A wiring device including an interrupting device and a controller. The interrupting device electrically connects one or more line terminals to one or more load terminals when the interrupting device is in a reset condition and disconnects the line terminals from the load terminals when the interrupting device is in a tripped condition. The controller is configured to, determine a frequency of an input voltage at the one or more line terminals, determine whether the frequency is within a predetermined range, and when the frequency is within the predetermined range, perform a test of the wiring device.

An electrical system includes a ground fault detection unit including a low frequency ground fault detection circuit and a high frequency ground fault detection circuit, and/or a ground fault control unit connected to the low frequency ground fault detection circuit and the high frequency ground fault detection circuit. The ground fault unit may be configured to detect a ground fault according to an output of the low frequency ground fault detection circuit and/or an output of the high frequency ground fault detection circuit. The electrical system may include a first current sensor connected to the low frequency ground fault detection circuit and/or a second current sensor connected to the high frequency ground fault detection circuit.

The present disclosure relates to a recloser control that detects islanding based on a continuous analysis of frequency and rate of change of frequency. For example, a recloser control may include protection circuitry that is communicatively coupled to a recloser. The recloser control may receive measurements of an electrical characteristic in an electric power delivery system. The recloser control may determine frequency (F) and a rate of change of frequency (ROCOF) based on the received measurements. The recloser control may detect islanding of a microgrid in the electric power delivery system based at least in part on F and ROCOF. The recloser control may send a signal to the recloser to trip the recloser based on the islanding of the microgrid.

A system includes a transformer rectifier unit (TRU) having three inputs, a first AC bus configured to supply power to a first of the three inputs, a second AC bus configured to supply power to a second of the three inputs, and a third AC bus configured to supply power to a third of the three inputs. The system includes a power quality sense device electrically connected to each of the first, second and third AC busses. The system includes an electrically held contactor electrically connected between the TRU and the power quality sense device. The electrically held contactor is configured and adapted to be switched ON or OFF depending on whether the power quality sense device is energized or de-energized.

When in the independent system: a natural energy generating apparatus, a storage battery system, a power generator, and a first load is connected to a power supply system; the natural energy generating apparatus supplies generated power to the power supply system; the storage battery system is a regulated power supply; and the power generator performs a constant power operation, information indicating states of the natural energy generating apparatus, the storage battery system, the power generator, the first load, and a second load is obtained. Operations of the natural energy generating apparatus and the power generator, connection of the second load to the power supply system, and paralleling off the second load from the power supply system are controlled based on the information so that a demand-supply balance of power in the independent system is maintained, with the first load maintained to be connected to the power supply system.

A method for reducing leakage currents in a protective conductor of an electricity network including a neutral conductor and a phase conductor in addition to the protective conductor. A differential current is determined depending on a phase conductor current in the phase conductor and a neutral conductor current in the neutral conductor. A compensation current is fed into the phase conductor and/or into the neutral conductor. The compensation current compensates for a leakage current caused by the differential current. Also described is a device for carrying out such a method.

A method for reducing leakage currents in a protective conductor of an electricity network including a neutral conductor and a phase conductor in addition to the protective conductor. A differential current is determined depending on a phase conductor current in the phase conductor and a neutral conductor current in the neutral conductor. A compensation current is fed into the phase conductor and/or into the neutral conductor. The compensation current compensates for a leakage current caused by the differential current. Also described is a device for carrying out such a method.

Systems and methods for detecting an arc fault in a circuit breaker use a single-coil current rate of change (di/dt) sensor for monitoring both low frequency alternating current (AC) and broadband high frequency noise on a power line. The di/dt sensor is optimized to amplify any broadband high frequency noise, typically from about 1 MHz to 40 MHz, that may be present on the power line. Low frequency signals representing the current being monitored, typically from about 1 Hz to 10 KHz, is provided to an active integrator circuit with a high gain to enable the single-coil sensitivity. To shorten capacitor charge up time of the active integrator circuit, a charging current is provided to the active integrator circuit upon startup of the circuit breaker.

Systems and methods for detecting an arc fault in a circuit breaker use a single-coil current rate of change (di/dt) sensor for monitoring both low frequency alternating current (AC) and broadband high frequency noise on a power line. The di/dt sensor is optimized to amplify any broadband high frequency noise, typically from about 1 MHz to 40 MHz, that may be present on the power line. Low frequency signals representing the current being monitored, typically from about 1 Hz to 10 KHz, is provided to an active integrator circuit with a high gain to enable the single-coil sensitivity. To shorten capacitor charge up time of the active integrator circuit, a charging current is provided to the active integrator circuit upon startup of the circuit breaker.

An oscillatory electric signal having an oscillation frequency is processed by time-sampling to generate a sampled oscillatory electric signal. A nonlinear circuit driven by the sampled oscillatory electric signal outputs a hysteretic response signal as a function of the sampled oscillatory electric signal. The hysteretic response signal has a frequency in a first frequency range as a result of an increase in the oscillation frequency of the oscillatory electric signal, and a frequency in a second frequency range as a result of a decrease in the oscillation frequency of the oscillatory electric signal. A detection circuit processes the hysteretic response signal to compute an envelope signal of the hysteretic response signal, perform a comparison of the envelope signal with a threshold, and produce a signal indicative of an increase or a decrease in the oscillation frequency of the oscillatory electric signal as a result of the outcome of the comparison.