A Beginners Guide to Sizing a Rotary Phase Converter for Your Machine Shop

Well, you’ve done it! You have your own shop just like you’ve always wanted and it is in the perfect location. There is only one problem. You have the equipment of your dreams in your shop, but it is just sitting there, not being able to be used or make you money because it is three-phase and your shop only has single phase power. What do you do now? Well, the good news is, American Rotary is here to save you! With an American Rotary phase converter, you can get your three-phase equipment up and running just like it would run if you had utility three phase power. Below are common questions and tips that will smooth the process of picking out the right phase converter and proper set up for your needs.

Where do I start with sizing a phase converter?

It can be a bit overwhelming just finding out that you need a phase converter and not knowing where to start looking. There is a lot of information out there about phase converters. Some of it is true and some of it is incorrect. The best thing to do is to contact someone that is familiar with the different types of converters out there and can go over what your current and future needs are. This will help design a phase converter that will not only work for you now but also as you grow and add in more equipment. Once you have that initial conversation, of how a phase converter can benefit your shop, then it is time to start tailoring it to the size converter that you need.

What information should I have available to help smooth the process along? 

There is actually not too much information that is needed when it comes to sizing a phase converter.  All that is needed is the type of machine it is, the machines power requirements (this will be listed in HP, AMPs, kW, or kVA), and the voltage listed. There are different types of phase converters that are designed for different style loads. There are phase converters set up light duty loads, CNC, resistive, and hard starting loads. Each load runs different and has different starting loads. Going over the type of machine will help determine which phase converter will work best. One thing to keep in mind with an American Rotary system is, there is no harm in going with a phase converter for a larger load even if your current load does not require it. It is better to go bigger now than find out later that you need it.

Have an idea on the setup and if you are planning to add in more equipment.

Knowing where you want to place the phase converter will help determine how we tailor the phase converter to your needs. In some cases, the phase converter may need to be portable, you may need it to run multiple machines, or you may need the phase converter to be mounted in a separate location than where the machines will be running. American Rotary has designed many different phase converters options to best fit your particular shop’s needs.

Where does my phase converter have to be installed?

The phase converter can be installed where ever you need it to be. There are different options available depending on where you need the phase converter set up. The unit comes standard as an indoor unit but there are options to split the converter and have the panel inside and the idler outside, vise versa, or even the complete unit outside. There are customers who even have the phase converter split even when installed inside. They will place the panel in one spot and the idler in another. This makes it versatile to meet any shops space considerations and environments.

How loud is the phase converter?

Many people are taken back by the idea of an idler running to manufacture the third leg.  They think it will be very loud and distracting in their shop. As this may be the case with some phase converters, that is not the case with an American Rotary Phase Converter. At American Rotary, we utilize a custom designed VIT induction generator. American Rotary worked with Baldor to design and engineer this custom technology to have an idler that runs very efficiently, quietly, and cool. The VIT generator will operate at less than 60 Db, which is comparable to a box fan running. The idler will also operate at a cooler temperature compared to other phase converters of similar size.

What if my shop is extremely dirty?

The American Rotary Phase Converter is designed to withstand your typical shop environment. But we also understand that there are shops out there that produce more dirt than normal. American Rotary took that into consideration and we designed our AI-Industrial line. This line is designed to be in extremely dirty environments or even installed outside. The AI-Industrial line is made as a full NEMA-3R enclosure with solar reflective paint. It also features a washable air filter to filter out any dust and debris from circulating through the phase converter. Since the phase converter is in an all in one, NEMA-3R enclosure it makes for a simpler installation. You just have to run your single phase in and your three-phase out!

My machine is a CNC, I’ve heard you can’t run CNC Machines with a Rotary Converter, is this true?

This is not true with an American Rotary Phase Converter. American Rotary offers a digitally controlled Rotary Phase converter that was designed to run CNC and other computer controlled equipment. Our Patented Micro-smart controller monitors and controls your voltages across the three legs of power ensuring that clean and balanced power is always being produced and provided to your machine. With an American Rotary Phase Converter that features the Micro-Smart Controlled you can expect to see voltages around a 2-5% balance across the three legs. To give some comparison, utility three phase is generally around 10% balance.

Sizing 2:1 Rule of Thumb

A general and quick rule of thumb when sizing a rotary phase converter is that when looking at the HP rating of your machine, you want to double that to get the size phase converter that is needed. For example, if you have a 10 HP motor then a 20 HP phase converter is needed. This is related to the start load of a machine and the fact that you are pulling from single phase power to operate a three-phase machine. However, there are exceptions to this rule but during your first planning stages of looking at a phase converter, this will give you an idea to help budget and plan towards.

One thing that is worth noting is that not all phase converter companies size their phase converters the same. Rotary phase converters all still apply to the 2:1 rule of thumb, but the label on the different phase converter may not be the same. With American Rotary, we size the phase converter based on the actual size of the converter so that way you are aware of the size converter you can expect. Some other companies will label their phase converter based on the size load it can operate. This can be misleading because you may be expecting a 10 HP phase converter since your load is 10 HP, but in reality, you are getting a 20 HP phase converter. This can affect your planning, cost analysis, electrical rough in, and even breaker sizing.

Following these steps and recommendations will help you get started in planning towards utilizing an American Rotary Phase Converter in your shop.  Having the ability to run three phase equipment in your shop opens up a lot of options for additional equipment that you can run.  A lot of times three phase equipment is less expensive than a comparable single-phase machine due to the availability of three phase.  Always feel free to reach out to American Rotary with any questions that you may have, and remember, if it doesn’t carry the American Rotary logo, it isn’t the real thing!

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