The electric motor is one of the most commonly used equipment. Whether it is industrial production or daily life, the electric motor always appears next to us. Motors are usually divided into DC motors and AC motors according to different power sources. Most of the motors in power systems are AC motors, synchronous motors or asynchronous motors.

When we use the motor, we have to mention the resistor. The resistor and the motor can be said to be in the shadow. When the motor is in use, the resistor usually acts as a step-down current limiting circuit in the circuit to ensure the normal operation of the motor. The following is a link between the step-down and current limiting of the resistor in the motor.

In the use of the motor, the resistor is connected in series to perform a step-down start control circuit, that is, a certain number of resistors are serially connected in the stator circuit of the motor. When the motor is started, the resistors in series are used to reduce voltage and current limit. When the motor is started, the series resistors are short-circuited through the circuit to make the motor enter the normal operating state of full pressure. 

 
From the above we can understand that the series resistors in the control circuit of the motor step-down starting, the whole operation process includes three steps of step-down starting, full-pressure running and stopping. In this process, many circuit designers usually use resistor series to better perform the step-down and current limiting of the motor.