Abstract: A photovoltaic power system includes a DC/AC inverter circuit, N DC/DC converter circuits that are located at a previous stage of the DC/AC inverter circuit and that are respectively connected to photovoltaic strings, and a controller connected to the DC/AC inverter circuit and the N DC/DC converter circuits. The controller is configured to: perform MPPT control on n DC/DC converter circuits, and perform CPG control on (N?n) DC/DC converter circuits. In the two control manners, a fast and accurate power reserve or limit of a photovoltaic string inverter with any illumination intensity and ambient temperature can be implemented, and fluctuation of a DC bus voltage and AC output power of the photovoltaic string inverter can be eliminated. Control on a virtual synchronous generator of the photovoltaic string inverter is implemented, and a lifespan of the photovoltaic string inverter is prolonged, without a need to add an energy storage element.

Abstract: A circuit for detecting arc due to a bad contact includes a rectifying unit for rectifying an arc pulse voltage due to the bad contact, an arc voltage detection unit for detecting an arc voltage through the rectifying unit, a high-frequency pass filter combined in a front end or a rear end of the arc voltage detection unit, a control signal generation unit for generating a relay driving control signal using the arc voltage detected by the arc voltage detection unit, and a relay unit controlled by the relay driving control signal and electrically connecting a ground line and a power line of the interior wiring.

Abstract: A power-supply control device includes a power-source input terminal, an output circuit outputting power to load, power interrupting circuits connected in parallel between the power-source input terminal and the output circuit, and a control circuit controlling each power interrupting circuit separately. Each power interrupting circuit includes an interrupting circuit and a switch element connected in series between the power-source input terminal and the output circuit. The interrupting circuit permits power to pass when receiving a passage permitting signal from the control circuit and interrupts passage of power when not receiving the passage permitting signal. ON/OFF of the switch element is controlled by the control circuit. When any of the power interrupting circuits is set as a diagnostic target circuit, the control circuit stops supplying the passage permitting signal to the interrupting circuit of the diagnostic target circuit and turns off the switch element of the diagnostic target circuit.

Abstract: Disclosed herein are a method and apparatus for restoring a mechanical relay from a stuck fault to a normal condition. The method may include detecting, by an MCU, a short state or open state of a relay, repeatedly transferring, by the MCU, a current application signal and a current non-application signal to a relay driver when the relay is in the short state, repeating, by the relay driver, an operation of periodically applying an electric current from a power source unit to the relay in response to the current application signal and the current non-application signal so that the release of the contact point of the relay is induced, detecting, by the MCU, the release state of the contact point of the relay, and maintaining, by the MCU, an ECU in an operating state when the contact point of the relay is released.

Abstract: An exemplary safety circuit includes a plurality of contacts that are configured to establish a conductive path across the contacts when the contacts are in electrically conductive contact with each other. The contacts selectively interrupt the conductive path across them when the contacts are separated. A controller selectively introduces a voltage pulse across the contacts at a voltage level that is effective to overcome an electrical resistance of any contamination on at least one of the contacts. The controller introduces the voltage pulse at least when the contacts are expected to be in contact to establish the conductive path.

Abstract: The present disclosure relates to devices, systems and methods for programming base units of communication headset systems with new or updated configuration parameters by a portable or handheld programming unit.

Abstract: A plug-in power line conditioner is configured to receive an AC voltage from a circuit and insert a correction signal onto the circuit.

Abstract: The present disclosure provides an apparatus and a method for preventing an Intermediate Frequency (IF) connector from being corroded in a portable terminal. The apparatus may comprise an IF connector and a load switch that is mounted in a main board. The load switch is configured to communicate with the IF connector and to prevent a reverse voltage from being applied to the IF connector.

Abstract: A motor drive device includes first to third system main relays, a limiting resistor, and a control device. Upon start of the motor drive device, the control device determines whether or not the first and third system main relays are welded, based on voltage VH. If the control device determines that the first and third system main relays are both welded, then it prohibits a discharging process, which is to discharge a capacitor using motor generators.

