Pilot arc conversion of basic cut40 hf start machine with a pt-31 torch.

Need help on pilot arc conversion of my basic cut40 hf start machine. Do i need to add a resistor/current limiter in series with the relay contactor connection to the ground and nozzle tip? I want to use a magnetic reed sensor to turn off the relay contactor when it detects enough current through the ground wire after the cutting arc initiates with the workpiece.