It isn't the motor I'll be using the VFD on. I suppose what I should do
is get some hydraulic oil and fire up the forging press with it
(intended 3HP use).

Gunner, I think your idea is how I got to where I'm at...except it was
more than $5.

Steve

Gunner wrote:

On Sun, 10 Apr 2005 11:16:30 -0500, "R. O'Brian"
wrote:



The motor is the problem. Chances are it is not a high quality motor and
this means the windings and laminations are not supported by resin
impregnation as well as they could be. Even a high quality motor will make
some noise, but it will be more of a hiss than a whine depending on the
enclosure type and pwm freq.

Randy



A quick check would be to pick up a used $5 motor and wire it up while
its sitting on the floor and fire the sucker up.

Gunner



"Steve Smith" wrote in message
...


I have two different VFD's. Both turn a motor (different motors) just
fine. One is completely silent (TECO), the other one makes a noticeable
and irritating whine (actually the motor makes the noise). The noise is
coming from the PWM in the drive.

I haven't tried every PWM frequency, but I have tried about a dozen.
They all whine until I get up to 16kHz, where I don't hear it. This
would be fine except that above 12kHz the drive is only rated at 80%
(2.4HP); I intended to run a 3HP motor with it.

The noisy VFD is a 3HP Cutler Hammer that I just bought. I have it set
up for test with 4' of Romex connecting between the VFD and a 3HP
motor. The motor is grounded to the VFD and has no load.

I would appreciate suggestions on how to quiet the drive but keep the
PWM frequency at 12kHz or below. Will a load change things? Will a
different motor change things?

Thanks,
Steve Smith




Leftwingers are like pond scum. They are green, slimy, show up where
they are not wanted, and interfere with the fishing.

Strider