GB565877A - Improvements in or relating to electric switchgear - Google Patents

Abstract

565,877. Switchgear structures. REYROLLE & CO., Ltd., A., CHRISTIE, J., and ALLAN, A. April 29, 1943, No. 6795. [Class 38 (v)] A switchgear structure employing an airblast or " low-oil " switch as the main circuitbreaker, has the latter screened against accidental contact and mounted over the housing of the metal-clad associated parts to which at least one of its poles is connected by a conductor passing into the housing. The latter comprises, in Figs. 1 and 3, a compartmented metal housing A, the feeder B entering compartment A<1> and being connectible to one breaker-terminal E<1> by cable isolator B<2>. Current and voltage transformers C, D and an isolator D<1> for the latter are also housed in A<1>. The duplicate bus-bars F, F<1> in compartments A<2>, A<3> are connectible by switches F<2>, F<3> of the type set out in Specification 472,656, alterna- . tively to earthing contact F<8> or to contacts G<1>, G<2> on a post insulator G serving as one pole of an air-break isolator G<3>. The low-oil type breakers E have insulating containers E<2> and metal housing E<3> for a fixed contact and explosion pot E<4>, such as set out in Specification 435,250, 435,308, 452,146 or 460,219. The movable contact E<8> is slidable within a hollow insulator E<6> on the housing A and connects the fixed contact to spring contacts E' in the housing E 5. The breaker and isolator are sequentially operated by means such as described in Specification 637,302 and the breaker may be short-circuited by the arm G3 in the open position, as in that Specification ; both are surrounded by an earthed screen H of expanded metal. The invention is applicable also to ring bus-bar systems, such as described in Specification 505,638, Figs. 5-7 (not shown), to a single bus-bar system not provided with bus-bar sectionalizing switches, Figs. 8, 9 (not shown), and to systems in which one pole of the breaker is connected to an overhead line. In Fig. 10, an air-blast switch P and isolator T, T<1> are mounted on a carriage P<2> which is vertically movable by a pneumatic motor W <2> supplied from a reservoir W, as shown in the left-hand unit of Fig. 10, and carries phaseseparating screens W<1>. The terminals P<1>, R<2> extend, in the operative position, through the floor V into contact with feeder and bus-bar terminals N<1>, R<1> in compartments N, M of housing A<7>. The latter also includes a voltage transformer S<1> and isolating switch S<2> adapted to earth it at S<4>. A current transformer T<2> is supported by the floor V. The metal compartments may be filled with compound, liquid, or gas, for example, air at two atmospheres, and may be separated from the breakers by a framework supporting both.