The duty cycle refers to the period you can weld using a specific power output without overheating or burning the source of power. Welding machines manufactured in the USA and some other countries use a duty cycle calculated by means of a standard time of 10 minutes.
If you own an enthusiast-type TIG welder, then the appropriate duty cycle would be around 20 percent. Nevertheless, an automated TIG setup might need a duty cycle worth 100 percent. This is due to the capability to weld for extended periods. For most handheld TIG procedures, duty cycles ranging between 40 and 60 percent are, in most cases, adequate, especially in industry and construction.