Which of the following is not a type of DC welding machine?

Which of the following is not a type of DC welding machine?

• A. Motor or engine-drive DC generator
• B. Motor or engine-driven DC generator with an AC rectifier
• C. An AC transformer with a DC rectifier
• D. Motor or engine-driven generator with a DC rectifier

Answer: (B)

DC welding current is produced either directly by a DC generator or by converting an AC supply to DC with a rectifier. A motor- or engine-driven DC generator delivers welding current in DC without needing any rectification, so that arrangement is a valid DC welding machine. A transformer fed from AC and followed by a DC rectifier is also a standard DC welding setup, since the AC is converted to DC for welding. A motor- or engine-driven generator paired with an AC rectifier isn’t a practical DC welding machine configuration—the rectifier is designed to convert AC to DC, so feeding DC from a generator into an AC rectifier would not produce the intended DC welding current. That’s why this option isn’t a type of DC welding machine.

DC welding current is produced either directly by a DC generator or by converting an AC supply to DC with a rectifier. A motor- or engine-driven DC generator delivers welding current in DC without needing any rectification, so that arrangement is a valid DC welding machine. A transformer fed from AC and followed by a DC rectifier is also a standard DC welding setup, since the AC is converted to DC for welding. A motor- or engine-driven generator paired with an AC rectifier isn’t a practical DC welding machine configuration—the rectifier is designed to convert AC to DC, so feeding DC from a generator into an AC rectifier would not produce the intended DC welding current. That’s why this option isn’t a type of DC welding machine.