Hypersensing questions

rodw wrote: But we are not interested in the voltage at idle.

We are only interested in sensing when it rises when there is a good connection with the material by the shield. It should get to 24 volts. The conductivity of the water around the world will vary greatly with the water source and the additive used. Remember that pure water is an insulator, its the dissolved salts and the like that conducts electricity.

I don't understand how you aren't interested in the voltage at idle? if at idle it is spiking just below 23.5v with your threshold at 23.8v and your max at 24v then I would say you're REALLY close to having a problem. Add a little more ionization to the water and you could have a problem where your voltage level trips the probe ... at idle. In which case, it will fail to probe.

Hmm.. 24.5V full scale and 23.5V from leakage means that you have about 1K leakage resistance when wet...
Sounds like you have a very high salt concentration in your water or some issue with your torch

PCW wrote: Hmm.. 24.5V full scale and 23.5V from leakage means that you have about 1K leakage resistance when wet...
Sounds like you have a very high salt concentration in your water or some issue with your torch

On well water with a water softener, so the salt concentration could be a factor.

Torch is basically brand new, so I wouldnt expect that to be the issue. But like I said, my consumables are all brand new, where Uthayne's are 50% remaining.

It's worst case, so we're still probably in the green. Just reporting back in case it changes any thinking or direction.

I put a brand new set of consumables in (copper plus electrode and fine cut nozzle). My ohmic shield is the same, I don't have a spare for that.

First I took the torch and soaked it in the water for about 10 seconds, covering up the entire ohmic shield. Pulled it out of the water and it was reading 22-23V, and tripping my ohmic sensor. However, after pulsing the torch for 0.1 seconds, it went right back to 0v.

Then I did a second test where I pulsed the torch to get air flowing with it 1 inch over top the water. I let the air run the entire time and soak the torch. Same thing, 22-23v at idle afterwards. I did another post pulse air flow over steel and it immediately went to 6-7v, and lowered to 1-2 about 10 seconds later.

I agree that ohmic-volts can still hover around 22-23v when the torch is completely soaked, but I haven't been able to not clear it up via pulsing. Before the 22K (sensitivity adj resistor), I would pulse the torch and it still wouldn't clear a really wet torch. It would stay at 22-23v after air turned off. Now I can't seem to replicate it.

In the second picture, I increased the gain on the ohmic-volts signal 50X to show that it is indeed at 0v. 200mV per division instead of 10V.

Can you tell us what happens when you pulse the torch and have air flowing through it? Does it stay at 23v or drop?

Ok I feel better now about what I’m seeing. A torch pulse definitely clears it out. So I think we are seeing the same thing. At least now I know I’m not an anomaly.

Once I figure out halscope, I’ll get some screen shots to add to the data set.

You’re using mode 1 with N=10, correct?

Good! Worst thing you'll have to do is pulse the torch before you run the job, no big deal. Post cut air flow clears it before you go to probe.

Yes, mode 1 with N=10.