Arc OK intermitent issues on torch fire

My take is that if you have an arcok output on your plasma cutter be sure to use it.
This plot I shared on another thread shows the voltage fluctuation on piercing before the ArcOK is turned on.

See: forum.linuxcnc.org/plasma-laser/41420-arc-voltage-on-piercing

You can see there is quite some fluctuations in the voltage and the risk is that Plasmac's low threshold could force the ArcOK to drop out. The current synthesised ArcOK algorithm is a little simplistic for my liking. The plasma cutter does more work than just looking at the torch voltage before enabling ArcOK. I'd like to see an algorithm based on tracking the arc behaviour shown in the plot.

I have NO issues at all with synthesised ArcOK.

tommylight wrote: The derived arcok from THCAD works perfectly although i am sure there might be situations where it might fail but not due the the way it works but due to how plasma sources work.
The reed version has no way of failing if done right as it relies on a big amount of current passing through that wire.
By now i have 4 machines using the derived arcok from thcad and they never failed, but that needs a bit of tweaking...

Just so I am clear. The 'derived' ArcOk is from a plasma source with ArcOk output, and the 'reed version' is the 'synthesized' method?

When you say the reed version has no way of failing 'if it is done right' ... what are 'wrong' ways you see it done? Also, does it need any tweaking?

phillc54 wrote: I have NO issues at all with synthesised ArcOK.

Synthesized = reed relay method?

Synthesized = derived = from THACD so no reed or plasma's own ARCOK signal.
It is synthesized or derived from the voltage measured with THCAD and generates the (missing) arcok signal if the voltage is between the setpoints set as "OK High Volts" and "OK Low Volts" in PlasmaC.

tommylight wrote: Synthesized = derived = from THACD so no reed or plasma's own ARCOK signal.

Thanks for the explanation tommylight. Sometimes the simplest solutions are the best.

I already have ArcOk wired from my CPC port, so I will go that route for now. It's good to know that other options exist.