space formed by the insulating housing 301 the movable end cap 302 and the stationary end cap 303 and the inner part of the closed space is in the vacuum state a movable conductive rod 305 passes through the movable end cap 302 to allow one end of the movable conductive rod 305 to be disposed inside the closed space and the other end of the movable conductive rod 305 to be disposed outside the closed space and the movable conductive rod 305 is capable of moving upward and downward the end of the movable conductive rod 305 disposed inside the closed space is nested within a bellows 304 and comprises an end point being fixed together with a movable contact 311 one end of the bellows 304 is fixed on the movable end cap 302 and the other end of the bellows 304 is fixed on the movable conductive rod 305 a stationary conductive rod 306 passes through the stationary end cap 303 to allow one end of the stationary conductive rod 306 to be disposed inside the closed space and the other end of the stationary conductive rod 306 to be disposed outside the closed space a stationary contact 312 is fixed on an end point of the end of the stationary conductive rod 306 disposed inside the closed space the movable.