Patent ID: 7919720
Filing Date: 2011-04-05
Classification: H01H

Abstract:
1. An earthing switch comprising: a container filled with insulating gas; a stationary contact unit firmly secured to an interior of the container; a movable contact unit, an end of which is capable of moving toward or away from the stationary contact unit; a lever coupled with other end of the movable contact unit; a puffer cylinder that is arranged coaxially around the movable contact unit; a puffer piston integrated with the movable contact unit and defines an arc cancelling chamber in conjunction with the puffer cylinder, wherein the puffer piston slides along the inner wall surface of the puffer cylinder in the axial direction so as to exert a puffing function when the movable contact unit is retracted from the stationary contact unit by expanding the arc cancelling chamber to cause insulating gas to be drawn into the arc cancelling chamber through a clearance between the movable contact unit and the stationary contact unit wherein insulating gas flowing through the clearance exerts the puffering function, and also to exert the puffing function when the movable contact unit is moved toward the stationary contact unit by contracting the arc cancelling chamber to cause insulating gas in the arc cancelling chamber to blow out from the arc cancelling chamber and pass through a clearance between the movable contact unit and the stationary contact unit; and a release mechanism that releases pressure stored in the puffer type arc cancelling chamber by releasing the pressure when the movable contact lies within a predetermined region of its movement during a full stroke extent of the movable contact unit so that the puffering function is terminated when the movable contact unit lies within that predetermined region.