Abstract: A system is provided for implementing a series interlock loop. An example of the interlock system includes a series interlock loop, a data table, and a control module. The series interlock loop has an overall electrical characteristic. The series interlock loop includes first and second safety interlocks electrically coupled in series. Each interlock includes a switch coupled in parallel with an impedance value. The data table is configured to store values corresponding to the impedance values. The control module is communicatively coupled to the data table and configured to receive an indication of the overall electrical characteristic and to compare the overall electrical characteristic to the values in the data table to thereby identify an open one of the first and second safety interlocks.

Abstract: Power control circuitry for controlling connection of a voltage source to a switched power rail powering an associated circuit is provided. A plurality of switch blocks are connected in parallel between the switched power rail and the voltage source, each switch block being controlled by an enable signal provided by a switch controller. The switch controller performs a turn-on sequence providing a series of enable signal patterns to the switch blocks. The switch controller applies a time varying generation operation to at least one sequence stage of a predetermined turn-on sequence to produce a corresponding enable signal pattern for that sequence stage. When the turn-on sequence is later repeated, the enable signal pattern produced for at least one of the sequence stages differs from the enable signal pattern previously produced for that sequence stage.

Abstract: The life of load tap changer contacts is monitored by detecting an arcing event; identifying arcing surfaces involved in the arcing event; calculating a per-unit loss of life for the identified arcing surfaces as a result of the arcing event; updating estimates of cumulative erosion for the arcing surfaces; comparing the updated estimates of cumulative erosion to a first threshold value; and signaling for action when at least one of the updated estimates of cumulative erosion exceeds the first threshold value.

Abstract: An input terminal is electrically connected to a contact point. An anti-corrosion current supplying section is operable to supply an anti-corrosion current to the contact point through the input terminal so as to remove corrosion in the contact point. A series resistor is electrically interposed between the input terminal of the signal processing circuit and the contact point. The anti-corrosion current is supplied to the contact point through the series resistor.

Abstract: A power switching control apparatus for acquiring pieces of making operation time information of individual phase switches more precisely according to loads and making instants. Making operation time information detecting means outputs the making operation time information of at least one of individual phase switches on the basis of the motion of the movable contact of the phase switch, and outputs the making operation time information of at least another of the individual phase switches on the basis of the phase current of the phase switch. Moreover, the making operation time information detecting means outputs the making operation time information ITA, ITB and ITC of an A-phase switch, a B-phase switch and a C-phase switch individually on the basis of either the detected output of a contact operation sensor and the detected output of a phase current sensor.

Abstract: A circuit for preventing corrosion of a contact, includes an input terminal, a signal line, a switch, an impedance element, and a comparator. The input terminal is to be connected to the contact, which is outside the circuit. The signal line is connected to the input terminal. The switch is connected to the signal line. The impedance element is connected to the signal line in parallel to the switch. An impedance of the switching section is smaller than that of the impedance element. The comparator compares a potential of the signal line with a predetermined potential. The switch is turned on based on a comparison result output from the comparator.

Abstract: A preventive maintenance tapping technique includes noting a tap position of a load tap changer and noting a duration that the tap position has been held. The duration that the tap position has been held is compared to a threshold value, and the tap position is changed if the tap position has been held for longer than the threshold value. Similarly, a duty cycle monitoring technique for monitoring life of load tap changer contacts includes detecting an arcing event. Arcing surfaces involved in the arcing event are identified and the effects of the arcing event on the arcing surfaces are calculated. Estimates of the erosion on the arcing surfaces are updated, and the estimates are compared to a threshold value. A signal for maintenance is generated when the estimate exceeds the threshold value.

