A signal generation module injects a signal in a pilot conductor with a DC component and one or more AC components. Pilot conductor current is injected in a grounding conductor of power cables connecting power source to load. A current monitor module monitors current in the pilot conductor or ground return, a DC detection module determines DC current present in the monitored current, an AC detection module determines AC current corresponding to each frequency of the AC components in the monitored current, a DC minimum threshold module determines if the DC current is below a DC current minimum threshold, an AC threshold module determines if any of the AC currents is below an AC threshold, and a trip module opens a contact after determining that the DC current is below the DC current minimum threshold or that at least one of the AC currents is below an AC threshold.

A device for generating a virtual neutral point includes a first terminal, a second terminal and a third terminal connectable respectively to a first phase, a second phase and an earth node of a multiphase power grid. A control circuit is connected to the first, second and third terminals and is configured to maintain a constant value of the electrical potential of the third terminal in response to a disturbance signal generated on the third terminal by a low voltage load; the control circuit includes a storage stage and a control stage operatively interposed between the storage stage and the third terminal and configured for drawing energy from the first storage device when the electrical potential of the third terminal falls below a reference value and drawing energy from the second storage device when the electrical potential of the third terminal rises above a reference value.

A device for generating a virtual neutral point includes a first terminal, a second terminal and a third terminal connectable respectively to a first phase, a second phase and an earth node of a multiphase power grid. A control circuit is connected to the first, second and third terminals and is configured to maintain a constant value of the electrical potential of the third terminal in response to a disturbance signal generated on the third terminal by a low voltage load; the control circuit includes a storage stage and a control stage operatively interposed between the storage stage and the third terminal and configured for drawing energy from the first storage device when the electrical potential of the third terminal falls below a reference value and drawing energy from the second storage device when the electrical potential of the third terminal rises above a reference value.

A detecting apparatus for a circuit breaker and a circuit breaker are provided. The detecting apparatus includes: a micro control unit including an analog-to-digital conversion port and a digital-to-analog conversion port; and a zero-sequence current transformer coupled in a line of the circuit breaker and including: an induction coil encircling the line of the circuit breaker; a detection winding coupled to the induction coil and connected to the analog-to-digital conversion port, so as to induce an induction signal from the induction coil at least during a leakage period or a leakage detection period and send a leakage signal related to the induction signal to the analog-to-digital conversion port; and a self-detection winding coupled to the induction coil and connected to the digital-to-analog conversion port, so as to receive a self-detection signal sent by the micro control unit via the digital-to-analog conversion port to perform a leakage detection.

A detecting apparatus for a circuit breaker and a circuit breaker are provided. The detecting apparatus includes: a micro control unit including an analog-to-digital conversion port and a digital-to-analog conversion port; and a zero-sequence current transformer coupled in a line of the circuit breaker and including: an induction coil encircling the line of the circuit breaker; a detection winding coupled to the induction coil and connected to the analog-to-digital conversion port, so as to induce an induction signal from the induction coil at least during a leakage period or a leakage detection period and send a leakage signal related to the induction signal to the analog-to-digital conversion port; and a self-detection winding coupled to the induction coil and connected to the digital-to-analog conversion port, so as to receive a self-detection signal sent by the micro control unit via the digital-to-analog conversion port to perform a leakage detection.

A system for remote locating earth fault in a multi-phase power grid powered by a power source, at least one remote detector arranged in the power grid not communicatively connected to the control unit wherein each remote detector has a unique current pattern identity. The control unit, when in a remote earth fault detection mode, is configured to adjust a voltage from the alternating voltage source with respect to the determined earth fault impedance RF and a corresponding delta angle step X to generate a zero-sequence current pattern based upon said impedance and said delta angle step X, wherein each detector is configured to identify a zero-sequence current pattern, and to determine which remote detector has a unique current pattern identity that corresponds to the identified current pattern.

A circuit interrupting device including a phase conductor, a neutral conductor, an interrupter configured to disconnect the phase conductor and the neutral conductor from a load, and a sensor configured to generate a signal indicative of current flowing through the phase conductor and the neutral conductor. The circuit interrupting device further includes a microcontroller that includes an electronic processor and is electrically connected to the first sensor and the interrupter. The microcontroller is configured to generate a reference signal, receive a first signal from the sensor, determine whether a difference between a voltage of the first signal and a voltage of the reference signal exceeds a threshold, determine whether the microcontroller has performed a ground fault self-test, and activate the interrupter when the difference exceeds the threshold and the microcontroller has not performed the ground fault self-test.