by spumco » Fri Feb 08, 2019 2:18 am
Based on suggestions here and on other forums, here's what I've done on my mill to eliminate noise-related bugs. So far I've not had any problems.
RFI filter on mains input
Line reactors on input/output to VFD
Ferrite rings on VFD output cables
VFD cables run through metallic conduit to motor
VFD cables twisted in conduit (ground not twisted with power conductors)
VFD cables/conduit not near anything else except in the energy chain to mill head - and the conduit is separated by 3" or so when it's parallel to the other cables.
Signals, including limit switches, are 24vdc.
Limit switches & spindle index proxy run as NC
Motor encoder has complimentary signals in a double-shielded cable well away from VFD conduit. Enters the enclosure at a different point than the VFD cables.
Star ground for all components. Paint scraped at all ground points on backplane, motor, machine cabinet, etc.
I'm sure there are other techniques for managing noise, but that above didn't really cost much.