Contact sensor, touching the plasma cutting nozzle?

Question

Electronics

I am assembling plasma cutting with CNC ... I did this with a Z-axis sensor on a CNC milling machine and on a 3D printer ..
Actually, plus on the burner, minus on the sheet that we will cut, when the nozzle contacts the sheet, we get a contact that the arduino brains take for the signal, everything is super ... But here's one thing, but when the arc lights up, between plus and minus about 200 volts ... I collected the signal through an optocoupler .. But the measurement takes place before the arc lights up .. And I'm a little scared to imagine what will happen when the arc lights up ....
In order to transmit a signal through an optocoupler, you need about 50mA and up to 12 V voltage for the LED inside ... Correct if anything ...
Actually .. I can transmit a signal before the arc is ignited, but I don’t know what can happen next ... and the solutions are still scarce :(((It seems to come up with something with diodes and resistors, but the prospect is still vague.
Please tell me how be!??? (:

Answer 1

An arc is a current (no, I know that an arc is a discharge; it's easier for me to express the idea in the style of "a hole is a Rabbit, and a Rabbit is the right company"). So you need to measure the current. I have no experience with arcs, so I have no idea what kind of current you might have. I only know that with conventional electric welding, the arc current is damn big (like a few hundred amperes, if I'm not mistaken).
So you need to measure with a current transformer. To begin with, you can take a professional tool - current clamps with a measurement limit of at least 200 amperes, or better, more, because. hell knows, and with these pliers to measure the current during the arc - there will already be some approximate value. On this basis, it is already possible to somehow calculate the current transformer.