GB559011A - Improvements in flame-proof electric switchgear - Google Patents

Abstract

559,011. Switchgear structures. MURET, D. A., and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. July 22, 1942, No. 10263. [Class 38 (v)] A switchgear structure suitable for use in mines comprises a flame-proof enclosure 3 housing a main switch, for example, of the airbreak type, and a separate flameproof enclosure 4 in the casing 1 housing a pair of isolating switches which control the connections of the main switch to, for example, a cable 26 and busbars 21, the arrangement being that a single control member is adapted selectively to operate the main switch and the isolating switches together. The breaker comprises a fixed and movable contact 5, 6 connected to plug contacts 5a, 12a co-operating with socket contacts 28a, 33a whereby the breaker unit can be withdrawn for inspection. Connections 28, 33 from contacts 28a, 33a are taken through flameproof insulating bushings 27, 32 into chamber 3 for insulatingly receiving shafts 29, 34 on which are insulatingly carried isolating switch blades 31, 35 in permanent rubbing engagement with the connections 28, 33 and co-operating, respectively, with a cable contact 24 and a contact 23 carried on the busbar-supporting insulator 22. Cranks 46, 43 on shafts 29, 34 carry pins which cooperate, respectively, with a V-shaped slot 44 and a slot 41 on a member 40 on a reciprocable rod 37 guided at 38 and passing in flameproof manner through sleeve 39 for connection to a lever 62 and link 61. The latter is connected to crank 60 on a sleeve 52 rotatable about a shaft 51, which carries a further crank 58 for operating breaker-contact 6. Sleeve and shaft are provided with cranks 53, 54 (the latter having two arms) engageable, selectively, by an operating member 47 which is loose and rockable on the shaft 51 and also passes through a gate 48. Fig. 3, having parts 65a, 65e for the breaker, part 65c for the isolating switches, and transverse parts 65b, 65d to allow the member 47 to be moved from one crank to the other. In operation, first the breaker is opened, then both isolating switches are opened, one being moved to earthing contact 36 whereas the other is reclosed on to the cable-contact, and the breaker can then be re-closed. The cover 8 is locked until the opening of the isolators opens a recess in crank 60 to a spring bolt 67. The cover is secured to casing 1, as described in Specification 559,040 by keyhole-like slots which engage a series of headed studs 1b in the flange 1a, whereby the cover is first applied normally to the flange-surface and then slid therealong, Fig. 4 (not shown). Alternatively, a series of interengaging castellations can be formed on the cover-edge and a speciallyshaped flange, Fig. 5 (not shown).