Liquid SF.sub.6 interrupter with arc energy driven piston and contact

A circuit interrupter, comprising:

• a housing containing a substantially incompressible dielectric material in the liquid phase at a pressure higher than the pressure immediately surrounding said housing;
• stationary contact means in said housing;
• movable contact means in said housing and movable therein between an engaged position, in which it engages said stationary contact means, and a disengaged position, in which it is physically spaced from and electrically isolated from said stationary contact means;
• stationary piston means in said housing;
• movable piston means secured to aid movable contact means and having a bore in which said stationary piston means is slidably received;
• the interior of said bore communicating with a region between said stationary and and said movable contact means to cause fluid flow into said region when said movable contact means is displaced from its said engaged position;
• said movable piston means having a piston member which has a first face exposed to said pressure of said dielectric material in the interior of said housing and having a second face exposed to said lower pressure immediately surrounding said housing;
• sliding seal means disposed between said movable piston means and said stationary piston means for preventing flow of fluid between the volumes which include said first and second faces during contact interruption;
• and
• control means for maintaining said movable contact means in said engaged position to maintain a current therethrough, and for releasing said movable contact means to allow it to move from said position engaged toward said disengaged position for interrupting a current flowing through said interrupter.