[efinkg]

I have a mostly retrofitted Hurco KM3, replacing the relays with a Teco FM50 VFD that is also being used to convert the 220v single phase input to a 3phase output. The VFD works fine, but it also causes the servo motors to fluctuate slightly. It has vastly improved since I ensured all grounding lines were properly setup, but there is enough that i don't feel comfortable running the machine.

It looks like I might need an EMI filter, but I'm having trouble locating the right one for my application.

Also when the VFD has been on for a little while, maybe a minute or so, the servos stop running at all, which is almost certainly related.

Any help would be greatly appreciated.

[Al_The_Man]

In some cases I have put them in both, but some VFD manuf, suggest at least between VFD and motor particularly if a non-vector motor is used.
At 50 to 600hz, the inductive reactance is low, but offers a high impedance to the high frequency switching pulses.
There was another link here today showing a 1 phase reactor for the VFD that uses 1ph input.
Al.

[efinkg]

My main issue at the moment is that my VFD when hooked up to the spindle, causes the servo motors to run unwantedly, where would be best for this problem?

[Al_The_Man]

Make sure your VFD and spindle motor frame have a earth ground conductor.
Ground the PC case to the Earth ground star point and ensure all the metal work on the machine is bonded to ground.
http://www.cnczone.com/forums/phase_...se_issues.html
Al.

[efinkg]

So the X and Y servos are pretty good, maybe one or two thou motion, while the Z can be as much as a ten thou jump.

I'm going to look to see if the servo amp board is well grounded now, or if I accidentally pulled that. The power to the Mesa boards is through the serial cable, do I need to worry about that getting well-grounded and/or do you have any ideas where to go about that?

I will double check that I'm running a grounded input to the control computer as well, although I'm pretty sure on that one.

[efinkg]

Al, thanks so much for that link. Once I powered the daughter Mesa board off a 5v and Earth ground all is working right, hopefully I can test a full CNC'd path rather than just fiddling around with jogging soon.