The VFD cable shield is capacitively coupled to the motor wires and has a high impedance. Grounding at both ends of high current PWM motor is recommended to clear the cable. Might be able to see a voltage spike on the shield when the motor is turned off, and compare the spike with one and both sides grounded. Low voltage, high impedance, analogue and digital signal cables should be shielded on only one side, near the input. Grounding both ends may add noise to the signal cables from a ground loop. The ground should not go through the choke because the choke increases impendence. Some manuals show each VFD phase choked individually, then again with all of the phases together. Hope this explains the conflicting "don't ground at both ends" advice. The other grounding recommendation in the manual may be to reduce current flow across the motor's bearings. If your VFD has a modbus interface, that might be used to backup the VFD register contents. May be able to use the analouge output pin connected to a 0-10V gauge to show the spindle load. Best wishes
Thanks for sharing that! I don't have the right equipment to measure voltage spikes so it's difficult to know what's going on - but this VFD manual was a lot clearer than my previous one. I cut a few things out today as well, and nothing went wrong but I still need to ground the low voltage shielding. I was thinking of using some stainless bulldog clips to contact each cable shielding foil - from what I read they work best when 360 degree contact is made and not just soldering to the drain wire. It feels like it will be a lot of work which I should have done when I had more space to expose the foil.
My next CNC will have a spindle and not a router. Your work on this is saving me loads of time. Your methodology for trouble shooting and managing complexity is inspiring. Hope you are well and doing well. Great to see a video.
Thanks for your word of encouragement! Spindles do have some advantages especially with speed control. I feel like I skimped out on mine and now wondering if I should open it up and re-grease.
OMG. this is certainly not aimed at a beginner. What is the basic wiring connection/interface between VFD and PC now that I have wired the VFD to the spindle?
The VFD cable shield is capacitively coupled to the motor wires and has a high impedance. Grounding at both ends of high current PWM motor is recommended to clear the cable. Might be able to see a voltage spike on the shield when the motor is turned off, and compare the spike with one and both sides grounded. Low voltage, high impedance, analogue and digital signal cables should be shielded on only one side, near the input. Grounding both ends may add noise to the signal cables from a ground loop. The ground should not go through the choke because the choke increases impendence. Some manuals show each VFD phase choked individually, then again with all of the phases together. Hope this explains the conflicting "don't ground at both ends" advice. The other grounding recommendation in the manual may be to reduce current flow across the motor's bearings. If your VFD has a modbus interface, that might be used to backup the VFD register contents. May be able to use the analouge output pin connected to a 0-10V gauge to show the spindle load. Best wishes
Thanks for sharing that! I don't have the right equipment to measure voltage spikes so it's difficult to know what's going on - but this VFD manual was a lot clearer than my previous one. I cut a few things out today as well, and nothing went wrong but I still need to ground the low voltage shielding. I was thinking of using some stainless bulldog clips to contact each cable shielding foil - from what I read they work best when 360 degree contact is made and not just soldering to the drain wire. It feels like it will be a lot of work which I should have done when I had more space to expose the foil.
My next CNC will have a spindle and not a router. Your work on this is saving me loads of time. Your methodology for trouble shooting and managing complexity is inspiring. Hope you are well and doing well. Great to see a video.
Thanks for your word of encouragement! Spindles do have some advantages especially with speed control. I feel like I skimped out on mine and now wondering if I should open it up and re-grease.
Good info, having seen the result of an eye making contact with a cable tie please trim back the tails as soon as they are installed.
OMG. this is certainly not aimed at a beginner. What is the basic wiring connection/interface between VFD and PC now that I have wired the VFD to the spindle?
Realy helpfull video!
Where do you have this excle sheet from?
would you mind sharing it?