hey gene sorry for the slow reply
just getting to this grounding thing now. currently I have single large copper block with a lot of holes in it for terminals, this is connected to the earth(ground) wire that goes back to the whole shed main ground wire rod in the dirt all my servo drives and vfd main grounds go back to this point as do all motor grounds etc. this is how heidenhain set up the machine originally and they have a whole grounding schematic showing how it all works. I have basically copied that. I have 2 meanwell 24v powersupplies that have the ground wire on the input side also connected to ground. the output side (phase and neutral) are floating relative to ground and not connected to ground at all I think. as the meanwell switching powersupply output should be isolated from the input. I think this is correct the computer cord ground wire is currently connected to this same large copper block. my computer via the 5i25 currently supplies 5v logic power to the 7i76 and one of the 24v meanwell powersupplys supplies the 24v field io for the 7i76 my encoder problems started when I connected up the servo drive simulated encoder output to the 7i76 encoder counter. I haven't connected the 5v and 24 v grounds together. they did work for awhile but don't now I have a 7i89 and 7i84 coming soon and will need a external 5v powersupply anyway i think so will change when they arrive here from america. anyway I read your reply and got a bit confused could you read my email here and let me know what I need to change and why I should do it this way just so I understand. regards Andrew On Thu, May 21, 2020 at 9:31 PM Gene Heskett <ghesk...@shentel.net> wrote: > On Thursday 21 May 2020 01:57:06 andrew beck wrote: > > > hey peter > > > > I had a look and the unless there is a shorted out pin in the servo > > drive connector itself I think the wiring is all good. > > > > and I highly doubt the servo drive has problems all I did was connect > > the 24v back into the servo on pin which is how it has been running > > for the last ages. > > > > anyway how do you recommend commoning the grounds? > > > > it is as simple as connecting the field power 0v ground with a wire to > > the logic power 0v ground? > > > Yes, but how you do it can be very important. > > In your control box, install a longer bolt, #6 or #8-32 to the chassis. > 4mm if metric. > > Connect all grounds to this bolt, checking that they are not grounded at > the far end. By doing this, you are establishing a single point ground > that is the zero volt reference for the whole system. Connect this bolt > to the building static ground, the bare wire in most power cabling. > > Connect the machines frame to this bolt. > > Connect the - rails of all supplies to this bolt. > > Connect the - terminals of all cards to this bolt. > > Break the 3rd pin off the computers supply cable and connect the > computers chassis to this bolt. Power the computer not from the wall, > but from the same power feeding this box. > > Connect the shielding of all shielded cabling to this bolt. Do not > connect the far end of this shielding to anything that is otherwise > grounded. > > By making sure these grounds are not connected anyplace else you are > breaking any ground loops which can and will act as antennas to insert > noise into your control signals. > > By having this single point ground, a nearby lightning strike can inject > a 100k volt pulse into the system ground as what would be called > a "ground bounce", but the system will not see it as noise nor be > damaged, because everything is bouncing in unison. > > Regardless of what that bolt does during the strike, the 5 volt supply > remains at 5 volts to this bolt, and the 24 volt supply remains at 24 > volts to this bolt. > > And when the storm is done, your chances of having anything damaged is > reduced to the vanishing point. > > Stay well Andrew. > > [...] > > 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) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > 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
