the implementation of the busbar as a riser bus in electrical distribution equipment, such as switchboards, switchgear, and the like.

Abstract: A switchgear construction utilizes improved modular bases to serve as individual, insulative backwalls for the stacked array of cubicles in a vertical switchgear section. The back sides of the bases, assembled to the switchgear frame in end-to-end vertical relation, are channelled to receive and mount H-shaped vertical busbars in electrically isolated, side-by-side relation. Apertures in the bases accommodate electrical connections of device line terminal run-in straps with the vertical bus, and the rearward extension of device load terminal runbacks which isolatively pass through openings in the vertical bus. The vertical bus, the horizontal bus, and the bus joints therebetween are completely isolated from external contact.

Abstract: A control circuit utilizes a system voltage monitoring control relay for applying a DC control voltage across a UVR solenoid and a voltage dropping resistor to maintain the UVR in its reset condition in the absence of an undervoltage condition. An RC network maintains the UVR reset condition for momentary dips in the system voltage. If the UVR does drop out to trip its circuit breaker, a second relay temporarily switches out the dropping resistor to render the control voltage capable of electromagnetically resetting the UVR. To accommodate drawout breaker applications, means is provided to sense when the UVR is reconnected to the control circuit pursuant to automatically initiating a UVR reset function via the second relay.

Abstract: In an integrated circuit for a ground fault circuit interrupting device, a power supply voltage regulator is utilized to turn on a double grounded neutral excitation oscillator and to inhibit trip initiating thyristor triggering while the half-wave rectified supply voltage is in regulation and, as the supply voltage goes into regulation near the beginning of each alternate half-cycle, condition a comparator to issue a thyristor triggering pulse if an integrated fault signal voltage has achieved an established trip threshold level.