Puffer type gas-insulated circuit breaker

A gas-insulated circuit breaker for opening and closing an electric circuit comprising:

• a stationary electrode;
• a movable electrode movable into and out of contact with said stationary electrode;
• gas compression means for causing an insulating gas to flow when said movable electrode separates from said stationary electrode;
• cover means for covering said movable electrode;
• and
• nozzle means for forming, in cooperation with said cover means, a passage for introducing said insulating gas from said gas compression means to an arc occurring between said stationary electrode and said movable electrode when said movable electrode moves out of contact with the stationary electrode,
• wherein at least said cover means is made of an insulating material containing a filler for preventing energy lines of the arc from entering said cover means, said cover means being shaped so as to cover an outer periphery of the movable electrode and a front end thereof disposed in opposition to the stationary electrode, and
• wherein the cover means has a specific inductive capacity greater than a specific inductive capacity of the nozzle means.