The present invention discloses a system for limiting a peak current of short-circuit current, which comprises a first a first high-frequency branch configured to provide a first high-frequency current to a first switch (1SKa) of a first phase branch of a three-phase AC when the first phase branch occurs a short-circuit, wherein the first high-frequency current is configured to cause a zero-crossing point of a short-circuit current to appear before a zero-crossing point of the three-phase AC; a second high-frequency branch configured to provide a second high-frequency current to a second switch (1SKc) of a second phase branch of the three-phase AC when the second phase branch occurs a short-circuit, wherein the second high-frequency current is configured to cause a zero-crossing point of a short-circuit current to appear before a zero-crossing point of the three-phase AC, a third phase branch of the three-phase AC connected in parallel with the first phase branch and the second phase branch and configured to always supply power. The present invention superimposes the high-frequency current on the original short-circuit current of the switch, thereby the total time from the arc generation to extinction at the zero-crossing point and then to the judgement by the control system is shorter than the time that the short-circuit current peak appears. Therefore, it can effectively lower the damage of the short-circuit current peak to the dynamic stability of the switch and lower the impact on system equipment.

The present disclosure provides a DC mechanical circuit breaker that can utilize two switches, one of which can generate zero-crossing with an alternate oscillatory circuit for the other one, which can be a conventional zero-crossing-based AC breaker and can be used in the main circuit. This is different from the conventional single-switch commute-and-absorb method currently used. The present disclosure shows that disclosed circuit breaker improves the fault current extinction and significantly reduces the voltage rate-of-change while creating the current zero-crossing faster compared to the available technology. Thus, disclosed circuit breaker is capable of interrupting high DC currents with minimal arc through a less expensive AC circuit breaker. Simulation and hardware results are provided to show the efficiency of the disclosed circuit breaker.

A heating device includes a heater, an AC-voltage input section between which an AC voltage is applied, a fuse, a switcher, an AC-voltage-abnormality detector configured to detect an abnormality of the AC voltage, a controller. The controller is configured to execute a current-flowing operation in a state in which connection of a first connection terminal to a second connection terminal is a non-connecting state. The current-flowing operation is an operation in which an electrical current flows through the heater. The controller is configured to execute a connecting process in response to detection of the abnormality of the AC voltage by the AC-voltage-abnormality detector detected in the middle of the current-flowing operation. The connecting process is a process of switching a connection of a first connecting point to a second connecting point from a non-connecting state to a connecting state.

A system for limiting a peak current of short-circuit current comprises a first high-frequency branch configured to provide a first high-frequency current to a first switch (1SKa) of a first phase branch of a three-phase AC when the first phase branch occurs a short-circuit; a second high-frequency branch configured to provide a second high-frequency current to a second switch (1SKc) of a second phase branch of the three-phase AC when the second phase branch occurs a short-circuit; and a third phase branch of the three-phase AC connected in parallel with the first phase branch and the second phase branch and configured to always supply power.

A solid state circuit breaker that may include a metal oxide varistor (MOV) that is connected in series to a thyristor, the MOV to clamp voltage of current flowing through the solid state circuit breaker; the thyristor including a gate to control flow of the current to the MOV along a first path to the MOV; a breakover diode to activate at a target voltage level to allow the current to flow to the MOV along a second path; and a Zener diode to close the gate and allow current to flow along the first path in response to the current on the second path.

A contactor apparatus and method for operating the contactor apparatus can include a contactor assembly with a contactor coil operably coupled to a contactor switch. One or more sensors can be provided in the contactor assembly adapted to measure one or more aspects of the contactor assembly. Based upon the measured aspects, a controller can initiate operation of the contactor switch to effectively toggle the contactor switch at a zero-crossing point along an alternating current waveform.

A circuit breaker comprises a solid-state bidirectional switch, a switch control circuit, current and voltage sensors, and a processor. The solid-state bidirectional switch is connected between a line input terminal and a load output terminal of the circuit breaker, and configured to be placed in a switched-on state and a switched-off state. The switch control circuit control operation of the bidirectional switch. The current sensor is configured to sense a magnitude of current flowing in an electrical path between the line input and load output terminals and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage on the electrical path and generate a voltage sense signal. The processor is configured to process the current and voltage sense signals to determine operational status information of the circuit breaker, a fault event, and power usage information of a load connected to the load output terminal.

The DC electrical network comprises an electrical load supplied with electricity by an electrical power source to which the electrical load is linked by a first electrical line and a second electrical line. An overcurrent protection system comprising an input pole and an output pole is mounted in series on the first electrical line. The overcurrent protection system comprises an electronic switch mounted in series between the input pole and the output pole, an electrical current sensor, and a controller configured to control the electronic switch. It also comprises an electronic device linked to the input pole and to the second electrical line. The controller is configured to command a conducting state of the electronic device when a current measurement from the electrical current sensor is above a predetermined current threshold, then to command an opening of the electronic switch.

The present disclosure describes a system and method for protecting an electronic device from high voltages that may exceed tolerance limits for circuitry within the electronic device. A protection circuit blocks high voltages from the device components through gating techniques. Such gating techniques may similarly be used to control whether power is received by the electronic components when an error condition is detected by a control unit.

A method for operating a circuit breaker includes: initiating a shutdown process when a fault current caused by body contact or ground contact is detected; and during the shutdown process, reducing a voltage value between a neutral conductor and at least one current-carrying conductor at an output of the circuit breaker to substantially zero from an operating-voltage value according to a predetermined shutdown curve by a shutdown unit. During the shutdown process, the circuit is not suddenly interrupted, but the voltage value is reduced from a starting point according to the shutdown curve and only reaches substantially zero after a predetermined first time period.