GB398207A - Improvements in or relating to electric alternating current circuit breakers - Google Patents

Abstract

398,207. High-tension switches; arcrupturing in switches. WHITNEY, W. B., WEDMORE, E. B., and BRITISH ELEC-, TRICAL & ALLIED INDUSTRIES RESEARCH ASSOCIATION, 36, Kingsway, London. March 1, 1932, Nos. 22721/33 and 22722/33. Divided on 398,213. [Class 38 (v).] A fluid-blast circuit-breaker has means for lengthening the arc close to, substantially parallel with, and alongside a conductor, for example a contact, and magnetizable material is arranged in said conductor whereby a field is produced which tends to force the arc against the conductor to counteract the effects of the arc-lengthening means and to minimize extension of the arc. The movable contact 19 is split at 38 to ensure resilient contact with the fixed contact 37, which is shaped so as to guide the fluid blast from the port 20 inwardly to the arc. The contact 19 is also engaged by a spring-pressed brush 18 mounted on a ring 15, both the latter and the contact 37 being provided with a peripheral groove into which is inserted a stack of soft iron plates 38a, which may be mutually insulated and U-shaped in plan, Fig. 2. The action of the plates is to resist the tendency of the fluid blast to bow the are formed between 19, 37 into the hollow contact 37 or the ring 15, by setting up a magnetic field which forces the arc against the side of the corresponding contact. In Fig. 3, the fixed contact 39 is a radially-split ring held by a spring 40, and an additional fixed contact 45, through which the movable contact 44 loosely passes, is carried on a cone 46 carrying fingers 48 as disclosed in Specification 398,249. The upper face of the cone 46 is segmented and provided with radial insulating inserts, as disclosed in Specification 398,213, and a conducting spiral 49 serves as a cooling grid. In opening, when the tip of contact 44 is below the top surface of 45, the arc is transferred thereto, but any tendency of the fluid blast to lengthen the arc, as described with reference to Fig. 1, is resisted by inserts 50, 51 of magnetic material. The distance between 45 and 39 is preferably substantially equal to the diameter of the outlets therein. The first Provisional Specification refers to Specifications 278,764, 330,616, [both in Class 38 (v), Electric switches &c.], 366,998, 375,309, and 378,493.