A leakage current interruption device comprises: the leakage current interruption device in which it is coupled electrically between the power switch and the load: the first and second input stages coupled with a side of the power source; the first and second output stages coupled with a side of the load; the first and second switching members for turning on and off respectively the electrical connection between the first and second input stages and the first and second output stages; a switching driving member in which it is coupled between the first and second input stages and generates and outputs a switching driving signal to turn on or off the first and second switching members according to the on or off signals of the power switch.

The present invention discloses a short-circuit-protection electronic switch serial connect to the load, which is applied to the load control in a DC or AC power supply occasion. With load over-current and short-circuit-protection function, it is characterized in that the primary switch component is a part of the cut-off-type positive feedback protective trigger circuit, the primary switch component and the positive feedback gate element form a cut-off-type positive feedback protective trigger circuit. It can be widely applied to directly turn-on and turn-off control of all kinds of serial connection AC or DC load devices phase angle control and PWM control fields.

A detector is provided that generates a leakage signal corresponding to a current imbalance between a line conductor and a neutral conductor for a load, and selectively injects a test signal into the neutral conductor. A frequency of the test signal substantially corresponds to a utility frequency. The detector measures a first value of the leakage signal, determines if the first value is less than first threshold value, and begins injection of the test signal into the neutral conductor in response to determining that the that first value is less than the first threshold value. In response to injecting the test signal, the detector measures a second value of the signal, determines if the second value is greater than a second threshold value, and disconnects the line conductor from the load in response to determining that the second value is greater than the second threshold value.

A ground fault circuit interrupter is provided, including a main control chip, a tripping unit and a self-test detection unit, wherein the tripping unit is connected with the self-test detection unit at a detection point and coupled with a load circuit; the self-test detection unit is coupled with the main control chip, and configured to detect a signal at the detection point and output the signal to the main control chip; the main control chip is coupled with the self-test detection unit, and configured to in a self-test state, simulate a circuit fault, perform self-test, and determine whether the circuit fault could be detected and an alarm signal response to the circuit fault is generated, based on the signal. A self-test function and alarm function response to a circuit fault in a ground fault circuit interrupter can be tested during a final test of production.

A power cord includes multiple current-carrying wires covered by an outer insulating layer, each wire including a current-carrying conductor covered by an insulating layer. At least one wire further includes a shield layer covering the insulating layer and a metal conductor between the insulating layer and the shield layer. The shield layer is formed of a band wound around the metal conductor and insulating layer. The outward-facing surface of the band is insulating; the inward-facing surface has one or more conductive regions and one or more insulating regions. One insulating region is located along a longitudinal trailing edge of the band. Consecutive turns of the band partially overlap each other; the trailing edge of a subsequent turn is disposed over part of a previous turn. The structure ensures effective insulation of the metal conductor from other components. The power cord is used in a leakage current detection and interruption device.

Devices herein may include conductor lines connected between a power supply and load, each of the conductor lines coupled to an AC contactor and a contactor control circuit, wherein the contactor control circuit is operable to open and close one or more contactors of the AC contactor. The devices may further include a current transformer coupled to the conductor lines, the current transformer operable to output a secondary current corresponding to a primary current magnitude of an electrical current not flowing to the load, wherein the AC contactor is connected between the power supply and the load. Devices may further include a zero cross detection circuit operable to generate an interrupt at each of a plurality of zero crossings for a microprocessor, and determine whether to open the one or more contactors of the AC contactor in a predetermined optimum interval calculated with respect to the zero crossing points.

Devices herein may include conductor lines connected between a power supply and load, each of the conductor lines coupled to an AC contactor and a contactor control circuit, wherein the contactor control circuit is operable to open and close one or more contactors of the AC contactor. The devices may further include a current transformer coupled to the conductor lines, the current transformer operable to output a secondary current corresponding to a primary current magnitude of an electrical current not flowing to the load, wherein the AC contactor is connected between the power supply and the load. Devices may further include a zero cross detection circuit operable to generate an interrupt at each of a plurality of zero crossings for a microprocessor, and determine whether to open the one or more contactors of the AC contactor in a predetermined optimum interval calculated with respect to the zero crossing points.

A coupling circuit (20) with switching function for coupling an insulation monitoring device (6, 6a, 6b) to an unearthed power supply system (2, 2a, 2b), consisting of a coupling module (22) or a plurality of identical coupling modules (22) connected in series, wherein the coupling module (22) has at least one switch unit (25), which comprises a coupling impedance (26), a switch (24), arranged in series to the coupling impedance (26), for mains disconnection and a control circuit (28) for controlling the switch (24), and also exactly one transformer (30) for voltage supply and for potential separation.

Disclosed are a circuit with a timing function and a leakage protection plug. An output terminal of a timing chip U2 is connected to an isolating switch U3; the isolating switch U3 is connected to a rectifier module D3; the rectifier module D3 is connected to a circuit breaker X1; a switch tube Q4 and the switch tube Q3 are connected to a resistor R21, and a second switch terminal of the switch tube Q4 is grounded; an output terminal of a zero sequence current transformer is connected to a first input terminal of a microprocessor U1; and an output terminal of the microprocessor U1 is connected to a control terminal of the switch tube Q4. The leakage protection plug of this disclosure has both leakage protection and timing functions.

A grounded neutral fault detector that includes induction circuits and a controller is provided. The controller is configured to determine a frequency of a test signal by measuring load noise based on a first leakage signal corresponding to a first current imbalance between the line conductor and the neutral conductor for the load without the test signal being injected, analyzing a frequency spectrum of the load noise, and selecting the frequency of the test signal. The controller is further configured to inject the test signal at the selected frequency to the neutral conductor, measure impedance of a current loop formed by a potential grounded neutral fault based on a second leakage signal corresponding to a second current imbalance with the test signal being injected, and determine a grounded neutral fault.