Megger Test

No. 1Mohm is quite low. When I test the motors etc with my megger by passing 1000V, the reading is 10-200Mohems which we consider ok. 1Mohm mean some problem.

While 1 megaohms is certainly not an indisputable good insulation value, I would say that it now depends on the application in question to say this passes or fails. If your motor/generator has for a normal operating range 12V @ 500A then this leakage current would be considered negligible.

hi,

so you mean to say that every motor has defferent value which determine if its ok or not, depending on how many voltage and how many amps going through that motor/generator winding?

thanks

Of course. Doesn't everything have a sliding scale that depends on circumstance.

If you had asked instead which is stronger, a black ant or a human Olympic weight lifter? The only true answer is it depends on how you define strength. If you go by solely the total amount of mass each can lift uninjured then clearly the much more massive Olympian wins. But if you consider strength across species as a percent of body mass each can lift, then by just as overwhelming a margin the ant wins.

It's always a matter of perspective.

The best way to test the insulation of a motor is to perform a Polarization Index, 10/1 Minute Ratio. To do this you will need to megg the motor for ten minutes, record the ohms at 1 minute and then again at 10 minutes. Do this for all phases of the motor. If the results are less than 1, Insulation Condition is Dangerous. 1 to 2, Insulation Condition is Questionable, 2 to 4 Insulation Condition is Good, Above 4 Insulation Condition is Excellent.