Which acronym indicates Alternating Current High Frequency used to start the GTAW arc?

• A. Direct Current Reverse Polarity
• B. Direct Current Electrode Negative
• C. Alternating Current High Frequency
• D. Direct Current Electrode Positive

Answer: (C)

Starting the GTAW arc with a high-frequency signal is about the arc initiation method. Alternating Current High Frequency is the acronym that describes using a high-frequency pulse to strike the arc when welding with AC. This HF pulse ionizes the gas and gap, allowing a quick, non-contact arc start, which is especially helpful on metals like aluminum that have surface oxides. After the arc is established, the welding current can continue in AC mode, with the high-frequency feature either left on or disabled depending on the machine and technique.

The other terms refer to polarity of direct current (which side is positive or negative) and do not indicate arc-start methods using high frequency, so they’re not the acronym used to denote the arc-start method in GTAW.