Which polarity was commonly used in early GTAW with helium shielding?

• A. AC
• B. DCEN
• C. DCEP (Direct Current Electrode Positive)
• D. Pulsed DC

Answer: (C)

In GTAW, polarity controls where most of the arc heat goes. Helium shielding makes the arc hotter and more energetic, and using the electrode as the positive terminal directs more heat into the workpiece. That hotter, workpiece-focused arc helps with penetration and bead formation when shielding gas is helium, which is why direct current electrode positive was commonly used in early GTAW with helium.

AC would switch polarity and isn’t the typical setup for this era, DCEN (electrode negative) shifts more heat toward the electrode rather than the workpiece, and pulsed DC is a waveform approach rather than the steady polarity practice that early helium GTAW relied on.