Abstract: In one aspect, a method of electrical arc fault detection when high frequency (e.g., RF noise) is present is disclosed. The method includes determining if first arcing criterion is met, determining if delay criterion is met, implementing a delay for a delay period if the delay criterion is met, and determining if second arcing criterion is met. If the second arcing criterion is met, then a trip signal may be sent to trip the circuit breaker. In another aspect, the method includes determining if first arcing criterion is met, starting delay period if the first arcing criterion is met, determining if delay criterion is met, and if the delay criterion is met, determining if second arcing criterion is met. An arc fault detection apparatus adapted to carry out the methods, and systems including the arc fault detection apparatus are disclosed, as are various other aspects.

Abstract: A device is provided for use with an AC power system having a line conductor, a neutral conductor and a transformer, the line conductor and the neutral conductor are coupled between a source and a load, and the transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a first circuit coupled to the secondary winding, providing a first detection signal if a current from the line conductor to ground exceeds a first predetermined threshold, and a second circuit coupled to the secondary winding, having a source that provides an AC signal at a specified amplitude and a specified frequency to the secondary winding. The second circuit provides a second detection signal if an impedance between the neutral conductor and ground is less than a second predetermined threshold.

Abstract: In a first aspect, a ground fault circuit interrupt (“GFCI”) device is provided for use with an AC power system that includes a line conductor, a neutral conductor and a transformer. The line conductor and the neutral conductor are each coupled between a source and a load, and the neutral conductor is coupled to ground at the source. The transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a grounded neutral fault detector circuit coupled to the secondary winding. The grounded neutral fault detector circuit: (a) drives the secondary winding with a multi-frequency AC signal, (b) monitors a multi-frequency load signal in the secondary winding, and (c) provides a first detection signal if the monitored load signal exceeds a predetermined threshold. Numerous other aspects are also provided.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or a ground fault circuit interrupt (GFCI) device is disclosed in which a low voltage DC power supply is used to generate a test stimulus signal for a self test of the GFCI device. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, and a secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the secondary winding of the differential current transformer to compare current generated in the secondary winding from an imbalance of magnetic flux in the toroid to a trip threshold. A wire conductor is routed through the toroid of the differential current transformer. A controller is configured to control a low voltage DC test stimulus signal to be generated in the wire conductor.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or ground fault circuit interrupt (GFCI) device is disclosed in which is a test stimulus signal for a self test of the GFCI device is generated on a second secondary winding on a toroid of a differential current transformer. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, a first secondary winding wound on the toroid to generate a current in response to an imbalance of magnetic flux in the toroid, and a second secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the first secondary winding of the differential current transformer to compare current generated in the secondary winding to a trip threshold.

Abstract: A device is provided for use with an AC power system having a line conductor, a neutral conductor and a transformer, the line conductor and the neutral conductor are coupled between a source and a load, and the transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a first circuit coupled to the secondary winding, providing a first detection signal if a current from the line conductor to ground exceeds a first predetermined threshold, and a second circuit coupled to the secondary winding, having a source that provides an AC signal at a specified amplitude and a specified frequency to the secondary winding. The second circuit provides a second detection signal if an impedance between the neutral conductor and ground is less than a second predetermined threshold.

Abstract: A device is provided for use with an AC power system having a line conductor, a neutral conductor and a transformer, the line conductor and the neutral conductor are coupled between a source and a load, and the transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a first circuit coupled to the secondary winding, providing a first detection signal if a current from the line conductor to ground exceeds a first predetermined threshold, and a second circuit coupled to the secondary winding, having a source that provides an AC signal at a specified amplitude and a specified frequency to the secondary winding. The second circuit provides a second detection signal if an impedance between the neutral conductor and ground is less than a second predetermined threshold.

Abstract: Testing an AFCI device includes providing an AFCI device to be tested and a load, wherein the AFCI device and the load form an electrical circuit, applying AC power to the AFCI device, generating a high frequency broadband noise signal, amplifying the high frequency broadband noise signal, modulating the amplified high frequency noise signal with a signal synchronized to the load current or load voltage to provide synchronized high frequency broadband noise bursts, coupling the noise bursts into the electrical circuit to simulate series arcing signals, determining if the AFCI device opens the electrical circuit within a predetermined amount of time, indicating the AFCI device has passed the test if the AFCI opens the electrical circuit within the predetermined amount of time, and indicating the AFCI device has failed the test if not.

Abstract: A self-test circuit is provided that includes a signal circuit adapted to periodically output a circuit inhibitor signal to inhibit a breaking signal from a ground fault detector. The signal circuit is also adapted to periodically output a test signal simulating a ground fault. The self-test circuit also includes an alarm circuit adapted to receive an output signal from the ground fault detector in response to detecting the ground fault, and adapted to output an alarm when the ground fault detector is not operative. The signal circuit may be further adapted to periodically output a second test signal simulating a grounded neutral condition. A ground fault circuit interrupter system and a method are also provided.

