Abstract: A method and system for controlling and/or limiting inrush current is described. The system includes a buck converter section; a power factor conversion (PFC) boost converter section; and a storage capacitor section. In a first mode of operation, the boost converter section is disabled and the buck converter section is active and in a second mode of operation, the boost converter section is active and the buck converter section is disabled.

Abstract: A method of detecting welded contacts in a relay. The method includes performing, at a first point in time, the applying of a drive to the activation coil to conduct a coil current through the activation coil, the coil current increasing to a first current level, the first current level being less than a pull-in current of the relay; responsive to the coil current reaching the first current level, turning off the drive to the activation coil to discharge the coil current at a first clamping voltage; and measuring a first discharge time corresponding to a first inductance from the turning off of the drive to the activation coil to the coil current reaching a second current level, the second current level being less than the first current level. These operations are repeated at a second point in time to obtain a second inductance. Comparison of the first inductance and second inductance determines whether a difference between the first and second inductances exceeds a comparison criterion.

Abstract: A controller for a multiphase switching converter has a voltage control circuit, a total current control circuit, a frequency divider and a plurality of sub control circuits. The voltage control circuit provides an on-time control signal based on an output voltage. The total current control circuit provides a current control signal based on a total current flowing through the plurality of switching circuits. The frequency divider receives the on-time control signal, and provides a plurality of frequency division signals based on the on-time control signal. The plurality of sub control circuits provides a plurality of switching control signals to control the plurality of switching circuits respectively. Each of the plurality of sub control circuits receives one of the plurality of frequency division signals and the current control signal, and provides one of the plurality of switching control signals.

Abstract: A device for controlling a current of an actuator, including: at least one control unit having a first terminal; a first switch; a second terminal; and a second switch for controlling a flow of current through the actuator via the first terminal and the second terminal independently of one another; a first current measuring apparatus for measuring a first current through the first terminal; and a second current measuring apparatus for measuring a second current through the second terminal; in which the first current measuring apparatus and the second current measuring apparatus are integrated into the at least one control unit so that fault currents can be acquired. Also described are a related electronic control unit, a commercial vehicle, and a method.

Abstract: A digital circuit device includes a power supply circuitry, a digital circuitry, a digital circuitry, and a protection circuitry. The power supply circuitry is configured to output a supply voltage. The digital circuitry is configured to be driven by the supply voltage, and is configured to perform at least one operation according to a first clock signal. The protection circuitry is configured to generate the first clock signal according to at least one of a voltage drop of the supply voltage and a load signal sent from the digital circuitry.

Abstract: The present disclosure provides a photovoltaic (PV) disconnect device used in an electrical system. The electrical system includes an energy control system electrically coupled to a utility grid. The electrical system includes a PV power generation system electrically coupled to the energy control system. The electrical system includes an energy storage system electrically coupled to the energy control system. The PV disconnect device is electrically coupled to the PV power generation system and the energy control system. The PV disconnect device electrically disconnects the PV power generation system from the energy control system.

Abstract: Modular circuit protection devices and configurable panelboard systems include arc-free operation, thermal management features providing safe operation in hazardous environments at lower cost and without requiring conventional explosion-proof enclosures and without entailing series connected separately provided packages such as circuit breaker devices and starter motor contactors and controls.

Abstract: The present disclosure provides a hot-swap circuit and a control apparatus. The hot-swap circuit includes: a power input terminal, a power output terminal; a startup module electrically connected to the power input terminal and the power output terminal; a switch module electrically connected to the power input terminal, the power output terminal, and the startup module; a detection module electrically connected to the startup module, the switch module, and the power output terminal. When a surge signal is input at the power input terminal, a voltage value of a first control signal output by the detection module doesn't fall in a voltage value range of a preset first control signal, then the switch module is controlled to be turned off, so as to cut off a power signal input to the power output terminal, reducing probability of circuit damage, and reducing sparking phenomena of hot-swap power interfaces.

Abstract: A gray zone prevention circuit includes: a first gain stage circuit including a first input terminal and a first output terminal, the first gain stage circuit amplifies a feedback signal received at the first input terminal and generates an amplified signal at the first output terminal; a second gain stage circuit including a terminal that is coupled to the first output terminal for receiving the amplified signal and a second output terminal, where the second gain stage circuit is configured to generate a monitored signal based on the amplified signal; a feedback circuit coupled between the second output terminal and the first input terminal and configured to convert the monitored signal into the feedback signal; and a comparator circuit including a monitoring node coupled to the first output terminal for receiving the amplified signal, wherein the comparator circuit is configured to monitor the monitored signal indirectly via the amplified signal.

