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.

An AFCI protective system includes a MOV circuit that has a plurality of line terminals comprising at least one phase conductor, a neutral conductor or a ground conductor. A MOV is coupled to a pair of line terminals through a low impedance circuit, and a response circuit configured to activate a human readable indicator when the MOV is experiencing an end of life condition.

A ground fault circuit interrupter device includes a switch module, a ground fault detection module, a self-testing module and a tripping module. The switch module is coupled between the input and output ends to control the electrical connection between the input and output. The ground fault detection module detects whether a leakage current signal exists at the output end. The self-testing module is coupled to the ground fault detection module and periodically generates a self-test pulse signal which simulates the leakage current signal. The tripping module is coupled to the ground fault detection module and the switch module, to control the movement of the switch module. The device includes at least two tripping drive components, which prevents the device from becoming ineffective when the tripping module malfunctions due to long time use or use under high temperatures. This greatly improves safety of the device.

Systems, devices, and methods for a transformer including: a first drive winding (206) wound on a first core; a second drive winding wound on a second core; a sense winding wound across the first and second cores; and a compensation winding wound across the first and second cores; where one or more utility lines are threaded through a middle of the first and second cores, a common mode current in the one or more utility lines causes one or more pulses to appear on the sense winding, a current on the compensation winding is adjusted until the one or more pulses on the sense winding are cancelled out, and the common mode current on the one or more utility lines is the adjusted current on the compensation winding multiplied by a turn ratio between the compensation winding and the sense winding.

A safety electronic switch, having a first terminal, a second terminal, a third terminal, a surge voltage suppression unit, a comparator, and a relay. The surge voltage suppression unit is connected to a safety circuit through the first terminal. The first terminal is provided with a live wire end and a neutral wire end. The surge voltage suppression unit is connected to the comparator. The comparator is connected to the relay. The relay is connected to the second terminal and the third terminal. The third terminal is connected to a low-voltage power supply. The third terminal is provided with a positive electrode and a negative electrode that are connected to the low-voltage power supply.

A ground fault circuit interrupter device includes a switch module having a reset switch, a control switch mechanically linked to the reset switch, a ground fault detection module, a self-testing module and a tripping module. The switch module controls the electrical connection between the input and output ends of the device. The ground fault detection module detects a leakage current signal at the output end. The self-testing module is coupled to the ground fault detection module and periodically generates a self-test pulse signal which simulates the leakage current signal. The tripping module is electrically coupled to the ground fault detection module and mechanically coupled to the switch module and the control switch, to control the movement of the switch module and the control switch. The control switch, which opens and closes at the same time as the reset switch, controls the power supply to the self-testing module.

A protection circuit provides a control voltage to a 3-phase contactor, where the three phases of the 3-phase power supply are inputs to the 3-phase contactor. The protection circuit includes: four input terminals, configured to be connected respectively to the three phases and to the neutral line of the 3-phase power supply; an output terminal, providing the control voltage to a control line of the 3-phase contactor; and control circuitry configured to provide the control voltage when any one or more of the three phases are live and when the neutral line is connected, and to provide no control voltage when all three phases are disconnected or when the neutral line is disconnected.

Circuit interrupting devices are provided. One circuit interrupting device includes a fault sensor configured to output a sensor signal; a voltage sensor configured to sense a reference voltage; and a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage. The circuit interrupting device further includes an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal; an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.

An auto-monitoring circuit including a first input structured to receive a signal from a processor of a circuit interrupter, a second input structured to receive power from a circuit protected by the circuit interrupter, a first switch structured to remain closed while the signal is received at the first input and remains above a predetermined threshold level and to open when the signal ceases to be received at the first input or drops below the predetermined threshold level, a second switch structured to remain open while the first switch is closed and to close when the first switch opens, and an output electrically connected to a trip circuit of the circuit interrupter. Closing the second switch causes a trip signal to be output to the trip circuit that causes the trip circuit to trip open the separable contacts.

Circuit interrupting devices are provided. One circuit interrupting device includes a fault sensor configured to output a sensor signal; a voltage sensor configured to sense a reference voltage; and a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage. The circuit interrupting device further includes an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal; an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.