Liquid sf.sub.6 interrupter with proportional feedback

Abstract

A liquid SF.sub.6 interrupter is disclosed comprising a housing containing a pair of pistons operable for movement in tandem. Stationary and movable contact assemblies are disposed between the pistons. At the beginning of the opening stroke of the interrupter, the pistons are caused to begin moving in the same direction as the movable contact. The pistons and housing are so shaped and dimensioned that the movement of the pistons produces a high pressure and a low pressure region located respectively relatively near the stationary and the movable contacts. This causes SF.sub.6 to flow across the area between the contacts. An arc between the contacts heats the liquid adjacent it, increasing the liquid pressure. The pistons are so dimensioned that the pressure rise accelerates them, which in turn further increases the pressure differential and the flow of SF.sub.6 across the arc region. A small clearance is left between the pistons and the housing, so that no sliding seals are required. Leakage through the clearances is small enough not to hinder the operation of the interrupter. At the downstream end of the travel of each piston is a wide-bore area in which the housing-piston clearance is relatively great, allowing quick equalization of the pressure on the two sides of each piston at the end of the opening stroke.