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Fault detection method for permanent magnet motors

Release time:

2023-05-12 14:19

1. Listen to the sound first, then carefully locate the fault point

During the operation of a permanent magnet motor, if there is a fine "buzzing" sound without any fluctuations in height, it indicates that it is a normal sound. If the sound sounds thick and sharp "buzzing" or "hissing", it indicates that it is a precursor to a malfunction. At this time, you should consider the following reasons:

(1) Loose iron core

The vibration of permanent magnet motors during operation, as well as changes in temperature, can cause deformation of the iron core fixing bolts, resulting in the loosening of silicon steel sheets and generating large electromagnetic noise.

(2) Rotor noise

The sound emitted by the rotor rotation is generated by the cooling fan, which is a "whine" sound that sounds like the "thud" sound when playing a drum. This is caused by the acceleration torque of a permanent magnet motor during sudden start, stop, reverse braking, and other variable speed situations, which causes the rotor core and shaft to loosen. For light cases, it can be used again, while for heavy cases, it needs to be disassembled for inspection and repair.

(3) Bearing noise

When a permanent magnet motor is running, we must pay attention to the changes in bearing sound, and also touch one end of the screwdriver on the bearing cover and the other end on the ear. At this time, you can hear the internal sound changes of the motor, different parts, different faults, and different sounds.

For example, the "creaking" sound is generated by the irregular movement of the rolling gun inside the bearing, which is related to the clearance of the bearing and the state of the lubricating grease. The "sizzling" sound is a metal friction sound, usually caused by a lack of oil in the bearing during grinding. We should disassemble the bearing and add lubricating agent to it.

2. Use your sense of smell to analyze faults

Permanent magnet motors have no odor during normal operation. If you smell something strange, it is a fault signal, such as a burnt smell. This smell is emitted by insulation barbecue, and as the motor temperature continues to rise, in severe cases, it can also smoke; If it smells like oil tar, it is mostly caused by the lack of oil in the bearings, and the peculiar smell of oil vapor evaporation occurs near the dry grinding state.

3. Use hand feeling to check for faults

We can use our hands to touch the shell of a permanent magnet motor and roughly determine the level of temperature rise. If we feel very hot or have a high temperature value when touching the motor shell with our hands, we should immediately check the cause, such as heavy load and high voltage, and then troubleshoot the cause.

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