PlasmaC torch starting problem (Solved with help from the famous three)

First I must thank you all for helping to debug this.
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phillc54 wrote: @Clive
As a test could you unlink plasmac.arc-ok-high and setp it to some ridiculously high value.
Edit: you could do that in Hal Show with "unlinkp plasmac.arc-ok-high" then "setp plasmac.arc-ok-high 10000"
Hopefully it will get you cutting so we can see some more halscopes.
Could you also include the pin plasmac.state-out.

I will try this and report back: I actually already tried to increase the max volts to 900 but the software only defaults back to 300

Proma has only min voltage for arcok, if i remember correctly. And it has a delay of only 0.1 seconds on all my machines.
I still think this is a hardware issue, namely the arc voltage is wired to the plasma output terminals, hence it gets the whole pilot arc voltage at torch start.
Since i do not have an inverter type plasma, and no THCAD for now, i can not check the wiring. All plasma sources must have high voltage protection for the rectifier during pilot arc, and that is where the THCAD should be wired. It usually consists of 2 bigger resistors and one or two capacitors located on a separate board near the rectifier.
@Clive,
Can you please take some pictures of the plasma and post here, i can try to figure out where that potection is located.
Or since you already have resistors in series with THCAD, can you find a 0.1 uF bipolar capacitor rated at over 300V and wire it in parallel to the THCAD input. Beware that it may blow or smoke during pilot arc, or burn the resistors, so have some spare ones ready.

Proma has only min voltage for arcok, if i remember correctly.

Maybe this is the reason why...

Clive S wrote: First I must thank you all for helping to debug this.
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phillc54 wrote: @Clive
As a test could you unlink plasmac.arc-ok-high and setp it to some ridiculously high value.
Edit: you could do that in Hal Show with "unlinkp plasmac.arc-ok-high" then "setp plasmac.arc-ok-high 10000"
Hopefully it will get you cutting so we can see some more halscopes.
Could you also include the pin plasmac.state-out.

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I will try this and report back: I actually already tried to increase the max volts to 900 but the software only defaults back to 300

Also re this:
rodw wrote:
Thats not 100 ms! Its one second.

The division is the minor tick. 10 minor ticks per vertical line.

That doesn't make sense to me, so in the first of Clive's Halscopes the sawtooth is 5Hz and the arc voltage is around 1400V or am I missing something?
I have always thought the full length line was the division and the minor ticks were a subdivision.

I would think that the arc voltage in the following scopes 100/div would = to about 210V ie ( two and a bit divisions high).
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This is "ok cut after air stopped setp1000"

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This is "ok cut after air stopped setp900"

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fail arc setp 1000


fail arc setp 900

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fail arc setp 200

Clive
Ones like this look artificial and not an expected plot (your OK cut ones are )



There is no deviation in the torch voltage and that will happen becasue the "anode spot" where the arc terminates oscillates the top of the material to the bottom.

The arc voltage rise time is not instantaneous as shown here by the square wave shape so I think something is faking your arc voltage. What is on the plot is not real.

I think there is something going on here and I don't know if Plasmac is manipulating a bad case to make it worse. But then again so many users use Plasmac and it works perfectly so I suspect its your machine.

I would be looking carefully at every connection and component on the torch voltage monitoring side.

It might be helpful if you shared some details again of your plasma cutter and the wiring in of the THCAD.

For what its worth, here is a plot of my old 50 amp Everlast with the THC not enabled

There is definitely no immediate instantaneous rise time as you show.

I Personally think you should walk away from this for a while, stop cutting and relax for a day or so then work back through the electronics to ensure they are perfect. Something is wrong.