[funding33]

Hi all,

Looking in to Neuron THC controller and its description confuses me at one place:

If collision avoidance is enabled(provided that the Ohmic sensor is used), the arc voltage is automatically increased any time contact is sensed between the torch (ohmic sensor) and the plate, provided that the Ohmic function is enabled. If the torch contacts the plate while a AVC OFF or THC OFF signal is applied, the torch retracts to the programmed Cut Height

Can someone explain what is that? How can ohmic sensor be switched on and measure something while ARC is ON? To my understanding it is some 100Volt of plasma arc at some 40Amps between tip and workpiece. How can it measure ohmic contact at a same time between same electrodes what are workpiece and torch tip?

What I miss here?

thanks

[bdrotaru]

Hi!
1. If ohmic sensor sense dross it will rise (or stop cutting - you have that option too) to avoid collision.
2. On small circles is recommended to be cut with 60% to 100% of cutting speed depending on circle diameter and material thickness. If speed is reduced then metal is removed at a smaller speed so arc voltage value will increase. Torch will lower trying to adjust the arc voltage in search for material. Then collision will issue.
For avoiding that Automatic Voltage Control - AVC can be disabled (is your option) in some cases (small circles, corners with specific angles, lead ins and leadouts, etc). If ohmic sensor will sense contact with the sheet metal while AVC is disabled then it will temporary (until next IHS) set Z0 value and retract very fast at cutting height (usually 1.5 mm).

Hope this helps.

[Beefy]

How can ohmic sensor be switched on and measure something while ARC is ON? To my understanding it is some 100Volt of plasma arc at some 40Amps between tip and workpiece. How can it measure ohmic contact at a same time between same electrodes what are workpiece and torch tip?

I sometimes use the same wording as yourself and say the "tip". However, we should be saying either electrode or nozzle, which are 2 separate items.

The torch volts is not measured between the nozzle and the workpiece, it is actually measured between the electrode and the workpiece. Likewise the cut current of 40 amps is coming from the electrode, not the nozzle.

The ohmic sensor is using the nozzle instead, and has its own circuit which will not be affected by whatever the torch volts/amps is doing.

In electrical/electronic circuits you can have 2 separately controlled circuits that share a common line, yet what one circuit is doing does not affect the other circuit.

Keith.