Monthly Archives: March 2017

The Benefits of a Rotary Phase Converter Compared to Utility Three Phase and Three Phase Generator

why rotary phase converter

It is true there are other options out there to get three phase power to your equipment. Each option has their pros but it does come down to what is affordable for you and your situation. The options are to get three phase power are through your utility line, a gas or diesel generator, or through a rotary phase converter. Here we give you a breakdown of the costs associated with each option so you can make an educated decision on which route is best for you.

Three Phase Generator

This option is good if no power is available at the site. These generators can run on gas or diesel fuel. Generators are also available in both single phase and three phase options.  There are many different sizes available depending on specific needs. The price is also reflected by the size of the generator and can range greatly.

What we can look at to evaluate this option is the operating costs of a generator.  With a generator, the operating costs will fluctuate with the cost of oil as it would with driving our cars. Because of this, we are looking at an average of $0.46 per (kW-HR) for your cost to create power off a generator. Then, with it being an engine that is running to create the power you have to keep up with the standard engine maintenance schedule. This option does provide three phase power but the quality of the power can vary depending on the manufacturer of the generator.

Utility Three Phase

This is typically the first option that comes to mind when someone thinks about getting three phase power. Three phase power from the utility company is not always available in all areas and if it is, it can be cost prohibited. On average, the cost to bring in three-phase utility power is approximately $50,000 per mile plus site prep costs. The cost on average for usage is about $0.10 per (kW-HR) plus minimum usage requirements and demand charges. With utility three phase power your power quality is roughly at a 10% voltage balance across the three legs. If three phase utility is a route you choose, it’s a good idea to do a true cost analysis to know all of your cost up front before investing in having it brought in.

Digital Rotary Phase Converter

A digital rotary phase converter is a very cost effective option to provide three phase utility to your shop. This choice gives you the option to run three phase equipment off single phase power whether it’s from the utility company, a generator, or a solar power system.  The American Rotary digital phase converter is available in many different sizes. You can tailor your needs to operate one single load at one time all the way up to a whole three phase operation. Since the converter is available in a wide range of sizes, it’s also very affordable compared to the other three phase options.

One item that a lot of people fear when running their equipment is the quality of power they use. This can be a true statement depending on the rotary system that you are running. This is not true however with an American Rotary system.  Within our digital rotary phase converter lines (AD, ADX, and AI) we feature our patented MicroSmart Controller. This digital controller monitors and controls your voltages across the three legs of power providing precise voltage balance to your equipment and adding additional fail-safe features to your phase converter operation. By monitoring your voltage every 50 Milliseconds and providing better voltage control, this helps prolong the life of your converter, allows significantly more load capacity (ADX and AI), and will run your equipment more efficiently.

With all American Rotary phase converters, we utilize a custom designed induction generator as our idler. This features our VIT Generator which is a true soft start idler that uses a 1/3 of the inrush current of a comparable three-phase motor. This technology also allows you to run the phase converter 24/7 a little to no load without any negative effects. Our idlers run very smoothly, quietly, and efficiently.

Lastly, this technology produces a true three phase sine wave allowing you to run your equipment on full three phase power off a single-phase power source. You will have a voltage balance of about 5% or greater when measured leg to leg. The approximant cost to running a phase converter is $0.12 per (kW-Hr).

Having a phase converter saves you from having to worry about the large expense of bringing in three phase utility power, having minimum usage requirements, and having to worry about having fuel on site to run your generator. To find out how affordable it is to make your American Dream your reality, contact American Rotary today.

Your Most Common Questions Answered When it Comes to Three-Phase Power

frequently asked questions phase converter

Recently, Jim out of California called us and inquired about who exactly American Rotary is and why we do what we do. He was starting up a shop in his pole barn behind his house and had acquired a few solid pieces of three-phase equipment but only had single phase power.  It was a great conversation had by all. From the viewpoint of American Rotary, we were excited to be part of another customer following their American Dream. From Jim’s standpoint, he was very educated about what he needed, to begin with. However, he did have some very good questions we find others ask as well and wanted to share them with you.

