# Micromaster 420 vfd



## JRaef (Mar 23, 2009)

Noble 32 said:


> I have a question
> Last night we had motor go bad on a brine pump. No big deal swapped it out with a new one. The issue is after we swapped it over the vfd would only run in min frequency and would not except inputs to adjust the feq.
> What could be the cause? I am at the point of banging my head against a wall.
> Any help is greatly thanked.


If you have it in Vector Control, you need to perform the Auto Tune function when you change the drive or the motor. If you didn't do that, the drive doesn't know what it's connected to so it doesn't know what to do. Either perform the Auto Tune, or revert to V/Hz control so that it no longer cares.

If you DID do an auto tune, then whatever event lead to your having to replace the motor may have damaged the drive. Or maybe the motor was never bad in the first place, only the drive! Most of the time though, the drive will show a fault if it is the drive. My money is on the fact that you are trying to run in Vector mode but have not done the Auto Tune procedure.


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## Noble 32 (Feb 25, 2013)

Well the motor megged out bad. I know which parameter is the autotune so when floor goes to lunch i will run it and see if that helps. Thank you.


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## starter (Oct 24, 2010)

I had a problem much like that before u need to check your motor leads to see if your wire co figuration is correct. that my also cause your vfd run in min frequency.


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## Noble 32 (Feb 25, 2013)

sorry bout the delay
After digging into it more found a wire that had corroded to the point of only one or 2 strands left underneath the terminal. Just enough to give me a voltage reading but not enough to supply the amps to the drive. Gave it a new wire and she took off like a champ.


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