Abstract: A thermal overload detector and interrupter has a current transformer for monitoring load current and providing a current value signal, a microprocessor for calculating values related to load current and the thermal characteristics of a load, and an interrupter for selectively conducting and interrupting load current. The microprocessor computes a square current value from the current value signal and multiplies the square current value by a predetermined constant to obtain a multiplied square current value. The predetermined constant is related to the heat transfer characteristics of the load. A present running sum is computed in the microprocessor by adding the multiplied square current value to a past test value. The microprocessor then computes a proportionate present running sum by multiplying the present running sum by the predetermined constant. A present test value is computed by subtracting the proportionate present running sum from the present running sum.

Abstract: The invention is a current regulator having a source of electric current, a switch connected in series with the source of electric current, and a load receiving current through the switch from the source of current. Means are provided for sensing the current through the load, and means responsive to the current through the load turn the switch on and off so that the average current through the load has a predetermined value. A filter smooths out the variations in the current. An inductor and a diode serve as the filter. A gate turn on thyristor (GTO) control electrode serves as the load and the current regulator maintains the control current needed to sustain conduction of the GTO. The current regulator is incorporated in an inverter using GTO devices to generate AC drive current for a motor.

Abstract: An apparatus for measuring the direction of power flow through conductors connecting a load to a source of alternating electric current, the load being capable of generating electric current, and the source of alternating electric current being capable of accepting power flow from the load. The invention comprises at least one wattmeter connected so that the sum of their outputs is proportional to the power flow through the conductors and the sign of the sum of their outputs is indicative of the direction of the power flow. A detector is provided for detecting the sign of the output of the at least one wattmeter. The detector is capable of generating an indicator signal. The indicator signal has a first value when the power flows from the source of alternating electric current into the load and the indicator signal has a second value when power flows from the load into the source of alternating electric current.

Abstract: A proximity switch including a base assembly rotatably carries a sensing head formed of a support part rotatable about one axis extending through a base assembly for positioning a sensing face on a complementary sensing part in any one of four planes parallel to the one axis. A pivot between for the support and sensing parts enable the sensing face to be placed in a plane transverse to the one axis by rotation about a second axis at 45.degree. to the one axis. Flexible connections extend along the one axis and stops between the sensing and support parts avoid undue twisting of the connections. An annular printed circuit board supported by the base assembly and a plurality of fine wires carried on an elastomeric member supported in the support part provides separable multiple connections between each conductor on the board and the flexible connections.

Abstract: The invention is an electrical shock prevention apparatus for electrical equipment having conductors capable of being connected to a voltage source comprising, a shield made of nonconductive material and guarding the conductors on at least three sides, and a cover attached to the shield by a living hinge so that when the cover is closed, the conductors are not accessible from a fourth side, and when the cover is open, the conductors are accessible from the fourth side. The invention also has rails molded into the side of the electrical apparatus, and grooves molded into a side of the shield so that the shield is attached to the apparatus by the grooves sliding over the rails. Protrusions extending from the side of the electrical apparatus snap into a recess of the shield, thereby locking the shield into position on the rails.

Abstract: The invention solves the problem of loss of contact between jaws of a stationary contact with a switchblade of a knife switch when the switchblade undergoes lateral motion, as for example, under the influence of electromagnetic forces during short circuit conditions. A jaw for a switch has a base, a pair of electrically conducting jaws for accepting a blade of a switch between the jaws, a pin mounted in a hole passing through the base; retention springs mounted on the pin and producing force against the jaws so as to maintain electrical contact between the jaws and the switchblade, wherein the pin may slide in the hole in the base so that the jaws may follow lateral motion of the switchblade.

Abstract: A circuit for controlling a display panel identifying malfunctions in an engine generator receives a plurality of electrical signals from the engine generator, each of which identifies a particular trouble. The electrical signal may be produced by closing a switch. It is caused to operate a latch that lights a light associated with the particular malfunction. Indications of other malfunctions are suppressed until the circuit is reset. A manual reset tests all lights and then leaves them off ready to respond. A power-up reset does not test lights but leaves all lights off ready to respond. The circuit is rendered especially appropriate for military use by hardening against radiation and against pulses of electromagnetic interference.

Abstract: A light detector measures the intensity of two different light beams, computes a ratio of an AC to a DC component for each light beam, and computes a quotient by dividing a first of the above ratios by a second of the above ratios. A light detector has a first photodetector, means, responsive to the first photodetector, for computing a first ratio of an AC component to a DC component of the intensity of a first light detected by the first photodetector, means for producing a first average value of the first ratio, a second photodetector, means, responsive to the second photodetector, for computing a second ratio of an AC component to a DC component of the intensity of the second light detected by the second photodetector, means for producing a second average value of the second ratio, and means for computing a quotient by dividing the first average value of the first ratio by the second average value of the second ratio.

Abstract: A high saturation three coil current transformer for use with electrical apparatus having a U-shaped conductor portion. The current transformer has a ferromagnetic core surrounding one leg of the U-shaped conductor. The core is formed from two U-shaped core portions. A first coil and a second coil are wound on bobbins, with one bobbin being placed around each juncture between the core portions. A third coil is wound about the middle section of one of the U-shaped core portions prior to the core portions being joined. The current transformer is positioned so that the U-shaped conductor surrounds the third coil.