How do I size a Rotary Phase Converter and what information is needed to have someone help me size?

To size a rotary phase converter, you want to look at the type of machine you are running and the power requirements the machine needs. Typically, the power requirements are listed in a few different types of measurements; HP, AMPs, kW, or KVA. You will also want to verify the voltage the machine requires. These numbers are typically listed at 208-250v, 380v, or 480v. Once you know this information you can reference one of our load charts at or call one of our Application Engineers to help size a phase converter for your needs.

How does American Rotary stand apart from the competition?

American Rotary features a number of industry leading benefits and patented technology.  With all American Rotary rotary phase converters, we utilize a custom designed induction generator as our idler. This features our VIT Generator which is a true soft start idler that uses a 1/3 of the inrush current of a comparable three-phase motor. This technology also allows you to run the phase converter 24/7 a little to no load without any negative effects. Our idlers run very smoothly, quietly, and efficiently.

Within our Digital Rotary phase converter line (AD, ADX, and AI) we feature our Patented Microsmart Controller. This digital controller monitors and controls your voltages across the three legs of power providing precise voltage balance to your equipment and adding additional fail-safe features to your phase converter operation. By monitoring your voltage every 50 Milliseconds and providing better voltage control, this helps prolong the life of your converter, allows significantly more load capacity (ADX and AI), and will run your equipment more efficiently.

In addition to industry leading technology, American Rotary also offers industry leading support. When you purchase an American Rotary phase converter you become part of the American Rotary family.  We will support you with the best tech support in the industry and back you with the best warranties in the industry. The American Rotary Digital Series (AD, ADX, AI) panels are backed by a Lifetime Warranty.

I’ve read on forums to stay away from rotary phase converters, is this true?

Depending on the technology behind the rotary phase converter this can be true.  Phase converter companies that are using old technology, can produce imbalanced power which can have a negative effect on your equipment. This is not the case with an American Rotary phase converter. American Rotary has a lot of patented technology standing behind it. With our Patented VIT Generator producing a true three-phase sine wave and our patented Microsmart controller monitoring and controlling your voltages, your equipment is receiving very clean balanced power. To give an example, typical utility three-phase power is balanced around 10%. With a Digital Series phase converter, you will get roughly 2-5% balance. This means with a Digital Series phase converter, you are providing your equipment with cleaner power than utility three-phase.

I do not want a loud motor running in my shop.  How loud is the rotary converter?

This is another advantage to using a phase converter that utilizes the custom designed VIT generator versus a standard three phase motor as the idler. Our Induction Generator runs much smoother and quieter than a typical three phase motor. The idler will operate less than 60 Db which is comparable to a box fan running. In most cases, your three-phase machine will drown out the sound of the phase converter.  There are also options available for outdoor rated phase converters if that is desired.

Are rotary phase converters safe to run on CNC machines?

The simple answer is YES! When running a CNC or other computer controlled machine we recommend going with one of the Digital Series (AD, ADX, AI) converters since they are going to produce the tightest voltage balance. The digital phase converter produces power well within a CNC voltage tolerances. Running a CNC machine off of one of American Rotary’s phase converters is a common practice.

I have many different three-phase machines I wish to run; do I need a separate phase converter for each individual machine? 

When you are running a rotary phase converter you can tie in multiple three-phase machines. When going through the sizing process it is a good idea to know which machines will be starting at the same time and which machines may possibly run at the same time if started separately. This is important to know so you can get a phase converter that is going to be large enough to allow for current and future use. Typically, when multiple machines are in use a three-phase load center is added. In this setup, you would come out of your phase converter and feed the three-phase load center which would work as a distribution panel to each machine.  When sized properly, we have customers who power their whole shop off the phase converter.

We hope this helps answer some of your questions when it comes to three-phase power and using a phase converter. Please feel free to contact us should you have any additional questions. One of our Applications Engineers will be happy to go over your plans to ensure you are getting the phase converter that will work best for your needs.  All of us at American Rotary are proud to be part of making your American Dream a Reality!