Abstract: A circuit breaker includes a housing having an opening, separable contacts within the housing, and an operating mechanism for opening and closing the separable contacts. The operating mechanism includes a generally transparent operating handle having a portion protruding through the opening of the housing. An auxiliary switch associated with the operating mechanism provides a first normally closed output when the separable contacts are open and a second normally open output when the separable contacts are closed. A first LED indicator cooperates with the first output, is proximate the operating handle and is illuminated when the separable contacts are open. A second LED indicator cooperates with the second output, is proximate the operating handle and is illuminated when the separable contacts are closed. One of the first and second LED indicators illuminates the operating handle.

Abstract: An externally controllable circuit breaker includes a set of main contacts, an operating mechanism for opening and closing the main contacts; and a set of secondary contacts electrically connected in series with the main contacts. A control mechanism to open and close the secondary contacts includes an electromagnet with an armature having a first position, which opens the secondary contacts, and a second position, which closes the secondary contacts. The electromagnet also includes a coil electrically interconnected with the main contacts for energization therefrom and adapted for control by one or two external signals from one or two external contacts to operate the armature between the first and second positions.

Abstract: A circuit breaker includes a housing, separable contacts disposed in the housing, a latchable operating mechanism structured to separate the separable contacts, and a magnetic trip mechanism coupled to the latchable operating mechanism. The magnetic trip mechanism includes a plunger assembly support structure and a plunger assembly having a moveable core. The plunger assembly support structure includes a wall having a slot therein. The moveable core rests in the slot. A positioning member has a hook and an opening. The hook engages the wall of the plunger assembly support structure. The moveable core passes through the opening of the positioning member, which retains the moveable core relative to the plunger assembly support structure.

Abstract: A tester for verifying the integrity of insulation in a branch circuit of a power distribution system. Two test circuits are included; the first providing an insulation test; and a second, a shared/grounded neutral test. In the insulation test, a 500-volt ac output limited to 5 milliamps is selectively applied to the pairs of wires of the branch circuit. If an output current of greater than 3 milliamps is recorded, an insulation failure is noted and the operator proceeds to the second test which applies a pulsed 3 volt, 1 ampere current-limited voltage across the suspected leads. One of the suspected leads is monitored with a portable ammeter to detect any pulse current.

Abstract: Effective arc-quenching is desired for current interrupters as defined to include circuit breakers, contactors, fuses and the like under conditions of operation where an electrical arc is produced that must be quenched to eliminate an undesirable current flow. An improved mode of arc-quenching coatings comprising urethane, melamine and acrylic based resin compositions containing inorganic nitrides such as boron nitride, aluminum nitride and silicon nitride are found to be effective as arc-quenching materials for current interrupters. Other coating compositions comprising urethane, melamine and inorganic nitrides mentioned above and high nitrogen organic compounds such as urea, hydantoin, allantoin, guanidine carbonate, guanine, melamine cyanurate and 1,3-diphenyl guanidine are also found to be effective as arc-quenching materials for current interrupters.

Abstract: A cable holding device for holding a communication cable beside an electrical power outlet box. The cable holding device comprises a frame having a main portion and an integral base portion, extending at a right angle to the main portion of the frame, for attachment to the side wall of a power outlet box with a front face of the main portion of the frame preferably substantially coplanar with a front face of the outlet box defined by the front edges of the walls of the outlet box. The frame has at least one tab to which a communication cable may be secured. A variety of tabs are disclosed, some of which have a hole connected with an access slot for receiving the cable. The tab may be manually bent to enlarge the slot to allow passage of the cable to the opening after which the slot may be at least partially closed to retain the cable in the opening.

Abstract: The movable contact arm of a circuit breaker is mounted on a pivot pin by a slot which extends generally transverse to the longitudinal arm of the contact arm, so that when the contacts are welded, initial motion of the circuit breaker operating mechanism to open the contacts is translated into pivoting of the contact arm about, and thereby breaking the weld. In a circuit breaker in which the contact arm is coupled to the operating mechanism through a cam mechanism which allows the contact arm to blow open in response to very high overcurrents, the slot extends generally longitudinally so that the cam mechanism translates initial movement of the operating mechanism into longitudinal movement of the contact arm to apply a shear force tending to break the weld.

Abstract: A molded case circuit breaker having current limiting capabilities optimized for relatively smaller frame sizes. More specifically, one aspect of the invention relates to a two-piece carrier assembly for carrying the main and arcing contact arms which allows the main and arcing contacts to be blown open during short circuit conditions. The two-piece carrier assembly includes an inner carrier and an outer carrier pivotally connected together. The contact arms are carried by the inner carrier. When sufficient magnetic repulsion forces are exerted on the contacts due to a short circuit condition, the inner carrier pivots relative to the outer carrier to allow the contact arms to blow open. In order to control the amount of force required for blow open, a compression spring loaded cam assembly is provided.

Abstract: A microprocessor based switch such as a circuit breaker has a memory capacitor charged by the microprocessor to generate an analog equivalent of a digitally modelled heat state signal. A selected resistor discharges the capacitor at a rate which models a cooling rate of a load. Alternatively, the memory capacitor may be charged to a preset value and discharged at a rate representative of the time since a trip generates digital rms representations of analog load. Terminals for rapidly resetting the analog trip memory for calibration and field testing of a long delay trip are hidden behind a removable rating plug.

Abstract: Process and apparatus for calibrating an electrical device such as a circuit breaker, motor controller or monitor is taught. A precision power supply device is interconnected by way of appropriate input channels to the device to be calibrated for supplying a precise accurate calibration variable as an input. A personal computer PC is interlinked by way of a communications network with the apparatus to be calibrated and is also interlinked with the precision supply device so that the personal computer PC has available the exact value of input variable utilized. Gain adjustment calibration is made by supplying the predetermined value of circuit variables, for instance 10 amperes or 120V to the input terminals of the device being calibrated. Upon command, the personal computer PC instructs the device being calibrated to deliver to the personal computer PC those values of input variable which the device being calibrated interprets as the input variable value.

