Motor megger
hanacookie- What voltage does the motor run at? I agree with zog. Some automatic mergers will limit the test voltage if the leakage current is too great. If the motor in question is wet or damp, we have heated them up to get the megger reading acceptable. While this works, you eventually will need a new motor or rewind. Our criteria for acceptable megger readings are: 1 Mohm per 1KV of operating voltage plus 1 Mohm. Therefore, a motor operating at 480 VAC will need at least 1.5 Mohm to pass. We also use the PI test (Polarization Index) to determine the condition of the insulation. This test gives you a number between 1 and 10. You divide the 1 minute reading into the ten minute reading to get the number. Good Luck
