The HF Contact type typically found in budget machines uses a high frequency high voltage spark to ionise the air through the torch head and initiate an arc. The arc can only be formed if the torch is in contact with the job material. HF Contact type machines are not suitable for applications involving CNC cutting.

Since plasma cutters produce a very hot and very localized 'cone' to cut with, they are extremely useful for cutting sheet metal in curved or angled shapes.

especially those without power factor correction, cannot be run from a generator. However newer models have internal circuitry that allow units withour power factor correct to run on generators.