VFD squeal


I'm trying to reduce noise on my water bin dump water pump...
I installed a VFD this morning. Had to remove it immediately because the
pump motor got a new high pitch squeal. Anybody know why a VFD would do
that? More importantly, how could you stop it?
Karl
Reply to
Karl Townsend
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The drive generates a pulse width modulated sine wave - you're hearing the carrier frequency. Most drives allow you to adjust the frequency. Lower is better for the motor, but doesn't always fix the noise. A higher frequency setting will move the noise out of the audible range, but the switching transients may be harder on the motor.
Reply to
Ned Simmons
Are we talking about a squealing bearing sound, like really loud? Or is it just a whistling sort of noise? Assuming you are running the motor at the correct RPM (60 Hz) then the only logical thing it could be is acoustic output from the PWM frequency of the VFD. Some models have a choice of frequencies available, try changing it. If it really is a bearing squeal, ie. really loud, then make sure you are running at 60 Hz. If that is right, then maybe the bearings are bad or the windings have a short, and current is going through the bearings. If the motor frame isn't grounded, check for a shrt to ground and then ground the frame.
Jon
Reply to
Jon Elson
So, aside from the noise did it work better? In other words, are you half way there?
Reply to
Tim Wescott
No, the VFD was no help at all. I tried 30 45 and 60 HZ. Not enough flow at the lower settings and no noise reduction at all. Plus I got this new squeal from the carrier frequency. Back to the drawing board. main crop starts next week, there's no more time for a month. I got something to think on.
I think I'll shop eBay for a submersible three phase pump motor. Bruce's suggestion would have no noise at all.
Karl
Reply to
Karl Townsend
You need the volute and prop to fit BEFORE you buy the motor, so you know which motor you need - unless you want to mill it from scratch.
And it's probably still going to be 1/2 HP just a different (and much quieter) form factor.
-->--
Reply to
Bruce L. Bergman
Does the VFD allow you to change the carrier frequency? Often the problem is the motor windings mechanically resonating at some harmonic of the VFD switching frequency. Sometimes, it's adjustable to a frequency that doesn't cause the problem. Sometimes it's adjustable to the point where us old farts can't here it any more :-)
I've had to do this on all three of the VFD drives I've set up so far.
Mark Rand RTFM
Reply to
Mark Rand
I guess I'm lucky. I know a machinist that can make ANYTHING adapt. I cruised eBay today, not a single offer. I may have to look for this motor as a repair part.
karl
Reply to
Karl Townsend
Exactly what rpm range are you looking for in the prop? Are you serious about the submersible motor? Will your situation allow a "V" belt drive?
Paul
Reply to
co_farmer
And the noise itself is no sign of danger to the motor, so you did not need to pull it off immediately.
Good Luck, DoN.
Reply to
DoN. Nichols

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