Abstract: Automatically changing the tap position in a load tap changer includes noting a polarity of a first tap position of a load tap changer. A duration for which one or more consecutive tap positions of the load tap changer collectively have had the noted polarity also is noted. The one or more consecutive tap positions include the first tap position. The duration for which the one or more consecutive tap positions collectively have had the noted polarity is compared to a threshold value. A change is made from the first tap position to a second tap position with a polarity that is different than the noted polarity when the duration for which the one or more consecutive tap positions collectively have had the noted polarity is longer than the threshold value. A change may be made from the second tap position back to the first tap position.

Abstract: An apparatus for preventing a contact from being corroded includes a power source, a signal line connected to the contact, a resistance connected to the signal line, a switching section, a comparator, and an overheat detecting section. The switching section has a switch between the power source and the signal line. An impedance of the switch is smaller than that of the resistance when the switch is turned on. The comparator compares a potential of the signal line with a predetermined potential to determine as to whether or not the contact is corroded. The comparator outputs a driving signal when the comparator concludes that the contact is corroded. The overheat detecting section detects whether or not temperature of the apparatus exceeds a predetermined temperature. The overheat detecting section decreases current flowing through the switching section when the temperature of the apparatus exceeds the predetermined temperature.

Abstract: An electronic circuit for use with an exhaustible power source and at least one load such as a light bulb, a radio or motor, includes a microchip with an input that transmits a signal to the microchip when the load is activated or deactivated. The input does not form a serial link between the power source and the load. The power switch, by on/off switching, controls energy flow from the power source to the load. The input to the microchip acts as an activation/deactivation user interface. The microchip allows the user to select a specific load, specific functions for the selected load based on the time duration of activation signals, the time duration between activation signals and the number of activation signals at the input.

Abstract: Circuit arrangement for detecting the state of at least one electrical switch having at least one set input (Set1, Set2, Set3) in each case and at least one sensor output (Sensor1, Sensor2, Sensor3) in each case, each of which is allocated to an electrical switch (S1, S2, S3), wherein the sensor output (Sensor1, Sensor2, Sensor3) is connected via a first current path to a first potential if a signal with the value logic “1” is present at the set input (Set1, Set2, Set3) and is connected via a second current path to a second potential if a signal with the value logic “0” is present at the set input (Set1, Set2, Set3), and wherein a wake-up signal is generated at a wake-up signal output (wakeup) if a current which is greater than a predetermined threshold current is detected in the first or second current path.

Abstract: A method and an electronic circuit for regenerating an electrical contact are provided in order to remedy the problem of electrical contacts becoming highly resistive over time. Electrical contacts become highly resistive over time, particularly when the contacts are thermally highly stressed and/or exposed to corrosive gases. To remedy this undesired effect and to reestablish the low resistance of the contacts, an electrical regenerating signal is applied to these contacts.

Abstract: In methods and circuits for using associated circuitry to enhance performance of a micro-electromechanical switch, one of the method embodiments is a contact conditioning process including applying a time-varying voltage to the control element of a closed switch. In another embodiment, a voltage profile applied to the control element of the switch can be tailored to improve the actuation speed or reliability of the switch. In another method embodiment, the performance of a switch may be evaluated by measuring a performance parameter, and corrective action initiated if the switch performance is determined to need improvement. An embodiment of a circuit for maintaining performance of a micro-electromechanical switch includes first and second signal line nodes, sensing circuitry coupled to the signal line nodes and adapted to sense a performance parameter value of the switch, and control circuitry operably coupled to at least one terminal of the switch.

Abstract: A signal bounce inhibiting device and a signal bounce inhibiting method are provided for preventing power/ground bounce resulting from simultaneous switching output. The signal bounce inhibiting device includes an electric level toggling circuit and an electric level recovering circuit. The electric level toggling circuit receiving an internal signal of the first chip, and toggling the internal signal into a first output signal in response to a first toggling control signal. The electric level recovering circuit receiving the first output signal, and recovering the first output signal into the internal signal required by a second chip in response to a first recovering control signal.

