Key technical points for maintaining normal operation of permanent magnet motors

Once the permanent magnet motor is demagnetized, basically the only option is to replace the motor; the cost of repair and a large amount of how to determine the permanent magnet motor demagnetized it, we go on to see.
The machine at the beginning of the operation of the current is normal; after some time, the current becomes large, and over time, it will report the inverter overload. First, need to determine whether the air compressor manufacturer inverter selection is correct and then confirm whether the parameters within the inverter have been changed. If there is no problem with both, it is necessary to judge by counter-electromotive force, disconnect the head from the motor, carry out no-load identification, and run to the rated frequency at no-load; the voltage output at this time is the counter-electromotive force, if it is lower than the counter-electromotive force on the motor nameplate by more than 50V, it can be determined that the motor is demagnetized.

1. Keep the permanent magnet motor working at the rated current.
The main reason for permanent magnet motor overload operation is due to the dragging load being too large, the voltage being too low, or driven mechanical stagnation, etc. caused by. If the overload time is too long, the permanent magnet motor will absorb much active power from the grid, the current will increase, the temperature will rise, the insulation of the permanent magnet motor will age at high temperatures, and the magnets will be demagnetized. Therefore, the permanent magnet motor in operation frequently checks whether the transmission device’s operation is flexible and reliable; whether the concentricity of the coupling is standard; the flexibility of the gear transmission, and other conditions. If the phenomenon of stalling is found, you should immediately stop to identify the cause of the troubleshooting before running.
2. Often check whether the three-phase current balance of the permanent magnet motor.
Three-phase AC permanent magnet motor, the three-phase current of any one phase current and the other two currents’ average difference is not allowed to exceed 10% to maintain the safe operation of the permanent magnet motor if more than indicates that the permanent magnet motor has a fault, must be identified.
3. Check the temperature of the permanent magnet motor to frequently check the permanent magnet motor bearings, stator, shell, and other parts for the temperature of any abnormal changes.
Whether the permanent magnet motor bearing is overheated or lacks oil, if the temperature rises near the bearing is found to be too high, it should be immediately shut down to check; if the rolling body of the bearing, the raceway surface has no cracks, scratches or defects, whether the bearing gap is too large shaking, the inner ring in the shaft has no rotation, etc., for hearing must be updated before working again.
4. Observe the permanent magnet motor vibration and noise for the above phenomena.
If the vibration of the permanent magnet motor causes the load connected to its part of the different degrees, the formation of permanent magnet motor load increases, overload operation, it will burn the motor. Therefore, the permanent magnet motor in operation, especially the high-power permanent magnet motor, must frequently check whether the foot bolt, end cover, bearing gland, etc., is loose, whether the grounding device is reliable, and find the problem in time to solve.
5. Keep the permanent magnet motor clean.
A permanent magnet motor in operation, into the air around at least 3m does not allow dust, water stains, and other debris to prevent the inhalation of the internal motor, the formation of short-circuits medium, or damage to the wire insulation, resulting in short circuit, burn the motor, so to ensure that the permanent magnet motor has sufficient insulation resistance, as well as good ventilation and cooling environment, to make the permanent magnet motor in a long time to maintain a safe and stable working condition.