Phase Converter for a Welder

Phase Converter for a Welder

Three-phase welders—MIG, TIG, stick, and plasma arc—deliver significantly more power and arc stability than single-phase units. If you have access to utility single-phase power but your welder requires three-phase, a rotary phase converter is the cleanest, most cost-effective solution.

How Sizing a Welder Differs from Other Equipment

Welders are resistive loads, which means they do not have the high startup current spike you see with motors. You size a phase converter for a welder based on its full-load input amps—not the output amps printed on the front panel.

Check your welder’s nameplate or spec sheet for Full Load Input Amps. That number maps directly to the converter size you need.

Sizing Example

A welder with 40 amps full-load input would need a GP40NL phase converter. A 25-amp welder would need a GP25NL. It is that direct.

Why Input Amps—Not Output Amps?

The output amps on a welder are the amps at the electrode, which vary with settings. The input amps are the actual load placed on your power supply—and that is what the phase converter has to supply. Using output amps to size a converter is a common mistake that leads to undersizing.

Checking Voltage

Most industrial welders run on 230V three-phase. Some larger shop welders operate on 460V. Make sure you confirm the voltage from the nameplate before selecting a converter. 460V welders require a transformer package (NLT or PLT model).

Which Phoenix Model Is Right for My Welder?

• Standard welders: GP series NL model
• 460V welders: GP series NLT model (includes step-up transformer)
• CNC plasma arc or precision welding: GP series PL model (added voltage protection)

Phoenix GP series converters are rated for continuous industrial duty—ideal for long welding runs. They run cool and quiet and carry a full 5-year warranty.

📞 800-417-6568 — Our team can verify sizing from your nameplate data.