GB413642A - Improvements relating to the control of direct current electric motors - Google Patents

Abstract

413,642. Master control of D.C. motors ; interlocked controllers. GRAY, W. T., Darroch, Wainwright Road, Altrincham, Cheshire, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. Jan. 16, 1933, No. 1421. [Class 38 (iii).] In a master control system for two motors or two groups of motors 1, 2, Fig. 1, in which either of the motors or groups of motors may be cut out when desired, a switch associated with the master controller MC is arranged to co-operate with interlock contacts on the motor cut-out switches C1, C2, so that the control circuits for the motor power connections are completed only when the switch associated with the master controller, and the motor cut-out switches are both in positions corresponding to all the motors being in circuit, or in positions corresponding to one of the motors or groups of motors being cut out, and a mechanical interlock is provided between the main control drum of the master controller, and its said associated switch, so that if the switch is in a position in which one of the motors or groups of motors is cut-out, the main control drum cannot be moved beyond the position in which the motors or groups of motors are in series. As shown, the cut-out switches C1, C2 are of the knife type and the switch associated with the master controller is incorporated in the reversing switch forming part of the master controller, which reversing switch, for this purpose, has four positions. The main drum 9, Fig. 5, of the controller is mounted on a shaft 10 which carries a ratchet 13 having a radial hole 15 engaged by the head of a lever 17 pivoted at 16. The associated reversing switch is mounted on a shaft 19 which carries a ratchet 21, against the notches 22, 23, 24, of which the lever 17 is biassed with the reversing switch in the " off " position shown, a roller 18 on the lever 17 is engaged in the notch 22 which maintains the head of the lever 17 in the bore 15, so that the main drum cannot be operated. When the reversing switch is moved to a " motor cut-out " position, either for forward or reverse operation, the roller 18 engages one of the deeper notches 23, which allows the head of the lever 17 to leave the bore 15, and ride on the outside of the ratchet 13, to an extent limited by the stepped portion 14. Thus, the main drum may be operated to its series, but not its parallel positions. If the reversing switch is moved to a " both motors in " position, either for forward or reverse operation, the roller 18 engages one of the still deeper notches 24, which allows the head of the lever 17 to clear the stepped portion 14. Thus, the main drum may be operated to series and parallel positions. The cut-out switches may take the form of a drum, combined with, or independent of the reversing switch, and the cut-out switch or switches may be combined with a power-brake switch. Specification 413,641 is referred to.