John Kasunich wrote: > Gene Heskett wrote: > > >>A possible test to see if its VFD generated noise would be to see if it >>largely goes away when the motor is at full speed, and gets progressively >>worse as the speed is lowered. >> >>Basically, look for a correlation between spindle speed and the extra noise >>pulses. > > I doubt you'd see much difference. The VFD switches 340 V pulses across the motor windings no matter whether it is at 1 Hz or 400 Hz. Would it be because at high speed the motor is at greater load and the current is more in phase with the back EMF? Or, would the noise be gtting worse with reduced on-time of the transistors? I haven't had to play detective with VFD interference, so maybe it would really show such a characteristic, but I wouldn't have expected it. (Might also be a difference between the BIG drives and motors you play with and the ones I have experience with.) > A very easy way to see if the spindle drive is generating the noise is > to run the spindle up to top speed and then cut the drive completely and > let the spindle coast to a stop. Now, this is an EXCELLENT idea! You have to set up the VFD to not do any decelerating or braking, but that is usually a setting that can be done.
I did have some non-CNC interference from my mill's VFD, mostly to my computer monitor. I put a Corcom-type line filter box on the line in to the VFD, and it solved the problem. Jon Jon ------------------------------------------------------------------------- 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
