Phase Converter for a Lathe

Phase Converter for a Lathe

Running a metal lathe on single-phase power is one of the most common challenges in small machine shops. Whether you are turning aluminum, steel, or specialty alloys, your lathe’s three-phase motor delivers smoother power, better torque, and longer tool life than single-phase alternatives. A rotary phase converter is the most reliable and cost-effective solution.

How to Size a Phase Converter for Your Lathe

Lathes are a moderate starting load, so sizing is straightforward:

For example, a 5 HP lathe needs at least a GP10NL phase converter. A 10 HP lathe needs a GP20NL. The 2× multiplier accounts for startup current draw and ensures your converter handles the load without straining.

CNC Lathes: Choose the PL Model

If you are running a CNC lathe, we recommend the PL series (pushbutton controls + built-in voltage monitor). CNC machines are sensitive to power interruptions. A power outage or voltage spike can cause an automatic restart—dangerous to your workpiece, tooling, and operators. The PL model includes protections that guard against this.

Running a Mill on the Same Converter

Many shops pair a lathe with a small milling machine. If your mill is 1–3 HP, the same phase converter that runs your lathe will typically handle both machines—provided you do not run them at full load simultaneously. This shared-converter setup is one of the most common configurations we help customers build.

Which Model Should I Choose?

• Manual lathe: GP series NL model (standard controls)
• CNC lathe: GP series PL model (pushbutton + voltage monitoring)
• Lathe + mill combo: Size for the lathe HP; confirm the mill fits within the same unit’s range

Finding Your Lathe’s Horsepower

Check the motor nameplate—it will list HP or kW. If listed in kW, multiply by 1.34 to convert to HP. Still unsure? We can help you confirm the right size before you order.

Our GP series phase converters are built for industrial shop environments, with heavy-duty capacitors, quiet operation, and a 5-year warranty. They are designed to run all day, every day.

📞 800-417-6568 — Talk to a phase converter specialist.