| 51% of all motor failures are bearing related according to EASA. Lubrication issues, vibration (in storage and operational) and stray currents all seem to take their toll. Recently many new motors have been supplied with Polyurea grease (see chart this page) and may not be compatible with greases you've used in the past.
–em2solutions |
One of the most useful test for determining when to remove a motor from service for overhaul and/or rewinding is the insulation resistance test. To be effective, this test must be conducted at regular intervals, typically annually. The results must also be recorded for comparison with future readings. This is known as "trending". When the results show a downward trend, the test should be done more frequently.
–EASA |
