power supply grounding advice needed

[finyuk2005]

Hi there
Almost have my plasma table working, unfortunately the manual for my Jasic cutter has the wiring for Arc start and Arc ok back to front, and because of that it sent 12v to my torch height controller ! So it blew up!
I have now sorted that wiring out and am waiting for a new THC board,

But the maker of the THC mentioned that i was asking for trouble having my grounds isolated as I asked him if having the +5v and 0v connected directly to the 5v power supply, instead of having the 0v connected to ground, may have caused issues.

The reason i have not connected any of the 0v of the power supplies was because i was getting interference and encoder issues when everything was connected to ground.
I have a separate 24v dc supply for the logic side of things (motion controller and the servo drives) and another for the limit switches and relays and z axis brake etc. And then a 5v supply for the THC and an arduino,
Am i right or wrong to have the 0v/negative of easy of these DC supplies isolated from ground?

I do have all 240v supplies for the servo drives and the power for the DC supplies as well as one end of each cable shield, and all parts of the table itself all connected to earth/ground

Any wisdom, do's or don'ts much appreciated!

sorry for the long essay

[weldguy]

I would connect all your negative leads as they should be to your connected devices rather than to ground. Your interference will be from something else. When do you get the interference issues? When you turn the system ON? When the torch fires?

[finyuk2005]

Yeah thats the way i have it now,
Originally I had everything connected to ground and was getting encoder errors left right and center, so I isolated the DC side from ground and that help a lot, but i still had issues so ended up replacing the X and Y servo motors and drives.
The original drives where old DC motors and drives powered from a big transformer, so i had -18v,0v,+18v and 24vac and then 24vdc for the newer z axis servo drive, plus 240 and a few others! so it was complicated,
I now have all new AC servo drives, all the same brand and everything is working well!

i do just think the mixed up wiring from the plasma cutter sending 12+v to the 5v torch height controller is what did the damage!

I just wanted to know if i am wrong to not ground all the 0v of the dc supplies, but there does seem to be 2 schools of thought on that subject!

[finyuk2005]

https://en.cs-lab.eu/wp-content/uploads ... -drive.pdf

that wiring diagram seems to want the 0vdc separate from the PE or protective earth i guess they are meaning?

[weldguy]

https://en.cs-lab.eu/wp-content/uploads ... -drive.pdf

that wiring diagram seems to want the 0vdc separate from the PE or protective earth i guess they are meaning?

Yes, that's how I read that diagram. Glad things are smoothing out with your setup. If you get a chance post some pics. Always cool to see the different DIY builds

[finyuk2005]

will do indeed! thanks very much!