| 摘要 |
686,355. Control of A.C. motors. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 21, 1951 [March 2, 1950], No. 4227/51. Class 38 (iii) [Also in Group XXXV] Series commutator traction motors 31 are supplied from a transformer having low and high voltage taps 14, 15, an adjustable resistor 17 being included in the motor circuit. The resistor is adapted to be regulated by means of contacts 1-5 which are operated in sequence by cams driven by a pilot motor 21. A battery 23 supplies the armature of the pilot motor and its reversible field winding 22. The pilot motor is started by movement of a controller 24 which also closes a line contactor 36-37, the traction motors being initially energised from tap 14 through the whole of the resistor 17 and the camoperated contact 1. Contact 2 is then closed after which contact 1 opens, this sequence continuing until the traction motors are connected directly to the tap 14. The pilot motor then closes an interlock contact 29 to energise contactor coil 20, so reversing the pilot motor and closing contact 19. An additional cam-operated contact 30 maintains the energisation of the coil 20 through contact 20a so that the pilot motor continues to operate in the reverse direction. Upon energisation of the contactor coil 20 the traction motors are supplied through the whole of the resistor 17 from the tap 15. The cam-operated contacts are then closed in the reverse order until the traction motors reach the full voltage of the tap 15. The cam-shaft is returned to its initial position when the controller 24 is moved to the "off" position. A current limit relay 33 halts forward movement of the pilot motor when the traction motor armature current exceeds a given value. |
