| 摘要 |
496,590. Field control of D.C. motors. WHYMAN, F., . and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. June 11, 1937, No. 16320. [Class 38 (iii)] The motors M1-M4 of a locomotive are controlled by a master controller having a final position in which the motor fields F1-F4 are shunted by a circuit including inductance and resistance and the resistance is regulated by a drum-type controller D.C. positioned by a pilot motor PM under the control of a relay CR responsive to the motor current. With the motors M1-M2 connected in parallel movement of the master controller to a weak field position establishes a connection Y whereby the pilot motor PM is energized over interlock contacts L1 on the series-parallel switch and interlock contacts T1, T2. controlled by the master controller. The controller D.C. is thus operated from its position shown. Operating coils P1, P2, energized through interlock contacts L2 on the series parallel switch, close their contacts p1, p2 to connect diverter resistance R5 across the motor fields. As the controller DC is operated further coils W1-W5 are energized in a predetermined sequence to operate contacts w1-w5 and gradually weaken the motor fields until the motor current reaches a predetermined value and the relay CR opens its contact b1. If the motor current exceeds a predetermined maximum value the relay CR operates to close its lower contact b2. The armature connections of the motor PM are thus reversed and the motor returns the controller DC to strengthen the motor fields. Contact fingers C1-C3 on the controller DC operate as limit switches for the motor PM. Resistances R6, R7, are connected in series and in parallel with the motor PM, the resistance R6 being in parallel and the resistance R7 in series for one direction of operation of the motor, and the resistance R7 in parallel and the resistance R6 in series for the opposite direction of rotation. |
