When megging motors....

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mickeyrench

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edison, n.j.
When megging motors I most of the time megg at the starter bucket which could be 25' 100' away from motor only because it saves time in disconnecting motors and reconnecting again. Is this a bad practice? Thanks again
 
Are you doing this for PM or troubleshooting? We do this for PM purposes on a lot of plants I work in. We then print the results, instrument used and the date. I also include the motor temperature at the time of the test. We place a copy of the printout on the inside of the bucket door.This allows their in house people to have a quick reference for troubleshooting later on.
 
Recording winding temps and correcting your values is vital, your results are meaningless without that info.

Now to the OP's question, your results are going to be skewed from the cable insulation resistance, as I am sure you understand, but it makes your values lower, so it is not realy a bad thing. As long as you megger from the same point every time I dont see a problem with the way you are doing it, a megger test is not so much about the values you get as it is comparing those values over time for trend anaylsis. test from the same point every time and compare to previous tests.
 
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