Abstract: An electroporation system and method for directing high-voltage currents to a suspension of cells contained in a cuvette. A high-voltage switch controls the coupling of a charge control to a high-voltage capacitor and, additionally, controls the coupling of the high-voltage capacitor to the cuvette. A current diverter diverts current away from the sample whenever an arc condition commences or a low sample resistance is detected across the cuvette. The current diverter includes a current diverter switch, which is triggered when a sense resistor measures a second predetermined voltage indicative of an arc-over event (or a low sample resistance condition).

Abstract: A tester for an arc fault circuit breaker plugs into a socket in the protected branch circuit. An actuator includes a first spring biasing a moveable contact carried by a pivoted contact arm away from a fixed contact and a momentary closer for momentarily closing the contacts. The momentary closer includes a push button and a second spring coupling the push button to the pivoted contact arm to close the contacts when actuated. Closing of the contacts completes a circuit across the branch circuit resulting in a current producing a magnetic repulsion force which blows the contacts open thereby striking an arc. The arc, which should trip the arc fault circuit breaker is visible through a translucent or transparent section of the molded tester housing. A fuse interrupts any overcurrent and a test light verifies initial energization of the protected circuit and operation of the arc fault circuit breaker.

Abstract: A circuit for a direct current electric motor system for reducing contamination in contactor tips includes a semiconductor element in a parallel circuit arrangement with the contactor. The motor system includes a direct current power source coupled to an electric motor through the contactor. A capacitor is coupled in a parallel circuit arrangement with the motor. When the contactor is open, the capacitor is charged by the direct current power source through the semiconductor element. The capacitor will not charge to the same voltage as the direct current power source because of the semiconductor element, creating a voltage differential across the open contactor tips, which is equivalent to the voltage drop across the semiconductor element. Accordingly, the surge of current flowing across the contactor when its is closed cleans the contactor tips.

Abstract: A switching device including a measuring means for monitoring contact erosion, which is provided between a contact element and an associated contact support. The switching device includes an electrically insulated signal line, which is usable in individual and/or multiple contacts, is used as the measuring means, the signal line being integrated into a single monitoring circuit. In the switching device, there is arranged, between at least one of the contact elements and the associated contact support or in the contact material, an electrical conductor with insulator as the signal line, damage to or destruction of the insulator and/or the conductor being utilized to generate an external signal as an indication of the end of the service life of the contact element.

Abstract: An overcurrent protection system which will give a rapid response to overcurrents which cause a reduction in the voltage across the load, e.g. a partial or complete short across the load, and which will preserve the trip endurance of a PTC device used in the protection system. The new system maintains the trip endurance of the PTC device by removing the source voltage from the PTC, while still keeping the circuit protection arrangement in a fault state, thereby continuing to protect the load.

Abstract: The failure of a motor to maintain a commanded speed is detected by the disclosed variable speed fan failure detector. The commanded speed varies as a function of temperature, such that at temperatures below a first predetermined temperature the motor runs at minimum speed and at temperatures above a second predetermined temperature it runs at maximum speed, with the speed varying substantially linearly between the first predetermined temperature and second predetermined temperature. The failure detector develops a first voltage proportional to motor speed, senses a temperature at a point where a predetermined temperature is to be maintained, develops a second voltage proportional to a desired speed based on the sensed temperature.

Abstract: The arc suppression circuit includes an insulated gate bipolar junction transistor (IGBT) connected across the electrical switch contacts to be protected. When the contacts open, the combination of added Miller capacitance and the gate-to-emitter capacitance of the IGBT results in the IGBT turning on. The IGBT is quickly turned off thereafter by a second transistor, which turns on as the voltage across the suppression circuit rises following turn-on of the IGBT. The turning on of the second transistor results in the first power transistor quickly and abruptly turning off so that relatively little of the load energy is dissipated in the power transistor.

Abstract: Disclosed is a low current binary input subsystem for providing a binary input signal to a data acquisition system. The binary input subsystem monitors the open/close state of a field contact and provides galvanic isolation of noisy field contacts, high noise immunity, a steady state current of approximately 1.2 milliamps resulting in power dissipation of approximately 0.25 watts for a 125 VDC input, and a momentary high current pulse of approximately 150 milliamps for a duration of approximately 4 milliseconds during field contact closure to aid in cleaning of oxides from the field contact.

