FAQ

Rotary Phase Converters

General Questions

What is a rotary phase converter?
A rotary phase converter is an efficient way to produce 3 phase power from a single phase power source. It generates one line from a generator motor and combines that with your two single phase lines.

What does CNC mean? Can a North America Rotary Phase Converter run a CNC machine?
CNC stands for Computer Numerical Control. CNC equipment has a computer that can be programmed to run the operation of the machine. Computer operated machines are generally very voltage sensitive. Our Pro-Line Rotary Phase Converter has +/-5% voltage balance to run these types of machines.

What size rotary phase converter do I use for my load?
Correctly sizing a rotary phase converter cannot be overemphasized.  Generally, we recommend sizing for the largest load it will start and run by itself or the total of all the loads that it will start and run together. A load chart list is available for help on the rotary phase converter page.

These questions are also a good place to start when trying to size the correct rotary phase converter:
What type of load (machine/equipment/motors) are you running?
What is the horse power, amps or KVA rating of your load?
How old is the load?
Where were the machines, equipment or motors made?

This is just some of the information needed to properly size a phase converter. Learn How to Size a Rotary Phase Converter for sizing guidelines. You may also email us at info@napces.com or call us toll free at 877-545-2926 for sizing help.

How long will a North America Rotary Phase Converter last?
Average life span for a rotary phase converter is 30+ years. NAPCco is a UL 508A Industrial Control Panel Builder. Careful selection was made in the design and build phase for our product line. Every electrical panel component has the appropriate certifications and meets or exceeds the standards for its use. All components have a minimum rating of 100,000 starts and/or 50,000 hours of operation.

Does NAPCco offer a UL Listed rotary phase converter?
Yes, NAPCco is a UL 508A Industrial Control Panel Builder and we offer a complete line of Pro Line UL Industrial Control Panels.

Will a NAPCco rotary phase converter run resistive and inductive loads?
Yes, a properly sized rotary phase converter will produce balanced 3 phase power for every type of load.

Can I run a 480 volt piece of equipment on a North America rotary phase converter if my single phase voltage is 240?
Yes, however, a transformer is also needed. A rotary phase converter produces a three phase voltage identical to its input voltage. For example, if your input is 240 volts single phase, then your output is 240 volts three phase. The rotary converter does not change voltages. In this case, a step up 3 phase transformer (240 volt to 480 volt) is needed after the phase converter. NAPCco offers a complete line of phase transformers for situations like this.

Will my machine lose power running on a rotary phase converter?
Absolutely not, provided the rotary phase converter is sized correctly. Our Pro Line generates a balanced three phase output allowing your equipment to furnish full rated power.

How efficient is a NAPCco rotary phase converter?
North America Rotary Phase Converters are extremely efficient. More than 97% of the total power utilization is transformed into working power for your load.

What is the difference between an ODP and TEFC idler generator? Why are they important?
These idler generators are enclosure types for motors. An ODP motor means “open-drip proof” and TEFC stands for “totally enclosed fan cooled”.

There has been a lot discussion about what type is better and which one makes a better phase converter idler motor. Honestly, the enclosure type has no bearing on the performance of the rotary phase converter. Both types have their advantages and disadvantages. An open-drip proof (ODP) is vented so air can pass over the windings, helping the idler motor to run cooler than a TEFC. An ODP is designed for use indoors that is dry and ventilated. A totally enclosed fan cooled(TEFC) doesn’t have vents and is tightly enclosed with an external fan blowing air over the frame. TEFC motors are better suited for outdoor (damp and wet) locations.

North America Phase Converters offers both types of idler motor enclosures.

Will my utility company approve of a North America Rotary Phase Converter?
Most utility companies will recommend the use of a rotary phase converter. In fact, it is much more cost favorable compared to installing 3 phase power lines.

Is there a US standards organization specifically for phase converters?
The answer is a resounding “no!” Unfortunately, one of our competitors felt the need to invent a fake organization and website to promote their own line of phase converters. We feel this is very dishonest and gives the entire industry a black eye.

The only organizations we are aware of and adhere to are UL (Underwriters Laboratories) and the N.E.C.(National Electric Code) Article 455. These are the organizations and standards that North America Phase Converter follows.

Starting and Running Questions

How does the rotary phase converter start? Do I need a starter/motor starter?
Every rotary phase converter needs a manual or magnetic motor starter or some other approved motor starting mechanism, such as a disconnect switch. A circuit breaker panel is not motor duty rated and is not an approved means for starting a phase converter.

Every North America Pro-Line Rotary Phase Converter includes a built–in motor starter.

How much electricity does a phase converter use?
Inconsequential! A rotary phase converter, by itself, is in an idle state and draws only the amount needed to keep it energized. This is only a few kilowatts and in some cases is less than a kilowatt.

Your true electrical consumption is based on what the load draws. The rotary phase converter is merely a device electricity passed through on its way to your load.

What voltage will my rotary converter run on?
A NAPCco rotary phase converter will generate a 3 phase voltage output equal to the single phase voltage input. NAPCco manufactures 208-240 and 480 volt units.

How noisy is the rotary phase converter?
Our Pro Line was diligently designed for quiet performance. An ODP idler generator is quieter than a TEFC idler generator.

How hard is a North America Rotary Phase Converter to install? Who can install it?
Installation is very simple! All wire terminations are made on interior power distribution blocks. It is as simple as two wires in and three wires out.

