AVHC Woes

[pirateducky]

We took delivery of Torchmate X and TD Cutmaster A120 earlier this year, and this thing's a lot of fun. We've been having some issues with the AVHC lately, though. We had a replacement from Torchmate about a month ago because the old one read 335 volts no matter what. New one came, plugged it in and we were back up and partying, until yesterday.

Yesterday, we were cutting 16ga material at 113 volts/40 amps/115 ipm. Everything was going smooth, then we had to cut some quarter, reset the machine for 100 amp, knocked out the pieces, switched back to 40amp settings and the height controller went crazy.

What it's doing :

Arcs, runs at .16" while sensing, then lifts way off material. It usually keeps arc, but doesn't penetrate or makes unacceptable cuts. After letting it set overnight, it seemed to be cured this morning, but after a few cuts, started doing it again.

What we've checked:

• Wiring from AVHC to plasma. Was okay, replaced or cleaned any connections en route.
  
• Ground on table, all connections are tight. Ground is 3/4" ground rod 8' through slab attached to lift point on table. Paint was ground and bolt passed through to attach ground.
  
• Consumables - all new out of the package
  
• Air - We're dryer crazy and use copper line, so moisture isn't generally a problem, drained down the system, drained all separators and replaced cartridges in the plasma's two dedicated desiccant driers.
  
• Measured voltage between sensing points and compared to readout on AVHC - AVHC displayed voltage about 15-18 volts different from what the Fluke read while cutting.
  
• Fuse in back of AVHC is good.
  
• Cleared EPROM

My operator called Torchmate and was told to run line speed and voltage tests, but we've probably cut more 16ga than we have any other material and have always seemed to be dialed in pretty close. I had him run the tests again and didn't come up with any earth shattering realizations.

Has anyone else ran into this? Calling tech support again and hopefully we'll come up with something. Will post whatever we find.

[jimcolt]

One other thing to do...and this is a common issue with all arc voltage based torch height control systems...

Attach a piece of welding ground cable the same gauge as your plasma's work ground to the grounding bolt where the work ground is attached on your table....attach an alligator clip or ground clamp on the other end of this cable and attach it directly to the plate you are cutting. This makes for a far better connection to the plate you are cutting...and may make a difference on your height.

What happens if you adjust the voltage (higher and lower) on your AVHC control box....does the torch move higher and lower?

Jim Colt

[pirateducky]

We started grounding to the plate with no change. I disconnected everything - plasma, signal generator, AVHC and it seemed to fix it for now, I'm guessing something somewhere was loose. To be honest, we haven't run it much and it seemed to act up when it was run for a while. We have some column bases to take care of next week so we'll see how it goes. If anything else happens with it, will post. Hopefully this did it.