| 摘要 |
452,948. Control of D.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London. July 1, 1935, No. 18817. Convention date, June 30, 1934. [Class 38 (iii)] Non - regenerative braking ; varying E.M.F. -A locomotive motor is supplied during normal running from an alternating current source through a transformer t and a grid -controlled rectifier, and during rheostatic braking, when its armature a is connected to a resistance r, its series field f is separately excited from the grid-controlled rectifier through which the motor is supplied during the running operation. The braking is regulated by grid control of the rectifier, the resistance r being constant. The voltage for the separate excitation of the field is suitably reduced by making connection to low-voltage tappings on the rectifier transformer t or by operating a switch u to establish a suitable fresh neutral point on the transformer winding. Sudden field changes may be avoided by connecting a choke d in the field circuit, and, if necessary, shunting the field by capacity-inductance circuits. The field circuit may include a stabilizing resistance carrying the armature current. |