Abstract: A contactor control system for a DC electric power system for reducing contactor tip contamination from dry-switching includes a first switch connected in circuit between a power source and a controller for enabling the controller upon closure of the first switch. A PTC resistor is connected between the first switch and a filter capacitor whereby charging current is supplied to the capacitor upon closure of the first switch. A solid-state switch is connected in series circuit with an electromagnetic actuator of a contactor having power contact tips in circuit between the power source and a load. The series combination of the actuator and solid-state switch is connected in parallel circuit with the filter capacitor.

Abstract: A system and method for protecting relay contacts from erosion utilizes a sensor which senses voltage change in a switch controlling a load relay. In response to operation of the switch, the sensor sends a current to a set of pass transistors which are connected in series to the load power source and the load to turn off the transistors thereby cutting off load current flow to the load. A delay element is connected in series between the sensor and the set of transistors which cuts off the current flow to the set of transistors for a period of time selected to enable the load relay contacts to fully close or fully open before conducting electrical current therethrough.

Abstract: A drive train for an electric vehicle includes a traction battery, a power drive circuit, a main contactor for connecting and disconnecting the traction battery and the power drive circuit, a voltage detector across contacts of the main contactor, and a controller for controlling the main contactor to prevent movement of its contacts to the closed position when the voltage across the contacts exceeds a predetermined threshold, to thereby protect the contacts of the contactor. The power drive circuit includes an electric traction motor and a DC-to-AC inverter with a capacitive input filter. The controller also inhibits the power drive circuit from driving the motor and thereby discharging the input capacitor if the contacts are inadvertently opened during motoring. A precharging contactor is controlled to charge the input filter capacitor prior to closing the main contactor to further protect the contacts of the main contactor.

Abstract: A circuit breaker comprises a static switch electrically connected in series with a disconnecting switch having an operating mechanism with a handle to close and open a system of main contacts. A voltage sensor ocmprises an electromagnet with a moving core capable of occupying an active locking position and an inactive unlocking position of the mechanism, respectively in the on state and in the off state of the switch. Opening of the disconnecting switch is inhibited if voltage is present on the output terminals.

Abstract: A power integrated-circuit device is protected against load voltage surges. This is done by providing an alternate current-carrying path that is activated only in response to the occurrence of such surges. This alternate path is independent of and separate from the connection that extends between the device and its power supply source. In addition, circuitry is connected to the device to limit the portion of the surge voltage that can appear across critical elements of the device.

Abstract: A device for arcless switching of electrical circuits, wherein power leads of a controlled semiconductor device - transistor 9 are connected parallel to a movable contact (2) and a fixed make contact (3) of a make-and-break contact assembly (1). A control lead of the transistor, which is its base, is connected to a resistor (11) and a fixed break contact (10) of the contact assembly (1), which are components of a control circuit. The movable contact (2) and the resistor (11) are connected to opposite poles of the supply source.

Abstract: A system is disclosed for sequentially disconnecting multiple phases of a first power source (12) from an electrical load (14) requiring a minimum of interruption and connecting a second power source (28) to the electrical load. A first embodiment of the invention disconnects immediately the phase in which a trip condition requiring disconnection of the first source power is detected and disconnects phases of a first power source (12) in which a trip condition is not detected upon the detection of zero current flow in those phases. In a second embodiment of the invention, each of the phases of the first power source (12) is disconnected immediately from the electrical load (14) upon the detection of a trip condition in any one of the phases requiring disconnection of the first power source. In both embodiments of the invention, the phases of the second backup power source (28) are connected upon the detection of the occurrence of zero voltage points in the respective phases.

Abstract: A reduced arcing contact switching circuit. It is desirable to control the switching of electrical contacts so that opening and closing occur at the time when zero power is being transferred to the load so as to substantially reduce arcing at the contacts and thus extend contact life. In a purely resistive circuit, for example, the supply voltage and current will be in-phase and contact switching should occur when the current and voltage signals pass through zero degree phase angle. Control of contact switching is accomplished with this invention by producing a count value that represents the phase angle at which contact movement should be initiated, so that the actual closing or opening will occur at the desired phase angle. When the count value and a preselected count are approximately equal, a flip-flop is enabled to pass the control information (open or close contacts) to a relay driver. The relay driver energizes or deenergizes (as the case may be) the relay to open or close the contacts.

