GB234573A - Improvements in and relating to electric switch-gear - Google Patents

Abstract

234,573. British Thomson-Houston Co., Ltd., Heath, H. C., and Wood, C. W. March 14, 1924. Controllers; systems for main working motor with auxiliary starting motor.-A system of starting a synchronous machine 11 by a direct coupled starting motor 12 is shown in Fig. 1. A circuit breaker 14 is included in the primary circuit of a transformer 13, the secondary of which is connected, when the switches 15 are closed on to contacts 17, to the windings of both motors in series, and when the switches 15 are open and the switches 16 are closed, to the windings of the motor 11 only. If it is desired to run the motors, with the motor 11 not excited the switches 15 are closed on to contacts 38. The no-volt release 18 is energized by momentarily closing a switch 22, thus completing a circuit through a fixed contact 55 on an auxiliary switch bridge piece 64, segment 54 and lead 19. The circuit-breaker 14 then closes, and with it a maintaining switch 21 to complete a circuit from coil 18 through an emergency release 23 segment 53 and either bridge piece 64 or contact 58 to segment 54 and lead 19. Unless the switch gear is " off " the circuit breaker cannot be closed for the bridge piece 64 is not on the contact 55. When the circuit is broken at contacts 58, 56 by reverse movement of the switch gear which is atranged so that the contacts 58, 56 open on the slightest reverse movement of the switch gear. the no-volt release ceases to function and the circuit breaker is opened. If the circuit breakers were opened by a tripping-coil instead of a no-volt release, then the contacts 53, 54 and 56, 58 would be series connected so as to complete a tripping circuit immediately a reverse motion of the handle occurred. The switch-gear is arranged so that the successive closing and opening of the switch 15 in respect of the contacts 17 and the closing of the switch 16 is effected by a continuous forward movement of a handle from an " off " position, whereas a backward movement of the handle from the " off " position closes the switch 15 on to the contacts 38.