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 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.

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.

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 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.

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 abnormality occurring in a ZCT is detected simply and reliably. A zero-phase-sequence current transformer (ZCT) (11) detects zero-phase-sequence current in power wires inserted therethrough, and in addition to the power wires, has inserted therethrough a wire through which a constant DC offset current flows.

A ground fault circuit interrupter with a reversed wiring protection function is provided. The ground fault circuit interrupter may include a main circuit switch, a middle layer bracket, a reset button, a trip coil, an electromagnetic trip mechanism, a lifting piece, a locking piece, and an elastic reset mechanism. Sides of the lifting piece may be sleeved upon live line and neutral line metal rods, respectively. Reset springs may be sleeved upon the metal rods. In a correct wiring state, an upper end of the live line metal rod may be in conductive contact with a live line movable metal sheet of the main circuit switch, and an upper end of the neutral line metal rod may be in conductive contact with a neutral line movable metal sheet of the main circuit switch, the movable metal sheets extending from the power load end.

A GFCI circuit that includes an electronically controllable main switch that can turn on, and turn off, the delivery of electrical power from the GFCI circuit. The main switch is controlled and monitored by a microcontroller unit using at least digital input and digital output signals, and which includes analog to digital converter. The microcontroller unit may also use the on-off functionality of the main switch in connection with repeatable detection of miswiring of the GFCI circuit. The GFCI circuit can further be adapted to conduct a self-test that can temporarily disable the ability of a trip signal generated by a GFCI integrated circuit in response to a test fault to cause the tripping of the main switch. The microcontroller unit further monitors one or more characteristics of the GFCI circuit, including the main switch and trip signal(s), and can determine whether the GFCI circuit has reached its end-of-life stage.

An electric leakage determination circuit for an electric leakage circuit breaker according to the invention comprises a zero current transformer on an alternating-current circuit to provide an electric leakage detection signal upon occurrence of electric leakage, a filter circuit unit connected to an output terminal of the zero current transformer to remove noise, and an electric leakage determination circuit unit comparing a voltage value of the electric leakage detection signal with a first reference voltage value, to be charged with electric charges when the voltage value is not smaller than the first reference voltage value and discharge electric charges when being smaller than the first reference voltage value, and comparing a charged voltage value with a second reference voltage value to determine occurrence of electric leakage when the charged voltage value is not smaller than the second reference voltage value.