A gas circuit breaker comprises: a first arc contactor 21; a cylindrical second arc contactor 41; a rod-shaped trigger electrode 31 that is disposed to be movable between the first arc contactor 21 and the second arc contactor 41, and moves inside the cylindrical second arc contactor 41 to ignite an arc at the second arc contactor 41 in the latter half of the current break interval; and a guide portion 41b that has an inner diameter larger than the outer diameter of the trigger electrode 31, has an inner diameter smaller than the inner diameter of a portion of the second arc contactor 41 which is close to the trigger electrode 31, and is disposed in the cylinder of the second arc contactor 41 so as to go around the trigger electrode 31 when the trigger electrode 31 is in a closed state with the first arc contactor 21.

An object is to enhance direct-current insulating performance of a gas-blast circuit breaker. The gas-blast circuit breaker includes: a pair of main contacts disposed in a gas tank to face each other and configured to operate for opening and closing a circuit; a pair of arc contacts disposed to face each other and configured to operate for opening and closing the circuit, the arc contacts being disposed coaxially with the main contacts at locations close to the centers of the main contacts, respectively; and an elastic electrically conductive material disposed on an outer surface of an insulating nozzle facing an inner surface of one of the main contacts.

A gas circuit breaker includes a gas suppresser composed of a protruded portion which is formed on a horizontal surface facing an exhaust cylinder of a shaft guide and which forms a gap between itself 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 so that the shaft guide, which operates along an inner circumferential surface of the exhaust cylinder, which is provided to an inner circumferential portion of a movable side main conductor and is provided to outer circumferences of an exhaust shaft and an operation rod, and couples the operation rod with the exhaust shaft, is axially adjacent to a sliding member that slides along the exhaust cylinder with no space to the exhaust cylinder and suppresses discharge of heated and pressurized insulating gas.

There is provided a gas circuit breaker that can suppress the mechanical vibration during movement of the moving electrode, reduce the generation of a triple junction during operation of the gas circuit breaker and the generation of the metal foreign materials, and maintain the electrical insulation performance more reliably. A first arc contactor 21, a cylindrical second arc contactor 31, a bar-shaped trigger electrode 31 arranged to be movable between a first arc contactor 21 and a second arc contactor 41, and moving in the cylindrical second arc contactor 41 during the latter half of the current breaking action to ignite the arc to the second arc contactor 41, and a guide portion 41b having an inner diameter larger than an outer diameter of the trigger electrode 31, and the inner diameter smaller than an inner diameter of a portion of the second arc contactor which is close to the trigger electrode 31, and arranged in a cylinder of the second arc contactor 41 so as to circulate around the trigger electrode 31 when the trigger electrode 31 is in the closed state with the first arc contactor 21, are included.

An object is to enhance direct-current insulating performance of a gas-blast circuit breaker. The gas-blast circuit breaker includes: a pair of main contacts disposed in a gas tank to face each other and configured to operate for opening and closing a circuit; a pair of arc contacts disposed to face each other and configured to operate for opening and closing the circuit, the arc contacts being disposed coaxially with the main contacts at locations close to the centers of the main contacts, respectively; and an elastic electrically conductive material disposed on an outer surface of an insulating nozzle facing an inner surface of one of the main contacts.

While lowering sliding resistance of an exhaust cylinder and reducing effects on a circuit breaking operation, an amount of high temperature and high pressure gas discharged into an insulating support cylinder is reduced, and both ground insulation performance and circuit breaking performance are improved. To solve the above problem, a gas circuit breaker of the present invention is characterized by including a gas suppressing means composed of a protruded portion which is formed on a horizontal surface facing an exhaust cylinder of a shaft guide and which forms a gap between itself 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 so that the shaft guide, which operates along an inner circumferential surface of the exhaust cylinder, which is provided to an inner circumferential portion of a movable side main conductor and is provided to outer circumferences of an exhaust shaft and an operation rod, and couples the operation rod with the exhaust shaft, is axially adjacent to a sliding member that slides along the exhaust cylinder with no space to the exhaust cylinder and suppresses discharge of heated and pressurized insulating gas.

A switch includes a first contact and a second contact that are placed along an operating shaft and can reciprocate with respect to each other. An end of the second contact opposite to an end thereof on the side of the first contact is housed in a housing space of a housing box. The pressure in the housing space is increased due to an arc generated when the first contact approaches the second contact. The increased in the pressure causes the second contact to move toward the first contact.

A medium-, high-, or very high-voltage circuit breaker (10), comprising at least one arc-control chamber (12) and an outer casing (14) in which the arc-control chamber (12) is arranged. In the invention, the circuit breaker includes sealing ring (52) for sealing an opening (50) in a discharge cap (40) of the arc-control chamber (12), the ring (52) being movable between a sealing position and a retracted position in which they allow the gas to pass, the circuit breaker being configured in such a manner that in the closed position, the sealing ring (52) are in their retracted position, and in such a manner that passage from the retracted position to the sealing position takes place during an operation of opening the circuit breaker.

A switch includes a first contact and a second contact that are placed along an operating shaft and can reciprocate with respect to each other. An end of the second contact opposite to an end thereof on the side of the first contact is housed in a housing space of a housing box. The pressure in the housing space is increased due to an arc generated when the first contact approaches the second contact. The increased in the pressure causes the second contact to move toward the first contact.

A medium-, high-, or very high-voltage circuit breaker (10), comprising at least one arc-control chamber (12) and an outer casing (14) in which the arc-control chamber (12) is arranged. In the invention, the circuit breaker includes sealing ring (52) for sealing an opening (50) in a discharge cap (40) of the arc-control chamber (12), the ring (52) being movable between a sealing position and a retracted position in which they allow the gas to pass, the circuit breaker being configured in such a manner that in the closed position, the sealing ring (52) are in their retracted position, and in such a manner that passage from the retracted position to the sealing position takes place during an operation of opening the circuit breaker.