Re: VFD interference problem
Maybe I'm wrong but I dont see any grounding wires for your control cables, so I think you have to do that first. and perhaps a power line filter for the VFD and ferrite beads on all of them as well, also physically separating power lines from control lines.
maybe someone with more experience can comment as well :)
Re: VFD interference problem
I am not surprised that you have emf problems I think I would remove the vfd from the control box plus sort out the rats nest of wires try to keep or the signal wires away from the power wires and avoid running them side by side.
If you have to cross power wires do so at 90' if possible. Have you connected all the screens to one star point? I don't think it helps having the PP ribbon cable I would try and replace that by connecting the PP cable from the PC direct to the BOB without the ribbon cable.
You have the basis of a good control box but you have not made the best use of the cable management in there.
edit: Is that a plastic control box? have you mounted everything on to a backplane (ie metal plate) I think one of your main problems will incorrect grounding
Re: VFD interference problem
Different VFDs generate different levels of interference, I have a .55kW Omron on a small manual mill in the workshop that kills the radio and knocks the benchtop CNC mill about and yet the .75kW Siemens on the CNC mill itself causes no interference from 750rpm through to 7000.
It is fairly standard to have all the kit in one box but if it's a dirty VFD it may be worth relocating it if problems persist after you add an RF filter on it's mains input
- Nick
Re: VFD interference problem
Geoffrey got to be methodical to find this. Make one change then test before making another.
Start with small trivial things first like removing the Tie raps holding cables together around the machine and separate the VFD cable from Stepper or signal cables.
Next make sure the screens from the long cables go to the Star Earth not just the cables inside the box.
I See you have 4 wires going to the spindle and suspect one of them you have connected to the Spindle for Earth.? Remove this at the VFD end and try.
Also Only connect the spindle cable Shield at the VFD Earth not both ends.
After doing these I would remove the VFD from the Box as a test. If solves then fit a Line filter and try again but it still may not work if you have sensitve elelctronics in the control box.?. . Like Cheap nasty BOB.!!!!!
One last thing you haven't earthed the PC case to control box have you.? If so remove.
Re: VFD interference problem
Alright, so after spending the day trying to fix this with Graeme on Skype, we seem to have found the source of the problem.
I have connected all screens to the star point. I've taken the VFD out of the box, power is separate, it's completely diconnected from the control box, and still, no improvements.
Turns out disconnecting the PC solves the issue. So it seems like there is a grounding problem with the BOB. As JAZZ said, it's a cheap chinese BOB, so I might have to change it.
Quote:
Originally Posted by
Clive S
edit: Is that a plastic control box? have you mounted everything on to a backplane (ie metal plate) I think one of your main problems will incorrect grounding
Fiber glass cabinet. Fireproof plate in the back. No metal.
Quote:
Originally Posted by
JAZZCNC
Like Cheap nasty BOB.!!!!!
Jee JAZZ, you don't like them.. :D !
Quote:
Originally Posted by
JAZZCNC
One last thing you haven't earthed the PC case to control box have you.? If so remove.
Nope, not intentionally, but apparently it is through the BOB.
One thing to note. When there is no power to the control cabinet, but the PC is plugged and turned on, the BOB receives 5V, but the 5VDC PSU led turns on, apparently because it receives power through the BOB ! Weird...
Re: VFD interference problem
Quote:
Originally Posted by
eurikain
Jee JAZZ, you don't like them.. :D !
Nope and now you know why. You have been lucky to find it quickly this isn't always the case, in fact often not the case. Which is exactly why when these troubles come my way first thing I do is rip out the BOB.:grief:
Re: VFD interference problem
You're most likely getting a ground loop through the parallel cable shield. As you're using a ribbon cable internally, try unscrewing the parallel connector from the cabinet and see what happens. If it cures the problem, you can either come up with some way of insulating the connector, or just cut the cable shield near the connector.
Re: VFD interference problem
Quote:
Originally Posted by
JAZZCNC
Nope and now you know why. You have been lucky to find it quickly this isn't always the case, in fact often not the case. Which is exactly why when these troubles come my way first thing I do is rip out the BOB.:grief:
Okay but now, where do I go ?
Re: VFD interference problem
Quote:
Originally Posted by
m_c
If it cures the problem, you can either come up with some way of insulating the connector, or just cut the cable shield near the connector.
It's Fibre Glass cabinet so won't be that.!!
Quote:
Originally Posted by
eurikain
Okay but now, where do I go ?
The good old US of A. . . . . PMDX126.