Abstract: In one aspect, a method of electrical arc fault detection when high frequency (e.g., RF noise) is present is disclosed. The method includes determining if first arcing criterion is met, determining if delay criterion is met, implementing a delay for a delay period if the delay criterion is met, and determining if second arcing criterion is met. If the second arcing criterion is met, then a trip signal may be sent to trip the circuit breaker. In another aspect, the method includes determining if first arcing criterion is met, starting delay period if the first arcing criterion is met, determining if delay criterion is met, and if the delay criterion is met, determining if second arcing criterion is met. An arc fault detection apparatus adapted to carry out the methods, and systems including the arc fault detection apparatus are disclosed, as are various other aspects.

Abstract: An electrical fault detection device for use in a branch of a power circuit that utilizes signals from an AC line current sensor coupled to an electrical distribution line having a primary and neutral lines, a line high-frequency sensor coupled to the electrical distribution line, a differential current sensor coupled to the primary and neutral lines, and a ground fault current sensor coupled to the primary and neutral lines. A signal conditioner receives the signals outputted by AC current line current sensor, the line high frequency sensor, the differential current sensor and the ground fault current sensor and generates a signal indicative of the load current associated with a branch of the power circuit. Output of the signal conditioner is sampled and processed by a processing resource. The processing resource has stored therein data representing a plurality of time-versus-current curves that define a plurality of regions in which tripping may or may not occur.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or a ground fault circuit interrupt (GFCI) device is disclosed in which a low voltage DC power supply is used to generate a test stimulus signal for a self test of the GFCI device. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, and a secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the secondary winding of the differential current transformer to compare current generated in the secondary winding from an imbalance of magnetic flux in the toroid to a trip threshold. A wire conductor is routed through the toroid of the differential current transformer. A controller is configured to control a low voltage DC test stimulus signal to be generated in the wire conductor.

Abstract: An apparatus and method for a supervisory circuit for a ground fault detection device or ground fault circuit interrupt (GFCI) device is disclosed in which is a test stimulus signal for a self test of the GFCI device is generated on a second secondary winding on a toroid of a differential current transformer. The GFCI device includes line and neutral conductors configured to connect an AC power source and a load. A differential current transformer includes a toroid, through which the line and neutral conductors pass, a first secondary winding wound on the toroid to generate a current in response to an imbalance of magnetic flux in the toroid, and a second secondary winding wound on the toroid. A differential ground fault detector is electrically connected to the first secondary winding of the differential current transformer to compare current generated in the secondary winding to a trip threshold.

Abstract: In a first aspect, a ground fault circuit interrupt (“GFCI”) device is provided for use with an AC power system that includes a line conductor, a neutral conductor and a transformer. The line conductor and the neutral conductor are each coupled between a source and a load, and the neutral conductor is coupled to ground at the source. The transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a grounded neutral fault detector circuit coupled to the secondary winding. The grounded neutral fault detector circuit: (a) drives the secondary winding with a multi-frequency AC signal, (b) monitors a multi-frequency load signal in the secondary winding, and (c) provides a first detection signal if the monitored load signal exceeds a predetermined threshold. Numerous other aspects are also provided.

Abstract: In a first aspect, a device is provided for use with an AC power system that includes a line conductor, a neutral conductor and a transformer, the line conductor and the neutral conductor are each coupled between a source and a load, the neutral conductor is coupled to ground at the source, and the transformer includes a first primary winding coupled in series with the line conductor, a second primary winding coupled in series with the neutral conductor, and a secondary winding. The device includes a first circuit coupled to the secondary winding, wherein the first circuit provides a first detection signal if a current from the line conductor to ground exceeds a first predetermined threshold. The device also includes a second circuit coupled to the secondary winding, wherein the second circuit includes an AC signal source that provides an AC signal at a specified amplitude and a specified frequency to the secondary winding.

Abstract: A self-test circuit is provided that includes a signal circuit adapted to periodically output a circuit inhibitor signal to inhibit a breaking signal from a ground fault detector. The signal circuit is also adapted to periodically output a test signal simulating a ground fault. The self-test circuit also includes an alarm circuit adapted to receive an output signal from the ground fault detector in response to detecting the ground fault, and adapted to output an alarm when the ground fault detector is not operative. The signal circuit may be further adapted to periodically output a second test signal simulating a grounded neutral condition. A ground fault circuit interrupter system and a method are also provided.

Abstract: An electrical fault detection device for use in a branch of a power circuit that utilizes signals from an AC line current sensor coupled to an electrical distribution line having a primary and neutral lines, a line high-frequency sensor coupled to the electrical distribution line, a differential current sensor coupled to the primary and neutral lines, and a ground fault current sensor coupled to the primary and neutral lines. A signal conditioner receives the signals outputted by AC current line current sensor, the line high frequency sensor, the differential current sensor and the ground fault current sensor and generates a signal indicative of the load current associated with a branch of the power circuit. Output of the signal conditioner is sampled and processed by a processing resource. The processing resource has stored therein data representing a plurality of time-versus-current curves that define a plurality of regions in which tripping may or may not occur.

Abstract: A method and apparatus for testing an AFCI device.