In recent years, the permanent magnet frequency conversion screw air compressor has been trusted by more and more customers because of its high efficiency, energy saving, pressure stability and other characteristics. However, the permanent magnet motor production enterprises on the market are uneven. If the choice is improper, it may lead to the risk of permanent magnet motor magnet loss. Once the permanent magnet motor loses magnet, it can only choose to replace the motor, resulting in large maintenance costs.
How to judge whether the permanent magnet motor is lost magnetic:
1. The current is normal when the machine starts to run. After a period of time, the current becomes large. After a long time, the inverter will be reported to overload. First need to determine the air compressor manufacturer inverter selection, confirm whether the parameters in the inverter has been changed, if both have no problem, then need to judge the head and motor off, no-load identification, no load running to the rated frequency, the output voltage is the reverse electric momentum, if lower than the motor nameplate above 50V, can determine the motor demagnetization.
2. The running current of permanent magnet motor will generally exceed the rated value, and those reported or occasionally only at low speed or high speed operation are generally not caused by demagnetization.
3. Demagnetization takes some time for the permanent magnet motor. In some of a few months or even one or two years, if the manufacturer's type selection error leads to current overload, it does not belong to the motor demagnetization.