GB341250A - Improvements in and relating to systems of electric motor control - Google Patents

Abstract

341,250. Control of two D.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Umansky, L. A. ; 1212, Rugby Road, Schenectady, New York, U.S.A.) Dec. 30, 1929, No. 39751. Convention date, Dec. 31, 1928. [Class 38 (iii).] Field control.-The speed of a motor 10 is regulated smoothly over a wide range by means of a dynamo electric machine 11, electrically and mechanically connected with it. The field 14 of the motor 10 is controlled by an adjustable rheostat 16, and the field 15 of the machine 11 by a plurality of adjustable rheostats 17, 18. A single adjusting means 19 for all the rheostats is provided. When the contact arms occupy position 1, both fields are fully excited, and both machines run in series as motors at the lowest speed. During movement from position 1 to position 2, the field 15 is weakened so that, machine 11 still running as a motor, the speed increases. During movement from position 2 to position 3, the double potentiometer rheostat 17, 18 is balanced, field 15 is not excited, and machine 11 neither motors nor generates ; the field 14, however, is reduced, and the speed continues to rise. During movement from position 3 to position 4, the field 14 is kept constant, but the field 15 is reversed and strengthened so that, machine 11 now acting as a generator, the speed is still further increased.