Abstract: In a combination switch having both rotary and pushbutton momentary switches, a method for determining which switch has been selected by a user. The method also includes distinguishing between the selection of a rotary switch from a pushbutton switch.

Abstract: An electromechanical switching device ensures automatic selected polarity interconnection between terminals of two power sources. A double pole double throw (DPDT) switch has three pairs of contacts. A first pair of leads connect to two pairs of contacts in a manner that reverses polarity when switched, while a second pair of leads connect to the other pair of contacts. A switch controller employs a plurality of coils in electrical communication with the two pairs of leads. The coils are arranged and configured so that, when the two pairs of leads are connected to the respective power sources, the coils cause an actuator to move the switch automatically into the correct polarity state regardless of the connections of the leads. The invention is described as a battery jumper cable and to automatically connect like terminals of a pair of batteries. The invention encompasses the method of this device.

Abstract: A closed loop feedback system controls electrical switchgear that moves at least one contact relative to another contact to switch power on and off in an AC electrical circuit. The control system includes a position feedback device that is operatively coupled to at least one of the two contacts to produce contact position information. A processor receives and analyzes the contact position information to control contact motion to provide AC waveform synchronized switching. The electrical switchgear may be a capacitor switch that includes a bi-stable over-toggle latching device. The latching device maintains the contacts in one of an open stable position in which electrical current does not flow through the contacts or a closed stable position in which electrical current flows through the contacts.

Abstract: In a power distribution system, synchronizing switchgear operations with an AC voltage or current waveform can be accomplished more precisely with a closed-loop feedback, microprocessor-based motion control design. By employing a closed-loop feedback, microprocessor-based design, switchgear contact position and velocity can be monitored and optimized in real time during a switching operation, thereby assuring a more accurate switching operation. Moreover, the closed-loop feedback design intrinsically compensates for the effects of such things as ambient temperature, AC waveform fluctuations, and changes in the physical condition of the switchgear. The closed-loop position feedback design is also capable of optimizing various transfer function parameters associated with the closed-loop feedback process, both during and subsequent to a switching operation, to further assure that switching operations are more accurately synchronized with the AC voltage or current waveforms.

Abstract: A relay control circuit enables releasing of welding of contacts in a short period by applying an bombardment pulse effective for welded contacts of the relay. Welded contacts of a relay are detected and subsequently input a signal to a microcomputer. A first driver is connected to an output port of the microcomputer which controls the relay, and a second driver is provided to another output port for driving the relay in parallel. This configuration allows to drive the first and second drivers alternately when contacts of the relay are welded, in order to apply an effective bombardment pulse for ensuring rapid separation of the welded contacts.

Abstract: A power filter circuit for protecting electronic equipment from electromagnetic interference introduced by a supply system circuit includes a fault condition sensing circuit capable of detecting whether the supply system circuit is properly wired. The sensing circuit controls switching circuits in accordance with the determination of whether the supply system is properly wired. The sensing circuit activates a first switching circuit to form a short circuit between the neutral and ground conductors of the power filter circuit when it is determined that the supply system circuit is properly wired. If any wiring fault conditions, including a reverse polarity wiring, is detected by the sensing circuit, the first switch is not activated and the short circuit is not formed between the neutral and ground conductors.

Abstract: A circuit for use with optical inspection lamps, e.g., tungsten-halogen or Marco lamps, in semiconductor fabrication machines performing ADI and AEI operations, that will lower the operating voltage of the lamps when the machine is not being used by an operator, while providing full light intensity during optical inspections. The circuit is coupled into the Marco lamp power supply and contains two micro-switches, each containing two sets of switch contacts normally configured with one set closed and one set open to render one micro-switch closed providing the operating voltage to the lamp and the other open rendering the circuit inactive in this condition. The micro-switches have operating levers that cooperate with indexes which follow the position of cassette elevators that deliver the semiconductor wafers for processing and each of which has an "up" and a "down" position.

