What is the duty cycle of the Millermatic 350P and what happens if it overheats?

The Millermatic 350P has a 60% duty cycle at 300 amperes and a 40% duty cycle at 350 amperes, meaning it can weld at rated load for that percentage of a 10-minute period. If the unit overheats, thermistors open, output stops, and the cooling fan runs. You must wait fifteen minutes for the unit to cool, then reduce amperage, voltage, or duty cycle before welding again. Exceeding the duty cycle can damage the unit and void the warranty. (Page 9)