A circuit for detecting arc due to a bad contact includes a rectifying unit for rectifying an arc pulse voltage due to the bad contact, an arc voltage detection unit for detecting an arc voltage through the rectifying unit, a high-frequency pass filter combined in a front end or a rear end of the arc voltage detection unit, a control signal generation unit for generating a relay driving control signal using the arc voltage detected by the arc voltage detection unit, and a relay unit controlled by the relay driving control signal and electrically connecting a ground line and a power line of the interior wiring.

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.

A circuit for a circuit interrupter is provided. The circuit may in include a first SCR configured to receive a first trigger signal at a gate of the first SCR, a second SCR configured to receive a second trigger signal at a gate of the second SCR, and a third SCR configured to receive a third trigger signal at a gate of the third SCR. A cathode of the first SCR may be connected to an anode of the third SCR. A cathode of the second SCR and a cathode of the third SCR may be connected to a ground. Methods of operating a circuit interrupter and a circuit are also provided.

A circuit for a circuit interrupter is provided. The circuit may in include a first SCR configured to receive a first trigger signal at a gate of the first SCR, a second SCR configured to receive a second trigger signal at a gate of the second SCR, and a third SCR configured to receive a third trigger signal at a gate of the third SCR. A cathode of the first SCR may be connected to an anode of the third SCR. A cathode of the second SCR and a cathode of the third SCR may be connected to a ground. Methods of operating a circuit interrupter and a circuit are also provided.

The present invention provides a trip control circuit for a circuit breaker capable of breaking a circuit when a fault current occurs due to a DC current component, as well as an AC current. The trip control circuit comprises a current transformer that has a core allowing a circuit to pass through and a secondary coil for detecting a current flowing on the circuit and providing a current detection signal; an oscillation circuit section that configured to apply an electrical signal to the secondary coil to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current and an AC current; and a trip determining circuit section that configured to compare a current value indicated by the current detection signal with a predetermined reference current value.

A control circuit for an electric leakage circuit breaker, capable of preventing an error in determining an electric leakage generation due to an offset voltage of an input amplifier, including, a zero phase current transformer configured to detect a zero phase current on a circuit as a leakage detection signal, a filter circuit section configured to remove a high frequency noise included in the leakage detection signal, an input amplifier configured to a voltage formed by a current of the leakage detection signal and an impedance of the filter circuit section, and includes a pair of transistors, a base current generator commonly connected to the bases of the pair of transistors and configured to supply the same amount of base current to the pair of transistors, and a trip determination circuit section configured to determine whether to output a trip control signal.

A DC-to-AC power conversion system includes DC power source assemblies each having a plurality of DC power sources and a combiner coupled to the DC output from the DC power source assemblies. A power inverter is coupled to a DC output of the combiner and configured to invert the DC output to an AC output. The system includes a controller programmed to identify a potential ground fault using current data received from a ground current sensor provided on a ground conductor. After identifying the faulty DC power source using sensed current data received from a current sensor provided on at least one of the positive conductors and the negative conductors, the controller opens the DC breaker switches on a positive conductor and a negative conductor of the combiner to disconnect the faulty DC power source assembly from the power inverter.

A system for detecting and controlling an abnormal state of an electrical signal, includes: an abnormality decision part determining whether or not an electrical signal detected from a power line is abnormal by using the electrical signal and generating a control signal for controlling ON/OFF of N switches included in a leakage breaker. The system for detecting and controlling the abnormal state of the electrical signal is capable of controlling an operation of the leakage breaker by using voltage and current signals detected from the power line through which commercial power is supplied and functioning as a black box when an accident occurs such as a fire, etc.

A device for monitoring a neutral grounding resistor (NGR), including first and second NGRs electrically connected in parallel, a rectifier circuit electrically connected in series with the second NGR and a voltage source and a logic resistor electrically connected in series with the second NGR. A logic circuit measures current passing through the logic resistor and determines the resistance of the first NGR based on the measured current and the resistance of the second NGR. As such, a failed-open or failed-short condition of the first NGR may be identified based at least in part on the determined resistance of the first NGR.