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: A low power consumption switch interface circuit (100) includes a current source (109) for providing switch current (144) having a magnitude dependent on a state of a current range signal (135). An input terminal (142) is provided to conduct the switch current (144) to an external switch (102). A circuit (101, 103, 119) for detecting a signal (141) present at the input terminal (142) provides a measured pulse (127) when the signal (141) is detected. A current range selector (129), coupled to the current source (109), outputs a first state of the current range signal (135) while the measured pulse (127) is outputted from the circuit (101, 103, 119), and a second state of the current range signal (135) while the measured pulse (127) is not outputted from the circuit (101, 103, 119).

Abstract: The arrangement of resistors is intended for the switching of capacitive loads in an eletromagnetic switching device with main contacts (3) and auxiliary contacts (4). One of the terminals (7) of the auxiliary contacts (4) and one of the terminals (6) of the main contacts of the same phase are located above each other on the same side of the switching device. The auxiliary contacts (4) close before the main contacts (3) and open after same. A rigid resistor (8) is connected between the terminals (6) and (7) of each phase. The rigid resistor (8) facilitates upgrading of existing electromagnetic switching devices (1) with resistors (8) that are required for switching of capacitive loads.

Abstract: There is described method and apparatus to obtain synchronized switching of switchgear. A superposition of forces is used wherein the moving contacts of switchgear driven by a conventional operating mechanism has a secondary force, either opposing or aiding, superimposed upon the mechanism force under predetermined conditions to incrementally either slow down or speed up the moving contact. The computed secondary force is applied by a small servo-motor attached to the moving contact shaft. The energy of the secondary force is derived from a real time comparison of the measured position of the moving contact with its preprogrammed position in ROM at each predetermined point on the voltage or current waveform. From this comparison the required pulse energy is calculated and fed to the servo-motor which translates into the secondary force of appropriate duration thereby making the necessary incremental velocity correction.

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: In the case of a circuit arrangement with switching contacts made from silver or a silver alloy for the purpose of switching an inductive load, for example a motor, in a direct-current circuit, the arcing time is adjusted as a function of the breaking current by appropriate design of the ratio of inductance and ohmic resistance in accordance with the prescribed relationship. It is possible as a result to prevent or at least minimize the material migration between the anode and cathode of the pair of switching contacts.

Abstract: A load current detection circuit restrains the generation of noise spikes with a minimum of circuitry when changing between current detection sensitivity ranges by providing a plurality of sensitivity resistors between the output of a voltage source, such as a negative feedback voltage amplifier, and a load. Sensitivity range changing is performed via switches that increase or decrease the number of sensitivity resistors between the voltage source and the load. When a current detection sensitivity change is commanded, a voltage difference across the sensitivity resistors is measured, and a control processor generates a control voltage for changing voltage difference gradually until the voltage difference is zero without changing the voltage across the load. The sensitivity range switching then occurs when no current flows through the sensitivity resistors so that no noise spikes are produced.

Abstract: Disclosed is a corrosion preventing circuit for a switch which, even if a large current switch is used for a small current system such as an electronic unit, can improve long-term durability of the switch in a manner similar to the present level without increasing the burden on the system side, thereby ensuring the reliability of devices belonging to the system. A series circuit consisting of a switching means and a current limiting resistor is connected in parallel to a resistor that is connected in series between a dc power supply and a large current switch. A control circuit turns on the switching means by generating a pulse of a predetermined time width after a predetermined time in accordance with the turning on of the large current switch. The current flowing while the switching means is being turned on is applied to the large current switch, so that an oxide film formed at the contact of the switch is destroyed.

