Spindle occasional stutter

[Yurtman]

Setup: MACH 3, PDMX 126 BOB, PDMX 107 PWM spindle controller, Danfoss 2800 VFD with3 phase 400V input, ELTE 2.2KW air cooled spindle

The problem I am experiencing is that occasionally, and sporadically maybe 4-6 times a day it sounds like the spindle cuts out for a fraction of a second during operation. It's an audible blip, but resumes operartion immediately. Prior to this setup I was running a single phase 230V VFD powering a 2.2kw spindle without such blips, powered from the same circuit board. I have a 3 phase vacuum motor on the same supply which operates without symptoms.

I wonder if the VFD could be transmitting some noise to the motor. Would this translate to a very momentary cutout? Has anyone experienced anything similar? Any insight people could shed on this siyuation would be very much appreciated.

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[Yurtman]

I noticed that the PWM led on the PMDX 107 board dims when the spindle cuts and so I believe that the PWM signal is the cause. I'm not sure where it originates, my ESS is mounted on and connected to the PMDX 126 with the short ribbon cable so I think it's unlikely to be electrical noise. I did change the switch 5 of the 107 board which slows the response to the PWM input, this did change the nature of the cutouts from being a quick slowdown and acceleration to a slower deceleration and speed up. Can anyone help with this or suggest a way of diagnosing where the PWM signal may be slipping?

[spett]

Hi! Did you find a solution to this problem? I ask because I have the same setup as you (just a different spindle & vfd) and have the same problem..

[Yurtman]

I'm afraid not, I just live with the problem. Never solved the mystery.