GB372027A - Improvements in electrical switchgear - Google Patents

Abstract

372,027. Electric switchgear and automatic circuit-breakers. WHITEHEAD, G. E., and WHITEHEAD'S ELECTRICAL INVENTIONS, Ltd., 102, St. Mary Street, Cardiff. March 14, 1931, No. 7922. [Class 38 (v).] In an electric switchgear structure involving the connection of a feeder cable to bus-bars or the equivalent through a circuit-breaker, one terminal or set of terminals of the circuitbreaker is carried vertically upwards towards the overhead bus-bars or is or are connected therewith by vertical conductors, bus-bar isolation being provided by a vertically sliding switch or switches of the type described in Specification 286,429, [Class 38 (v), Electric switches &c.], or by lowering the appropriate contact or contacts and terminal stem or stems of the circuit-breaker, whilst isolation of the cable side is effected by a switch or switches disposed between the current transformer or transformers and the cable sealing or dividing box and situated adjacent the latter. As shown in the Figure, a structure involving a circuit-breaker of the type described in Specification 350,529 the terminal stem or stems 6 carrying one or a set of the relatively fixed contact or fixed contacts terminate upwardly in sockets 7 adapted to engage plug contacts 8 depending from the bus-bars 9. The stems 6 may be lowered for isolating purposes by means of a carrier 11 operated by screw gearing (not shown). The other relatively fixed circuitbreaker contact or contacts are connected through the terminal stem or stems 12 to horizontal conductors 13 mounted in a casing 3, the ends of the conductors 13 being connected by further downwardly-extending conductors 14 to a current transformer or transformers 15 in a casing 20. The lower ends of the current transformers 15 are adapted to be connected to, or isolated from, the ends of a cable 4 by means of a switch member 16 connected to the current transformer by a flexible lead 19 and mounted for operation on a cradle 17 which on operation by screw gearing (not shown) may extend into a cable sealing or dividing box 5 to engage fixed contacts 18 on the cable ends. Alternatively a telescopic type of isolating switch or a rotary type as described in Specification 337,056, [Class 38 (v), Electric switches &c.], may be employed. If the gear is mounted on a wheeled carriage it may, after the opening of the cable isolating switch, be wheeled away from the cable box 5, which may be provided with automatically - operated shutters for covering the orifices therein. The casing 3, which may alternatively contain the bus-bars 8 also contains the circuit-breaker trip gear consisting of a linkage 25, 26 normally held inoperative by a catch 30 but which, when released by an overload solenoid 32, 33, is moved by a spring 28 to impart a hammer blow to a catch 22 which is unhooked from a pin 23 on a rod 24 carrying the movable contact bridge 25 of the circuit-breaker. A portion of the casing 3 is hinged at 35 to permit ready inspection of the circuit-breaker trip gear.