"Ohmic Sensor" Definition Please.

[plasmafreshman]

Hello!
A cnc mill head here getting into cnc plasma now.

so...I've searched on the forum the term "Ohmic Sensor" and read alot of posts. Some writers seem to use the term "Ohmic Sensor" different than others.

What is the industrial definition of a plasma torch "Ohmic Sensor" ? what is it? what does it do?

are we talking about simply closing an input via copper torch tip touching anything conductive? or is there more to it?

I see advertisements for "Ohmic Sensors" like this one. https://neuroncnc.com/products/004 what are these black boxes actually doing? between the torch tip and the plasma cnc controller? is it just an isolator so the high voltage doesn't work its way back to the cnc controller input? or is it performing some other black magic?? thanks for helping me understand this term/device in advance!

[djreiswig]

Basically an isolated continuity tester. It is used to detect when the tip of the plasma torch just touches the material. It's more accurate that a microswitch on a floating head on the z axis when using thinner material that tends to push down when the torch contacts it.

It has to be able handle the potential high current from the plasma arc and keep it from getting to the controls.