Direct-current circuit breaker

A direct-current circuit breaker that creates a current zero point by superimposing a resonance current on a direct current flowing along a direct-current line and interrupts the direct current at the current zero point, the direct-current circuit breaker comprising:

• a first breaker that is inserted into the direct-current line and becomes a path for the direct current when in a steady state;
• a resonance circuit that is connected in parallel with the first breaker and superimposes a resonance current on the direct current after the first breaker is opened;
• a second breaker that is connected at one end to a first connection point where the first breaker and the resonance circuit are connected and that forms a path for the direct current together with the first breaker when in a steady state;
• and
• a third breaker that is connected at one end to a second connection point where the first breaker and the resonance circuit are connected and that forms a path for the direct current together with the first breaker and the second breaker when in a steady state, wherein
• the resonance circuit includes
• a series circuit that includes a capacitor and a reactor and generates the resonance current,
• a charging resistor that is used for charging the capacitor with a direct-current potential of the direct-current line when in a steady state,
• a high-speed switch that is connected in series with the series circuit on the capacitor side and superimposes the resonance current on the direct current after the first breaker is opened, and
• an arrester that is connected at one end to the first connection point and is connected at another end to a connection point where the capacitor and the reactor are connected, that is connected in parallel with the capacitor and the high-speed switch, and that limits a current flowing into the capacitor from the direct-current line, and
• the second breaker or the third breaker is opened after the direct current is interrupted by superimposing the resonance current on the direct current.