GB337036A - Improvements in or relating to electric motor control systems - Google Patents

Abstract

337,036. English Electric Co., Ltd., and Morris, F. July 25, 1929. Master control. - In a traction system the actuating coils of the contactors, either electromagnetic or electropneumatic, for arranging the series parallel connections of the motors 1, 2 and for cuttng out the resistances 3, 4 are energized in the correct sequence by a drum or cam shaft controller A notched automatically under the control of a twoway relay to a position corresponding to that of the master controller C. After the reverser E is thrown to the required position, and the controller C placed at its first position i, a conductor 23 is energized and contactors are closed for the first position, and through this conductor the power is obtained for all the contactor coils when energized. In position s of the controller C., a relay 30 is energized and completes a circuit through contacts of an accelerating relay B to a notching coil 16, which intermittently interrupts its own circuit at contact 17 and causes step-by-step rotation of segments which complete a circuit for a notching coil 13 of the drum A. The relay 30 also completes the circuit of a holding coil 14 to prevent backward movement of the drum A. At this position s the two-way relay 18 is also energized, so that when the drum A reaches the full series position a segment 36 complete a shunt circuit around contacts 17 and so prevents further notching until the relay 18 is de-energized by moving the controller C to position p, whereafter notching is resumed until a segment 38 arrests further movement in the same manner. In the system, backward movement of the drum A is only obtainable by denergization of holding coil 14, that is by returning the controller C to the "off" position. A modification is described in which it is possible to drop back from the full parallel to the full series postion without having to go to " off " and notch up again. In this arrangement the two-way relay has two separate coils energized respectively for full series and full parallel positions. The notching coil may act directly upon the drum A, and an overload circuit-breaker can be arranged so that its closing coil can only be energized in the " off " position of the master controller.