Patent ID: 7763821

Claim:
A puffer-type gas blast circuit breaker comprising: an electrode section in which stationary side arc contact and moving side arc contact are disposed facing each other so as to come in contact with and go separating from each other, said electrode section being mounted on a stationary member supported in an insulating manner on an insulating support; a hollow piston rod and an insulating rod that are connected to said moving side arc contact so as to come in contact with and go separating from said stationary side arc contact, said connected hollow piston rod and insulating rod being inserted in a body portion of said stationary member; and a gas flow blocking member mounted on an end portion of said piston rod side of said insulating rod, said gas blocking member preventing an insulating gas heated by the arc generated at the time of breaking and coming to said stationary side from the hollow part of said piston rod from getting into said insulating rod side in an opening state of said circuit breaker; wherein said body portion of the stationary member is formed to be cylindrical so that a gap between said body portion of the stationary member and said gas flow blocking member is minimized within the operation range of said gas flow blocking member, said body portion including a gas flow discharge port which is positioned on a same side as a heated gas discharge port of said piston rod with respect to said gas flow blocking member when said gas blast circuit breaker is in a closed state.