The general purpose variable frequency speed regulation motor has the following characteristics:
● it adopts frequency converter for power supply.
● change the traditional motor fan into an independent fan.
● the insulation performance of motor winding shall be higher than that of ordinary motor.
● motor resonance is easy to occur during the starting of variable frequency speed regulation motor. The rigidity of motor components and the whole shall be fully considered to prevent vibration and noise of the motor.

●   The insulation grade is generally f or higher. Strengthen the ground insulation and turn to turn insulation strength to improve the ability of motor insulation to withstand impulse voltage.
● special electromagnetic wire for variable frequency motor shall be adopted.
● forced ventilation cooling requirements. Generally, axial flow fan is used for strong near ventilation; Special attention should be paid to that the fan cannot share the power supply with the motor. The fan should be started before the motor is started, and the motor power should be turned off before shutdown.

● shaft current problem. Bearing insulation measures shall be taken for motors with a capacity of more than 160kW, such as insulated bearing, insulated bearing chamber, increase of leakage carbon brush, etc.
● grease. For constant power variable frequency motor, when the speed reaches 2p motor speed, special grease with high temperature resistance shall be used to prevent bearing grease loss due to temperature rise, resulting in bearing damage and winding burning.
● manufacturing process control. VPI and special insulation structure are adopted to ensure the insulation, withstand voltage and mechanical strength of electrical winding.
● rotor dynamic balance control to improve the machining accuracy of parts and components, and select high-performance bearings for high-speed operation.

Inverter power supply is generally required for variable frequency motor test. Since the output frequency of the frequency converter has a wide variation range and the output PWM wave contains rich harmonics, the frequency conversion power analyzer and frequency conversion power sensor with clear ratio difference and angle difference indexes should be used as the main power measurement instrument.