Page 4 of 5 on selecting the right converter.

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Gentec American Rotary Converter  

     I have seen many advertisements for rotary converters. First in magazines and now on the internet.

     So by an informal seat of the pants popularity contest, I have decided to feature American Rotary converters along with the other manufacturers that I have mentioned. 

Why American?

     I like what they are doing. They seem to be paying attention to business and trying to improve on their product line. They have videos on their site and a blog.

     They have made some improvements that I have seen others hide, or pretend didn’t exist.

     Like the starting power of the rotary’s and the voltage imbalances. 

     Rotary converters are very feeble when it comes to starting power. This means that if you want to start a 10 hp motor, such as I had on my vacuum cleaner, then you would need a 40 to 50 horse rotary converter. (it was an extremely hard to start machine) A ten horse air compressor needs a 30 hp rotary. This was a problem because how can you start a 40 hp rotary when you can’t start a 10 hp motor. It is just getting too big.

     Now if you do have a 40 hp rotary how are you going to run a 1/4 hp motor? You could only do that if you ran the big motor along with it, to put some load on the converter.

     So I have copied and pasted some selected information from the Gentec American Rotary site here.

     There are some things that could use further research.

     Gary Werner from Smith Electric said; 

“That the High Resistance rotor is bad.”

“That trying to balance the converter by switching capacitors in and out is bad.”

     I don’t know if American Rotary uses a High Resistance rotor or not. They don’t say anything about it, but they do claim they can start the rotary with out big power surges.

     American Rotary also balances the converter for the load, but I don’t think that they are using a crude capacitor method as Gary has mentioned.

     Just thoughts to keep in mind and ask questions about.

     The only complaint that I have about the American Rotary website is I would like to see the videos show the things running and starting.

     Show us the voltages balancing out. Show us the amps running and idling.

     As a disclaimer I don’t have any connection to any of these companies or receive any money from them.  

    Below are some of the advertising descriptions from their website.

American Rotary Advantage

American Rotary has been making premium rotary phase converters for more than 20 years.  American Rotary provides 24/7 telephone support for technical, application, and sizing questions.  American Rotary stands behind its products with the best warranty in the industry.  American Rotary uses premium components to ensure that its products perform for you.  American Rotary is a UL Certified Control Panel Builder, and its rotary phase converters are available UL Listed to US and Canadian Safety Standards.  American Rotary has partnered with Baldor Electric one of the world’s largest and most respected manufacturers to supply its custom-engineered idler/generators.  American Rotary is listed with D&B as well as the Better Business Bureau, and is committed to high ethical and privacy standards.

Product Innovations/Advancements

For more than 21 years, American Rotary has led the industry in innovation and design. American Rotary has introduced, field-tested, and proven several technologically advanced features which have driven increases in the reliability and precision voltage balancing capabilities of phase conversion unmatched in the industry.

  • American Rotary generators are available with a digital controller, which replaces electro-mechanical relays to more reliably and precisely start the phase converter while constantly monitoring voltage and making automatic adjustments when necessary. This industry-changing advancement not only provides critical protection to the starting circuit, induction generator, and equipment, but also balances the voltage so precisely that our phase converter is preferred by high-end equipment manufactures and many regional and state power companies.
  • The engineers at American Rotary worked with the engineers at Baldor for over a year designing a custom induction generator for phase conversion, which reduced the inrush current on start-up so drastically (83% reduction…a stock motor requires 600% more inrush) that American Rotary’s induction generator was granted a Soft Start rating, and a resulting reduction in operating cost!
    Voltage Balance Testing Claims
  • The load range is very important when verifying voltage balance claims. A claim of 2% voltage balance may be true for a very limited operating condition, but won’t exist for your application under load, even with field adjustments. This is especially true for stock or modified TEFC or ODP motors. American Rotary precision balances all CNC units over 100% load of the phase converter. In addition, American Rotary’s custom Baldor induction generators are wound with ISR magnet wire, which makes them immune to current spikes common in CNC equipment. Some companies offer motors from more than one manufacturer to go with their phase converter panel. However, different brands and different types of motors balance differently. Induction Generator vs TEFC and ODP Motors There are many differences between American Rotary’s Phase Converter Induction Generator and stock or modified TEFC and ODP electric motors. American Rotary has constructed the following table to summarize the most critical differences.


There is a chart that I did not reproduce extolling the benefits of their custom designed rotor. Actually they don’t even call it a rotor or idler.

They call it an induction generator. Then on the next page they offer to sell you one of their panels and you can use any motor you want.??

     However those panels look like a good deal. It appears they are selling you the ones with the smart controller voltage balancer.

     I think that this is a good deal for a person looking to save a bit of cash and get a good rotary.

     I would say that you are giving up the custom built rotor/generator but if American Rotary is saying your motor will work then go for it.


Go here for the final conclusion.