Detecting reduction in degree of vacuum of vacuum switching valve - determining discharge current caused by bulge, e.g. in protective shield, whilst holding shield at same potential as electrodes

摘要

The method involves maintaining a function protection shield (4) at the same potential as a movable (3) and a stationary (2) electrode and detecting a discharge current induced by a bulge (10) in the outer surface of the shield or in the inner surface of an insulating container (5) when the degree of vacuum is reduced. The discharge current is detected by a current sensor (14) and used as a measure of the reduction in the degree of vacuum of the vacuum switching valve (1). USE/ADVANTAGE - For use with valve in vacuum overload circuit or vacuum protection switch. Enables reduction in degree of vacuum of valve to be determined during operation without degrading reliability of valve.