Abstract: A method of operating a power conversion system including converting variable frequency AC voltage to constant frequency AC voltage by a power converter, setting a first peak current reset threshold above operating currents previously observed during steady state short circuit current regulation in by a controller of the power converter, setting a second peak current reset threshold at a current lower than the previously observed steady state short-circuit regulation point observed during previous operation during steady state short circuit current regulation by the controllers of the power converter, resetting inverter converter AC output regulating voltage to 0 volts, and ramping AC output regulating voltage back up into steady-state operation when the second a peak current reset threshold is exceeded.

Abstract: An apparatus includes a surge protection device, a current sensor configured to sense a current through the surge protection device, and a surge discriminator circuit coupled to the current sensor and configured to discriminate among a plurality of surge levels for the surge protective device responsive to the sensed current. The current sensor may include a current transformer configured to generate a secondary current responsive to the sensed current and the surge discriminator circuit may be configured to discriminate among a plurality of surge levels responsive to the generated secondary current.

Abstract: A switching regulator includes a first switch circuit, a second switch circuit, and a protection circuit. The first switch circuit has a first connection node coupled to a first reference voltage, and a second connection node coupled to one end of an inductor. The second switch circuit has a first connection node coupled to a second reference voltage, and a second connection node coupled to the one end of the inductor. The protection circuit senses a voltage level at the first connection node of the first switch circuit, and selectively enables an auxiliary current path in response to the voltage level at the first connection node of the first switch circuit, wherein the auxiliary current path and at least the first switch circuit are arranged in a parallel connection fashion.

Abstract: A circuit includes comparator circuitry to sense a current through a load and compare the intensity of the current with a comparison threshold which can be set to a first, lower threshold value and a second, higher threshold value. Logic circuitry receives from the comparator circuitry a comparison signal having a first value or a second value based on whether the intensity is lower or higher than the comparison threshold. The logic circuitry is configured to assert a first overcurrent event signal or a second overcurrent event signal based on the comparison signal having the first value or the second value and the comparison threshold set to the first or second threshold value.

Abstract: A circuit breaker distribution system is configured to provide selective coordination. The system comprises a solid-state switch disposed as a main or upstream breaker and a switch with an over current protection disposed as a branch or downstream breaker. The microcontroller to: allow repeated pulses of current through to the branch or downstream breaker in an event of an overload or short circuit, choose a maximum current limit for the solid-state switch as a “chop level” such that the chop level is chosen higher than a rated current of the solid-state circuit breaker but low enough that the solid-state switch is not damaged from repeated pulses over a period of time needed to switch OFF the branch or downstream breaker and add a pulse interval after the current chops to zero but before the solid-state circuit breaker returns to an ON state for a next pulse to begin.

Abstract: A circuit breaker distribution system is configured to provide selective coordination. The system comprises a solid-state switch disposed as a main or upstream breaker and a switch with an over current protection disposed as a branch or downstream breaker. The solid-state switch comprises a microcontroller including a processor and a memory, and computer-readable logic code stored in the memory which, when executed by the processor, causes the microcontroller to: allow repeated pulses of current through to the branch or downstream breaker in an event of an overload or short circuit, and choose a maximum current limit for the solid-state switch as a “chop level” such that the chop level is chosen higher than a rated current of the solid-state circuit breaker but low enough that the solid-state switch is not damaged from repeated pulses over a period of time needed to switch OFF the branch or downstream breaker.

Abstract: A drive circuit of a voltage-controlled power semiconductor element, including first to fourth switching elements, first and second delay circuits, an overcurrent detection circuit, a slow shutdown detection circuit and a flip-flop. The first switching element turns on upon receiving an off signal. The second switching element is turned on by the first delayed signal generated by the first delay circuit. The third switching element turns on upon receiving a second delayed signal generated by the second delay circuit through the flip-flop. The fourth switching element is turned on by the slow shutdown detection signal generated by the slow shutdown detection circuit. The first to fourth switching elements extract electric charges from the gate terminal of the voltage-controlled power semiconductor element, with first to fourth extracting capabilities, respectively. The first and fourth extracting capabilities are larger than the third extracting capability and smaller than the second extracting capability.

