GAS-INSULATED VACUUM BREAKER

摘要

A gas-insulated vacuum breaker configured in such a manner that the pressure in an intermediate-pressure space does not rise to an abnormal pressure value, the intermediate-pressure space being formed to reduce the difference between the inner and outer pressures which acts on a bellows due to a minute leakage from an air-tightness holding section. A pressure monitoring closed chamber (23) is formed on the closed container (37) side filled with an insulative gas, and insulated piping (19) connects the pressure monitoring closed chamber (23) and an intermediate-pressure space (18) which is formed in order to cause an intermediate pressure to act, on the basis of the operation of a movable electrode (5), on a bellows (8) on the surface thereof which is on the opposite side of the vacuum container (2), the bellows (8) retaining the vacuum in the vacuum container (2). The pressure monitoring closed chamber (23) is provided with a pressure monitoring and controlling means for monitoring the pressure in the chamber and performing control for opening the chamber when the pressure exceeds a predetermined set value. The pressure monitoring and controlling means comprises an electromagnetic valve device (28) capable of releasing the inside of the pressure monitoring closed chamber (23) to the atmosphere, a pressure detection device (26) for detecting the pressure in the chamber, and a pressure monitoring device (27) for operating and opening the electromagnetic valve device (28) when the pressure detection device (26) detects a previously set abnormal pressure value.