What does the reduced voltage motor mean?

The reduced voltage motor starting of the motor refers to the use of starting equipment to reduce the voltage and apply it to the stator winding of the motor for starting, and then restore the voltage to the rated value after the motor is started.

There are four common methods for reduced voltage motor starting:

1. Starting control of series resistance of stator winding

The principle of reduced voltage motor starting is that when the motor is started, a resistor is connected in series in the stator winding of the motor, and the voltage applied to the motor winding is lower than the power supply voltage due to the voltage drop generated by the resistor. After starting, the resistor is short-circuited to make the motor run at the rated voltage, thus achieving the purpose of safe starting.

2.  Reduced voltage starting of autotransformer

The reduced voltage  starting of autotransformer motor is one of the steps of step-down starting of cage induction motor. This step-down starting method of motor has the advantages of compact circuit structure, no limitation of motor winding connection mode, and different transformer voltage taps can be selected according to the allowable starting current and required starting torque, so it is suitable for motors with larger capacity.

3. Reduced voltage starting of Y-△ motor 

The reduced voltage starting of Y-△ motor is characterized by simple and economical method. The starting current of this motor starting method is 1/3 of that of direct starting, so it is only suitable for starting the motor under no-load or light-load conditions.