In ERW, how is electrical current supplied to the workpiece?

• A. A transformer provides the current and it is transferred to the work through electrodes.
• B. A generator supplies the current directly to the work.
• C. Battery provides current to the work via wires.
• D. Chemical reaction in the weld flux supplies current.

Answer: (A)

Electrical resistance welding relies on a power source that delivers a high current to the seam. In ERW, a transformer-based welding power supply provides that current and sends it to the workpiece through the electrodes (or roller electrodes) that clamp the sheet edges. The current passes through the metal at the seam and, due to electrical resistance, heat is generated locally enough to fuse the edges together. Flux or chemical reactions aren’t involved in supplying current, and a battery can’t provide the required high current for this process, while a simple generator delivering current directly isn’t how ERW power is typically configured.