How many polarities are used in GTA welding according to early advancements?

• A. All three polarities
• B. One polarity
• C. Two polarities
• D. Four polarities

Answer: (A)

GTA welding uses three polarities—DCEN, DCEP, and AC. Early advancements in GTAW established that different metals and thicknesses benefit from different heat directions and cleaning actions, so having all three options is essential. DCEN (electrode negative) puts more heat into the workpiece for deeper penetration, which is typical for steels. DCEP (electrode positive) concentrates more heat into the electrode, which can help control penetration on thinner sections and reduce tungsten wear in some setups. AC, used especially for aluminum and other non-ferrous metals with oxide layers, provides both arc cleaning and a balanced heat input by alternating polarity. Because each polarity serves distinct welding needs, all three are used in GTA welding.