Abstract: Methods, apparatus, systems and articles of manufacture are disclosed to allow dynamic changing between current limiting methods. A power delivery controller comprising: a power control device; a first current control device, the first current control device to control the power control device when a current level associated with a current flowing between a first device and a second device exceeds a first adjustable current threshold value; a second current control device to control the power control device when the current level exceeds a second adjustable current threshold value; and a configuration manager to, during runtime, set a first configuration setting of the first current control device and a second configuration setting of the second current control device, the first configuration setting and second configuration setting based on a negotiated contract corresponding to the first device and the second device.

Abstract: A power supply system includes: a first power circuit having a first battery, a second power circuit having a second battery, a voltage converter which converter voltage between the first power circuit and second power circuit, a current sensor which acquires a passing current value Iact of the voltage converter, a passing power control unit which operates the voltage converter, and a failure determination unit which determines failure of the voltage converter. The failure determination unit determines that the voltage converter has failed in a case of the passing current value Iact becoming negative in a state in which the passing power control unit is not operating the high-arm element of the voltage converter to ON, and makes a time from when the passing current value Iact first became negative until determining that the voltage converter failed shorter as the passing current value Iact increases to the negative side.

Abstract: A vehicle management system (VMS) computer includes a power distribution controller that includes a plurality of power distribution circuits that are each controlled by the controller to supply power to end component loads. The power distribution controller is communicably coupled to a data processing system by a bus. The VMS computer also includes a plurality of settable circuit breakers, wherein each of the plurality of settable circuit breakers corresponds to a respective one of the plurality of power distribution circuits. The power distribution controller is configured to monitor various values such as voltages, currents, powers, power spikes, and interruptions and to interrupt a respective one of the plurality of power distribution circuits via a settable circuit breaker upon detecting an indication of a fault from the monitored values.

Abstract: A circuit includes two input nodes and two output nodes. A rectifier bridge is coupled to the input and output nodes. The rectifier bridge includes a first and second thyristors and a third thyristor coupled in series with a resistor in series. The series coupled third thyristor and resistor are coupled in parallel with one of the first and second thyristors. The first and second thyristors are controlled off, with the third thyristor controlled on, during start up with resistor functioning as an in in-rush current limiter circuit. In normal rectifying operation mode, the first and second thyristors are controlled on, with the third thyristor controlled off.

Abstract: A power connection/disconnection system for connecting/disconnecting an electric power module in a high-power modular uninterruptable power supply installation includes: a frame, a rigid support extending along a first direction, a set of connectors mounted on the support and including a ground connector and power connectors. The connectors are successively aligned along the first direction and each shaped to be electrically connected along a second direction orthogonal to the first direction with bars of a power connection box of the installation and a translation device configured to move, using an actuator, the support in the second direction. The ground connector extends higher along the second direction than the power connectors. The ground connector is intended to be electrically connected to a ground bar of the box.

Abstract: A state output circuit that outputs a state signal indicating a state of a power supply apparatus, including: a state output terminal that outputs the state signal; a reference potential line to which a reference potential is applied; a first pull-up terminal to which a first pull-up potential is applied, wherein the first pull-up potential is a potential higher than the reference potential; a connection switch unit that is provided between the state output terminal and the reference potential line, and switches whether to connect the state output terminal to the reference potential line or not, in accordance with the state of the power supply apparatus; a first protection resistor provided between the connection switch unit and the state output terminal; and a pull-up unit that pulls up a first connection line between the first protection resistor and the connection switch unit up to the first pull-up potential.

Abstract: A point-on-wave relay device includes a first contact relay and a second contact relay in series with the first contact relay. A first state of the first contact relay in conjunction with a first state of the second contact relay causes a point-on-wave open operation and second state of the first contact relay in conjunction with a second state of the second contact relay causes a point-on-wave close operation.

Abstract: A load switch circuit includes a power transistor. A first terminal is configured to receive a power supply voltage, and a second terminal is the output terminal of the load switch circuit and is coupled with an external inductive load. A clamping module includes at least a mutually coupled clamping unit and a driving unit. The clamping unit includes a voltage-current converter and a first resistor, the first resistor coupled between the output terminal of the voltage-current converter and the second terminal of the power transistor. The positive input terminal of the voltage-current converter receives the power supply voltage, and the negative input terminal is coupled to the second terminal of the power transistor.

