In earth leakage detection device, one end of coupling capacitor is connected to a current path of power storage unit connected to load in a state of being insulated from the ground. Voltage output unit generates a periodically changing periodic voltage, and applies the periodic voltage to the other end of coupling capacitor via first resistor. Second resistor and third resistor are connected in series between a node between coupling capacitor and first resistor and a predetermined fixed potential. Voltage measurement unit measures a voltage at a voltage dividing point between second resistor and third resistor. Earth leakage determination unit determines presence or absence of an earth leakage between the current path of power storage unit and the ground based on the measured voltage.

An earth leakage detecting device comprises following elements. A first end of coupling capacitor is connected to a current path of power storage connected to load in a state of being insulated from a ground. Voltage output unit generates a periodic voltage that changes periodically, and applies the periodic voltage to a second end of coupling capacitor via impedance element. Voltage measurer measures a voltage at a connection point between coupling capacitor and impedance element. Earth leakage determiner determines presence or absence of an earth leakage between the current path of power storage and the ground on the basis of the measured voltage. Voltage output unit has a preparation period for constantly outputting a potential between a high-side potential and a low-side potential of the periodic voltage before a measurement period for outputting the periodic voltage.

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.

A circuit interrupting device including a phase conductor, a neutral conductor, an interrupter configured to disconnect the phase conductor and the neutral conductor from a load, and a sensor configured to generate a signal indicative of current flowing through the phase conductor and the neutral conductor. The circuit interrupting device further includes a microcontroller that includes an electronic processor and is electrically connected to the first sensor and the interrupter. The microcontroller is configured to generate a reference signal, receive a first signal from the sensor, determine whether a difference between a voltage of the first signal and a voltage of the reference signal exceeds a threshold, determine whether the microcontroller has performed a ground fault self-test, and activate the interrupter when the difference exceeds the threshold and the microcontroller has not performed the ground fault self-test.

A system topology may use intentional signal injection to monitor one or more power supply circuits that may supply electrical power to components of the system. The system topology may include voltage monitoring circuitry to monitor the output of the power supply. In some examples, a power supply rail fault may happen either inside or outside of the power supply circuit, but not be detectable by the voltage monitoring circuitry. Injecting a check signal in the presence of an actual fault, may cause oscillations at the output node of the power supply detectable by the voltage monitoring circuitry. Once the check signal, combined with the fault signal, at the output node reaches the monitoring threshold detectable by the voltage monitoring circuitry, the voltage monitoring circuitry may output an indication of the fault to processing circuitry of the system.

A main electrical cabling is subject to variations in ambient temperature over its length. A detection system for detecting fault in the main electrical cabling able to cause a serial arc, or heating within a connection, includes a monitor electrical cabling placed as a return loop alongside the main electrical cabling, a monitoring device, and a return cable bringing back electrical potential at the output of the main electrical cabling to the monitoring device. The monitoring device includes a controllable current generator injecting, into the monitor electrical cable, a current dependent on current flowing through the main electrical cabling. Electronic circuitry determines a difference in voltages at inputs and outputs of the main electrical cabling and of the monitor electrical cabling, to detect a potential fault in the main electrical cabling leading to a serial arc or increase in temperature. A fault in the main electrical cabling is detected despite variations in temperature.

An abnormality detection device includes: a coupling-capacitor having a first-end and a second-end coupled with a high-voltage circuit; a signal output unit; a signal extraction unit; and a signal input unit. The signal output unit is coupled with the first-end of the coupling-capacitor via a detection-resistor, and outputs an alternating-current inspection-signal. The signal extraction unit extracts the inspection-signal, as an extraction-signal, output between the detection-resistor and the coupling-capacitor. The signal input unit detects abnormality of insulation resistance of the high-voltage circuit based on a level of the inputted extraction-signal. The signal extraction unit includes a signal removing filter and a subtraction circuit. The filter removes a signal equal in frequency to the inspection-signal and passes low-frequency noises lower in frequency than the inspection-signal. The subtraction circuit outputs a differential signal, as the extraction-signal, between a signal having passed through the filter and a signal not having passed through the filter.

A multi-channel device with a single diagnosis status pin may be configured to detect if one or more channels has a fault. The multi-channel device, which may operate within a system, can communicate which channel, of a plurality of channels, has the fault using only a single diagnosis status pin and no additional diagnosis control pins. The multi-channel device may output a fault signal on the diagnosis status pin and in response to an interrogation input signal on the same channel as a fault channel indicate to the system which channel is the fault channel.

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.

A method for leakage current compensation in a photovoltaic system includes determining a reference current flowing from at least one current-carrying line under voltage via a capacitor to earth, and generating a compensation current, having a phase and a frequency of the reference current, and having an amplitude adjusted by a negative scaling factor based on the reference current. The method further includes determining a current sum using a differential current sensor for at least a portion thereof, wherein the addends of the current sum are the currents through a complete set of current-carrying lines and the compensation current, minimizing the determined current sum by adjusting the scaling factor, and routing the compensation current through at least one other differential current sensor, such that the compensation current compensates a leakage current component of a differential current monitored by the other differential current sensor. A related device and system is also disclosed.