Peter T. Keillor III wrote:

On Sun, 10 Apr 2005 17:12:48 -0400, Bob Engelhardt
wrote:



R. O'Brian wrote:


The motor is the problem. ...


I'm certainly no expert, but I have a little direct experience with
this. I have a 3 ph motor and VFD on my drill press. It is the 2nd
VFD. The first one sang, this one does not. Same motor, same wiring.

Bob



The Mitsubishi drives I have at home allow modification of the PWM
frequency. Allen-Bradley drives I use at work do as well. Changing
this frequency may reduce the noise generation, particularly if it
moves away from a mechanical harmonic frequency.

Pete Keillor


I've tried a number of frequencies with no effect. I should continue and
try the rest.

Thanks,
Steve