High-voltage DC current breaker and high-voltage DC current breaking method

A DC current breaker for breaking a DC current at the time of occurrence of an accident, comprising:

• a main conduction unit including a commutate switch, a protection switch, and a close/open switch which are connected in series to each other in this order on a main conduction path where a current is flowed in a normal operation state, the protection switch protecting the commutate switch, and the close/open switch finally breaking a flow of a current of the main conduction unit;
• a power semiconductor switch connected in parallel to the commutate switch;
• a capacitor connected in parallel to the commutate switch and the protection switch;
• and
• a surge arrester connected in parallel to the capacitor,
• wherein the commutate switch is a mechanical switch having a rated voltage which is lower than rated voltages of the protection switch and the close/open switch,
• wherein an opening response characteristic of the commutate switch is faster than opening response characteristics of the protection switch and the close/open switch, so that an arc voltage is more speedily increased than those of the protection switch and the close/open switch,
• wherein the capacitor has electrostatic capacitance so that, when a transient voltage applied at the time point when a current of the main conduction path is broken by the power semiconductor switch is shared by the protection switch and the commutate switch, a magnitude of a transient voltage across the protection switch and the commutate switch does not exceed a limit value of a withstand voltage of the power semiconductor switch.