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.
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 ATO rotary phase converter. We have 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 of 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 ATO’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 ATO are proud to be part of making your dreaming shop a reality!