GB329336A - Improvements in and relating to the control of electric motors - Google Patents

Abstract

329,336. British Thomson-Houston Co., Ltd., (General Electric Co.). Nov. 15, 1928. Master control systems.-In a master control system, after the line-breaker LB and series switch S are closed, an electromagnetically controlled pneumatically operated cam-shaft closes contactors 49 to 59 in a sequence fully set out in the Specification, opening them as succeeding ones close until full series position is reached. Thereafter transition is effected by closing switches P and H and opening switch S, the motors then being in parallel with full resistance in circuit. Thereafter the cam-shaft is driven backwards, operating the contactors in the reverse order until the initial position is attained with contactors 49 and 55 closed, which position is now the full parallel position. The control circuit includes a switch 14 for energizing an overload relay closing coil and thereafter the master controller 21, which has reversing segments 32, 33 co-operating with segments on the reverser 22. Position 35 of the master controller causes throwing of the reverser if necessary, closure of the line-breaker and series switch and the energization of a holding-coil 29 which prevents movement of the cam-shaft, and thus gives the first or non-automatic running position. Position 36 gives acceleration to the full series position under control of an accelerating relay 23, and position 37 gives transition and acceleration to the full parallel position. The actuation of the cam-shaft is as described in Specification 11658/15, and function is similar to that described in Specification 188,471 for a motordriven screw-shaft cutting out resistance in the series position and then reversing its motion in the parallel position.