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.

Analog plasma cutters, typically requiring more than 2 kilowatts, use a heavy mains frequency transformer. Inverter plasma cutters rectify the mains voltage into DC, which is fed into either an IGBT or a MOSFET. IGBT transistors operate independently of one another whilst MOSFET transistors need to be paralleled. With paralleled MOSFET transistors if one of the transistors activates prematurely it can lead to a cascading failure of one quarter of the inverter. IGBT transistors do not have this problem as they are independent however are very expensive to manufacture and generally used in high current machines where it is not possible to parallel sufficient MOSFET transistors. The transistors are switched at thousands of Hertz, which greatly reduces the magnetic flux in the step down transformer, and therefore the size of the transformer is reduced accordingly. The switch mode topology is referred to as a dual transistor off-line forward converter.

Plasma torches were once quite expensive, usually at least a thousand U.S. dollars. For this reason they were usually only found in professional welding shops and very well-stocked private garages and shops. However, modern plasma torches are becoming cheaper, and now are within the price range of many hobbyists. Older units may be very heavy, but still portable, while some newer ones with inverter technology weigh only a few pounds yet equal or exceed the capacities of older ones.