Digital Phase Converters 101
A digital phase converter uses solid-state electronics to convert single-phase power into clean, balanced three-phase power with no rotating parts, so you can run CNC machines and other voltage-sensitive three-phase equipment wherever utility three-phase power is unavailable.
What is a digital phase converter?
A digital phase converter is a solid-state device that converts single-phase power into three-phase power electronically, without the rotating motor used in other converter types. Where a rotary converter spins an idler generator to create the missing third phase, and a static phase converter only helps a three-phase motor start, a digital phase converter uses high-speed solid-state switching and an integrated microprocessor to produce a smooth, continuous three-phase output.
Proudly made in the USA, NAPCco digital phase converters maintain phase-to-phase voltage balance within 2% under any load condition, a tighter tolerance than rotary converters. That precision, combined with quiet operation and high efficiency, makes them the ideal choice for CNC machines, VFDs, and other voltage-sensitive equipment.
How does a digital phase converter work?
A digital phase converter converts the incoming single-phase supply to DC and then electronically rebuilds it into three-phase AC using solid-state switching. There are no moving parts in this type of phase conversion. An integrated microprocessor continuously monitors the output and corrects the voltage balance in real time, maintaining it within 2% of the setpoint regardless of load.
Because the output is regulated electronically rather than mechanically, a digital converter delivers a clean, continuous sine wave with minimal heat and low standby power consumption. That efficiency makes a digital converter a cost-effective choice for equipment that runs unattended for extended periods, such as elevators, pumps, and air compressors.
Digital Phase Converter vs Rotary Phase Converter: What’s the difference?
Both a digital phase converter and a rotary phase converter convert single-phase to three-phase power, but they do it in very different ways, and the right choice depends on your equipment and your budget.
| Feature | Digital Phase Converter | Rotary Phase Converter |
|---|---|---|
| How it works | Solid-state electronic switching, no moving parts | Spins an idler generator motor to create the third phase |
| Voltage balance | Within 2% under any load | Within 5% |
| Power quality | Clean, continuously regulated sine wave | Balanced three-phase, corrected by run capacitors |
| Noise and moving parts | None, runs quietly | Rotating idler motor, some running noise |
| Efficiency | High, low standby power, minimal heat | Efficient under load, the idler runs continuously |
| Best for | CNC, voltage-sensitive and precision equipment, unattended loads | General motor, resistive and inductive loads, multiple simultaneous loads |
| Capacity range | 5 HP – 75 HP | 3 HP to 100 HP |
| Warranty | 1-year parts and labor, extended available | 10-year parts / lifetime labor |
| Relative cost | Premium | Mid-range |
| Shop | Shop Digital Phase Converters | Shop Rotary Phase Converters |
For a full breakdown of every converter type, including static converters, see Phase Converters 101.
Is a digital phase converter right for you?
A digital phase converter is the best fit for voltage-sensitive equipment and loads that run for long, unattended periods. Use the table below to see if your setup is a typical fit.
CNC Machines
Common Equipment: CNC mills, CNC lathes, CNC plasma cutters, CNC routers
Why a digital phase converter suits it: CNC machines require tight, balanced voltage to operate, and computer-operated machinery is sensitive to voltage fluctuations. A digital phase converter supplies the load with power balanced to within 2% phase-to-phase.
Farms and Agricultural Operations
Common Equipment: Irrigation pumps; grain processing equipment (grain dryers, mixers, bucket elevators, conveyors); augers
Why a digital phase converter suits it: Some agricultural equipment has to overcome high inertia at startup. An irrigation pump, for example, moves water from a low source, such as a lake or well, through pipes to the field. The motor has to overcome significant resistance to move that water upward, which is why it benefits from the Smart-Boost.
Elevator Applications
Common Equipment: Residential elevators in single-family homes and apartment buildings, commercial elevators
Why a digital phase converter suits it: Digital phase converters are ideal for equipment that runs throughout the day because they use less standby power when idle. An elevator may run for around 4 hours a day and sit idle for the other 20, making a digital converter the most cost-effective solution.
HVAC Equipment
Common Equipment: Rooftop air conditioning units, VRF systems
Why a digital phase converter suits it: Most rooftop and VRF systems are built for three-phase power but are often installed in apartment buildings or commercial settings that only have single-phase power. Because these units run for long periods, often 24/7, they benefit from a digital converter’s energy-efficient design.
Automated Systems
Common Equipment: Conveyors, air compressors, pumps
Why a digital phase converter suits it: Automated systems often run for prolonged periods, known as a continuous duty cycle, and are frequently left unattended, so they suit a digital converter’s efficient, low-standby operation.
Equipment with VFDs or Drives
Common Equipment: Machinery with built-in variable frequency drives
Why a digital phase converter suits it: Equipment with built-in VFDs or drives is often very sensitive to voltage fluctuations, much like CNC machines, so the three-phase output voltage needs to be as close as possible to the single-phase input voltage.
Woodworking Equipment
Common Equipment: A wide range of woodworking machines
Why a digital phase converter suits it: Runs a wide variety of woodworking equipment, much like the Pro-Line rotary phase converter.
Sizing Your Digital Phase Converter
Proper sizing is critical. A digital phase converter is sized to the amperage or horsepower of the equipment it will run, so an undersized unit will struggle to sustain full three-phase output, particularly if you run multiple machines at once. Use the tool below or call us at 877-545-2926 for free sizing help.
For model-by-model amperage and full specifications, see the digital phase converter range.
How do I size and install a digital phase converter?
Digital phase converters are designed for plug-and-run installation from a single-phase supply, with no programming required. Watch the walkthrough below, or call 877-545-2926, and we will help you size and set up the right unit for your equipment.