Abstract: The present disclosure relates to a method for monitoring an electromechanical component of an automation system. The method includes sensing a current mechanical state variable of the electromechanical component, sensing a current electrical state variable of the electromechanical component and determining a state of the electromechanical component based at least in part on a behaviour model of the electromechanical component, wherein the behaviour model takes into account an effect of the sensed current mechanical state variable on the sensed current electrical state variable.

Abstract: An overvoltage absorption circuit and a single-phase HERIC topology are provided. The overvoltage absorption circuit is applicable to the single-phase HERIC topology, and includes a clamping capacitor, an absorption resistor, a first diode, and a second diode. One terminal of the clamping capacitor and one terminal of the absorption resistor are each connected to collectors of two cross transistors in the single-phase HERIC topology. The other terminal of the clamping capacitor and the other terminal of the absorption resistor are each connected to the anodes of the first diode and the second diode. The cathode of the first diode is connected to the emitter of one of the two cross transistors. The cathode of the second diode is connected to the emitter of the other of the two cross transistors.

Abstract: Systems, methods, and computer program products for protecting circuits are provided. Aspects include receiving, by a processing element, a feedback signal, the feedback signal taken from an output of a circuit, determining a range of expected feedback values, comparing the feedback signal to the range of expected feedback values, and based at least in part on determining that the feedback signal is outside the range of expected feedback values for a first length of time, disabling the circuit.

Abstract: A protective circuit (301) and a display drive device. The protective circuit (301) comprises: when an electrical overstress problem occurs in a logic signal, the voltage of an output end of a controlled switch circuit (100) is greater than a first preset voltage, so that a voltage threshold circuit (101) is turned on, and the controlled switch circuit (100) turns off an input end and the output end thereof, thereby preventing electrical overstress from affecting a driver chip (300) and causing damage to the driver chip (300). Moreover, the voltage potential of a controlled end of the controlled switch circuit (100) is clamped by means of a voltage clamp circuit (102) to stabilize the operating characteristics of the controlled switch circuit (100).

Abstract: A linear regulator system is described. The linear regulator system includes a linear regulator core circuit including a pass element adapted to provide an output voltage, and a voltage error amplifier circuit coupled to the pass element and adapted to regulate the output voltage to form a regulated output voltage, based on an output reference voltage. The linear regulator core circuit further includes a current limit circuit comprising a current limit switch element coupled to the voltage error amplifier circuit and adapted to selectively modulate the output reference voltage of the voltage error amplifier circuit to form a current limited reference voltage, based on a current limit control signal received at a current limit control terminal associated therewith, in order to limit a load current through the pass element from exceeding a predefined maximum allowable load current limit.

Abstract: The invention relates to a novel approach for the protection of electrical circuits from ground faults and parallel and series arc faults in a fully solid-state circuit configuration. Solid-state circuits and methods of use are described that provide the key functions of low-voltage DC power supply, mains voltage and current sensing, fault detection processing and high voltage electronic switching.

Abstract: A power supply apparatus includes a rectifier unit, a power factor correction circuit, and a control unit. The control unit correspondingly provides a reference voltage according to an amplitude of an input power source. When a voltage signal corresponding to an inductance current of an inductor of the power factor correction circuit is higher than the reference voltage, the control unit controls an energy release switch of the power factor correction circuit to be repeatedly switched on/off, and when the voltage signal is lower than the reference voltage, the control unit controls the energy release switch to be turned off.

Abstract: A power distribution system and method has a controller and at least one semiconductor switch. The power distribution system additionally has an on status detector which detects the status of the semiconductor switches, and an overcurrent status circuit which checks for overcurrent conditions.

Abstract: A power conversion system with abnormal energy protection includes a plurality of DC input power sources, a plurality of DC power converters, two output capacitors, and a protection circuit. An input side of each DC power converter is correspondingly coupled to one of the DC input power sources, and output sides of the DC power converters are coupled in parallel to each other to form a DC output bus. Two output capacitors are coupled in series between a positive voltage end and a negative voltage end of the DC output bus. The protection circuit is coupled between the DC input power sources and the two output capacitors. When one of the two output capacitors is abnormal, the protection circuit decouples the DC input power sources from the two output capacitors in a shorted-circuit manner.

Abstract: A system may include an output driving stage comprising a first switch configured to selectively open and close an electrical path between a first supply voltage and an output terminal of the output driving stage and a second switch configured to selectively open and close an electrical path between a second supply voltage and the output terminal of the output driving stage, wherein the second supply voltage is lower than the first supply voltage. The system may also include detection and protection circuitry configured to monitor a physical quantity indicative of the second supply voltage and responsive to the physical quantity exceeding an overvoltage threshold, electrically isolate the output terminal from the second supply voltage.

