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.

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 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.

Systems and method for detecting potentially harmful harmonic and direct current signals at a transformer are disclosed. One system includes a protection circuit electrically connected to a transformer neutral, the transformer electrically connected to a power grid, the protection circuit including a DC blocking component positioned between the transformer neutral and ground and one or more switches selectively actuated to form a path between the transformer neutral and ground in the event of unwanted DC current at the transformer neutral. The system also includes a control circuit electrically connected to the protection circuit and positioned to selectively actuate the switches based on observed conditions within the protection circuit. The system further includes a plurality of test connections disposed within the protection circuit and useable to test electrical properties of the protection circuit.

A DI-circuit breaker device includes a summation current converter for detecting fault currents in a phase conductor and a neutral conductor, and a detection device for detecting fault states of a protective ground conductor. The detection device detects the presence of a phase voltage on the protective ground conductor as a fault state. The detection device has a capacitive sensor which, when touched by a user, forms an electric capacitor with an impedance relative to ground potential. The detection device further has evaluating electronics adapted to determine a phase position by connecting the sensor to the phase conductor and, separately therefrom, to the neutral conductor. The evaluating electronics determine the absence of a phase voltage on the protective ground conductor when there is no voltage between the neutral conductor and the protective ground conductor when phase is present at the phase conductor. Further, a corresponding operating method is described.

A GFCI latching apparatus and circuit is provided. The latching apparatus includes a solenoid; a solenoid plunger, wherein the solenoid plunger comprises a groove; a conical spring disposed at one end of the solenoid plunger; a forked latch, wherein the forked latch engages the groove with its forks. The latch also includes a bevel surface. Also included is a contact carrier having a first position when the solenoid is energized and a second position when the solenoid is deenergized. The contact carrier includes a bevel surface for mating with the latch bevel surface when the solenoid is energized. Also included is a GFCI configured to deenergize the solenoid upon the occurrence of a fault to disengage the latch, the latch thereby disengaging from the contact carrier, causing the contact carrier to move from the first position to the second position. The GFCI circuit detects ground faults and deenergizes the solenoid when a ground fault is detected. The GFCI includes GFCI detection circuitry, wherein the GFCI detection circuitry includes an SCR switch for controlling energizing current for the solenoid; SCR Test Bias circuit for biasing the SCR switch; Self-Test Fault circuit for testing the operation of the GFCI detection circuitry; an Isolation circuit for isolating GFCI detection circuit while self-test is preformed; and power supply circuits for powering the GFCI circuit.

A system for providing power from an AC power supply to an external load. The system includes a current limiter circuit, connected to an input of a switched-mode power supply. The system includes the switched-mode power supply that provides a first voltage signal and a second voltage signal. The system includes a supervisor circuit that is connected to the first output of the switched-mode power supply and coupled to a relay control circuit. The supervisor circuit monitors the first voltage signal and enables the relay control circuit. The relay control circuit provides a first voltage corresponding to the first voltage signal to a first voltage rail and provides a second voltage corresponding to the second voltage signal to a second voltage rail. A relay powered by a connection to the first voltage rail or the second voltage rail connects the AC power supply to an external load.

A GFCI latching apparatus and circuit is provided. The latching apparatus includes a solenoid; a solenoid plunger, wherein the solenoid plunger comprises a groove; a conical spring disposed at one end of the solenoid plunger; a forked latch, wherein the forked latch engages the groove with its forks. The latch also includes a bevel surface. Also included is a contact carrier having a first position when the solenoid is energized and a second position when the solenoid is deenergized. The contact carrier includes a bevel surface for mating with the latch bevel surface when the solenoid is energized. Also included is a GFCI configured to deenergize the solenoid upon the occurrence of a fault to disengage the latch, the latch thereby disengaging from the contact carrier, causing the contact carrier to move from the first position to the second position. The GFCI circuit detects ground faults and deenergizes the solenoid when a ground fault is detected. The GFCI includes GFCI detection circuitry, wherein the GFCI detection circuitry includes an SCR switch for controlling energizing current for the solenoid; SCR Test Bias circuit for biasing the SCR switch; Self-Test Fault circuit for testing the operation of the GFCI detection circuitry; an Isolation circuit for isolating GFCI detection circuit while self-test is preformed; and power supply circuits for powering the GFCI circuit.

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.

Safety device for an electrical apparatus powered by an AC mains power supply, the safety device comprising: an electric circuit having inputs for connecting to an active, neutral and earth conductors of the electrical apparatus which are in turn coupled to the AC mains power supply, the circuit being operable to: produce and apply a stepped down voltage and current to the earth conductor from the main supply; and electrically isolate the active and neutral conductors from the earth conductor in response to detecting that either: the active conductor is incorrectly wired to the neutral circuit of the AC mains power supply; the neutral conductor is incorrectly wired to the active circuit of the AC mains power supply; or the neutral conductor is switched; wherein one or more solid state relays are employed by the circuit for both producing the stepped down voltage and electrically isolating the conductors from earth.