Patent ID: 8030590

Claim:
A gas-circuit breaker that extinguishes an arc that is generated at a contact upon current interruption by blowing arc-extinguishing gas on the arc that is held in a container, the gas-circuit breaker comprising: a stationary contact that includes a stationary arc-contact and that is fixed to a first side of the container; a moving rod that extends towards a second side of the container; and a moving contact that is arranged on one end of the moving rod so that the moving contact faces the stationary contact, and includes a moving arc-contact that electrically contacts and separates from the stationary arc-contact due to movement of the moving rod, wherein the moving contact includes a cylinder that is fixed to the one end of the moving rod, and includes a gas exhaust on one side that is facing the stationary contact, and an opening on another side, the moving rod being inserted in the cylinder; a stationary piston that is fitted into the opening of the cylinder and fixed on the second side of the container, and creates a puffer chamber inside the cylinder; a moving piston that is fitted in the puffer chamber and divides the puffer chamber into a first puffer chamber and a second puffer chamber on stationary piston side, and slides according to a difference in pressure in the first puffer chamber and the second puffer chamber; and a stopper arranged to regulate sliding distance of the moving piston from the first side, wherein the first puffer chamber functioning as a thermal puffer chamber at a large interruption current to blow the arc-extinguishing gas on the arc through a gas exhaust of the first puffer chamber due to a pressure rise caused by a thermal expansion of the gas in the first puffer chamber, and functioning as a mechanical puffer chamber at a small interruption current to blow the arc-extinguishing gas on the arc through the gas exhaust of the first puffer chamber due to a mechanical pressure of the stationary piston.