GB209243A - Improvements in automatic electric motor control systems - Google Patents

Abstract

209,243. Ferguson, A. D., and Metropolitan-Vickers Electrical Co., Ltd. Nov. 13, 1922. Master control systems; automatic starting systems.- In motor starting systems where a sequence of accelerating steps proceeds automatically subject to the siuspending action of a current limit relay, an automatic sequence switch is driven by the spindle of the main controller and a manual contact device in combination with a single-coil notching relay is used to short circuit the contacts of the limit relay so as to make one or mere non-automatic steps in case of unusual mechanical resistance during the accelerating period. The apparatus described comprises two motors 1, 2, Fig. 1, accelerated by a series of rheostatic and series-parallel steps effected by a group of separate switches closed bv cams from a drum rotated in a known manner by pneumatic cylinders 19, Fig. 3, with electromagnetic valves 20, 21. After a master controller 22 has been moved to the series accelerating position b<1>, the valves 20, 21 are intermittently energized and the main controller 18 is advanced automatically. The circuits controlling the automatic progression are subject to interruption by a current limit relay 9 but can be restored for one further step only, by closure of a manual switch 52. The circuits controlling further advance of the drum are then broken by the action of the notching relay 46 which can only be reset by opening of the manual switch 52. Further non - automatic stops can subsequently be effected by closing and opening the switch 52 for the required number of times. Advance of the main controller bevond the full series notch cannot take place until the master controller has been moved to its parallel position c'. The circuits may be modified so as to alter the conditions under which automatic acceleration can be resumed after a non-automatic step. The invention is applicable to motors for traction and other purposes.