Fault-protection is provided in electrical devices by redundancy in diodes on diode legs of the bridge rectifier and a fault-protection circuit. The fault-protection circuit is configured: (i) for electrical coupling between a return of input DC power to a step-down switching DC-DC converter and a return rail of rectified DC voltage of the output DC power generated by the bridge rectifier, and is configured to perform opening the switch based on sensing a current fault or voltage fault, or (ii) to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

Passive monitoring the integrity of current sensing devices and associated circuitry in GFCI and AFCI protective devices is provided. A protection circuit interrupter employs a capacitively coupled noise signal obtained by an arrangement of one or both of line side arms relative to a Rogowski coil. The noise signal is monitored while the line and load sides of a protective circuit interrupter are disconnected, and the connection of the line and load sides disabled if the noise signal fails to correlate sufficiently to a reference noise cycle. When the line and load sides are connected, the RMS value of the observed current signal is monitored such that the line and load sides are disconnected if the observed current signal fails to meet an RMS threshold. The observed current signal is compensated by subtracting the reference noise cycle prior to monitoring for the fault condition applicable to the protective device.

An adaptive electrical power distribution panel receives electrical power from at least an alternative power source other than a utility electric grid, and selectively outputs power to a plurality of branch circuits, appliances, or devices. An internal or remote controller monitors conditions. In response to the monitored conditions, the controller algorithmically divides the plurality of branch circuits, appliances, or devices into a first group to receive power from the alternative power source and a second group to not receive power from the alternative power source, and breaks electrical connections between the alternative power source and the second group. The monitored conditions may include operating parameters the grid; an instantaneous or average individual current flow; and a charge state of storage batteries. The division into groups may also be in response to stored information, such as a priority of, or history of current usage by, each branch circuit, appliance, or device.

Provided is an apparatus and method for protecting against unsafe electric current conditions. A protections circuit may be used in a device, such as an electric grill, that has one or more electric loads, such as heating elements. The protection circuit may protect against various failure scenarios, including, without limitation, instances of ground fault, over current, driver failure, and failure of a microprocessor. In response to a failure, the protection circuit may trip a latch relay or disable a triac driver to stop current from flowing.

A method is disclosed providing ground fault circuit interruption protection for a pump motor which includes determining a current difference between at least two leads located on a load side of an electromechanical device, wherein the electromechanical device is configured to mechanically drive a road, and wherein the method further comprises interrupting a flow of current in response to the current difference exceeding a threshold current difference.

Systems and methods for monitoring the isolation resistance of one or more fuel cells are described herein. In one example, a system includes a current transformer having a hollow core. First and second portions of a load line from a fuel cell are located within the hollow core. The first portion of the load line is electrically between an anode of a fuel cell and an electrical load, while the second portion of the load line being electrically between a cathode of the fuel cell and the electrical load. The current transformer is configured to output an electrical signal proportional to a current passing through the hollow core. This electrical signal can then be used to determine the isolation resistance of the fuel cell.

A ground detecting apparatus at least includes a metal oxide semiconductor field effect transistor and a high voltage resistor. The metal oxide semiconductor field effect transistor is used to replace a photo-coupler for switching. The high voltage resistor is used for safety isolation. A relay action detecting apparatus at least includes a metal oxide semiconductor field effect transistor and a high voltage resistor. The metal oxide semiconductor field effect transistor is used to replace a photo-coupler for switching. The high voltage resistor is used for safety isolation.

An arc fault detection device for detecting an arc fault in an electric line includes a first terminal and a second terminal for connecting the arc fault detection device to a conductor of the electric line. A sensor is adapted for generating a sensor signal from a current through the electric line; and a controller is adapted for detecting the arc fault from the sensor signal. The sensor includes an inductor connected to the first terminal and the second terminal and a capacitor connected in parallel with the inductor. The inductor and the capacitor form a resonant circuit with a resonance frequency, the resonance frequency determining an impedance behavior of the resonant circuit; wherein the inductor and the capacitor are chosen such that the impedance behavior of the resonant circuit corresponds to a desired impedance behavior over a relevant frequency range of the current through the electric line.

An arc fault detection device for detecting an arc fault in an electric line includes a first terminal and a second terminal for connecting the arc fault detection device to a conductor of the electric line. A sensor is adapted for generating a sensor signal from a current through the electric line; and a controller is adapted for detecting the arc fault from the sensor signal. The sensor includes an inductor connected to the first terminal and the second terminal and a capacitor connected in parallel with the inductor. The inductor and the capacitor form a resonant circuit with a resonance frequency, the resonance frequency determining an impedance behavior of the resonant circuit; wherein the inductor and the capacitor are chosen such that the impedance behavior of the resonant circuit corresponds to a desired impedance behavior over a relevant frequency range of the current through the electric line.