GB541235A - Improvements in or relating to a.c. electric circuit-breakers having arc-control devices - Google Patents

Abstract

541,235. Gas-blast switches. REYROLLE & CO., Ltd., A., and AMER, D. F. April 15, 1940, No. 6763. [Class 38 (v)] In a gas-blast switch employing a lateral discharge nozzle or vent, an auxiliary electrode is disposed in such a position that it lies in the path of the arc loop when bowed out into or through the nozzle by the blast, and with its length extending along the end of the loop so as to restrict the amount of looping. The blast may be externally produced and/or arc generated from solid material, and the arcing-contacts may be separable to a pre-determined short gap or alternatively bridged by a movable contact which transfers the are to one of the arcing- contacts, an isolator being provided in series with the arcing-contacts. The nozzle-throat should be small enough to provide an efficient blast, but large enough to allow the arc to loop through it; and in the case of:a metal nozzle, to prevent the arc striking on to the nozzle. In a form incorporating the invention of Specification 536,451, a lateral projection D of the main metal-clad insulating housing A, for the arcing contacts B<SP>1</SP>, C<SP>1</SP> and bridging-contact C, has an apertured insulating disc E extending across the interior of projection D and a rod-like auxiliary electrode F extends behind the disc with its length parallel to the shortest distance between the arcing-contacts. The disc may alternatively be of metal with a depending skirt to which the rod-like auxiliary electrode is attached, Fig. 4 (not shown). The latter may alternatively be attached to a nozzle-shaped metal part secured on the nozzle which is attached to a supporting insulator arranged as in Specification 541,236, Fig. 6 (not shown).