Abstract: A method of interchangeably using memory devices constructed from different memory technologies, and/or having different storage capacities, in a predetermined socket of an electrical circuit. The method includes the steps of determining which technology types of memory devices, and storage capacities thereof, are to be interchangeably inserted in the predetermined socket, determining which pin positions of the determined memory devices have like functions, and determining which pin positions have different functions. The method further includes the steps of connecting the socket in the electric circuit such that a predetermined placement position of each determined memory device in the socket will serve the pin positions determined to have like functions.

Abstract: A refrigeration system, which conditions the air of a conditioned space via heating and cooling cycles, includes a heat exchanger and, in a first embodiment, heat pipes. A cryogen is circulated through the heat exchanger during a cooling cycle. During a heating cycle the flow of cryogen is terminated and heat is transferred into the heat exchanger via the heat pipes. In another embodiment, the temperature of evaporation of a liquid cryogen in the heat exchanger is selected according to the desired temperature of the conditioned space, via selectable cryogen flow paths which provide different pressures and thus different evaporation temperatures. Vaporized cryogen drives a motor connected to a fan which circulates air between the conditioned space and heat exchanger.

Abstract: A pump controller coupling the electric motor of a cyclically operating well pump to a power line is arranged to measure instantaneous power consumption of the motor, to integrate the power consumption over pump cycles, and to assess the performance of the well and/or pump by using the total power consumption to estimate fluid flow. The controller determines a phase reference in the cycle of the pump by monitoring for a peak or zero crossing in the instantaneous power level, specifically the point at which the pump changes over from a power stroke to regenerative operation due to pump momentum. The integrated total power consumption is reduced by an offset factor representing frictional losses, and scaled to obtain an approximate fluid volume determination for the pump and well. The factors used for offset and scaling can be adjusted by calibration using at least intermittent measurements of actual fluid flow and fluid density.

Abstract: Methods and apparatus for controlling the air temperature of a conditioned space to a selected set point temperature, utilizing a supply of cryogen in liquid and vapor states. The two states are drawn from the supply and maintained in first and second separate, independent flow paths. The liquid cryogen provides a cooling mode for the conditioned space via a heat exchanger disposed in the first flow path, and the vaporized cryogen provides a cooling mode for the conditioned space via a heat exchanger disposed in the second flow path. Cryogen flowing in at least one of the flow paths is used to drive a vapor motor connected to a fan, with the fan moving air between the conditioned space and at least one of the heat exchangers. Heat is applied to the cryogen as required to hold the set point temperature, or to defrost a heat exchanger.

Abstract: The coil holding current of a contactor is regulated to the lesser of two measurements of coil current during each cycle of the full-wave rectified control voltage to compensate for induced flux in the coil generated by load current through the main contacts of the contactor, thereby preventing uncontrolled drop out of the contactor.

Abstract: An automatic voltage regulator senses and controls the terminal voltage of a separately excited generator by controlling the field current applied to the field winding. In order to improve the response time of the circuit, the circuitry relies on the phasor relationships between the generator phase voltages to obviate the need for a rectification and filtering circuit, used in known AVR's. More specifically, each of the sinusoidal phase voltages is sampled and squared. The squared phase voltages are then summed together. The square root of the sum is used to provide a DC voltage signal, proportional to the terminal phase voltages V.sub.A, V.sub.B and V.sub.C. The DC voltage signal may then be compared with a reference signal to generate an error signal for use in regulating the generator terminal voltage by controlling the field current applied to the generator field winding.

Abstract: A refrigeration system associated with a conditioned space to be controlled to a predetermined set point temperature via heating and cooling cycles. The refrigeration system includes a fluid flow path through which a predetermined liquid is circulated. The fluid flow path includes a slush tank and first and second heat exchangers, with cryogen from a supply vessel being expanded into liquid disposed in the slush tank. The first heat exchanger is disposed to condition the air of the conditioned space, and the second heat exchanger is in heat exchange relation with heating apparatus. The first heat exchanger and slush tank are interconnected when the conditioned space requires a cooling cycle, and the first and second heat exchangers are interconnected when the conditioned space requires a heating cycle. Cryogen of the cryogenic cooling apparatus is thus not expended to heat the conditioned space, or for defrosting purposes.

Abstract: A method and apparatus for producing plastic parts with a resilient projection, such as connectors for corrugated tubing. The method comprises the steps of flowing plastic material on a core provided with a recess to mould the resilient projection, camming the resilient projection out of the recess, after the mass of plastic material is solidified and extracting the solidified part from the core. The invention also extends to a novel connector for corrugated tubing.

Abstract: A method for detecting low level of alkylbenzene or mineral oil impurity in polyol ester lubricants for compressors. This method comprises mixing a mixture of alcohol and water with a sample of the lubricant and then observe the presence or absence of turbidity.

Abstract: A circuit breaker includes an electronic trip device which responds to sputtering arc-type faults. Level detectors compare the current in the protected circuit to a plurality of threshold levels and timers time the intervals that the current remains above each threshold, with the threshold levels and intervals selected to generate a response envelope for a trip signal which approximates, with a selected margin, the response of the protected circuit to introduction of a selected inductive load such as the starting of a motor into the circuit. If the sensed current falls below a threshold level which was being timed, the associated timer is not cleared unless the current falls below the lowest threshold, so that if the sensed current increases above the associated threshold, timing resumes where it left off, and a trip signal will be generated sooner than for an initial excursion above the threshold. Both analog and digital timer implementations are presented.