Dc servo motor control

Work lead or clamp is always positive on plasma cutters.
Seems like red is positive, but you can always use a DVM to check.

Ive it wired to the plug but Il leave it unplugged and check with a dvm when i first get cutting. 

When i go through the the pncconf i can select and encoder input as the arc voltage but i dont get a configuration page to setup the thcad. 

Tommy, I have now done a few cuts and got the arc voltage working correctly in qtplasmac. I was a little confused as there was nowhere to configure the thcad in the pncconf but then i realised it is simply set within the qtplasmac interface. 

I have a bigger problem now though, I have damaged 2 of the -10+10v AN outputs! They have got pinned at 13.4vdc, a reset does not change this so something on the board is damaged. Im not sure how this has happened, I have each driver signal ground to the tb5 ground pins and the shield to the cabinet ground. A few digital output have also failed. I have enough output to do but wont if I destroy another AN output. 

Im using a 5v 10 amp meanwell psu to supply to the 7i92 and supplying 5v to the 7i77 through the cable.

For field power I am using the ESAB 28vdc supply, perhaps this could be part of the problem, not sure. Temped to change to 24vdc meanwell.  

I had a cnc4pc ohmic sensor i had spare wired in, the enable relay inside it started to flicker very fast (even when it should have been disabled) this could also  be a cause of my problems. 

I have retained the esab grounding strip and shielding.

The plasma is a ht2000 running oxygen at 200 amps.

Problems seem to happen around times of starting arc.




  









 

Pictures of everything, wiring in the control box, mesa, thcad, etc.

     


very messy at rhe moment, i have removed the ohmic sens9r by the time i had too the pictures, it was a cnc4pc one as in link
Sensor

My ohmic sense wire runs into a box above the torch and then is took down with a multicore cable to the main panel, perhaps i should have it separate.

 

First picture, daisy chained ground is a no no, grounds for both power supplies must be connected to the screw on the door.
Second and third picture ... oh hell, the Mesa should have been installed where the monitor was in the control box, if at all possible move it there, together with the PC, power box is not a good place to have low voltage signaling.
THCAD should be mounted on the back of the plasma cutter, shielded cable wired to mesa and shield tied to one of the screws in the control box.
The cable for the new drive analog control must be shielded, shield grounded together with other analog drive shields.
There is a 220V cable in the control box, add a 3 socket power strip to it for the PC and monitor.