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  1. #1
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    Default Have a chance to pick up a Ronk

    I got a call about a couple of used Ronk converters. I haven't seen them yet, but were running when taken out. They are model 80A........looked up the Ronk site, but doesn't look like they still make that particular model. From the description I got of them, they are pretty heavy, like 100 pounds or more. That is kind of heavy for just a static converter, would it be a "phase shifter" model? One is a 10hp model the other 20hp

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    Likely they are actually Rotary Phase Converters.... RPCs

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    They are most likely an early type transformer type static converter.
    Known as the Ronk Add-A Phase.
    Here's a copy of an early manual page showing a model 64A
    aap2.jpg

    I believe that these early models are comparable to the current type S, and are intended for a single motor load. I would call and check with Ronk to see if they are suitable for your intended application, and if they have a manual for balancing them. They need to be adjusted to the load.

    ADD-A-PHASE - Static Phase Converters - Ronk Electrical

    add-phase-type-aa.jpg

    SAF Ω

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    Sounds like they have a transformer in them, because they sure aren't rotary. So that would mean they actually produce constant voltage on the third leg?
    They came out of a water treatment plant in a one horse town, literally a wide spot in the road, so no three phase power available. I was told that they were running two motors off of each.
    I was hoping from what I was told and what little I could find, that they were phase shifters, since it is obvious they aren't rotary

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    You said the magic words "water treatment plant", so yes, I think you folks are right, they are the transformer type.

    That type is really only good for a constant power load. Water pumping that operated continuously at one load is a perfect application, so irrigation is typical, but a treatment plant could also have a constantly operating pump like that.

    It would not be very helpful for most machine tool loads. .

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    rj1939,

    The Ronk Add A Phase is a static auto-transformer converter. Sounds like that is what you have. The Add A Phase has a heavy auto-transformer in the box, the Phase Shifter is just a box of relays and capacitors. Add A Phase will provide full rated horsepower. As has been previously noted they are tuned to the motor for full horsepower (by adjusting the running capacitance and transformer voltage). At full load the leg amps will be equal. They can be run at less than full load as in machine tools since, although not balanced, none of the leg amps will exceed the FLA of the balanced condition.

    Prior to the introduction of reasonable cost VFD's I built a number of these auto-transformer converters (same circuit as Add A Phase) for the machine tools in my shop. They have provided excellent trouble free service.

    Here is an interesting FAQ about the Add A Phase.

    Ronk Static Phase Converter FAQ

    The Add A Phase conversion method has been discussed at length in this Forum. If you are interested you can check out this thread and the links posted in it.

    Transformer Method 3 Phase Conversion

    Joe

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  9. #7
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    Thanks Joe..............that gives me some more info than what I have otherwise found. I've got some reading to do on that previous thread. Wasn't aware of the limitations of auto transformer setups til now.
    Had done a search on Ronk converters and had quite a few hits, but didn't notice that one.


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