Gas circuit breaker

A gas circuit breaker comprising:

• a filling container filled with insulating gas having arc-extinguishing properties;
• a movable side main conductor which is supported and fixed by an insulating support cylinder arranged inside the filling container, is connected to a movable side lead-out conductor connected to an electric power system, and has an exhaust hole for exhausting insulating gas heated and pressurized by an arc generated when a current is broken;
• an exhaust shaft which is provided movably in an axis direction of the movable side main conductor inside the movable side main conductor and has a shaft exhaust hole for exhausting the heated and pressurized insulating gas;
• an operation mechanism which is coupled to the exhaust shaft and outputs an operation force in an axis direction of the exhaust shaft through an operation rod;
• an exhaust cylinder which is provided to an inner circumferential portion of the movable side main conductor and is provided to outer circumferences of the exhaust shaft and the operation rod;
• a shaft guide which couples the operation rod with the exhaust shaft and operates along an inner circumferential surface of the exhaust cylinder;
• a cylinder which is coaxially coupled to the exhaust shaft and can slide in the axis direction on an inner circumferential surface of the movable side main conductor;
• a puffer piston which is fixed to inside of the movable side main conductor and has an opening portion that opens in the axis direction of the movable side main conductor and where the exhaust shaft can slide on an inner circumferential surface of the opening portion;
• a movable contact which is electrically connected to the movable side lead-out conductor;
• a fixed contact which is electrically connected to a fixed side lead-out conductor connected to the electric power system and is attachable to and detachable from the movable contact;
• and
• a sliding member which is mounted on the shaft guide and slides along the exhaust cylinder with no space to the exhaust cylinder, wherein
• the shaft guide includes a gas suppressing means, which suppresses discharge of the heated and pressurized insulating gas, adjacent to the sliding member in an axis direction, and
• the gas suppressing means is composed of a protruded portion which is formed on a horizontal surface facing the exhaust cylinder of the shaft guide and which forms a gap between the protruded portion and the exhaust cylinder, and an enlarged portion which is adjacent to the protruded portion and where a gap to the exhaust cylinder is enlarged.