High Frequency

(as applied to gas-tungsten arc welding) An alternating current consisting of over 50,000 cycles per second at high voltage, low amperage that is superimposed on the welding circuit in GTAW power sources. It ionizes a path for non-touch arc starting and stabilizes the arc when welding with alternating current.

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High frequency
Extremely high frequency
Very high frequency
Ultra high frequency
What is High Frequency (HF)? – Definition from Techopedia