Vacuum bulb for an electric cut-off device at least providing the function of a disconnecting switch

摘要

The bulb (A) has an envelope (1) with a fixed contact (13) mounted at center of the bulb by extending radially inside the bulb. Another fixed contact (16) is integrated to bottom (3) of the bulb. A movable contact (15) is slidingly mounted on another bottom (4) of the bulb. The fixed contacts are connected to ground and a source of an external circuit, respectively. The movable contact is displaced between two contact positions in contact with the fixed contacts. A support surface of the movable contact on the fixed contact (13) is in the shape of rising moon.