Abstract: System and method for detecting arcing faults in a dynamoelectric machine by monitoring the neutral lead of the machine for a radio frequency voltage produced by arcing, providing a warning signal in response to a change in the radio frequency voltage, and providing a shutdown signal in response to a radio frequency voltage greater than a predetermined level. An RF voltage coupler is capacitively coupled ot the neutrla lead, and a radio frequency monitor connected to the voltage coupler detects peaks in the RF voltage.

Abstract: The contacts of an electrical switch, such as a magnetic contact reed switch or a magnetic contact reed relay used in a burglar alarm system, are protected from being fused together by transient current surges. This protection is accomplished by providing a normally nonconductive shunting path in parallel with the switch. The shunting path includes a voltage responsive device which is biased to conduction in response to a current surge to thereby complete the shunting path and allow the current surge to bypass the switch.

Abstract: A control device for energization of a load employs a bidirection triggerable solid state switching device connected in series with an alternating current power source and the load. In order to prevent the passage of excessive, potentially destructive currents through the switch if the load is shorted out, the microprocessor which controls the energization of the switch senses the time required for the voltage across the switch to attain a predetermined value. If the load is shorted the potential difference across the switch increases and attains the predetermined value a shorter time after zero-crossing of the alternating current. When this occurs more than a predetermined number of consecutive times, the generation of triggering pulses for the solid state switch is inhibited for a predetermined time. In the preferred embodiment the control device is a thermostat for controlling a temperature modifying load such as a furnace or air conditioner.

Abstract: System and method of detecting arcing faults in dynamoelectric machines by monitoring the voltage on the neutral grounding lead to detect RF voltages produced by arcing in the machine. The voltage is monitored by an RF voltage coupler and an RF monitor having a high impedance input amplifier. In one embodiment, the voltage coupler is clamped onto the neutral lead, and in another it is connected electrically in series with it.

Abstract: The contacts of an isolation relay are positioned between a line interface circuit and the associated feed resistors, the relay being controlled to open the contacts in response to an excessive common mode alternating current through the feed resistors. The common mode a.c. is detected by a sensing amplifier, and is integrated and compared with a threshold level in a dectector unit. If the common mode a.c. is excessive, a zero crossing predictor enables the detector unit to control the isolation relay and open its contacts at a zero crossing of the a.c. A phase shifter in the zero crossing predictor compensates for the response delay of the isolation relay. As the excessive current is now interrupted, the sensing amplifier responds to the line voltage. When this falls below a predetermined peak level, a delayed resetting of the protection arrangement is automatically effected.

Abstract: A bias control circuit controlling the power transistor Q2 in a transistor amplifier circuit for supressing the arc formed across the contacts 12, 14, 16 in a glow plug controller 10 for diesel engines. The bias circuit generates a load line for the contacts 12, 14, 16 which has a high voltage, low current portion and a high current, low voltage portion. The arc is formed when the contact 14, which may be slow operating, is required to break a high current, high voltage line.

Abstract: A hybrid electrical power controller is provided with a relay having a coil and a pair of mechanical contacts. A solid state switching device is electrically connected in parallel with the mechanical contacts and the parallel combination of that switching device and the contacts is connected between an input and an output terminal. A relay coil energizing circuit is included and means is provided for producing a signal representative of current flowing in the relay coil following deenergization of the relay coil. A solid state switching device control circuit responds to this signal and turns off the switching device when the signals fall below a predetermined magnitude.

Abstract: A spark suppression circuit for a battery charger includes a large filter capacitor connected in series with a semiconductor switch across the terminals of the battery charger. The battery charger does not have any output voltage even though the input is energized because the circuit includes a device to delay supplying of voltage until after the charger output terminals are connected to a battery to be charged. The semiconductor switch is non-conductive until the battery charger output terminals are actually connected to the battery to be charged. At this time, a bias circuit connected across the charger output terminals supplies a bias to turn on the semiconductor switch so that only at that time is the filter capacitor connected across the charger output terminals, and hence this suppresses the possibility of a spark upon connection of the charger output terminals to the battery to be charged.

