A method of performing line insulation monitoring of a pair of conductor lines at least partially located in a cable is provided, comprising the steps of providing a first power switch in a first conductor line of the pair and a second power switch in a second conductor line of the pair, providing a line insulation monitor at a first end of the pair of conductor lines, electrically connected to the pair of conductor lines, at the second end of the pair of conductor lines, electrically connecting the first and second conductor lines, placing the first and second power switches into a monitoring configuration wherein the first power switch is closed while the second power switch is open, and using the line insulation monitor to monitor the insulation of the conductor lines.

A system for monitoring the integrity of a plurality of ground conductors has a plurality of monitors, with a different monitor associated with each ground conductor. Each monitor includes a voltage sensor which monitors voltage on a closed circuit of the monitor. Upon the voltage sensor sensing an unexpected voltage, a transmitter of the monitor issues an “alarm” signal, which may be wireless (e.g., being sent using LoRaWAN protocol). The transmitter may issue other signals, including a periodic “heartbeat” signal to confirm continued operation of the monitor, and a “movement” signal to indicate movement of the monitor. The monitor may be GPS-enabled, in which case each signal may include the GPS coordinates of the monitor. The signals issued by the transmitter may ultimately be analyzed by an operator via a user interface platform, which may simultaneously display information regarding two or more of the plurality of monitors.

A temporary power delivery system includes a power source, a booth stringer, and a portable GFCI device. The GFCI device is receives current from the power source by a first terminal and delivers current to the booth stringer by a second terminal. An electronic processor of the GFCI device compares a combined magnitude of current flowing through first and second phase conductors of the GFCI device to a magnitude of current flowing through a neutral conductor of the GFCI. The electronic processor also compares a first voltage between the first phase conductor and neutral conductor to a second voltage between the second phase conductor and neutral conductor. A circuit breaker of the GFCI device is opened if a difference between the combined magnitude of phase conductor current and neutral conductor current exceeds a first threshold or a difference between the first voltage and second voltage exceeds a second threshold.

A fault protection arrangement. The fault protection arrangement may include a neutral grounding resistor including a first non-ground end, connected to a neutralizing point, and a second non-ground end. The fault protection arrangement may include a neutral grounding resistance monitor assembly, directly coupled to the second non-ground end of the neutral grounding resistor. The neutral grounding resistance monitor assembly may include comprising a signal source coupled to the neutralizing-point; a first current sense circuit coupled between the signal source and the neutralizing-point; a first voltage sense circuit coupled between the signal source and the neutralizing-point; a second current sense circuit, comprising a current sensor, coupled between the second non-ground end of the neutral grounding resistor and a protective earth connection.

A method for detecting a fault in a battery charger circuit of a vehicle includes determining, based on at least one expected voltage value of an incoming alternating current source, a first threshold. The method also includes measuring at least one line voltage value associated with the incoming alternating current source that provides power to the battery charger circuit. The method also includes determining whether the measured at least one line voltage value is greater than the first threshold. The method also includes in response to a determination that the measured at least one line voltage value is greater than the first threshold, disconnecting the battery charger circuit from and/or preventing the battery charger circuit from connecting to the incoming alternating current source after a first predetermined period.

A method for detecting an insulation fault in a vehicle on-board electrical system having an HV and LV on-board electrical system branches. The LV branch has at least one first LV potential and a second LV potential that differs therefrom and corresponds to a ground potential of the vehicle on-board electrical system. The HV branch has positive HV negative HV potentials. These HV potentials are DC-isolated from the LV branch potentials. An insulation fault between at least one of the HV potentials and the first LV potential is detected by identifying a current flow. The current flow runs through a voltage limiting circuit connected between the ground potential and the first LV potential. This circuit connects the first LV potential, via a plurality of diodes, to a voltage limiting element connected to the ground potential of the vehicle on-board electrical system. A vehicle overvoltage protective circuit is also described.

An electrical apparatus comprises an earth input (10a) for connection to an earth wire (10) of an electrical supply from a distribution network, an earth interface for providing an earth connection from the earth input (10a) to an appliance (2) and current sensing means (40) for sensing a current flow through the earth input (10a). The electrical apparatus further comprises earth-wire disconnection means (48) for disconnecting the earth interface from the earth input (10a) when a sensed current flow through the earth input (10a) satisfies an earth-wire disconnection condition and live-wire disconnection means (42) for initiating a disconnection of a live wire (4) of the electrical supply to the appliance (2) before or at the same time as the disconnecting of the earth interface.

An apparatus for detecting an open neutral condition in a split phase power system is described. The apparatus includes two powered lines providing output electricity to an electrical distribution system and a shared neutral line providing a grounded neutral to the first and second powered lines. The apparatus is configured for detecting when an open neutral condition is present in the split phase power system by determining when a power current is present on one or both of the first and second powered lines while a return current is not present on the neutral line; and in response to detecting that the open neutral condition is present, causing an interrupter to interrupt the power supplied by the first and second powered lines or to generate a signal indicating an open condition.

A system for monitoring the integrity of a plurality of ground conductors has a plurality of monitors, with a different monitor associated with each ground conductor. Each monitor includes a voltage sensor which monitors voltage on a closed circuit of the monitor. Upon the voltage sensor sensing an unexpected voltage, a transmitter of the monitor issues an “alarm” signal, which may be wireless (e.g., being sent using LoRaWAN protocol). The transmitter may issue other signals, including a periodic “heartbeat” signal to confirm continued operation of the monitor, and a “movement” signal to indicate movement of the monitor. The monitor may be GPS-enabled, in which case each signal may include the GPS coordinates of the monitor. The signals issued by the transmitter may ultimately be analyzed by an operator via a user interface platform, which may simultaneously display information regarding two or more of the plurality of monitors.

A temporary power delivery system includes a power source, a booth stringer, and a portable GFCI device. The GFCI device is receives current from the power source by a first terminal and delivers current to the booth stringer by a second terminal. An electronic processor of the GFCI device compares a combined magnitude of current flowing through first and second phase conductors of the GFCI device to a magnitude of current flowing through a neutral conductor of the GFCI. The electronic processor also compares a first voltage between the first phase conductor and neutral conductor to a second voltage between the second phase conductor and neutral conductor. A circuit breaker of the GFCI device is opened if a difference between the combined magnitude of phase conductor current and neutral conductor current exceeds a first threshold or a difference between the first voltage and second voltage exceeds a second threshold.