Abstract: This disclosure depicts a novel apparatus for packaging components in a multiple type packaging arrangement which permits the multiply packaged components to either be opened as an entire unit or individually. In particular, this packaging arrangement comprises a plurality of aligned, open ended boxes having disposed over the open ends a U-shaped sheet, the sheet having a middle flat plane and two planes depending therefrom at right angles thereto, the middle plane sealing the open ends of the boxes. The U-shaped sheet dimensioned such that it will overlap the plurality of aligned open ended boxes and the U-shaped sheet having score marks therein corresponding with the ends of the individual boxes permitting individual boxes or groups thereof to be broken away from the plurality.

Abstract: A circuit breaker having an arc stack assembly that provides a longer arcing path resulting in decreased restriking characteristics during an interrupt cycle. The arc stack assembly has approximately parallel metal arc plates mounted in insulating sides. At the top of the arc stack assembly is an upper runner with a tail curving downwards to end near the uppermost arc plate. The arc horn has a prong that moves through the arc stack assembly and also through a groove in the upper runner. The tolerance between the arc and the upper runner is very close to facilitate transfer of the arc to the upper runner.

Abstract: An electrical terminal includes first and second members having elongated complementary arcuate surfaces thereon movable toward and away from each other by a clamping member. The second member is pivotally supported at one end on the first member and is configured so that different diameter conductors can be securely clamped between the arcuate surfaces.

Abstract: An assembly for joining together end to end sections of cable tray. Each section of cable tray comprises two parallel channel siderails connected by rungs. An L-shaped splice plate has holes in the flat portion to mate with holes in the middle portion of the siderails. The splice plate has a bottom flange with studs that are inserted into respective holes on the bottom portion of the cable tray siderails.

Abstract: An electronic circuit breaker having a trip solenoid assembly. The trip solenoid assembly includes a permanent magnet, plunger, trip coil and assist coil and is positioned adjacent to a phase conductor. At high current levels the phase conductor generates a flux that may cause the circuit breaker to nuisance trip. An assist coil is wound adjacent the trip coil. The assist coil is energized only when the current through the circuit breaker is of such a level so as to cause nuisance tripping. The assist coil is not energized during that time period when the trip coil is energized.

Abstract: An interlock scheme is provided for preventing access to a draw-out mechanism of a drawout circuit breaker which is in a contact "closed" position and preventing the contacts from being closed when the circuit breaker is only partially connected to the power bus. A sliding door, carried by the front cover of the circuit breaker, is movable between a first position providing access to a driver shaft assembly for operation of the drawout mechanism and a second position preventing access to the driver shaft assembly. A plunger and slider assembly is operable associated with the access door to prevent the door from being moved from the second position to the first position unless the contacts within the circuit breaker are open. A trip arm prevents the contacts from being closed when the circuit breaker is only partially connected to the power bus.

Abstract: An electrostatic fork shield for a layer wound transformer yielding a high degree of noise attenuation. A three phase transformer has three leg portions which are interconnected at both ends by a yoke. Around each leg portion is wound layers of primary coil and secondary coil. The transformer core, coils and shields lie within an enclosure. Both the inner wall and outer wall of each transformer coil is covered with a non-ferrous conductive shield. Between the primary and secondary coils of each phase and their respective vertical shields, is interposed a glastic spacer. A horizontal shield lies across each end of the transformer coil. The horizontal shield comprises a base and inner and outer fingers which cover a large portion of the surface of the coil ends but do not form a complete electric path around any leg portion. Two barrier shields are located on one side of the transformer between adjacent phases and are connected to the inner fingers of each horizontal shield.

Abstract: An improved plug-in assembly facilitating the tap-off of electrical current from bus bars carried in a busway section that includes opposite side rails and a plurality of plug-in openings formed in each of the side rails in back-to-back association or registration with each other. The plug-in assembly includes a substantially symmetrical insulating base and a door, each swingably connected to the side rail. Ears formed in the side rail adjacent the plug-in opening are aligned with ears formed on the door and a drive screw extends through holes in each pair of ears and into an opening in a support post provided on the side of each base. The screw is fittingly retained in the ear of the side rail while the door and base members fit loosely over the drive screw to permit those parts to swing between an open and a closed position. A metal cover latch is self-retained in one of a pair of symmetrically positioned latch retaining grooves on the front of the base which retains an integral catch portion on the door.

Abstract: A self-contained test feature for ground fault protection systems in circuit breakers. The ground fault protection system includes a sensing transformer having a primary winding that sums the currents through the phase current transformers. Upon the occurrence of an actual ground fault, the sensing transformer will transmit a signal to cause the breaker to trip. The test feature includes a test transformer having its secondary winding electrically connected in parallel with the primary winding of the sensing transformer. The current path between the test transformer secondary winding and sensing transformer primary winding is completed only upon the activation of a test switch. The primary winding of the test transformer is hooked to an external current source to provide the necessary current to simulate the ground fault.