Would it be better to do the programming inside the PLC and have the PLC trigger the THC up and down? I'm assuming the PLC has that programming capability.
The other hurdle is building a usable voltage divider. I know the basic concept and can breadboard a simple two resistor device that works on a clean power supply, but not sure if that will work on a plasma power supply. I suspect tip voltage is rather "noisy". We have one power supply with an automation interface and one without. Currently using a sound logic THC on that one, which works, but I need to add a PLC anyway for more inputs, so I'm trying to integrate the THC into that as well.