An AC welding transformer is a crucial part in AC welding machines and is used to convert high-voltage, low-amperage AC power from the mains to a low-voltage, high-amperage current suitable for welding. 

Heating transformers are also available and ideal for applications such as heating metals, crystal growth, and glass. They utilize water cooling for efficient heat removal, which helps extend the transformer's lifespan, reduces space requirements, and simplifies installation.