Vacuum switching apparatus with a drive unit at ground potential

In a vacuum switch apparatus including a switching vessel operable at and including parts at high potential, and a drive unit at ground potential equipped with a drive assembly for actuating the switch of the switching vessel, the drive assembly comprising:

• an actuating lever made of insulating material extending between the drive unit and the switching vessel;
• an electrically conductive bearing pin for pivotally supporting said lever, said electrically conductive bearing pin being mounted in said apparatus between said switching vessel and drive unit and being at a potential intermediate said high potential and said ground potential;
• a cover mounted on said switching vessel to define an enclosed space with respect to said parts of the switching vessel, said lever being connected to said switching vessel at one of said parts thereof, said electrically conductive bearing pin and the portion of said lever connected to the switching vessel being contained within said cover;
• a housing for accommodating the switching vessel therein, said electrically conductive bearing pin being mounted in said housing, and said cover being a removable part of the housing, said housing having an opening formed therein for accommodating the passage therethrough of the portion of said lever extending to the drive unit;
• and
• a membrane-like insulating and sealing member arranged at said opening in surrounding relation to said lever, whereby said space in said cover is maintained as a dust-free, dry zone.