GB738328A - Improvements relating to the control of electric traction motors - Google Patents

Abstract

738,328. Control of D.C. motors; controllers. METROPOLITAN - VICKERS ELECTRICAL CO., Ltd. March 22, 1954 [March 30, 1953], No. 8766/53. Class 38 (3). Traction motors have a number of armature resistance units R1-R15 controlled by contactors C1-C15 with operating coils CC1- CC15 regulated by means of a drum MD. A line switch LS has a coil CLS whereby the switch is closed on the first notch of the drum and the resistance contactors are successively energized as the controller is moved to the sixteenth notch. An auxiliary drum AD cooperates with contact fingers AF2, AF3, connected respectively with coils CC14, CC15, the arrangement being such that resistor R14 is short-circuited in the first operative position of the auxiliary drum and resistors R14, R15, are short-circuited in the second operative position thereof, independent of the position of the main drum. Acceleration normally proceeds under the control of the drum MD alone, but, when voltage increments are required, the auxiliary drum is actuated to one of its operative positions, so that, when the motors reach the maximum speed with the auxiliary controller in the second operative position, the latter may be returned to the " off " position and the drum MD advanced to its next notch. The values of the resistors R14, R15 are small in comparison with the earlier resistance sections. 'When the handle MH of the main controller is moved from one notch to another, a latch MT is operated and push rod PR1 rocks a lever L. Thus, if the handle AH of the auxiliary controller is in an operative position, a push rod PR2 releases latch AT and the handle AH is returned by spring BS to the " Off position. No notch corresponding with the " off " position of the handle AH is provided, so that it is not necessary to operate the latch AT when moving the auxiliary controller from the " off " position. The auxiliary drum may be incorporated in the main controller, and a reverser lever, or a member for selecting the various motor combinations in the case of series-parallel equipment, may be employed for the auxiliary handle AH. The contactors for controlling the armature resistors may be of the electromagnetic, electro-pneumatic, or of the cam-operated types.