Abstract: Modular circuit protection devices and configurable panelboard systems include arc-free operation, thermal management features providing safe operation in hazardous environments at lower cost and without requiring conventional explosion-proof enclosures and without entailing series connected separately provided packages such as circuit breaker devices and starter motor contactors and controls.

Abstract: Discussed is a display device including a plurality of semiconductor light-emitting devices applied to sub-pixels included in each pixel of a display panel; and a driving unit for driving the plurality of semiconductor light-emitting devices on the basis of a digital pulse width modulation (PWM) signal, wherein the driving unit further includes: a current sensing unit for sensing the value of a current flowing through at least one of the plurality of semiconductor light-emitting devices; and a current compensation unit for compensating for the current deviation between the plurality of semiconductor light-emitting devices on the basis of the current value sensed by the sensing unit.

Abstract: In a DC feed system configured by a plurality of DC electrical circuits being combined, when an arc fault occurs, it is difficult to identify a DC electrical circuit in which an arc has occurred. For this reason, a DC electrical circuit protection apparatus includes: a plurality of DC electrical circuits, each of which has a current sensor provided in at least one of a positive or a negative electrical path and has arc noise absorbing mechanism on the upstream side of the current sensor; and an arc detection device which compares respective arc noise signal strengths of the DC electrical circuits from current signals detected by the current sensors of the DC electrical circuits, and based on the signal strengths, identifies a circuit in which an arc has occurred, wherein a DC electrical circuit in which an arc has occurred is identified.

Abstract: An on-board control apparatus includes: a controller connected to a controlled device mounted in a vehicle via a signal line and configured to control the operation of the corresponding controlled device; and a power source box connected to a power source mounted in the vehicle via a power line, that is connected to the controlled device mounted in the vehicle via a power line, and configured to switch between supply and non-supply of power from the power source to the controlled device, wherein the power source box includes; a switch disposed in a power supply path from the power source to the controlled device; a reception unit configured to receive an input of the switching command; and a switching control unit configured to switch between conduction and interruption of the switch in response to the switching command received by the reception unit.

Abstract: This application discloses a driving device for a power device. It includes a detection module, coupled to the power device, configured to detect the overcurrent status of the power device; a drive module, respectively coupled to the detection module and the power device, configured to regulate the power device according to the detection result of the detection module; wherein, when the detection result is that the power device is in the first overcurrent state, the drive module is configured to cause the power device to enter the first protection mode that is softly turned off and does not respond to the system switching signal; when the detection result is that the power device is in the second overcurrent state, the drive module is configured to cause the power device to enter a second protection mode that is softly turned off but responds to a system switching signal; wherein the overcurrent degree in the first overcurrent state is higher than that of the second overcurrent state.

Abstract: A drive circuit anomaly diagnosing device of the present invention performs an anomaly diagnosis on a drive circuit including a power supply line on which a solenoid is disposed midway, a main switch disposed on the power source side relative to the solenoid, a first diode disposed on a protection line connecting a point between the main switch and the solenoid to ground with a forward direction corresponding to a direction from the ground side to the power source side, and a first capacitor interposed on a first line connecting a point between the protection line and the solenoid to the ground midway on the power supply line, the drive circuit being configured to supply power to the solenoid, on the basis of a current detected by a first current sensor disposed upstream of the main switch on the power supply line.

Abstract: A control circuit for controlling a power semiconductor element includes a temperature detection circuit configured to detect a temperature signal of the power semiconductor element, a current detection circuit configured to detect a current signal flowing through the power semiconductor element, a state determination circuit configured to receive the detected temperature signal and the detected current signal, determine a state of the power semiconductor element based on at least one of the detected temperature signal and the detected current signal, and output one or more output control signals indicating the determined state, and a driver circuit configured to control electric power supplied by the power semiconductor element based on the output control signals.

Abstract: The invention relates to a method and system for electronic current control for a flexible DC battery pack, in which the battery pack has a plurality of flexibly interconnectable modules having a respective energy store and at least two respective controllable switches and the modules are electrically connected to one another to form a section having a first and a second section end and the two section ends are connected to a respective high-voltage connection, in which the at least two switches of a respective module interrupt a battery current I or interconnect the respective energy store at least in series or parallel with or to bypass the respective energy store of the respectively adjacent module, in which the flexible interconnection of the modules is controlled by a battery control unit and hence a prescribed DC voltage V is provided.

