Patent GB-457877-A (GB)
Title: Improvements in or relating to metal clad oil filled electric switches
IPC: H01H33/75
Filed: 1935-04-02
Abstract: 457,877. Switchgear structures; oil-break switches. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and COATES, H. J., and GARRARD, C. C., c /o General Electric Co., Ltd., Witton, Birmingham. April 2, 1935, No. 10249. [Class 38 (v)] Electric switchgear structure comprises horizontally movable contact members co-operating with fixed contacts in explosion pots in such a manner that the products of arcing escape in a direction away from the insulators supporting the fixed contacts, in combination with isolating means disposed between the switchgear and the bus-bars and between the switchgear and a cable box, the said isolating means, bus-bars and cable box being arranged below the switchgear. In one construction, Fig. 1, the switchgear comprises two series - connected switches in separate oil tanks 1, 2, with an intermediate chamber 3 containing the operating gear. The chamber and tanks are bolted together, and the tops of the tanks are provided with inspection covers 10, 11. The inner metal walls of the tanks are lined with sheet insulating material 16. The movable contacts comprise main contacts 29, 39 and arcing contacts 28, 40, co-operating respectively with main fixed contacts 41, 42 and arcing contacts in explosion pots 43, 44. Each explosion pot is of the type with a side outlet and with baffles 45, 46 transverse to the direction of movement of the arcing element. The contacts 28, 29 are mounted on a disc 27 carried by tubes 24 ... 26, and the contacts 39, 40 are mounted on a disc 38 carried by rods 35 ... 37 which have a sliding and conductive engagement with the tubes. The rods and tubes are moved in opposite directions to engage the fixed contacts by means such as a rack and pinion or an endless chain. The fixed contacts and explosion pots are carried by insulators 14, 15 extending through the bottoms of the tanks. One switch may be arranged to open before the other, and a pipe may be led from the tank of the switch which opens first to the explosion pot of the second switch, so that the pressure created in the first tank causes oil to flow across the arcing space in the second tank. In a modification, Fig. 2 (not shown), all the contact sets and operating gear are housed in a single tank. In the arrangement shown in Figs. 4 and 6, three switches 93 of the kind already described are arranged side by side on a girder system 94, and are adapted to connect three-phase bus-bars 95 in ducts 96 to cables 97. Between each bus-bar duct 96 and the respective switch 93 is arranged an oil-filled chamber 98 containing isolating gear in the form of a double-break switch with rotary blades. Similar isolating gear is arranged at the other end in feeder isolator chambers 99, and connects or disconnects the main switches with vertical connectors in chambers 101, 102 respectively leading to potential transformers 106 through transformer isolators 103 and to the cables in boxes 104 through current transformers 105. The bus-bar, feeder, and potential transformer isolators are all linked together by linkwork 110 for conjoint operation by a handle 111, which is accessible from a platform 112. High-tension fuses are provided in a chamber in each potential transformer tank 106, the chamber being provided with a cover plate 113 interlocked through gear 114 with the linkwork 110, so that access to the fuses is only possible when the transformers are isolated. The pressure in the various parts of the system is maintained by oil conservators 115, 116, which may be of the kind described in Specification 427,877. The switches may be operated by means of compressed air from a pneumatic motor 117 supplied from a pipe line 118 through an air cylinder 119 and valve mechanism 120.