Tom, Hard to tell from the picture but I would make sure that ground is properly connected in "star configuration", i.e. there is only one ground point [1] in the cabinet and the CNC machine. I suspect you get some ground currents somewhere which possibly cause enough noise to mess up your VFD.
[1] ground could be a copper bar with enough holes to attach all ground wires from all cables, CNC chassis, and power filter to it. Connect ground wire to the door itself and whatever is mounted on it as well. It might be worthwhile to add ferrite toroids on critical (analog) lines including parallel cable; see https://en.wikipedia.org/wiki/Toroidal_inductors_and_transformers On 05/11/2015 06:00 PM, Tom Easterday wrote: > Early on we made a decision to put our VFD into the same cabinet as the rest > of the electronics on a lathe retrofit - I originally had two separate > cabinets, one for power with vfd and one for electronics. This was to save > space and bring the size of the cabinet on the machine down to a more > reasonable size so it might fit through doors, etc. In retrospect, perhaps > that was a bad idea. But here we are trying to address VFD induced noise > problems. The cabinet is shown in a picture here: > https://www.flickr.com/photos/37438950@N00/17219261571/in/album-72157651167328249/ > > <https://www.flickr.com/photos/37438950@N00/17219261571/in/album-72157651167328249/> > There is actually more wiring completed now then what is shown in the > picture but you get the idea. > > After having read about folks often using Rasmi input power filters to solve > noise issues I purchased one from ebay and installed it today. It didn’t > help, and may have actually made the problem worse. I installed it very > close to the VFD input power terminals as recommended. > > When I run the spindle motor on it’s lowest RPM I hear a high pitched whine > (at the motor) and strange things begin to happen in Axis. Windows pop up, > perhaps a homing window, perhaps a touch off, perhaps Axis switches to MDI > mode, sometimes it turns the machine off, sometimes it turns the machine off > but the spindle keeps moving! Sometimes the VFD shuts off and displays "oL > 1” on the screen. > > So now I want to understand how this noise is getting into the PC. I first > thought it was because the keyboard, mouse, and video cables ran past the VFD > in the cabinet and noise was being induced on the keyboard cable. So in > trying to isolate where the issue was I disconnected those cables and ran > them far away from the VFD. No help.. I then wondered if it was coming in > the AC power to the PC, so I rerouted the PC power to a completely different > outlet outside of the cabinet. No help. I then rerouted the network and > video cables to get those away from the VFD, no help again. Even with the > door open (as you see in the picture) I have noise. The only thing > connecting the PC to the rest of the system is the parallel cable which is > about 12” long that connects to the Mesa 7i85s card (and again, that is at > the other end of my cabinet from the VFD). Today I borrowed a friend’s > 0-1Ghz spectrum analyzer to see if I can find the source/frequency of the > noise and/or where it migh t be getting to the PC. I will start playing with that tomorrow. > > I am wondering if anyone has any ideas of where i can look, or what I can do? > -Tom -- Rafael ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