Abstract: An overcurrent detector for multiple level shifter circuits includes an overcurrent detecting circuit that senses currents acquired through level shifter circuits, and that outputs an indication signal indicating occurrence of overcurrent when one of the currents sensed thereby is greater than a predefined current level.

Abstract: A drive device adapted to drive a semiconductor power device, wherein the drive device comprises a drive circuit comprising a first terminal adapted for connection to a first terminal of the power device, a gate terminal adapted to provide a driving signal for a gate terminal of the power device, a sensor for detecting overvoltage conditions at the first terminal of the power device, and wherein the drive circuit is adapted to modify the driving signal when the sensor detects an indication of an overvoltage condition, and wherein the drive circuit including the sensor is integrated onto a single substrate.

Abstract: A tester tool for a sensor and related method includes connecting the sensor to the tester tool, activating the tester tool to operate the sensor, and testing the sensor. The tester tool includes a power supply, a control module, a display module and a connector plug adapted for releasable connection with a sensor connector plug, the connector plug being connected to the power supply for receiving power to operate the sensor, and to the control module for providing information to the control module from the sensor. The display module provides information to a user indicative of operation of the sensor when the sensor is active and receives power to operate from the power supply.

Abstract: The present invention discloses a DC solid-state circuit breaker with self-adapt fault current limiting capability. The topology of the DC solid-state circuit breaker is a H-bridge circuit consisting of two unidirectional breakable bridge arms and two series-connected diode bridge arms, wherein the two unidirectional breakable bridge arms are connected in series to the two series-connected diode bridge arms in a same direction to form two series branches, respectively; the series branches are connected in parallel; a series branch formed by a DC reactor L and a DC biased power supply is connected to the PCC between the two unidirectional breakable bridge arms and the PCC between the two series-connected diode bridge arms; the DC line is connected to the two PCCs, respectively.

Abstract: A display device includes: a display panel including data lines, gate lines, and pixels, the display panel is operated in an active period or in a blank period; and a driving circuit for driving the display panel, the driving circuit including: a signal controller for outputting clock control signals; a voltage generator for receiving the clock control signals, wherein the voltage generator outputs active clock signals synchronized with the clock control signals during the active period and outputs blank clock signals during the blank period; and an overcurrent detection circuit for receiving the clock control signals and the blank clock signals, the overcurrent detection circuit detects an overcurrent of the blank clock signals, and a phase difference between the clock control signals in the active period is different from a phase difference between the clock control signals in the blank period.

Abstract: A device, battery and method for spark detection based on transient currents is provided. The battery includes: a cell; an interface; a first protection circuit and a second protection circuit. The first protection circuit comprises a first switch between the cell and the interface. The second protection circuit comprises a second switch between the cell and the interface. The first protection circuit is configured to: measure a load current on the cell; and open the first switch according to a first delay time based on the measurement of the load current. The second protection circuit is configured to: measure a transient current on the cell above the load current; and open the second switch according to a second delay time, lower than the first delay time, based on the measurement of the transient current.

Abstract: A circuit breaker is proposed, comprising a live line and a neutral line and a semiconductor switching unit located in the live line, the circuit breaker further comprises a bypass line, which is connected in parallel to the semiconductor switching unit, with a first mechanical switch and a second mechanical switch located in the bypass line, with the first mechanical switch connected in series to the second mechanical switch, whereby the semiconductor switching unit, the first mechanical switch and the second mechanical switch are controlled by a processing unit of the circuit breaker, which is embodied to send a first opening command to the first mechanical switch in case of a short-circuit-detection, and sending a second opening command to the second mechanical switch a time-delay after sending of the first opening command.

Abstract: A short-circuit protection circuit for a self-arc-extinguishing type semiconductor element includes a first protection circuit and a second protection circuit. The first protection circuit is configured to reduce a voltage between a control electrode and a first main electrode of the self-arc-extinguishing type semiconductor element when detecting overcurrent flowing between the first main electrode and a second main electrode. The second protection circuit is configured to: detect current flowing in an interconnection adapted to supply the drive voltage; determine, based on the detected current, whether the first protection circuit is in an operating state; and change the drive voltage to turn off the self-arc-extinguishing type semiconductor element when the first protection circuit is in the operating state.