On 8 May 2018 at 14:27, John Kasunich <jmkasun...@fastmail.fm> wrote:
> Which cables have a braided shield? The ones taking DC power from the power > supply to the drives? > > There's nothing magic about those cables - replace them with two suitably > sized single-core wires. I know there is nothing magic, they are just some 3-core mains wire that I had. (Multiflex SY). In fact I am pretty sure the braid is only really meant for mechanical protection. > Is your drive DC supply floating (transformer) or rectified mains? Rectified mains. > If such a PE terminal exists, I would run the a PE lead from each motor frame > tightly bundled or twisted with the motor power leads and back to the drive > PE. (If the drive doesn't have a PE, I would make one using a pair of 0.1uF > or so film caps with suitable voltage and safety ratings.) That provides a > low inductance path for common mode current to return from motor frame to > drive DC bus. The PE terminals of each drive could be connected to a common > control chassis near the drives. The ferrite beads around the DC bus > connections to the common power supply would encourage common mode currents > to stay in each drive/motor loop instead of wandering off towards the supply > and the other drives. There is no PE terminal on the STBL, so I have the STMBL on DIN rail, and the motor earth cable (from the M23 connector) is connected to an earthing block on that DIN rail. Actually, at the moment, the earth wire isn't connected, I disconnnected it to put the drive outside the machine as one of my experiments. I intend to se if connecting makes things worse. But I had a working machine and parts to be finished, so I stopped experimenting and started machining. I will try what PCW suggests first (because it is easy) then if that doesn't work I will look at this more scientific approach. > Are your motor leads shielded? That shield can DEFINITELY be > counterproductive, since it acts as additional "motor-lead-to-ground" > capacitance. No, the motor wires are not shielded. I thought that they were, but inspection shows otherwise. -- atp "A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics." — George Fitch, Atlanta Constitution Newspaper, 1916 ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
