Why is the secondary output circuit of a DC TIG soldering machine connected to DC positive polarity?

The reason for using a DC positive polarity in the secondary output circuit of a DC TIG welder (tungsten inert gas welder) is that the tungsten electrode is the negative electrode, emitting electrons at its cathode. This low temperature prevents the tungsten electrode from burning out, allowing for the use of a larger welding current. This connection method is suitable for welding carbon steel, stainless steel, copper, titanium, and refractory reactive metals such as molybdenum, tungsten, and niobium.

Furthermore, with a DC positive polarity, the tungsten electrode acts as the cathode, maintaining a lower temperature and reducing the risk of burn-out. Therefore, it can withstand a larger welding current, improving welding efficiency and quality. This connection method offers significant advantages when welding the aforementioned metals.

In summary, the main reason for using a DC positive polarity in the secondary output circuit of a DC TIG welder is to protect the tungsten electrode from burn-out and to allow for the use of a larger welding current, making it suitable for welding a variety of metals.