Abstract: A method for interrupting an inductive load in a three-phase, high voltage network by means of a switch having a quick dielectric recovery, in particular a vacuum switch, in which two of the three vacuum switches, having a quick dielectric recovery, open at least 1/3 of a cycle of the network frequency later than the first vacuum switch, augmented with the minimum arcing time in the first vacuum switch, in order to prevent high over-voltages, caused by virtual chopping.

Abstract: The switching aid device includes, in the case of a main static switch, (1), a switching aid capacitor (10), parallel connected to the main static switch (1) via a loading diode (11) and, parallel connected to the latter, a series set up formed by an anti-return diode (12), primary winding (13) of transformer (14) of which secondary winding (15) is connected to an energy recovery circuit on an electrical power source (4) via diode (16) and an auxiliary static switch (17) fitted with control means (20) for closing the auxiliary switch in presence of an inverse voltage at the terminals of loading diode (11) and for opening the auxiliary switch in absence of such voltage.

Abstract: A method and apparatus for protecting switching elements, and, in particular, thyristor switching elements, which are used in a pulse generator to supply pulsed electrical voltage to a capacitive load, from damage resulting from a spark-over occurring in that load are described. Specifically, whenever the occurrence of a spark-over is detected, during, for example, the interval of time when a voltage pulse applied across the load is decaying, a trigger pulse is applied by a firing circuit to the thyristors to cause them to assume a substantially conductive state.

Abstract: A control system and method automatically control a glow discharge apparatus, as for ion nitriding, utilizing operator selected parameters (such as warm-up time, processing time, workpiece operating temperature and chamber pressure). During warm-up the control system provides a profile of the desired workpiece temperature, the desired profile temperature increasing with time at a rate that is reduced as the workpiece approaches its operating temperature. The control system compares the desired profile temperature with the measured workpiece temperature and compares the rate of change of the desired profile temperature with the rate of change of the measured workpiece temperature. It adjusts the level of electrical energy being supplied to the glow discharge in accordance with the comparison results. When the operator selected operating temperature is reached, the control system terminates the profile and operates to maintain that temperature.

Abstract: An arc suppression device (40) for protecting the load carrying contacts (30, 31, 32) of a power contactor (20) includes gate controlled semiconductor devices (TR1, TR2, TR3) connected in parallel with the contacts. A signal from a control circuit (45) causes gating current to be applied to the semiconductor devices nearly simultaneously with the application of current to and removal of current from the solenoid (25) of the power contactor. Circuit means (90) responds to the control signals to provide gating current for a limited period of time prior to, during and following the closing of the contacts. Gating current is not continued after the contacts have closed to protect the semiconductors from possible damage. Additional circuit means (110) responds to the removal of the control signal to provide gating current for a limited period of time prior to, during and following the opening of the contacts.

Abstract: In a control circuit to prevent the overheating of a conductively backed recording medium, a closed loop control circuit is provided wherein heat is provided to the heating electrodes of the circuit by one subcircuit under the control of a speed responsive control subcircuit. A feedback loop to a summing junction in the latter subcircuits is monitored to determine a deviation from virtual zero at that junction. A deviation from such virtual zero at that junction is used to control a shutdown safety circuit.

Abstract: In an output control apparatus for a microwave oven, it is known to insert a control switch in the primary side of a power transformer of a magnetron. In this invention, the control switch is provided in the secondary side of the power transformer either in a magnetron circuit or in a rectifier circuit. The actuation of the control switch is controlled by an on-off control signal such that the control switch is opened and closed respectively within zero-current time periods, of a half-wave current which flows through the rectifier or the magnetron. A transient rush current to the transformer is reduced and reliable intermittent operation of the magnetron is assured.

Abstract: A system is disclosed for switching a load between two ac sources wherein no degree of synchronization therebetween is required and wherein the switching is accomplished with the use of two electro-mechanical relays each having a three pole, double throw contact arrangement. Furthermore, this load switching is accomplished without the production of any interpower currents between the two sources.

Abstract: An arc quenching circuit senses initiation of an arc across the contacts of a contactor, commutates a capacitor discharge to the contacts that brings the contact voltage to zero for arc extinction and promptly recharges the capacitor to enable reoperation.

