On Monday 11 May 2015 22:19:11 Rafael Skodlar wrote: > Tom, > > Hard to tell from the picture but I would make sure that ground is > properly connected in "star configuration", i.e. there is only one > ground point [1] in the cabinet and the CNC machine. I suspect you get > some ground currents somewhere which possibly cause enough noise to > mess up your VFD. > > [1] ground could be a copper bar with enough holes to attach all > ground wires from all cables, CNC chassis, and power filter to it. > Connect ground wire to the door itself and whatever is mounted on it > as well.
I might add that plugging the monitor into a wall outlet, with its own static ground, would likely be a no-no as that puts the monitors static ground point clear back in the building service. If possible, even the static ground in the monitors power cable should be on this star ground bar. It would best be powered from power available in the servo/vfd box, and grounded, to this same star ground. What you are describing, to this old CET, sure sounds like the whole building is a ground loop. > It might be worthwhile to add ferrite toroids on critical (analog) > lines including parallel cable; see > https://en.wikipedia.org/wiki/Toroidal_inductors_and_transformers > > On 05/11/2015 06:00 PM, Tom Easterday wrote: > > Early on we made a decision to put our VFD into the same cabinet as > > the rest of the electronics on a lathe retrofit - I originally had > > two separate cabinets, one for power with vfd and one for > > electronics. This was to save space and bring the size of the > > cabinet on the machine down to a more reasonable size so it might > > fit through doors, etc. In retrospect, perhaps that was a bad idea. > > But here we are trying to address VFD induced noise problems. The > > cabinet is shown in a picture here: > > https://www.flickr.com/photos/37438950@N00/17219261571/in/album-7215 > >7651167328249/ > > <https://www.flickr.com/photos/37438950@N00/17219261571/in/album-721 > >57651167328249/> There is actually more wiring completed now then > > what is shown in the picture but you get the idea. > > > > After having read about folks often using Rasmi input power filters > > to solve noise issues I purchased one from ebay and installed it > > today. It didn’t help, and may have actually made the problem > > worse. I installed it very close to the VFD input power terminals > > as recommended. > > > > When I run the spindle motor on it’s lowest RPM I hear a high > > pitched whine (at the motor) and strange things begin to happen in > > Axis. Windows pop up, perhaps a homing window, perhaps a touch off, > > perhaps Axis switches to MDI mode, sometimes it turns the machine > > off, sometimes it turns the machine off but the spindle keeps > > moving! Sometimes the VFD shuts off and displays "oL 1” on the > > screen. > > > > So now I want to understand how this noise is getting into the PC. I > > first thought it was because the keyboard, mouse, and video cables > > ran past the VFD in the cabinet and noise was being induced on the > > keyboard cable. So in trying to isolate where the issue was I > > disconnected those cables and ran them far away from the VFD. No > > help.. I then wondered if it was coming in the AC power to the PC, > > so I rerouted the PC power to a completely different outlet outside > > of the cabinet. No help. I then rerouted the network and video > > cables to get those away from the VFD, no help again. Even with > > the door open (as you see in the picture) I have noise. The only > > thing connecting the PC to the rest of the system is the parallel > > cable which is about 12” long that connects to the Mesa 7i85s card > > (and again, that is at the other end of my cabinet from the VFD). > > Today I borrowed a friend’s 0-1Ghz spectrum analyzer to see if I can > > find the source/frequency of the noise and/or where it migh > > t be getting to the PC. I will start playing with that tomorrow. > > > I am wondering if anyone has any ideas of where i can look, or what > > I can do? -Tom Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
