1. Variable frequency motor Higher insulation level requirements
Generally, the insulation grade of the variable frequency motor is F grade or higher, which strengthens the insulation strength of the ground insulation and the turns, and especially considers the ability of the insulation to withstand the surge voltage.
2. Variable frequency motor requires higher vibration and noise
The variable frequency motor should fully consider the rigidity of the motor components and the whole, and try to improve the natural frequency to avoid resonance with each force wave.
3. Variable frequency motor cooling method is different
The variable frequency motor generally adopts forced air cooling, that is, the main motor cooling fan is driven by an independent motor.
4. Protection measures are different
Bearing insulation measures shall be adopted for variable frequency motors with a capacity exceeding 160 kW. Mainly due to the asymmetry of the magnetic circuit, the shaft current is also generated. When the currents generated by other high-frequency components work together, the shaft current will increase greatly, resulting in bearing damage, so insulation measures are generally taken. For constant power variable frequency motors, when the speed exceeds 3000/min, special high temperature resistant grease should be used to compensate for the temperature rise of the bearing.
5. Different cooling systems
The inverter motor cooling fan is powered by an independent power supply to ensure continuous heat dissipation.