You misunderstand, all those components are internally grounded I did not ground any of them. I just showed that the shell on each component is bonded to the ground connection on each device.
On 12/26/2015 12:05 PM, Bertho Stultiens wrote: > On 12/26/2015 04:33 PM, John Thornton wrote: >> The drawing so far as I understand it. > Ok, that is only part of the situation. > > I see that you have the spindle both go to earth via the chassis and > then run a wire to the VFD controller's GND, which then has its chassis > connected to earth. The same you have with the filter. > > These dual connections are possibly earth-loops. However, from your > other comment, you may be confusing the term "earth" and "ground" and > how those relate to the different devices and connections. > > It is a real pain that different manufacturers call one and the same > thing differently. It is up to the user to know which is which. > > > With a few assumptions, see my attached drawing. > > > >> I just checked the ground to housing on the VFD filter, VFD, >> computer, and the smaller filter and they are all internally >> connected to ground. The VFD is controlled via modbus so I don't know >> how to check that cable (which is just a phone cable with a phone >> jack on one end and a DB9 on the other end to connect to the >> computers serial port, it's a Automation Direct cable not home made. > It sounds like you have a ground-loop. > > Modbus is the protocol, which is connected using a serial interface. If > the serial interface is not isolated, then you are in trouble. > > >> Is injection to the mains coming back to the machine somehow? > Yes and no. With a ground-loop, you never know what is happening and you > are basically screwed. > > > > > ------------------------------------------------------------------------------ > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
