GB484596A - Improvements in and relating to electric braking systems for direct-current electric motors - Google Patents

Abstract

484,596. Control of D.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 7, 1936, No. 30381. Convention date, Nov. 7, 1935. [Class 38 (iii)] Dynamo-electric braking.-A motor 1 fed from a generator 2 is brought to rest by reversing the generator field 3, and shunting this field by a circuit comprising a rectifier 10 and the motor armature. This shunt circuit is ineffective on the generator field until the back electromotive force of the motor falls below a fixed value after which the generator field is increasingly short-circuited as the motor comes to rest. To compensate for the resistance of the rectifier 10, a resistance may be included in the circuit of the field 3 and arranged to carry the field current of the motor. Alternatively the generator may have an additional field acting in opposition to the field 3 and connected in series with a resistance 6 through which the field 3 is supplied. In a system described with reference to Fig. 3, not shown, a reversing switch is provided for the generator field 3 additional to the reversing switch effecting the braking connections, so that the motor may be reversed or stopped at will. In the case of a series motor the braking is effected by reversing the armature connections to the supply and connecting a braking resistance in circuit, the rectifier being connected in shunt to the motor armature.