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

Thanks Clive, the second trace shows PlasmaC behaving correctly.
It seems Tom and Rod are on the right track about the pilot arc not transferring so the pilot arc turns off.
It may be worthwhile doing some probe tests and check the height. It should end up at Pierce Height until it times out and returns to the start point.

rodw wrote:

I would look at your pierce height. Its possible with the air flowing the arc does not have sufficient force to transfer to the material. Its clear that there is no current sensed through the work ground cable. Was your plasma designed to accpet a pilot arc torch? IS the new torch compatible?
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I purchased my machine and torch at the same time. In fact I had a long conversation with them to make sure it was pilot arc.
The machine originally was sold with a hand torch but they kindly paired it with the 80A machine torch and they also wired the plug with the correct connections for that torch.

Here is a short vid showing that the torch will fire in air with a button I wired across the relay contacts.

photos.app.goo.gl/6zcqkkwaVM8b5MBN8

I have noticed that when the button is pressed it stops the air purge briefly

[="tommylight" post=160819]Clive, i am sorry for the mess we have created for you, and also sorry for having to ask you this, but several posts back i asked you to check the torch distance from the material after the first and the second probe, now Rod has mentioned the same thing, so please do check that.

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I have done that and they are the same
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So to recap:
-Please do not lower the low voltage threshold ever again, it did cause us some head scratching, and some stray answers .....,
-PlasmaC is configured and working correctly,
-Wiring is all good,
-The noise is present while the inverter power stage is on, so nothing to worry about, most probably,
-Please oh please lower the pierce height and the cut height !
Pierce at 2mm and cut to 1mm, test and report back

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pierce height is 1mm - cut height is 1.12 - Low voltage threshold is 60V
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I have posted this vid on Rods post as well photos.app.goo.gl/6zcqkkwaVM8b5MBN8
I noticed the air purge stops briefly when the button across the relay contacts is pressed. The button need to be pressed for about 250ms
I also noticed some times when the button is pressed I see a weak pilot but then it always goes to the full pilot
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If you can find a reed relay, you can get the arcok signal that never fails and gives no false starts ever, but you do have to remove one of the thick cables on the plasma and replace it with a longer one, with 3 turns made out of it and the reed relay located inside those turns. Use a piece of old pen or similar to prevent the reed relay from braking, they usually are made out of thin glass.

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I probably have a reed switch (not relay) as they are in a lot of alarm contacts.
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Clive S wrote: I probably have a reed switch (not relay) as they are in a lot of alarm contacts.

:blush:
They are also found in satellite dish motors, under a small magnet and are made of plastic, not glass.

islander261 wrote: I may be missing something here. It seems to me that the PlasmaC generated Ark Ok signal should only be true when the plasmac torch on signal is true

Yes, I believe this is correct. PlasmaC will only continue if both are true even though Arc OK is capable of being displayed without a Torch On signal.

@Clive.
Did you try a probe test?
I think you have your Pierce and Cut Heights reversed.
It may be worthwhile checking you gas pressure and setting it toward the lower end of the recommended setting.

Clive S wrote: I have noticed that when the button is pressed it stops the air purge briefly

I'm not sure that firing a torch in the air without cutting something proves anything. Its the arc transfer is the issue.

Does this interruption of the air flow happen when the CNC triggers it with a relay? If not, what is different about your switch and the relay?

Sounds like the air is halted to allow the pilot arc to fire when you press the button.