GB1229834A - - Google Patents

Abstract

1,229,834. Switchgear structures. DELLE ALSTHOM. 20 May, 1968 [18 May, 1967; 11 Sept., 1967], No. 24003/68. Heading H1N. A switchgear cubicle contains a multipole circuit breaker 7 with isolating devices 3, 4, each pole of the switchgear including at least one insulating bushing extending between a pair of isolating contacts, the bushings carrying auxiliary devices such as current transformers, 12 and the circuit breaking and isolating contacts and the bushings of each pole being disposed in straight lines and aligned one behind the other in the cubicle. The terminals 53, 60 of the circuit breakers form the fixed contacts of load and line isolators 3, 4 operable conjointly. When the isolators are off, the circuit breaker assembly can be withdrawn on rollers 63. Each circuit breaker comprises a two-part earthed metal gas filled cylindrical case 43, 44 and a pair of insulator bushings 46, 47 respectively housing a tripping mechanism 51 and a puffer 55 for extinguishing the arc. The bushings also carry current transformers 12, voltage transformers 61 and fuses 62. In modifications (Figs. 6, 7, not shown) one or both sets of isolators may be omitted, the terminals of the circuit breakers being staggered vertically or angularly to allow removal of the breakers. When both isolators are omitted isolation is by withdrawal or rotation (Figs. 10, 11 respectively, not shown) of the circuit breaker unit. In Figs. 1-3 (not shown) the cables are located at the bottom of the cubicle and the bus-bars 1 at the top; cable earthing switches (13) are fitted; the cables and fixed contacts of the cable isolators may be in a unit from which the remainder of the cubicle can be detached (Fig. 3, not shown). To prevent access to live terminals the front wall of the cubicle may be formed to fit closely about the circuit breakers when partially withdrawn (Figs. 8, 9, not shown), the opening being closed by a front plate (86) of the withdrawable unit when fully inserted and by a blind or rigid shutters when fully withdrawn, the shutters being coupled to close automatically. Current transformers may be mounted inside the pivoted bushings of the isolators (Figs. 12-15, not shown) and metal screens between the bus-bar, circuit breaker and cable chambers may conform to the outline of the pivoted bushings so that the latter serve as shutters. In alternative circuit breaker units (Figs. 18, 19, not shown) the insulator 46 contains respectively a disconnecting switch, allowing the poles to be used individually while others are earthed, and a cartridge fuse of the kind having a tripping pin for automatically opening the circuit breaker contacts.