GB417867A - Improvements relating to the control of compound-wound direct current electric motors - Google Patents

Abstract

417,867. Master control of D.C. motors. FLETCHER, G. H., Tapton Close, Tapton House Road, Sheffield, and ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Crown House, Aldwych, London. April 12, 1933, No. 10974. [Class 38 (iii).] Field control.-In a control system for a compound-wound motor in which resistance is first cut out of the armature circuit, and then resistance is inserted in the shunt field circuit, means are provided whereby resistance is inserted in the shunt field circuit during the armature circuit control, and removed before the shunt field control is effected. Movement of master controller MC causes successive closure of contacts 17-21, and then successive opening of contacts 22-28, the one set of contacts controlling contactors 1, 1A, 2 .. 5, whereby the motor is connected to the supply, and armature resistance cut out in steps, and the other set of contacts controlling contactors 6-12 whereby shunt field resistance is inserted in steps, and the shunt field circuit finally opened. The circuit of the contactor 6, controlled by the contact 22 of the master controller, is also controlled by the contact 20, so that the shunt field resistance section controlled by the contactor 6 is in circuit until the fourth controller notch is reached, whereupon it is excluded and reincluded on the sixth notch. Thus the shunt field is not at full strength until the fourth notch. Interlock contacts 1a, 4a, 5a, on the main and resistance contactors 1, 4, and 5, ensure the exclusion of armature resistance during complete return movement of the controller to the " off " position.