Technical Foundation
What Is a Phase Converter?
A phase converter allows three-phase equipment to run from a single-phase electrical supply, which is common in rural, residential and smaller commercial locations without three-phase utility service. A rotary phase converter uses an idler motor spinning continuously to generate a genuine, balanced third leg of power, suitable for sensitive loads like CNC machines and VFDs. A static phase converter uses capacitors to provide only a starting boost and does not produce balanced running power, limiting the connected motor to roughly two-thirds of its rated horsepower and making it unsuitable for multiple simultaneous loads or variable-speed equipment.
Digital or solid-state phase converters electronically synthesize a clean third phase and are increasingly used ahead of sensitive electronic loads where a rotary converter's power quality still isn't ideal. Sizing is based on the horsepower of the largest single motor being started (not just the total connected load) since starting current is the peak demand a converter must supply, and undersizing a converter is one of the most common causes of nuisance tripping or motor failure.
Prefer a quick quote?
Get Phase Converters Pricing in Your Inbox
Skip the search — tell us the equipment horsepower, input voltage and whether the load is a motor or CNC/VFD and we will come back with pricing.
| Spec | What It Means | Why It Matters |
|---|---|---|
| Converter Type | Rotary, static, digital/solid-state | Static converters can't support VFDs, CNCs or multiple simultaneous loads reliably |
| Horsepower Rating | Sized to largest motor's starting requirement, not total load | Undersizing causes nuisance tripping, poor motor performance or motor damage |
| Input Voltage | Typically 208V, 230V or 240V single phase | Converter input must match the available single-phase utility supply |
| Output Balance | Rotary/digital produce balanced 3-phase; static does not | Unbalanced output derates connected motor horsepower and can cause overheating |
| Load Type Compatibility | Simple motors vs. CNC/VFD-driven equipment | Sensitive electronic loads need rotary or digital converters for clean, stable power |
Shop Phase Converters
Browse Phase Converters Sub-Categories
Organised by converter type. Pick a sub-category, or describe the horsepower and type of three-phase equipment you're running and let ChatMRO match the converter.
How it works
From Half-Remembered Part Number to PO, in Three Steps.
Ask
Type an MPN, paste a spec sheet, or describe the part in plain English. ChatMRO understands engineer-speak.
Compare
Side-by-side specs, cross-references, and equivalents from multiple sources — without the clutter of endless browser tabs.
Quote & Buy
Request a quote or add to cart. Volume discounts, VAT-aware pricing, and consolidated procurement — all in one place.
Applications
Where Phase Converters Get Used
Phase converters are specified anywhere three-phase equipment must run from a location with only single-phase utility power available.
Machine Shops Without 3-Phase Utility Service
Rotary converters powering lathes, mills and CNC equipment in rural or residential shop locations.
Agricultural Operations
Phase converters running three-phase irrigation pumps, grain handling and processing equipment on farms.
Woodworking Shops
Static or rotary converters sized to run three-phase table saws, planers and dust collection motors.
Small Manufacturing & Fabrication
Rotary converters supporting welders, compressors and fabrication equipment where 3-phase service isn't available.
Well Pumps & Water Systems
Phase converters enabling three-phase submersible well pumps in areas without 3-phase utility power.
Mobile & Temporary Job Sites
Portable phase converter setups powering three-phase tools and equipment from generator or single-phase feeds.
FAQ
Phase Converters Questions, Answered
What's the difference between a rotary and a static phase converter?
A rotary phase converter uses a continuously spinning idler motor to generate genuine, balanced three-phase power suitable for sensitive equipment like CNC machines and VFDs. A static phase converter uses capacitors to give a motor a starting boost only, without producing balanced running power — it typically limits the connected motor to about two-thirds of its rated horsepower and can't reliably run multiple loads or electronic equipment.
How do I size a phase converter for my equipment?
Size the converter to the horsepower of the largest single motor that will start, not the sum of all connected equipment, since starting current is the peak demand the converter must handle. If multiple motors could start simultaneously, size for that worst case, and always check the converter manufacturer's sizing chart against your specific motor's starting characteristics.
Can I run a CNC machine or VFD on a static phase converter?
Generally no — CNC machines and variable frequency drives need clean, balanced three-phase power to operate reliably, and a static converter's unbalanced output can cause erratic behavior, error faults, or damage to sensitive electronics. Use a rotary or digital/solid-state phase converter for VFD and CNC loads.
What voltage should my phase converter be rated for?
The converter's input voltage must match your available single-phase utility supply — commonly 230V or 240V in most facilities — and its output should match the voltage the three-phase equipment is rated for. Confirm both input and output voltage compatibility before ordering, since mismatches can damage equipment.
Why does my rotary converter trip the breaker when starting a motor?
Nuisance tripping on motor start usually indicates the converter is undersized for that motor's starting current draw, or the breaker itself is undersized for the converter's rated input current. Recheck the converter's horsepower rating against the specific motor's locked-rotor amperage, not just its running horsepower.
Keep browsing
Related Categories
Explore More
Find Your Next Part Now.
Describe a part number, spec or what it does.