A switching device includes: two interrupter units connected in series; at least one drive unit for moving at least one contact; and two control capacitors, each of which is connected in parallel with the interrupter units. At least one control capacitor has mechanically movable components for changing the capacitance, and at least one of these components is mechanically coupled to the drive unit.

A DC circuit breaker system includes a first mechanical switch, a first parallel capacitor connecting a first terminal and a second terminal of the first mechanical switch, a second mechanical switch in series with the first mechanical switch, a second parallel capacitor connecting a first terminal and a second terminal of the second mechanical switch, a first diode connecting the first terminal and the second terminal; and a second diode connecting the first terminal and the second terminal. The first mechanical switch separates contacts in response to a fault current; the second mechanical switch separates contacts in response to the fault current; and opening the first and second mechanical switches and turning off the first and second diodes reverses current flow and clears a current fault. The DC circuit breaker system may also be equipped with a surge arrestor at its input and a freewheeling diode at its output.

An arc-extinguishing apparatus includes a first device, main loop electrodes of the first device include a first electrode and a second electrode; and a switch, which needs to be subjected to arc extinguishing and includes a first end, a second end and a contact bridge, the first electrode and the second electrode are respectively configured to connect to the first end and the second end. The apparatus further includes a capacitor and a first voltage detection switch, the first voltage detection switch and a third electrode and the second electrode of the first device constitute a first series circuit, the contact bridge and the second end constitute a second series circuit, the first series circuit is connected in parallel to the second series circuit, and the capacitor is connected in parallel to the second series circuit.