Gas-blast switch

Abstract

A movable, tubular-shaped contact element is displaceably guided in a partition wall subdividing the internal space of the gas-blast switch housing into an extinguishing chamber and an expansion chamber. During the cut-off stroke a current connection prevails by means of this contact element between both of the chambers or compartments. The contact element coacts with a stationary or fixed contact set having a rim of rated current contacts which, in the cut-on position, engage about the contact element. Further, there is provided a burn-off ring which is electrically connected with the contact element and has an electrically insulated, suspended intermediate electrode which, in the cut-on position, engages into the contact element or piece. The latter, during the cut-off stroke, initially comes out of engagement with the rated current contacts and first thereafter comes out of engagement with the intermediate electrode. In order to ensure that the part of the switching arc which burns between the burn-off ring and the intermediate electrode remains at this location and that its other part, even in the presence of low currents, is sufficiently blown, the burn-off ring is arranged within the rim of rated current contacts and is rearwardly inset with respect to the contact surfaces thereof, and furthermore, a pump device is coupled with the movable contact element. This pump device, during the cut-off stroke, conveys extinguishing gas out of the region of the extinguishing chamber which is remote from the separation path to the separation path.