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How to distinguish ordinary motor and variable frequency motor?

Time: 2018-05-14

 How to distinguish ordinary motor and variable frequency motor?

1. Structural differences between ordinary motor and variable frequency motor.

    01. The insulation grade is higher.The insulation grade of the general frequency conversion motor is F or higher, and the insulation strength of the ground insulation and the line turn is strengthened, especially the insulation resistance to impact voltage.

    02. The vibration and noise requirements of the frequency conversion motor are higher.The variable frequency motor should fully consider the motor components and the overall rigidity (the public number: the pump house), and try to improve its natural          frequency to avoid the resonance phenomenon with the various force waves.

    03. Variable frequency motor has different cooling modes.The variable frequency motor usually adopts forced ventilation cooling, namely the main motor cooling fan adopts independent motor drive.

    04. The protection measures are different.Bearing insulation measures shall be adopted for the capacity over 160KW variable frequency motor.Mainly produces magnetic circuit asymmetry, also can produce shaft current, while the rest of the high frequency      component generated by the current role in combination, shaft current will increase greatly, which can lead to bearing damage, so often insulation measures.For constant power inverter motor, when the speed is over 3000/min, special grease should be            used  to compensate the temperature of the bearing.The heat dissipation system is different.Variable frequency motor cooling fan adopts independent power supply to ensure continuous cooling capacity.

2. Differences in design of ordinary motor and variable frequency motor.

    01. Electromagnetic designFor ordinary asynchronous motors, the main performance parameters considered in the redesign are overload capacity, startup performance, efficiency, and power factor.And frequency conversion motor, because of the critical slip i   nverse ratio at power frequency, you can directly start when critical slip is close to 1, therefore, overload capacity and startup performance is not need to think too much, and to solve the key problem is how to improve the ability to adapt the motor of the         non sine wave power.

   02. Structural designIn structural design, it is also necessary to consider the influence of non-sinusoidal power characteristics on the insulation structure, vibration and noise cooling mode of the inverter motor.