John Kasunich wrote: > Kirk Wallace wrote: > >>Thanks for the e-mail Einar. There is a cabinet on each side of the >>lathe. The VFD is in the right cabinet and is grounded to the cabinet. A >>flex conduit with a plastic outer and a metal spiral inner carries three >>conductors to the motor connection box which is screwed to the motor >>housing. So, there should be metal surrounding the VFD to motor leads >>for the entire distance. > > > There may be metal surrounding it, but that "spiral" has a lot of > inductance and is not a good high frequency ground. If this is conduit > and not cable, I'd pull the three wires out, then pull them back in with > at least one ground wire added (three if you have room, one loosely > twisted around each power wire). Connect the ground wire(s) directly to > the motor housing, and directly to the VFDs ground terminal. > The ground wires can be smaller than the power wires, especially if you > have three. > > Even better, if you can get some, is a braid that can be expanded enough > to run the three motor leads through it, then stretched lengthwise so it > snugs down around the motor wires. Again, connect one end directly to > the motor frame, and the other directly to the VFD ground. > > The idea here is to have the return path for stray currents as close as > possible to the outgoing path. > > Regards, > > John Kasunich
As a wild idea, would it work to use hydraulic hose as a conduit for this type of interference? If you skive back the rubber on the end before you crimp on the fitting it would give you a solid layer of wire braid and two fittings of your choice to run the wires through. Ed. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