Abstract: A switchgear assembly which includes a vacuum interrupter, a current transformer, and a capacitive voltage sensor, all embedded within a cast epoxy housing mounted to a solidly grounded support structure. The voltage sensor includes a first capacitor, which is formed by an interrupter conductor stud, a plate, and the cast epoxy disposed therebetween, and a second capacitor, which is connected between the plate and a metal tube extending outside the housing. The tube is connected to ground through a conductive coating, applied to the housing, having an impedance which is very low in comparison to the impedance of the first capacitor.

Abstract: Disclosed herein is a direct current motor control circuit adapted for connection to first and second supply terminals of DC power source and to a DC motor connected between the positive and negative terminals of a DC power source, the control circuit including a solenoid including a solenoid coil having one end connected to the first supply terminal and having an opposite end, and having a pair of solenoid contacts connected in series relation with the DC motor between the positive and negative terminals and which close to energize the DC motor when current flows through the solenoid coil.

Abstract: A direct current circuit interrupting apparatus of the type wherein the arc of the circuit interruptor is extinguished by passing an oscillatory current from an oscillating circuit to the interrupted contacts via a switch means which is closed at the time when the circuit interruptor is opened includes a nonlinear resistor comprising a sintered mixture of metal oxides connected in parallel with the oscillating circuit.

Abstract: A relay control circuit is disclosed in which a timer circuit is actuated by a reference clock pulse in synchronism with an AC voltage supplied by a commercial power supply. An output signal of the timer circuit causes current to flow in the coil of the relay thereby to close the contact of a relay. The invention further comprises a polarity-reversing device for reversing the polarity in accordance with the variations in the output signal of the timer circuit. The reference clock pulse is applied to the timer circuit through the polarity-reversing device.

Abstract: The current surge, normally associated with the initial application of a nominal A.C. current to an inductive load, is prevented by preventing the magnetic core of the inductive load from being driven into saturation. Initially, the current is half wave rectified and amplitude limited. The amplitude limitation insures that the core will not be driven into saturation. A voltage detector connected across the inductive load senses only the counter E.M.F. of a polarity opposite to the polarity of the half wave current. When the sensed voltage reaches a predetermined value, a direct connection is provided between the A.C. supply and the inductive load, bypassing the half wave rectifier and the amplitude limiter.

Abstract: Apparatus for preventing the occurrence of possible transient phenomena in the circuit including a power source and its load connected thereto when the supply of electric power from the power source to the load, which has been interrupted, is restarted. The apparatus includes means for detecting the occurrence of the interruption of the power supply and means for memorizing the phase angle of the voltage or current of the power source at the time of the occurrence of the interruption of the power supply to maintain the circuit in off-condition. The apparatus further includes means for detecting the coincidence of the phase angle memorized in the memorizing means with a changing phase angle of voltage or current of the power source after the resupply of the electric power from the source to the load becomes possible whereby, upon detecting the coincidence, resupply of the electric power from the power source to load will be restarted.

Abstract: A battery spark suppression circuit uses an SCR controlled rectifier to control current flow from a direct current source. A circuit is provided for triggering the SCR a selected time after a load is applied to the current source.

Abstract: Equipment operating at high voltage which is subject to damaging voltage breakdown at relatively high altitudes and therefore relatively low pressures has a pressure sensitive switch such as a spark gap included in the high voltage circuit in shunting relationship. At lower altitudes no voltage breakdown occurs across the spark gap and the high voltage circuit operates normally.At high altitude voltage breakdown occurs across the spark gap shunting potentially harmful voltages from the high voltage equipment.

Abstract: Presented is an electronic circuit composed of various cooperating semiconductor-type devices controlling the degree and timing of triggering of a power switching device to effect controlled electrical conduction through the device. The circuit achieves a "zero-voltage-switch" (ZVS) function where the triggering of the power switching device can occur only during an interval when the main power terminal voltage is less than a predetermined value. The circuit comprises a high-voltage current limiting resistor comprised of a depletion MOSFET or JFET device used as a current limited source to drive other transistor amplifiers and switching circuits, the means of diverting this limited current through application of an external control signal separate from the power terminals, and a means of providing a limited source voltage to the external control means for use if required.