Technical Support
Run Haas, Mazak, Fadal, and any CNC machine on single-phase power.
Clean, balanced three-phase power for mills, lathes, and multi-axis machines.
Most CNC machines require three-phase power — but most garages, home shops, and small commercial spaces only have single-phase service. Running three-phase lines from the utility company costs tens of thousands of dollars. A rotary phase converter is the proven, cost-effective solution that machinists have used for decades to power Haas VMCs, Mazak lathes, Fadal mills, and every other brand of CNC equipment.
Phoenix Phase Converters builds industrial-grade rotary converters specifically for machine shops. Whether you're a one-man shop with a single knee mill or a production facility running multiple CNC machines, we'll size the right converter for your equipment — and back it with a lifetime warranty.
Proper sizing is critical. Too small, and your spindle won't start or will trip breakers. Too large, and you're paying for capacity you don't need. Here's the Phoenix method:
Check your CNC machine's nameplate or manual for the spindle motor horsepower. For Haas machines, this is usually listed on the control screen under "spindle specifications." Common sizes:
CNC spindle motors need at least 1.5× their rated horsepower in converter capacity to start reliably. Why? Because spindles start under load (holding a tool in the collet), and VFD-equipped spindles need clean three-phase input to avoid fault codes.
Quick Reference:
If you're running multiple CNC machines simultaneously, add their running loads together. Example: A Haas VF-2 (20 HP spindle) + a Haas ST-10 lathe (10 HP spindle) + coolant pumps and chip conveyors (5 HP total) = 35 HP running load. You'd need a GP40NL (40 HP) to handle the 20 HP starting requirement and 35 HP running load.
Some CNC machines have extreme starting torque requirements — large horizontal boring mills, heavy-duty lathes, or machines that start spindles under full cutting load. For these applications, Phoenix offers DualZone converters that provide extra starting capacity without oversizing the entire system. Call 800-417-6568 if you're running industrial-grade CNC equipment over 30 HP.
Rotary converters produce true three-phase power with balanced voltage on all three legs. No harmonic distortion. No voltage sag. No risk of damaging your CNC control board or VFD drive. Static converters and VFDs can cause electrical noise that corrupts position encoders and causes fault codes — rotary converters don't.
Modern CNC machines use VFDs (variable frequency drives) to control spindle speed. Rotary converters provide the clean three-phase input power that VFDs expect — no special wiring, no derating, no compatibility issues. Just plug in and run.
CNC spindles start under load — holding a tool in the collet, sometimes with residual coolant adding drag. Rotary converters handle these hard starts without voltage drop or tripping breakers. Static converters often fail at this.
One properly sized rotary converter can power your entire CNC shop — mills, lathes, grinders, coolant systems, air compressors. Size it for your largest single motor and total running load, and you're done.
Your CNC machine runs at full rated horsepower on a rotary converter. No derating. No reduced spindle torque. No cutting speed limitations. The machine performs exactly as designed by the manufacturer.
Rotary phase converters have been the industry standard for powering CNC machines in single-phase locations since the 1970s. They work. Period. No experimental technology. No firmware updates. Just reliable power conversion that machinists have trusted for decades.
Equipment: Haas VF-2 VMC (20 HP spindle), 5 HP air compressor, coolant pump
Converter: GP30NL (30 HP)
Result: Clean spindle starts, no VFD faults, runs all day without issues. Total cost: $4,295 (vs. $25,000+ for utility three-phase installation).
Equipment: Haas VF-2 (20 HP), Haas ST-10 lathe (10 HP), Fadal VMC (7.5 HP), 10 HP compressor
Converter: GP50NL (50 HP)
Result: Powers entire shop. Starts 20 HP spindle reliably. Can run all machines simultaneously (47.5 HP total running load). Lifetime warranty for peace of mind.
Equipment: Tormach 1100MX (2 HP), Bridgeport mill (3 HP), manual lathe (5 HP)
Converter: GP10NL (10 HP)
Result: Budget-friendly solution for smaller machines. Powers all equipment simultaneously. Perfect for hobbyist or startup shop scaling up.
Installing a phase converter for a CNC machine is straightforward. Most installations take 2–4 hours for a licensed electrician. Here's what's involved:
The converter panel mounts on the wall near your electrical panel. The idler motor (the generator that produces the third phase) sits on the floor or a concrete pad — it weighs 150–500+ lbs depending on HP rating. Mount it on rubber isolators to minimize vibration and noise.
