Is there a fixed polarity in an AC transformer welding machine?

In an AC transformer welding machine, the polarity is not fixed; it constantly changes. This is because alternating current (AC) reverses its direction of flow periodically, typically in a sinusoidal wave pattern. In such a setup, the voltage alternates between positive and negative values, which means that the polarity of the output also alternates accordingly. Unlike direct current (DC), where the flow of electricity is in a single direction, AC utilizes both polarities. This characteristic of alternating current is essential for certain welding processes, as it can impact the heat generated and the quality of the weld.

While some welding processes and machines may allow adjustments to polarity, in the basic operation of an AC transformer welder, the inherent nature of AC means there will always be a change in polarity, making it unsuitable to attribute a fixed polarity to the output.