Ground fault circuit interrupter is provided, including a transformer, a protection switch, a residual current protection control unit, a residual current simulation unit and a self-test unit, wherein the self-test unit is coupled with the line where the protection switch is located; in a self-test state, the self-test unit is configured to control the residual current simulation unit to generate a simulated residual current, detect a level change on the line where the protection switch is located, and control the protection switch to be disconnected from the residual current protection control unit or to make the line where the protection switch is located be conducted after a preset protection time period of receiving the residual current signal higher than a preset operating threshold. Improper actions of the ground fault circuit interrupter caused by a large electromotive force generated when a simulated residual current disappears are avoided.

An intelligent leakage current detection and interruption device for a power cord, including a switch module for controlling electrical connection of two power lines between input and output ends; a leakage current detection module, including two leakage current detection lines and a signal feedback line, one end of the parallelly coupled two leakage current detection lines being coupled via the signal feedback line to a point between the two power lines, for respectively detecting a leakage current on the two power lines; a detection monitoring module, coupled to the leakage current detection module, for detecting open circuit conditions in the two leakage current detection lines; and a drive module, coupled to the switch module, the leakage current detection module and the detection monitoring module, for driving the switch module to disconnect power to the output end in response to any detected leakage current or open circuit condition.

One embodiment provides an electric leakage detecting device for shutting off an AC electric circuit. A digital comparator generates a detection signal by comparing an output signal corresponding to output signals of a zero-phase current transformer with positive and negative thresholds, a control signal generator generates a control signal based on the detection signal, and a judging device generates a judgment signal if an electric leakage state is judged. In addition, a delay counter generates a final control signal if the judgment signal has been received continuously more than a first prescribed time, a reset counter resets every time the control signal is received, and resets the judging device and the delay counter if the control signal is not received in a second prescribed time, and a switch driving circuit shuts off the AC electric circuit based on the final control signal.

The present invention increases noise immunity of an electrical leakage detection circuit. A first comparator COMP1 generates a first comparison signal indicating a comparison result between a voltage corresponding to a detected signal from a zero-phase-sequence current transformer and a predetermined first threshold voltage V.sub.TH1. A judgment circuit outputs a judgment signal indicating if there is electrical leakage based on the first comparison signal and outputs a mask signal corresponding to the first comparison signal. A mask circuit generates a latch input signal based on the judgment signal and the mask signal. An output stage comprises a latch circuit which latches a state of the latch input signal when the latch input signal is asserted. The output stage generates a drive signal corresponding to the state of the latch circuit.

A device for detecting a fault in an AC supply comprising a detection circuit for detecting a fault in an AC supply to a load and providing a corresponding output. A disconnect circuit disconnects the load from the supply in response to an output from the detection circuit. The device also includes a generator of intermittent test pulses, and a test circuit coupled to the detection circuit and containing a first solid state switch. Each test pulse turns on the solid state switch for the duration of the test pulse so that a current simulating the fault flows intermittently in the test circuit and a corresponding output is provided by the detection circuit. The device further comprising means to disable the disconnect circuit in response to each test pulse.

The invention relates to a device for detecting a leakage current, comprising means (124) for measuring a current from an electrical circuit of a vehicle, in particular a motor vehicle, said detection device being configured to be placed on board said vehicle and being such that the measuring means (124) comprise: a magnetic core (128) configured to be passed through by one or a plurality of conductive elements (127) traversed by the current from the electrical circuit, said conductive element(s) (127) forming a primary winding; a secondary winding (130), wound around the core (128), to generate a magnetic flux from a reference current; and an oscillator (132) for generating the reference current though the secondary winding (130), the reference current being configured to saturate said core (128). According to the invention, the value of the current of the primary winding (127) is obtained from the average value of the current at the secondary winding (130) over a period of oscillation covering a complete core (128) magnetization and demagnetization cycle. The invention also relates to various on-board systems using said device.

The present invention is directed to an electrical wiring device that includes an automatic test circuit configured to commence an automatic test at a predetermined time such that a test current propagates on a test conductor. The sensor assembly provides a sensor test output responsive to the test current only if both the differential transformer and the grounded neutral transformer are operative. A fault detector circuit is configured to generate a test detection signal in response to the sensor test output only if the fault detector circuit is operable and the at least one power supply is substantially charged. A device integrity evaluation circuit includes a timer that effects a tripped state when a time measurement exceeds a threshold, the test detection signal resetting the time measurement when properly wired before the time measurement exceeds the predetermined threshold but does not reset the time measurement when miswired.

The present disclosure provides an improved leakage protection socket with reverse connection protection function. The electromagnetic tripping mechanism comprises a trip coil, an iron core and a permanent magnet that fit with a return spring, the iron core has, in its front end, a boss to pull the lock for horizontal movement, the movable input contacts are clamped by a rib slot of an upper tripper that can moves upward and downward along with the reset button. There is also provided a reverse connection trip device, which has a slope that coordinates with the boss of the iron core, upon reverse connection, the trip coil generates a magnetic field in the same orientation with the permanent magnet.

Methods and devices for insulation monitoring of an ungrounded IT power supply system having at least two phase conductors includes determining an insulation resistance separately for each phase conductor using a separate response value. In one embodiment of the invention, relevant current and voltage distributions are calculated. In another embodiment, a change time window is set within which a second response value is activated. In yet another embodiment, an option of shutting down/continuing operation of the IT power supply system is offered.

A method of performing line insulation monitoring of a pair of conductor lines at least partially located in a cable is provided, comprising the steps of providing a first power switch in a first conductor line of the pair and a second power switch in a second conductor line of the pair, providing a line insulation monitor at a first end of the pair of conductor lines, electrically connected to the pair of conductor lines, at the second end of the pair of conductor lines, electrically connecting the first and second conductor lines, placing the first and second power switches into a monitoring configuration wherein the first power switch is closed while the second power switch is open, and using the line insulation monitor to monitor the insulation of the conductor lines.