YD series pole changing multi-speed three phase induction motors are in the y series developed on the basis of a new type variable-pole multi-speed three phase induction motors, with high efficiency, high starting torque, low noise and little vibration and so on. This series motors can be changed by changing the speed of the motor, so as to achieve reasonable matching of power and transmission system is simplified, so widely used in the textile, printing and dyeing, chemical industry