Compared with single motor, three-phase asynchronous motor has better operating performance materials. According to the difference of motor rotor structure, three-phase asynchronous motor can be divided into cage type and wound type. Cage rotor induction motor is widely used because of its simple structure, low price, light weight and reliable operation. Its main disadvantage is that it is difficult to speed. The rotor, stator and winding three-phase asynchronous motor is also connected with the external rheostat through the brush with three-phase winding and slip ring. The starting performance and speed of the motor can be improved by adjusting the resistance of the rheostat. Seven classification methods of three-phase asynchronous motor:

1、 According to the rotor structure of three-phase asynchronous motor

It can be divided into winding motor and squirrel cage motor.

2、 According to the protection method of three-phase asynchronous motor

It can be divided into open type (IP three-phase asynchronous motor 11), three-phase asynchronous motor (IP22 and IP23), closed type three-phase asynchronous motor (IP44) and explosion-proof three-phase asynchronous motor.

Open type (IP11): good heat dissipation condition and low price. Because the rotor and winding are exposed to the air, they can only be used in a dry environment with little dust and no explosive and corrosive gases.

Protective type (IP22 and IP23): good ventilation and heat dissipation conditions can prevent iron filings, water droplets and other impurities from entering the motor. It is only applicable to the environment with dry climate, little dust, no explosive and corrosive gases.

Enclosed type (IP44): It is applicable to dusty, humid, vulnerable to wind and rain erosion, corrosive gas and other harsh working environments, and is most widely used.

3、 According to the ventilation and cooling method of three-phase asynchronous motor

It can be divided into self air three-phase asynchronous motor, self cooling three-phase asynchronous motor, other fan cooling three-phase AC motor and pipe ventilation three-phase asynchronous motor.

4、 According to the installation structure of three-phase asynchronous motor

It can be divided into vertical three-phase asynchronous motor, horizontal three-phase asynchronous motor, three-phase asynchronous motor with feet and three-phase asynchronous motor with flanges.

5、 According to insulation grade of three-phase asynchronous motor

It can be divided into Class E, B, F and H three-phase asynchronous motors.

6、 By work quota

It can be divided into interrupted three-phase asynchronous motor, continuous three-phase asynchronous motor and intermittent three-phase asynchronous motor.

7、 By power

It can be divided into small electric motors, micro motors and two kinds of large electric motors.