A switching unit for controlling at least one switching element, includes a control unit adapted to control the at least one switching element; a connection for applying a supply voltage for power supply of the control unit; an energy storage connectable to the connection for applying a supply voltage and adapted, when the supply voltage drops or fails, to supply the control unit with power that is sufficient to control the at least one switching element such that the switching element executes a predetermined switching operation; wherein the switching unit includes means for monitoring the operability of the energy storage. Furthermore, a method for controlling at least one switching element using the switching unit.

In the field of power distribution networks, a digital output circuit, for controlling an item of equipment within a power distribution network, comprises a switch element openable and closeable to selectively permit the flow of current to an item of equipment being controlled in use by the digital output circuit. The digital output circuit also includes a current acquisition circuit to measure the current flowing through the switch element. In addition, the digital output circuit includes a condition monitoring circuit that is arranged in communication with the current acquisition circuit. The condition monitoring circuit is configured to record the measured current flowing through the switch element as the switch element closes and thereby establish a switch element closing signature.

In a thermal protection circuit with two electrical connection terminals for an electrical device to be protected from overheating and at least one temperature-dependent switch, at least one electronic semiconductor switch for DC voltage is arranged.

A relay system is provided which is designed to avoid flow of inrush current through a capacitor in a pre-charge mode wherein the capacitor is pre-charged. The relay system includes a pair of power lines, a capacitor, a series-connected assembly, a control circuit, and a relay module. The relay module includes two main switches, a main coil, and a sub-coil. In the pre-charge mode, the control circuit energizes both the main and sub-coils to turn on only one of the main switches. Before entering the pre-charge mode, the control circuit diagnoses the sub-coil. When the sub-coil is determined as being malfunctioning, the control circuit inhibits the pre-charge mode from being entered.

Disclosed embodiments relate to a DC circuit breaker and a circuit breaking method thereof which comprises: a measuring portion for measuring a DC current conducted through a first circuit portion; the first circuit portion for conducting and blocking the DC current; and a second circuit portion for conducting and blocking the DC current which is bypassed from the first circuit portion and controlling the open/close operation of the first circuit portion according to a measuring result of the measuring portion, wherein, in the first circuit portion and the second circuit portion, switching elements, which are included in each of them, are connected in a parallel configuration such that a high switching operation during a blocking operation can be improved and the DC current can be blocked in a safer and more efficient manner, and a circuit breaking method of the DC circuit breaker.

A switching device for switching bipolar DC currents in a high-voltage system includes at least two electromechanical switching units and a semiconductor switching arrangement. The electromechanical switching units have a first switching status and a second switching status. In the first switching status, the DC current can be passed via at least one of the electromechanical switching units without in this case flowing via the semiconductor switching arrangement. In the second switching status of the electromechanical switching units, the DC current can be passed via the semiconductor switching arrangement and can be switched off.

A circuit-breaker device, comprising a main branch and an auxiliary branch electrically in parallel with the main branch, wherein the main branch comprises at least one mechanical switch-disconnector in series with a breaker cell constituted of at least one semiconductor switch, and a snubber circuit in parallel with the at least one breaker cell, the snubber circuit including an energy storage element, wherein the mechanical switch-disconnector is switchable to selectively allow current to flow in the main branch in a first mode of operation or commutate current from the main branch to the auxiliary branch in a second mode of operation, characterized in that the snubber circuit further comprises a bleeder resistor arranged to create a counter current in the main branch when current is commutated from the main branch to the auxiliary branch by discharging the energy storage element.

A current limiting device is provided. To elaborate, the device may include: a first current limiting unit configured to limit an electric current equal to or higher than a first threshold value applied thereto; a second current limiting unit configured to limit an electric current equal to or higher than a second threshold value applied thereto; and a passive element unit connected to both ends of the first current limiting unit, and including a first passive element and a second passive element connected in series.

A dual conductor Thomson coil actuator for use in opening the separable contacts of a circuit interrupter comprises two nested conductors wound to form a single coil, rather than the traditional design comprising one single conductor wound to form a coil of the same size. Each of the two conductors can be excited by half the capacitance that would be used to excite the traditional single conductor coil, using the same voltage as the single conductor coil. When the same total capacitor-stored energy that would be used to excite the single conductor coil is instead used to excite the dual conductor coil, the initial pulse of aggregate current through the dual conductor coil is greater than the initial pulse of current through the single conductor coil, resulting in a faster initial opening distance of the separable contacts during an opening stroke.

An AC switch that includes a semiconductor switch and a snubber circuit connected in parallel between a first terminal connected to an AC power supply via a circuit breaker and a second terminal connected to a load. The power converter is connected between a power storage device and the second terminal. The current detector detects a current flowing through the AC switch. When the AC power supply is normal, the controller turns on the semiconductor. When an open state of the circuit breaker is detected, the controller controls the power converter to supply a current having a phase opposite to that of the current detected by the current detector to flow through the semiconductor switch and supply the AC power to the load. The controller further turns off the semiconductor switch in response to that the amplitude of the current detected by the current detector is 0.