meg motor

[rayertz]

I need to meg quite a few motors that are already hooked up to starters and / or VFD's.

The motors are 3 phase 460 volt induction motors.

Spec says to meg it at 1000 volts.

Will I damage the motor or VFD if it is megged from the load side of the starter or VFD?

 

[drcampbell]

On-off magnetic starters with metal-to-metal dry contacts will be fine.

VFDs with semiconductor switches ought to be fine -- the internal DC buss nominal voltage is already 700 volts -- but their survival is not guaranteed and they'll almost certainly induce a false resistance measurement.

 

[Jraef]

ALWAYS disconnect a VFD (or soft starter) when performing a megger test on the motor leads.