GB186640A - Improvements in control systems for direct current electric motors - Google Patents

Abstract

186,640. Givelet, J. A. M. V. de P. March 31, 1921. Systems for continuous-current motors only.- Direct-current motors are started and accelerated by applying a counter electromotive force furnished by a dynamoelectric machine, the armature of which has a closed magnetic circuit. The dynamo d, driven by a small auxiliary motor m at a speed at which it furnishes a voltage practically equal and opposite to the mains, is connected in series with the working motor M across the mains. The speed of the dynamo is then reduced inserting resistances r, h in a rheostaticbraking-circuit for the motor m. A drum controller C<1>, C<2> effects the necessary circuit changes in order. The speed of the auxiliary motor may be reduced, before being rheostatically braked. The working motor may finally be connacted directly across the line. A seriesparallel group of working motors may be similarly controlled, and the generator may be cut out and reinserted in the transition from series to parallel running. The magnetic circuit of the armature may consist of a rotating or stationary laminated ring. In order to reduce sparking, the arm ature may have several windings in parallel, and subdivided brushes.