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 ------------------------------------------------------------------------- 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
