GAS BLAST SWITCH

The gas blast switch of the invention has an insulating housing which is divided into an arcing enclosure for an auxiliary arc intended to build up the pressure, a storage enclosure for storing fresh quenching gas, a quenching enclosure meant for the quenching of the main arc, and an expansion enclosure. An axially movable insulating follower piston is provided within the fixed contact piece. During switching-on, it is pushed into its resting position through the action of the movable contact piece and against the force of a spring. During switching-off, it will follow the movable contact piece until the latter leaves the dividing wall, whereupon the piston stops, thus closing the aperture in the dividing wall which connects arcing and quenching enclosures. An electrically conductive ring forms the mouth of the aperture and acts as an arcing electrode between the auxiliary arc and the main arc. During a switch-off with quenching action, the pressure built up by the auxiliary arc drives fresh gas from the storage enclosure into the quenching enclosure.