Load break device with arc-extinguishing material

Claim 1

An arc-interrupting gas-actuated circuit maker and breaker device comprising, in combination, a first hollow electrically insulating member having a closed and an open end and defining a chamber, a first electrode at said closed end of said hollow member, an electrically conductive piston slidably mounted in said first hollow member for axial movement in said chamber relative to said first electrode and being always electrically connected to said first electrode during said movement, said piston having an elongated passage formed therein opening on opposite ends thereof, a second hollow electrically insulating member movable toward the open end of said first hollow member and into fluid tight engagement therewith, a second elongated electrode secured at one end to said second hollow member and projecting therefrom at its opposite end, said second electrode being movable toward and into engagement with said electrically conductive piston, whereby an arc may be formed between said second electrode and said piston prior to engagement thereof, and means on at least one of said piston and said second electrode comprising gas-evolving arc-extinguishing material for producing an arc-quenching gas in the presEnce of an electrical arc, whereby an arc formed between said piston and said second electrode generates gas which passes through said passage in said piston to the end thereof remote from said second electrode and exerts a thrust on said piston for moving the latter rapidly toward electrical contact with said second electrode, said arcextinguishing material comprising a mixture of cyclo-aliphatic epoxy resin and about 25-65 percent by weight of hydrated alumina.