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.

An automated earth fault testing system and early warning system designed to be used with mobile towers for real-time monitoring of the earthing values. The automated earth fault testing system comprises an earth fault testing device powered by a low voltage direct current battery, a plurality of terminals, at least one calibration switch including a calibration pad for calibrating the earth fault testing device, a plurality of visual indication means for providing indication of a variety of conditions including high and/or normal value of the earth resistance value and for indicating a charge level of the earth fault testing device and a liquid crystal display for displaying the earthing values. The earth fault testing device is connected to an alarm system of a base transceiver station utilizing a relay for informing the mobile signal station and operator with information regarding a status of the earth fault testing device.

An insulation resistance detection circuit and method are disclosed. The circuit includes a controller configured to: open a first relay, and close second relays, or switch an on/off status of at least one of the second relays; determine, based on a first measurement value between a positive input terminal of an inverter circuit and an earthing point, whether the positive input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing; and determine, based on a second measurement value between a negative input terminal of the inverter circuit and the earthing point, whether the negative input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing, where the first relay is one of in M relays and is connected to at least one impedor in parallel, and the second relays are relays other than the first relay in the M relays.

An insulation resistance detection circuit and method are disclosed. The circuit includes a controller configured to: open a first relay, and close second relays, or switch an on/off status of at least one of the second relays; determine, based on a first measurement value between a positive input terminal of an inverter circuit and an earthing point, whether the positive input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing; and determine, based on a second measurement value between a negative input terminal of the inverter circuit and the earthing point, whether the negative input terminal of the inverter circuit is short-circuited or has low resistance to protective earthing, where the first relay is one of in M relays and is connected to at least one impedor in parallel, and the second relays are relays other than the first relay in the M relays.

A ground fault monitoring system includes a ground fault interface device including a power interface and a data interface. The ground fault interface device is structured to output power via the power interface and to receive data via the data interface. The ground fault monitoring system also includes a plurality of ground fault devices structured to detect a ground fault on an associated circuit, to output data of the detected ground fault to the ground fault interface device, and to receive power to operate the ground fault devices via power lines. The plurality of ground fault devices are electrically connected in a series connection with the ground fault interface device by data lines and power lines. Each of the ground fault devices is configured to pass through received data and power.

A system for checking the electrical insulation in converters for electric cars comprises at least one voltage generator connected to at least one line to be monitored of a high-voltage converter for electric vehicles and connected to the ground of said converter, and at least one current detection unit operatively connected to said voltage generator and configured to detect any current possibly present on the voltage generator and to generate a warning signal in the event of detection of the current.

A system for checking the electrical insulation in converters for electric cars comprises at least one voltage generator connected to at least one line to be monitored of a high-voltage converter for electric vehicles and connected to the ground of said converter, and at least one current detection unit operatively connected to said voltage generator and configured to detect any current possibly present on the voltage generator and to generate a warning signal in the event of detection of the current.

Provided is a grid-connected inverter safety detection device applied in a photovoltaic inverter system and including voltage detection circuit, a filter circuit, a comparison circuit and a controller. The voltage detection circuit is configured to detect a voltage between the point N and the ground, or a voltage between the first terminal for any phase of the three-phase power grid and the ground. The filter circuit is configured to filter out an alternating current component of the voltage detected by the voltage detection circuit and to retain an direct current component of the voltage. The comparison circuit is configured to compare the direct current component of the voltage with a preset voltage value and transmit a comparison result to the controller. The controller is configured to determine, according to the comparison result, whether an alternating current side at the output terminal of the inverter has normal insulation.

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.

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.