Rotary Phase Converter Control Panels 101
The NAPCco CP control panel turns a three-phase motor you already own into a complete rotary phase converter, so you can run three-phase equipment on single-phase power without needing to buy a complete unit.
What is a rotary phase converter control panel?
Already have a three-phase motor sitting on the shelf? The NAPCco CP series control panel is everything you need to turn it into a complete rotary phase converter.
The CP panel includes the same digitally controlled start circuit, built-in motor starter, CNC voltage balancing, and Total Power Shutoff Protection found in our Pro-Line units. You supply the motor, we supply the panel. It is a practical, cost-effective way to get reliable three-phase power without purchasing a complete unit.
CP panels are available from 3 HP to 60 HP and are built in Wisconsin by a UL 508A listed panel shop.*
*Not every panel is UL-Listed. UL-Listing is an added option you can specify when you place your order.
How does a rotary phase converter control panel work?
Your three-phase motor becomes the idler generator. The panel starts it on single-phase power, and once it’s spinning, the motor generates the missing third phase and delivers three-phase output to your equipment.
The control panel manages everything around that. It handles the start sequence, balances voltage for CNC machines and other sensitive equipment, corrects the power factor, and shuts the system down if power or a phase is lost.
Is a control panel right for you?
A CP control panel is the right choice for most standard three-phase applications, as long as you already have a suitable idler motor.
Woodworking Shop
Typical Equipment: Table saws, radial arm saws, chop saws, CNC routers, lathes, shapers, molders, jointers, planers, edgebanders, drill presses, boring machines
Why a CP panel suits it: Handles multiple machines running at once and lets you build your converter around a three-phase motor you already own. For high-inertia loads like dust collectors, consider the Smart-Boost™ instead.
Metalworking & Machine Shop
Typical Equipment: Bandsaws, shears, waterjets, lasers, EDMs, gearhead lathes, milling machines, CNC mills, press brakes, surface grinders, cylindrical grinders, welders, ironworkers, battery chargers
Why a CP panel suits it: CNC machinery is sensitive to voltage fluctuations. CP-5 to CP-60 panels balance voltage to within 2% to 5%, keeping mills, lathes, and machining centers running cleanly.
Food Service & Commercial Kitchens
Typical Equipment: Dough mixers, ovens, rotisseries, ice cream machines, ice makers, refrigeration units, food processors
Why a CP panel suits it: Adding a control panel to an existing motor is typically faster and less expensive than bringing in utility three-phase service, and if a business moves, the converter moves with it.
Agricultural
Typical Equipment: Center pivot irrigation systems
Why the Pro-Line suits it: Most farming operations are in rural areas with no access to three-phase utility power. For outdoor installations, add the NEMA 3R enclosure upgrade and use a TEFC idler motor.
Automotive & Industrial
Typical Equipment: Car lifts, chain hoists, cranes, parts washers and welders
Why the Pro-Line suits it: Automotive and collision shops often run several heavy three-phase machines on site. Building a converter around a motor you already have is usually more cost-effective than extending utility three-phase service.
Do I need a rotary phase converter panel or a complete converter?
A control panel is the right choice if you already have a suitable three-phase idler motor. Your motor needs to be:
- T-framed (newer than 1965)
- 2 pole (3400-3600 RPM) or 4 pole (1700-1800 RPM)
- Matched in horsepower to the panel (for example, a 20 HP motor pairs with the CP-20)
If you don’t have a motor, or yours doesn’t meet these requirements, a Pro-Line rotary phase converter is a complete package that includes the control panel with a custom idler generator built for phase conversion.
Quick Sizing Guidelines for the Phase Converter Control Panels
Proper sizing is critical: an undersized unit struggles to sustain three-phase output, runs hot, and wears out early. Sizing is based on the horsepower (or amperage) of your largest motor and how hard it is to start. Use the chart below, or call us at 877-545-2926 for free sizing help.
| Phase Converter Model (HP) | Motor Loads (Horsepower) | CNC, Resistive & Inductive Loads | Shop | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Easy | Med | Hard | Very Hard | Total Amps | Total kVA | Total kW | Spindle HP | ||
| CP-3 | 2.5 | 2 | 1.5 | 1 | 4 | 1.4 | 1.1 | 1.5 | Shop now |
| CP-5 | 3 | 3 | 2 | 1.5 | 7 | 2.4 | 1.7 | 2.5 | Shop now |
| CP-7 | 5 | 5 | 3 | 2.5 | 11 | 4.5 | 2.2 | 3 | Shop now |
| CP-10 | 7.5 | 6 | 5 | 4 | 15 | 6 | 3.7 | 5 | Shop now |
| CP-15 | 10 | 7.5 | 6 | 5 | 20 | 8 | 5.6 | 7.5 | Shop now |
| CP-20 | 15 | 12 | 10 | 7.5 | 25 | 11 | 7.7 | 10 | Shop now |
| CP-25 | 20 | 15 | 12 | 10 | 30 | 13 | 9.5 | 12 | Shop now |
| CP-30 | 25 | 20 | 15 | 10 | 37 | 15 | 11.8 | 15 | Shop now |
| CP-40 | 30 | 25 | 20 | 15 | 50 | 21 | 15.5 | 20 | Shop now |
| CP-50 | 40 | 30 | 25 | 20 | 61 | 25 | 21.5 | 25 | Shop now |
| CP-60 | 50 | 40 | 30 | 25 | 72 | 30 | 26.5 | 30 | Shop now |