I found this on amazon http://www.amazon.com/UT-211-Port-powered-Mini-size-PhotoElectric-Isolator/dp/B00GI9GS58/ref=sr_1_3?ie=UTF8&qid=1451156759&sr=8-3&keywords=serial+isolator
Not sure how I might isolate the VFD from the chassis at this moment. Well I could machine some delrin standoffs... I have a machine shop. I will need the control transformer to get power for the monitor or just plug the monitor into the wall outlet and power the PC with 240v? JT On 12/26/2015 12:51 PM, Bertho Stultiens wrote: > On 12/26/2015 07:36 PM, John Thornton wrote: >> 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. > Ok, now the real question is whether you can see the difference wrt. to > my drawing. > > The trick is that there should never ever be two or more paths for the > current to flow, even if it is just an earth connection (or GND for that > matter). > > The isolation barrier I drew is the low-to-high-power separation. It > should be kept physically separated everywhere until you join the power > and earth connections at the power supply input. > > The real problem I see is the connection of the VFD controller to the > computer's serial port. Apparently, the computer and the VFD controller > both have the GND connected internally to earth. > > I am pretty sure that the computer's GND is connected to the earth > (chassis) of the computer (most PCs have). > > The VFD controller probably has the same connection, where the modbus > serial port's GND is connected to the VFD controller's earth (chassis). > > If so, then you need to break that loop by electrically isolating the > serial port. > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