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 precharged capacitor connected in parallel with the contacts of an open switch discharges through the switch upon closure. Oxides on the switch contacts are broken through upon closure of the switch to produce a good electrical connection. The capacitor provides sufficient voltage and transient current to clean the switch contacts. A microprocessor having signals of only 5 volts can interrogate a plurality of such switches by multiplexing some semiconductor switching circuits that energize the interrogated switches and by synchronously multiplexing some microprocessor input circuits. The microprocessor's input circuits therefore receive signals indicating the status of each switch in turn.

Abstract: A method is described for maintaining silver cadmium oxide alloy tips of an electrical contactor clean and substantially free of contamination involving operating the electrical contactor normally, under its regular working operation, in a cold switching mode, and at intervals of time, separating the tips under a load condition. A procedure is described also for determining at what interval the tips should be separated under the load condition. Apparatus is described that will operate to perform this method automatically.

Abstract: A computer bus structure is provided which permits replacement of removable modules during operation of a computer wherein means are provided to precharge signal output lines to within a predetermined range prior to the usage of the signal output lines to carry signals, and further, wherein means are provided to minimize arcing to pins designed to carry the power and signals of a connector. In a specific embodiment, pin length, i.e., separation between male and female components of the connector, are subdivided into long pin length and short pin length. Ground connections and power connections for each voltage level are assigned to the long pin lengths. Signal connections and a second power connection for each voltage level is assigned to the short pin lengths.

Abstract: A method for releasing the contacts of a sticking relay by sensing whether or not the relay contacts stick together in a closed condition and when the contacts stick together, applying an AC voltage on pulsating DC voltage to the winding of the relay coil. The mechanism for sensing the sticking relay contact condition is a comparator to compare the output load of the relay with the exciting control signal to energize the relay coil.

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: The present invention is capable of applying a voltage across the contacts of a switch or connector in an audio system, the voltage being of sufficient level to provide a sufficiently high current to break down an insulating layer which has built up in the contacts thereof, improving the sound quality of the system. The invention may be an independent unit or may be incorporated in the overall audio system as an integral part thereof.

Abstract: A switching circuit for supplying electric power to a load from a power source includes a first relay device having a first switch and a semiconductor switching element connected in series with the first switch, power source and load. A second relay device is provided which is defined by a second switch connected parallelly to the semiconductor switching element and an actuating switch for enabling and disabling the semiconductor switching element. The second relay device is so arranged as to effect the make of the actuating switch and second switch in said order and to effect the break of the same in the opposite order. A delay circuit is provided for controlling the first and second relay devices such that when supplying a current to the load, the first and second relay devices are turned on in said order so that the first switch, the actuating switch and the second switch are turned on in said order.

Abstract: A circuit for driving a relay having at least two contacts and an excitation coil. An AC power source is connected to the contacts of the relay for applying a voltage of a prescribed frequency to these contacts. A detector section compares a pulse current, induced in phase with the AC current supplied from the AC power source, with a reference value, thereby producing a detection signal. In accordance with this detection signal, the positive and negative phases of a signal having a cycle longer than, and being asychronous with, said AC current, are delayed alternately or at random, thereby generating a timing control signal. This timing control signal closes and opens said relay at random timings, thereby protecting the relay from contact welding.

Abstract: Arcless circuit interruption from metallic contacts is accomplished by the combination of a solid state current interrupter with a control circuit and an impedance circuit. The impedance circuit diverts the contact circuit current through the solid state current interrupter prior to initiating contact separation. The contacts then open without sufficient current transfer to establish an arc.

Abstract: A power filter circuit for protecting electronic equipment from electromagnetic interference introduced by a supply system circuit includes a fault/condition sensing circuit capable of detecting whether the supply system circuit is properly wired. The sensing circuit controls switching circuits in accordance with the determination of whether the supply system is properly wired. The sensing circuit activates a first switching circuit to form a short circuit between the neutral and ground conductors of the power filter circuit when it is determined that the supply system circuit is properly wired. If any wiring fault conditions, including a reverse polarity wiring, is detected by the sensing circuit, the first switch is not activated and the short circuit is not formed between the neutral and ground conductors.