Frequently Asked Questions

Everything You Need to Know About Phase Converters

What is a phase converter?

A phase converter is a device that converts single-phase electrical power into three-phase power. Most residential and rural areas only have single-phase power available, but many industrial motors and machines require three-phase power to operate. A rotary phase converter uses a spinning generator (called an idler motor) to create the third phase, producing true balanced three-phase power that's indistinguishable from utility-supplied three-phase.

What's the difference between a rotary phase converter and a VFD?

A rotary phase converter produces true sinusoidal three-phase power and can run multiple machines simultaneously through a sub-panel — just like having a utility three-phase service. A VFD (Variable Frequency Drive) is an electronic device that varies motor speed but only powers one motor at a time and produces non-sinusoidal power that can damage sensitive electronics, CNC controllers, and circuit boards. For shops with multiple machines or sensitive equipment, a rotary phase converter is the better choice.

What's the difference between a rotary and a static phase converter?

A static phase converter only provides about 2/3 of a motor's rated power and cannot run sensitive electronics or CNC machines. It's a cheaper but limited solution. A rotary phase converter produces balanced, full-power three-phase electricity that can run any three-phase equipment at 100% capacity — including CNC machines, welders, HVAC compressors, and other demanding loads. We strongly recommend rotary converters for any serious application.

Can I run multiple machines from one phase converter?

Yes! This is one of the biggest advantages of a rotary phase converter. You install the converter, connect it to a three-phase sub-panel, and run as many machines as the converter's HP rating supports. It works exactly like having utility three-phase service. Size the converter for the largest single motor plus about 50% of any simultaneously running additional loads.

How do I size a phase converter for my equipment?

The general rule is to match the converter HP to the largest motor you'll run. For CNC machines, we recommend 2x the largest spindle motor HP to handle high inrush currents. For standard motor loads like compressors, pumps, and fans, 1:1 sizing is usually sufficient. If running multiple machines simultaneously, add up the total HP of all running loads. Not sure? Call us at 800-417-6568 — we do free sizing consultations every day.

What if I need 460V three-phase but only have 230V single-phase?

That's exactly what our NLT Series is designed for. It combines a rotary phase converter with a built-in step-up transformer that converts 230V single-phase input to 460V three-phase output — all in one unit. No need to buy a separate transformer, saving you space and installation costs.

What size breaker and wire do I need?

Wire and breaker sizing depends on the converter's HP rating and your installation distance. Each converter comes with a detailed specification sheet listing the required breaker size and wire gauge. As a general rule, the single-phase input draws roughly double the per-leg current of the three-phase output. Your licensed electrician will use NEC tables for the exact sizing. We include installation guides with every order.

How do I install a phase converter?

Installation is straightforward for a licensed electrician: mount the converter, connect single-phase input from your panel, and run three-phase output to your equipment or a three-phase sub-panel. Our converters come with detailed wiring diagrams and tech support. Most installations take 2-4 hours. We always recommend professional installation for code compliance and warranty coverage.

Can I install the converter outdoors?

Yes. All our converters use NEMA 4 sealed enclosures rated for indoor or outdoor use. They're sealed against dust, water, oil, and harsh environmental conditions. Many of our customers install them in barns, outdoor equipment yards, and exposed industrial settings with no issues.

How loud are your phase converters?

Our standard rotary converters produce about as much noise as a refrigerator — roughly 60-65 dB during operation. The idler motor spins continuously while powered on. Our GPX Digital Series is even quieter with digitally controlled operation. Most customers place the converter in a utility area or outside the main workspace.

Do your converters have automatic restart after a power outage?

Yes. All our converters include automatic restart functionality. When power is restored after an outage, the converter restarts itself automatically — no need to walk out to the shop and push a button. This is especially important for agricultural applications and remote installations.

How much does a phase converter cost compared to getting utility three-phase?

A phase converter typically costs $1,500 to $15,000 depending on HP rating, while extending utility three-phase service costs $20,000 to $150,000+ depending on distance from the nearest three-phase line. That's savings of 80-95%. Plus, a phase converter is portable — if you move your shop, it goes with you. Utility service stays behind.

How much electricity does a phase converter use?

A rotary phase converter is approximately 95%+ efficient. The idler motor draws a small amount of current while spinning (typically 15-20% of its rated capacity at idle). Under load, the converter passes power through efficiently. Your electric bill increase is minimal compared to the cost of the actual equipment you're running.

What does the lifetime warranty cover?

Our lifetime warranty covers the control panel and all panel-mounted components for the life of the original owner. The generator motor carries comprehensive warranty coverage as well. We repair or replace defective components at no charge. Normal wear items and damage from electrical events (lightning strikes, etc.) are handled on a case-by-case basis — but we always work with our customers to make it right.

What if I need help after purchase?

Call us at 800-417-6568 anytime. We provide free technical support for the life of your converter — installation questions, troubleshooting, sizing additional equipment, whatever you need. You'll talk to a real person who understands electrical systems, not a call center script reader.

Do you ship nationwide?

Yes. We ship to all 50 states from 12 warehouses across the USA. Common sizes ship quickly from the nearest warehouse. Custom configurations and larger units are built to order at our Phoenix facility and typically ship within 1-2 weeks.

Still Have Questions? We're Here to Help.

Our team of phase power experts is available to answer any question you have — no pressure, no obligation.

📞 800-417-6568