Run three-phase wire from the converter output to your CNC machine's disconnect switch. Use properly sized wire per NEC code (usually 10–4 AWG copper depending on distance and HP). Your CNC machine connects the same way it would to utility three-phase power — no special wiring required.
$2,695
15 HP / 230V
For smaller CNC machines: Tormach, Bridgeport CNC conversions, 7.5–10 HP spindles.
View Details$4,295
30 HP / 230V
For Haas VF-2, Fadal VMC 4020, and most mid-size CNC mills. Starts 15–20 HP spindles.
View Details$4,820
40 HP / 230V
For multi-machine shops or larger VMCs. Starts 20 HP spindles, runs 40 HP total load.
View DetailsNot sure which size you need? Call 800-417-6568 or visit our sizing help page.
Size your phase converter to match your CNC machine's largest motor (typically the spindle motor). For a Haas VF-2 with a 20 HP spindle, you need at least a 30 HP converter for reliable starting. If running multiple machines simultaneously, add their horsepower ratings together. Call 800-417-6568 for exact sizing.
No. A properly sized rotary phase converter produces clean, balanced three-phase power that CNC machines run on safely. Unlike VFDs or static converters, rotary converters deliver true three-phase power without harmonic distortion that can damage sensitive CNC electronics or VFD drives.
Yes. Size the converter for the largest single motor that will start, and ensure total running load stays under the converter's rating. For example, a 40 HP converter can start a 20 HP spindle and run multiple machines totaling 40 HP simultaneously.
No. Rotary phase converters work perfectly with VFD-equipped CNC machines. The converter provides clean three-phase input power to the VFD, which then controls the spindle motor. This is the standard setup for CNC machines in shops without utility three-phase power.
A licensed electrician can typically install a phase converter in 2-4 hours. Installation involves: connecting single-phase input power (200A service recommended for larger converters), wiring the three-phase output to your CNC machine, and mounting the idler motor. Full installation instructions included.
Get expert sizing help from engineers who understand CNC machines.
Phoenix Phase Converters manufactures industrial-grade rotary phase converters for CNC machining centers, CNC lathes, multi-axis mills, and manual machine tools requiring three-phase power in single-phase locations. CNC machines including Haas VF-2, Haas ST-10, Mazak Quick Turn lathes, Fadal VMC 4020, DMG MORI 5-axis machines, and Tormach mills require clean, balanced three-phase electrical power to operate. A rotary phase converter converts single-phase 230V power from residential or light commercial service into true three-phase 230V power, allowing CNC spindle motors, servo drives, and VFD controllers to function exactly as designed by the machine manufacturer. Unlike static phase converters or VFD-based solutions that can cause harmonic distortion, voltage sag, or fault codes in CNC control systems, rotary phase converters deliver clean sine-wave power with properly balanced voltage across all three phases. Phoenix Phase Converters are sized based on the largest starting motor (typically the CNC spindle motor) and total simultaneous running load. For a Haas VF-2 with 20 HP spindle motor, the recommended converter is a GP30NL (30 HP capacity), providing 1.5× starting capacity for reliable spindle acceleration under load. Multi-machine CNC shops running multiple mills, lathes, and auxiliary equipment can power their entire facility from a single properly sized rotary converter, eliminating the $25,000+ cost of utility three-phase service installation. Phoenix Phase Converters include a lifetime warranty, 90-day money-back guarantee, and expert sizing support from engineers with 50+ years of experience in electric motor systems and three-phase power conversion. Installation typically requires 2–4 hours for a licensed electrician and a 200A single-phase service for converters powering Haas VF-series VMCs or equivalent industrial CNC equipment. For hard-starting applications or CNC machines with extreme torque requirements, Phoenix offers DualZone technology providing additional starting capacity without oversizing the entire system. All Phoenix Phase Converters are designed, built, and load-tested in Phoenix, Arizona using American-made components including industrial-grade idler motors, heavy-duty contactors, and continuous-duty capacitors rated well above NEC minimums. For CNC sizing assistance, installation support, or technical questions about three-phase power conversion for machining equipment, contact Phoenix Phase Converters at 800-417-6568 or visit the sizing help page.
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