GB196279A - Improvements in or relating to dynamo-electric machines - Google Patents

Abstract

196,279. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Shand, E. B.). April 11, 1922, [Convention date]. Commutating poles and windings.-The commutation of dynamo-electric machines is improved by the provision of a commutating-pole winding which will set up a flux component substantially proportional to the load and an auxiliary winding automatically energized in accordance with changes in the load. Fig. 1 shows a rotary converter 6 having main poles 10 and commutating poles 13. The commutating poles are provided with a series winding 14 and an auxiliary winding 15 excited through a resistance 16 across a highly inductive impedance 17. In a modification, Fig. 4, the auxiliary coil 15a is connected across an auxiliary circuit-breaker 20 arranged to open before the main circuit-breaker 19. A transformer 21 may be provided to avoid the shortcircuited damping effect of the coil 15<a>; alternatively, back contacts may be provided on the circuit-breaker 20 so that the auxiliary circuit is opened when the contact-breaker is closed and closed just before the main circuit-breaker contacts are fully open. A current-limiting resistance may be connected in series with the auxiliary winding, and the main circuit-breaker, instead of having an individual tripping coil, may be mechanically tripped by the auxiliary breaker through a lost-motion device.