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.

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.

An intelligent leakage current detection and interruption device for a power cord, including a switch module configured to control electrical connection of first and second power lines between input and output ends; a leakage current detection module, including first and second leakage current detection lines coupled in series, configured to detect a leakage current on the first and second power lines, respectively; a detection monitoring module, coupled in series to the first and second leakage current detection lines and to the first and second power lines, configured to detect an open circuit condition in the first or second leakage current detection line; and a drive module, coupled to the switch module, the leakage current detection module and the detection monitoring module, configured to drive the switch module to cut off power to the output end in response to any detected leakage current or open circuit condition.

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.

Implementations of ground fault circuit interrupter (GFCI) self-test circuits may include: a current transformer coupled to a controller, a silicon controlled rectifier (SCR) test loop coupled to the controller, a ground fault test loop coupled to the controller, and a solenoid coupled to the controller. The SCR test loop may be configured to conduct an SCR self-test during a first half wave portion of a phase and the ground fault test loop may be configured to conduct a ground fault self-test during a second half wave portion of a phase. An SCR may be configured to activate the solenoid to deny power to a load upon one of the SCR self-test or the ground fault self-test being identified as failing.

A leakage current detection device connected between a power source and a load, which includes a self-testing or leakage current detection selection trigger unit, for selecting a leakage current detection mode or a self-testing mode; a self-testing unit, for periodically generating a simulated leakage current signal in the self-testing mode; and a leakage current detection unit, for detecting a leakage current signal in the leakage current detection mode and detecting the simulated leakage current signal in the self-testing mode. The selection trigger unit further causes the power source to be disconnected from the load when a leakage current signal is detected, and sends a self-testing result to the self-testing unit depending on whether the leakage current detection unit detects the simulated leakage current signal. The self-testing unit displays an indication of the self-testing result.

A switch includes: at least one conducting line led through the switch; switching contacts arranged in the at least one conducting line; at least one measurement transformer arranged at the at least one conducting line; an electronic trip unit, a measurement-input of the electronic trip unit being electrically connected to a measurement transformer secondary winding of a measurement transformer; a power supply unit; at least one power transformer arranged at the at least one conducting line, the at least one power transformer including a power transformer secondary winding which is electrically connected to the power supply unit in order to supply the electronic trip unit; a signal generating unit for generating a test signal with at least a first predefined frequency, with an output of the signal generating unit being electrically connected to the power transformer secondary winding; and a self-test unit electrically connected to the measurement transformer secondary winding.

Self-test circuitry for testing a circuit interrupter includes an active element coupled to an operating mechanism, a first sub-circuit for temporarily disabling the active element, a second sub-circuit structured to generate a simulated ground fault condition, and a processing unit coupled to the ground fault detection circuitry. The first sub-circuit and the second sub-circuit, the processing unit being structured and configured to control the first sub-circuit to temporarily disable the active element and to control the second sub-circuit to generate the simulated ground fault condition when the active element is disabled. Also, self-test circuitry that includes a sub-circuit structured to generate a simulated ground fault condition and a processing unit structured and configured to control the sub-circuit to generate the simulated ground fault condition only during a predetermined portion of a half cycle of energy passing through the circuit interrupter.

An apparatus includes an interruption circuit in a power delivery path, and a fault detection circuit configured to provide a fault signal to selectively cause the interruption circuit to interrupt power delivery, wherein the fault detection circuit includes a fault detection integrated circuit and a sensing coil configured to sense a differential current between a phase conductive path and a neutral conductive path in the power delivery path. A processor is configured to selectively control a fault simulation circuit to simulate a fault in the power delivery path, detect a response of the fault detection circuit to the simulated fault, and determine if the response of the fault detection circuit is an expected response. The processor provides an override signal to the interruption circuit to prevent the interruption circuit from receiving a fault signal from the fault detection circuit during, and for a predetermined time after, the simulated fault.

A wiring device including an interrupting device, a fault detection circuit, and a testing circuit. The interrupting device is electrically connecting one or more line terminals to one or more load terminals. The fault detection circuit is configured to detect a fault condition and generate a fault detection signal in response to detecting the fault condition. The fault detection signal being provided to the interrupting device to place the interrupting device in a tripped condition. The testing circuit is configured to determine a frequency of an input voltage at the one or more line terminals, filter the frequency of the input voltage, determine whether the filtered frequency is within a predetermined range, and when the filtered frequency is within the predetermined range, perform a test of the wiring device.