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Thread: Rotary Phase Converter for ShopBot PRS Alpha, Colombo spindle, Republic blower/vacuum

  1. #1
    Join Date
    Sep 2011
    Location
    Bowling Green, OH
    Posts
    23

    Default Rotary Phase Converter for ShopBot PRS Alpha, Colombo spindle, Republic blower/vacuum

    Hi there,

    My shop is about to move to a new location with only single phase power.

    Our ShopBot PRS Alpha with a 5HP Colombo spindle and a 16.9HP Republic blower/vacuum requires 3 phase power, though. We'd obviously need a rotary phase converter.

    Questions:
    - Any specific recommendations?
    - Should I get a cheaper 20HP phase converter for the blower/vacuum and a high-end 5HP converter for the spindle or is it better to one bigger high-end for both?

    I've looked at several models at
    Precision Electric
    https://www.precision-elec.com/produ...se-converters/
    as well as
    American Rotary
    https://www.americanrotary.com/produ...se-converters/

    Thank you for your help in advance!

    Erwin

  2. #2
    Join Date
    Dec 2011
    Location
    Piedmont, SD
    Posts
    728

    Default

    Erwin,
    A single 3 Phase convertor and circuit in your building is all you'll ever want to have to deal with.

    IMPORTANT: You will be advised by the manufacturer of any rotary to purchase a unit rated twice the required horsepower. This means you need a 40. Rotary's just need that headroom. Okay, some may say only 50% more, but you get the gist. 20HP rotary is not enough for the loads you're going to subject it to.

    I graduated out of a 40HP rotary last year for a similar load rating, and got a Phase Perfect. Due to the nature of these units, rather than the 40HP they'll recommend for a rotary, you may now use a 20. For the price I see AR quoting for an entry level 40HP, you can get a 20HP digital from Phase Perfect. I would never desire to go back to a rotary - big noise, and though obviously a brand new unit would be tuned in well, it still cannot compare to the accuracy of the Digital.
    I literally would have voided my warranty on a new shaper, had I fired it up with the old rotary I had, as the hot leg was putting out 270v. Up to that point, the wide-belt sander I was originally using it for has no microprocessor controls, so it didn't care. That old rotary needed re-balancing due to aging capacitors and the relation of incoming voltage to load. Every building and load configuration is different. Could have hired, (if I could find someone), to spend an afternoon on the phone in consultation with the manufacturer, testing and re-wiring capacitor array to pull into balance, but by then, I would have been half way invested in the digital from Phase Perfect, which automatically balances the load to within +/- 1% of incoming voltage. And no moving parts.

    Check it out. It is the ideal way to go. You will find it liberating, once you get a solid digital 3phase circuit going in your shop, as the stability of it's power for the ever-evolving world of microprocessor controlled machinery is eventually going to push you to this level of accuracy, IMHO.
    Might as well invest there at the outset, as I hope you are able to.


    Jeff

  3. #3
    Join Date
    Sep 2011
    Location
    Bowling Green, OH
    Posts
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    Thanks, Jeff!
    VFD is probably the way to go then. Did you try it was a ShopBot spindle and blower as well?
    Erwin

  4. #4
    Join Date
    Dec 2011
    Location
    Piedmont, SD
    Posts
    728

    Default

    Definitely not a VFD, which seems lately is regularly being sited as some sort of budget phase conversion shortcut. Just give them a call regarding your needs, and they can explain it much clearer.
    My spindle and hold-down systems are not 3phase so I cannot speak to that, but it all simply boils down to the horsepower ratings.

    jeff

  5. #5
    Join Date
    Sep 2011
    Location
    Bowling Green, OH
    Posts
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    Default

    Got it! Thanks again!

  6. #6
    Join Date
    Jun 2018
    Location
    Pennsauken, NJ
    Posts
    30

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    Interesting info that I'll keep on file. I use an OLD rotary converter for my sheet metal shear, if only because that's what it came with.

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