The present disclosure discloses a self-check chip of a leakage protector. The self-check chip includes a power-on reset circuit, used for resetting the self-check chip after being powered-on; a reference voltage module, used for providing a reference voltage for a comparator module; a bias circuit, used for providing direct-current bias for the reference voltage module, the comparator module and a ring oscillator; the comparator module, used for monitoring an open-circuit condition of a trip coil and the change of a thyristor anode voltage and generating a power frequency clock; the ring oscillator, used for providing a clock for a counting module and a digital processing module; the counting module, used for generating a self-check signal, a leakage trigger signal, a PHASE pin detection signal and a reset signal of the counting module and the digital processing module; a trip enabling signal generation module; and the digital processing module.

A power system includes multiple power units (PUs), each including a circuit breaker (CB), a local controller (LC) and an intelligent electronic device (IED). For any one of the PUs, the IED, when determining that the CB has mechanically failed, outputs a disconnect message via a network to the IED(s) of the remaining PU(s). For each of the remaining PU(s), based on the disconnect message, the IED thereof, when determining that the corresponding CB is a relevant CB, outputs a trip control signal that indicates to trip for receipt by the corresponding LC, so that the LC causes the CB to switch to an open state.

In one example, an arc fault circuit interrupter (AFCI) is provided. The AFCI may include a plurality of current arc signature detection blocks configured to output a plurality of corresponding current arc signatures, and a processor. The processor may be configured to receive each of the plurality of current arc signature from each of plurality of current arc signature detection blocks, respectively, and generate a first trigger signal. The processor may be further configured to assess each of the current arc signatures, determine whether an arc fault exists based on the assessment, and generate the first trigger signal if an arc fault is determined to exist. A method for detecting an arc fault is also provided.

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 method for monitoring a protective device, which has a series circuit of a multiplicity of thyristors. The protective device has a series circuit of N>1 thyristors. The series circuit is connected in a parallel circuit with an electrical device to be protected. A snubber branch is connected in parallel with each thyristor. For the purpose of testing a firing capacity, n<N thyristors in a first thyristor group are fired when a positive voltage is present across the series circuit and a negative snubber current is flowing through the snubber branches of the thyristors in the first thyristor group.

The present disclosure provides techniques for predicting failure of power switches and taking action based on the predictions. In an example, a method can include controlling the at least two parallel-connected power switches via a first driver and a second driver, the first a second driver responsive to a single command signal, measuring a failure characteristic of a first power switch, and disabling a first driver of the first power switch when the first failure characteristic exceeds a failure precursor threshold.

Various embodiments of the teachings herein include a sensor facility for determining a switching state of an electromechanical switching element. The sensor facility may include: connection elements for electrically contacting respective connection contacts of the switching element; a coupling capacitor having two capacitor connections, wherein the first is coupled to a first connection element; a voltage generator providing a temporally variable electrical voltage, coupled to the second capacitor connection; a first overvoltage protection circuit coupled to a second connection element and blocking an electrical voltage greater than a maximum value of the temporally variable electrical voltage of the voltage generator; and a detector circuit coupled to the first overvoltage protection circuit and detecting electrical voltage to determine the switching state of the electromechanical switching element by evaluating the detected electrical voltage.

First voltage an output unit generates a cyclic voltage that changes cyclically, and applies the cyclic voltage to the other end of a coupling capacitor via a first resistance. A second resistance and a third resistance are connected in series between a node and a second voltage output unit, the node being between the coupling capacitor and the first resistance. A voltage measurement unit measures a voltage at a voltage dividing point between the second resistance and the third resistance. In a period in which two types of fixed voltages are applied to the voltage dividing point in order, a diagnosing unit determines whether a leakage detecting device is in a normal state, based on the voltage measured by the voltage measurement unit.

In order to quickly and accurately diagnose the failure of a coupling capacitor of an earth leakage detection device, voltage output unit (11a, OP1) generates a periodically changing periodic voltage and applies the periodic voltage to the other end of coupling capacitor (Cc) via first resistor (R1). Second resistor (R2) and third resistor (R3) are connected in series between a connection point between coupling capacitor (Cc) and first resistor (R1), and a predetermined fixed potential. Voltage measurement unit (11b) measures a voltage at a voltage dividing point between second resistor (R2) and third resistor (R3). Diagnosis unit (11d) determines whether or not coupling capacitor (Cc) is normal based on a voltage measured when switch (MRp, MRm, MRpp) is turned on in a state where voltage output unit (11a, OP1) outputs a fixed voltage.

Ground-fault circuit interrupter positioned between energy controlled supply circuit and load circuit which includes fault detection circuit that senses ground path current leakage to the load circuit, fault processing circuit that detects presence of fault and generates fault output signal when fault detected, and control circuit switch connected to fault processing signal output, wherein control circuit switch is opened by presence of fault output signal, thus isolating load circuit from supply circuit. Preferably fault processing circuit and control circuit are optically linked, such that when fault is detected, control circuit switch is opened by optical fault output signal, thus isolating load circuit from the supply circuit. Circuit interrupter may couple another circuit interrupter via power distribution control unit, optionally manageable remotely via automated control interface.