Vacuum circuit breaker

A vacuum circuit breaker comprising:

• a grounded tank hermetically containing an insulating gas, the grounded tank being tubular;
• a vacuum valve insulated and supported inside the grounded tank, the vacuum valve including a movable contact and a stationary contact;
• a movable conductor electrically connected to the movable contact;
• a stationary conductor electrically connected to the stationary contact;
• a movable-side external conductor and a stationary-side external conductor disposed in a pair of bushings extending upward from the grounded tank;
• a movable-side frame electrically connecting a lower end of the movable-side external conductor to the movable conductor;
• a stationary-side frame electrically connecting a lower end of the stationary-side external conductor to the stationary conductor;
• an insulating operation rod connected to an operating device disposed outside the grounded tank to operate the movable contact;
• a movable-side insulating support tube to support the movable-side frame and insulates thereof from the grounded tank;
• a stationary-side insulating support tube to support the stationary-side frame and insulates thereof frame from the grounded tank;
• a movable-side flange covering a movable-side end of the grounded tank, the movable-side flange including a hole allowing passage of the movable-side insulating support tube;
• and
• a flexible member on an inner peripheral surface of the movable-side flange, wherein
• an arc-extinguishing chamber is formed by connecting:
• the movable-side insulating support tube;
• the movable-side frame;
• the vacuum valve;
• the stationary-side frame;
• and
• the stationary-side insulating support tube, and the arc-extinguishing chamber is housed in the grounded tank, and
• the movable-side insulating support tube is supported, at an end opposite from an end connected to the movable-side frame, by the movable-side flange via the flexible member and is movable along an axial direction and a radial direction of the arc-extinguishing chamber.