The highest peak observed on a large 6-pole motor running a direct drive axial fan in cleanroom service is .122 at exactly 3600 cpm/60 Hz. The motor rotational rate is 1195 rpm. The data was collected when the motor was being driven by a VFD, operating at full speed, (60 Hz.) When the motor is operated directly from line voltage (with the VFD in bypass), the 60 Hz peak drops to .001 ips. and there are no other changes in the spectrum. The motor picks up a couple of rpm in bypass.
The carrier frequency was varied between 2 kHz and 6 kHz with no appreciable effect, however an "auto-tune" procedure was performed by a factory rep. and a number or loose connections were tightened. This reduced the level of the 60 Hz peak to .06 ips, but it is still present. Any suggestions about what could be causing the problem or further testing would be greatly appreciated. I apologize for the confusion and misinformation in my previous post.
Regards,
Tim Wechsler
The carrier frequency was varied between 2 kHz and 6 kHz with no appreciable effect, however an "auto-tune" procedure was performed by a factory rep. and a number or loose connections were tightened. This reduced the level of the 60 Hz peak to .06 ips, but it is still present. Any suggestions about what could be causing the problem or further testing would be greatly appreciated. I apologize for the confusion and misinformation in my previous post.
Regards,
Tim Wechsler