Basic Parts of a Welding Machine

Denise Sullivan

Welding machines are used to permanently connect metal pieces with heat generated from electrical energy. They are available in a variety of sizes and output voltages, from a small hobby model with an 80-amp output to an industrial model with a 12,000-amp output for spot welding.


Welding machines take the electrical current from a high-voltage power source and convert it into a usable arc of energy to fuse two materials together.


Welding machines are either constant current (CC) or constant voltage (CV). Constant current welding machines maintain a set current by changing up the output voltage. Constant voltage machines keep the voltage steady by adjusting the output current.


Some welding machines use a transformer to convert the high voltage current from the wall outlet into a lower voltage current for output. The output current can then be adjusted within a certain range.

Alternator or Generator

Other types of welding machines use a motor or combustion engine to convert electrical energy into mechanical energy. An alternator or generator is then used to convert this mechanical energy into a low-current electrical output.


Inverter welding machines produce the high voltages needed for high-intensity arc welding. The machine stores the high voltage current from the wall outlet in a capacitor. A microprocessor then switches the stored energy into a transformed where it is converted into the desired output current.