Patent GB-365708-A (GB)
Title: Improvements in or relating to electric switchgear
IPC: H02B1/00
Filed: 1930-11-24
Abstract: 365,708. Switchgear structures. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and GARRARD, C. C., of General Electric Co., Witton, Birmingham. Nov. 24, 1930, No. 35370. [Class 38 (v).] In switchgear employing duplicate bus-bars and selectors for connecting different circuits with the bus-bars, a bus-bar coupler switch is adapted to operate in conjunction with the selector when the latter is effecting a connection between a circuit and the bus-bars, and is also adapted to earth one or other of the bus-bars and any selector connected therewith. The feeders 17, 18 are selectively connectible to either or both of two bus-bars 4, 5 through switches 19, 20, and the bus-bars are adapted to be coupled through a switch, the vertically withdrawable part 8 of which is operated by a motor 13 under control of a " raise switch 15 and " lower " swit h 16. To change the feeder 17, say, to bus-bar 4, the part 8 must be fully raised to connect its plugs 6, 7 with their sockets 2, 3, the coupler switch must be closed, and a key 35 must be in a socket 39 in the part 8. With these three requirements met, a key 23 may be withdrawn from a socket 38 in the part 8 and inserted in the door over the selectors 19, 20 to change them over, it being, however, impossible to remove the key 23 in the intermediate position wherein both selectors have to be in the closed position before the selector of the unwanted bus-bar is opened. Also, while key 23 is removed from the socket 38, the key 35 cannot be removed to bridge contacts 34 in the lowering circuit of the motor 13. If it is desired to inspect the contacts of (say) selector 17 without shutting down the other feeder, one bus-bar, say 4, must be earthed and the feeders changed over to the other bus-bar 5 as above described. The key 23 is returned to the socket 38, thus releasing key 35 which is returned to contacts 34, and the lowering switch 16 is closed to drop the part 8 to its isolating position in which a key 31 can be inserted where shown. A socket-member 24 is placed over plug 6 and the part 8 fully lowered, whereupon an earthing plug 25 is put over plug 7. The motor is then energized over " raise " switch 15 and closed limit switches 36, 37, back contacts 21, key 31, and bridge member 27, and raises the part 8 to the earth position. The coupler switch is closed to earth the bus-bar 4 through the member 24, coupler, and member 25, in which position the coupler may automatically be tripped open on overload. To remove the earth connection from bus-bar 4, the switch 16 is closed to move the part 8 to its fully lowered position, in which the plug 24 is removed. The shutters 9, 10 for the sockets 2, 3 being now closed, a circuit for motor 13 is made through " raise " switch 15, switch 36, and contacts 11, 12, so that the motor raises the part 8 to the isolating position where the limit switch 36 automatically opens and stops the motor. The plug 25 and key 31 are now removed and the rest of the raising operation performed by a further switch (not shown) which puts the motor 13 direct on to the mains through the switch 15.