When selecting the type of variable frequency motor, the factors of motor insulation performance will be considered. The insulation structure of the motor is composed of several insulating materials in a certain way and processed according to a certain insulation process. The interaction between several insulating materials is called the compatibility of material combination. If harmful interaction occurs between materials, the material combination is said to be incompatible. Therefore, when selecting the insulation structure of the motor, the compatibility of the material combination should be considered.

Factors affecting the insulation performance of variable frequency motor include:

1. Thermal factors, such as the influence of the hottest point temperature during operation;

2. Electrical factors, such as the influence of electrical stress caused by working voltage, operating overvoltage or atmospheric overvoltage;

3. Environmental factors, such as atmospheric pressure, chemical composition of surrounding gas and humidity;

4. Impact and vibration caused by mechanical factors, such as prime mover, mechanical load, transportation, frequent startup or electric power.

For small motors with scattered and embedded windings, thermal and environmental factors are the main factors; For medium and large motors with formed windings, electrical and mechanical factors also play an important role.