Abstract: A gas-blast load-break switch comprises a pressure storage chamber for storing pressure of arc-extinguishing gas with arc energy generated by the disconnection between contacts, and a suction chamber including a piston which is moved in connection with the cut-off movement of the movable contact. A gas flowing device is provided such that the pressure raised by the arc energy is stored in the pressure storage chamber before communicating the pressure storage chamber and the suction chamber and a gas chamber formed on the opposite side of the piston from the suction chamber. The volume of the gas chamber is greater than that of the pressure storage chamber and the suction chamber, and the distance of piston movement in the suction chamber is longer than the contact length when the movable contact is thrown into the fixed contact.

Abstract: A gas insulated switchgear system having two gas insulated switchgear equipments, each of which consists of first disconnecting switches, circuit breakers, and second disconnecting switches, three phase gas insulated buses which are respectively connected to the first disconnecting switches of the two gas insulated switchgear equipments in every three phases thereof, a single phase reserve buses which are commonly connected to all of the second disconnecting switches of the two gas insulated switchgear equipments, and an operating device for opening the circuit breakers and the first disconnecting switches in only one phase of the gas insulated switchgear equipments and closing the second disconnecting switch in only the one phase. A gas insulated switchgear system having single phase reserve bus is economical and switches one of the three phase main buses to the single reserve bus without forming short circuit.

Abstract: Gas-insulated switchgear equipment includes a plurality of vertical-type circuit breakers electrically connected in series, and outside led-out devices connected to connected portions of a series connection of the circuit breakers and at least one main bus bar connected to two of the plurality of circuit breakers located at both ends of the series connection. In the equipment, the circuit breakers are a vertical type circuit breaker and are arranged on a substantial straight line and led-out portions for leading out terminals formed in the circuit breakers in a direction perpendicular to a direction of the arrangement of the circuit breakers, and connecting bus bars interconnecting the circuit breakers in series and the outside led-out devices are disposed on one side of the circuit breakers and the at least one main bus bar is disposed on the other side of the circuit breakers.

Abstract: A gas-insulated switchgear apparatus including a three-phase circuit breaker, a three-phase disconnecting switch and a cable head, with the disconnecting switch and the cable head being accommodated in a cable head housing. To minimize the size of the disconnecting switch, movable insulators, connected to movable conductors, and stationary insulators, supporting connecting conductors, are arranged so that the movable and stationary insulators form triangles disposed substantially in the same plane with the respective triangles being inverted in relation to each other.

Abstract: A gas insulated switchgear equipment in which three circuit breakers are electrically connected in series between two main bus bars. The two main buses are parallelly mounted on a fixing base. The three circuit breakers are arranged on one side of the main buses and aligned in the axial direction of the main buses. Connecting buses for electrically connecting the circuit breakers are provided on one side of the circuit breakers where the main bus bars are also disposed. Thus, the circuit breakers are accessible from the other side thereof for their maintenance and inspection and the equipment mounting area can be minimized because the main buses are disposed in parallel.

Abstract: In a circuit breaker having puffer type circuit breaking units housed within a tank of metal material, an inspection opening is formed in the tank side wall at a position opposite to a contact assembly in each of the circuit breaking units and is tightly closed by a detachable cover.