When plasma cutting, the arc voltage is proportional to the distance between the tip of the electrode and the surface of the plate, and is typically between 100-150 volts.
The CNC controller uses this to monitor the arc voltage and keep it at a set value, by raising or lowering the head as the machine moves round the shape.
However, there are numerous aspects which effect arc voltage, these include:
- Cutting speed – the height sense is frozen at the start and whilst cornering to prevent it from crashing
- Consumable wear – as the electrode wears the torch moves nearer to the plate
- Material type
- Material thickness
- Plasma current
- Plasma gas
- Condition of the earth cables
- Condition of the work supports
- Condition of the plate – e.g. rusty or scaly