All installation must be performed by a licensed electrician and comply with National and Local Electrical Codes.

Can I run more than one machine on a North America Rotary Phase Converter?
Absolutely.  As long as the rotary converter is sized correctly, you may run a single load or multiple loads at the same time.

Can a NAPCco rotary phase converter run unloaded? What is the smallest motor I can run?
Yes, our rotary converters are designed to perform continuously with and without a load connected. Our Pro Line converters are balanced down to a no load condition; therefore, there is no minimum motor size you can run.

Are North America Rotary Phase Converters power factor corrected?
Power factor is defined as the measure of how useful current is converted into real power. Our Pro Line rotary phase converters are power factor corrected to help reduce wasted energy and help the efficiency.

Does the rotary phase converter start when I turn my machine on?
Generally no, a rotary phase converter must start first before a load is applied. Automatic controls can be added for unattended loads. Please contact us and our applications support team can provide more details.

Mounting, Installation and Wiring Questions

Do North America rotary phase converters have flexible mounting options?
A North America rotary phase converter is a two component design featuring an idler generator and the control panel.

What else do I need with a rotary phase converter?
Generally speaking, you will need wire, conduit, connectors and a single phase power source, such as a circuit breaker or disconnect switch. More materials may be needed depending on how elaborate your output connection is between the load and phase converter. Most are items you should be able to pick up at a local electrical distributor or home center.

All installation must be performed by a licensed electrician and comply with National and Local Electrical Codes.

How large of a single phase service do I need?
Your single phase service required is dependent on the loads connected after the phase converter. A North America rotary phase converter will run on a range of input amperage. As a general rule, determine your 3 phase load amps and double for your single phase feeder amps.

Can I wire a NAPCco rotary phase converter to a 3 phase panel?
Yes, in fact, we recommend wiring into a 3 phase panel when operating multiple machines.

Can I install a rotary phase converter outdoors?
Yes, NEMA 3R enclosures and TEFC idler generators are available as an upgrade for outdoor locations.

Do the control panel and idler generator have to be next to each other?
No, however, NAPCco recommends keeping them close together. A shorter wire run will help minimize voltage drop.

What size wire should I run to my phase converter?
The N.E.C. Article 455 governs the installation of rotary phase converters. Article 455.6 states that the input wire size shall not be less than 125% of the phase converter nameplate input full-load amperes(for variable loads) and/or not less than 250% of the sum of the full-load 3-phase current rating (for variable and fixed loads). Minimum wire size recommendations are listed in the installation manual.

What type of maintenance is required for a rotary phase converter?
A North America rotary phase converter is very dependable and maintenance free. Bearing grease may occasionally be needed.

Static Phase Converters

General Questions

What is a static phase converter?
A static phase converter simulates 3 phase power to start a motor. Once the motor starts, the static converter drops out and the motor runs on single phase power. There is about a 1/3 power reduction in the motor’s horsepower.

What type of equipment will a static phase converter run?
A North America static phase converter will only run motor loads. Because it does not produce a constant 3rd leg of power, a static converter will not run a resistive or inductive load.

Will my motor run at full power?
A static phase converter’s generated leg of power disengages after startup, leaving the electric motor to run on single phase power. Only two of the three motor windings are fully energized. The motor has about a 1/3 power loss. Therefore, it is not recommended for heavy loaded motors.

Why use a static phase converter?
A static phase converter is a cost-effective alternative to other types of phase converters. They are ideal for hobby and occasional use applications where motors don’t need full power.

Sizing

How do I size a static phase converter?
A static phase converter is designed around NEMA standards (North America) and T-frame motors (post 1965). Sizing is based on the horsepower of the motor you are trying to start. They are intended for easy to medium starting and running motor loads.

Can I oversize a static phase converter?
Oversizing a static phase converter can produce too much startup electricity and/or excite a motor. This can cause the motor not to start. In some cases, capacitors can be added or disconnected within the static phase converter. Please consult the factory.

Will a larger static converter produce more power?
Unfortunately not. A static phase converter is only used during the start cycle of the motor. Once the motor has started, the static converter has disengaged. The motor is now running on the 2 single phase legs of electricity.

Can I run 2 or 3 motors with a static phase converter?
Yes, as long as the largest motor is started first and falls within the starting size/range of the static phase converter. Once the largest motor is started, smaller motors can be started.

Will a static phase converter run a 460 volt motor? Will it work with a transformer?
A static phase converter will only work with 208 to 240 volt applications. Electrically, a static phase converter must see that a motor is trying to start; therefore, it cannot be used in conjunction with a transformer.

Can I use a static phase converter to make a rotary phase converter?
Yes, a static converter would be the starting mechanism for a rotary converter. A motor starter and power factor capacitors may need to be added for better results.

Mounting and Installation

Where can I install a static phase converter?
Generally it is mounted close to your equipment. It can be mounted directly to the equipment as long as there isn’t excessive vibration. A NAPCco static converter is equipped with two mounting brackets for easy installation.

Is a static phase converter easy to wire?
Absolutely, a NAPCco static phase converter has a simple three wire connection. A junction box is located on top of the converter’s enclosure wire a terminal block for wiring inside.

What size circuit breaker/fuse and wire do I use?
A circuit breaker/fuse and wire is determined by the size of the static phase converter and size of the motor you are starting. A recommended circuit breaker/fuse and wire chart is available in the operation and installation manual.