| 摘要 |
PURPOSE:To space-save the secondary side device and to obtain a continuous torque speed characteristic by providing a stepdown transformer between a wound-rotor induction motor and the secondary resistor at warmup operation time. CONSTITUTION:When a wound-rotor induction motor 1 is normally operated, a switch 3 is closed, and switches 41, 42 are opened to operate by the secondary resistor 2 at variable speed. On the other hand, the switch 3 is opened, and the switches 41, 42 are closed at warmup operation time to drop the secondary voltage of the motor 1 by a transformer 5 to operate by the secondary resistor 2. |
