In recent years, permanent magnet variable frequency screw air compressors have been trusted by more and more customers due to their high efficiency, energy saving, and stable pressure. However, the permanent magnet motor manufacturers on the market are uneven. If the selection is not appropriate, it may cause the risk of permanent magnet motor loss. Once the permanent magnet motor loses its magnetism, basically we have to replace the motor, which leads to high maintenance costs. How to judge whether the permanent magnet motor has lost magnetism?

1. When the machine starts to run, the current is normal. After a period of time, the current becomes larger. After a long time, it will report that the inverter is overloaded. First of all, you need to make sure that the inverter selection of the air compressor manufacturer is correct, and then confirm whether the parameters in the inverter have been changed. If there is no problem with both, you need to judge by the back EMF, disconnect the head and the motor, and perform the air Load identification, no-load operation to the rated frequency, the output voltage at this time is the back electromotive force, if it is lower than the back electromotive force on the nameplate of the motor by more than 50V, the demagnetization of the motor can be determined.

2. The operating current of the permanent magnet motor will generally exceed the rated value after demagnetization. Those conditions that only report overload or occasionally report overload at low speed or high speed are generally not caused by demagnetization.

3. Permanent magnet motor demagnetization takes a certain amount of time, some months or even one or two years, if the manufacturer selects the wrong model and causes the current overload to be reported, it does not belong to the motor demagnetization.

4. Reasons for motor demagnetization
-The cooling fan of the motor is abnormal, resulting in high temperature of the motor
-The motor is not equipped with temperature protection device
-The ambient temperature is too high
-Unreasonable motor design

Reported By Jessica