On Fri, 2010-02-12 at 16:42 +0000, Andy Pugh wrote: ... snip > I had a problem with noisy encoder signals with the spindle VFD > running. I didn't do a full step-by-step analysis but the problem went > away with: > 1) Braided shielded motor cables, grounded at the VFD end to the > terminal suggested by the manufacturer. The cables have a dedicated > earth/ground wire and I made sure this was well connected at both > ends. I have plugs and relays in my 3-phase VFD output runs, and I > used the earth wire to bridge the gaps in the shielding through these > parts. (rightly or wrongly) > 2) A filter on the input to the VFD. This prevents noise transmission > back down the lines, and emission from the input cables. I bought mine > from eBay for not very much. > 3) Ferrites on the output wires from the VFD. Just a ferrite bead for > each cable, looped through twice.
I had similar issues but: 1) I had plain single VFD output wires through metal conduit to the motor before and after the encoder noise problem. 2) Input filter fixed it. http://www.wallacecompany.com/cnc_lathe/HNC/00024-1a.jpg 3) Placed one ferrite on the group of three motor output wires because I spent money to get some. It had no effect. Only the spindle encoder (oddly, the furthest from the VFD): http://www.wallacecompany.com/cnc_lathe/HNC/00011-1a.jpg index had a problem, all other A, B and index signals were fine. I intend to put input filters on all of my VFD's. One remaining issue is how to size the filter to the VFD so I won't waste money on more capacity than I really need. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
