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Hi Guys,
I've been told a few different ways to do this by the blokes I work with.
Can anyone confirm to me though the correct and safe way to test single and three phase motors using a megger. Either balance testing (which I believe is using the ohms setting) or insulation testing (using the volts setting).
Many thanks in advance,
Bash
To megger test a 3-phase motor with a 1000volt megger tester:
Testing to earth
a) Switch off the circuit breaker.
b) Connect black megger test probe to earth. Check for ground continuity, to a terminal box bolt (this is check for good ground connection)
c) With black probe still connected to ground, connect the red test probe to a motor terminal. Push test button. Insulation resistance should indicate 1 meg-ohm or more.
d) Repeat test on remaining motor terminals
Testing between windings
e) Disconnect all line connections & remove bridging links.
f) Identify the individual winings
g) Connect black probe to one winding, test with red probe to other windings. Again, insulation resistance should indicate 1 meg-ohm or more.
g- ur only testing resistance so the reading will be in ohms- in 3 phase they should be equal in a single phase compressor they will be different according to start and run windings
An important note, never ever megger a compressor when it is under vacuum!!
That can happen?