Single phase to three phase - where to start?
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    Default Single phase to three phase - where to start?

    I am looking for guidance when it comes to converting single phase 120/240 to three phase 120/240. A buddy just came into a bunch of three phase equipment from a machine shop liquidation.

    The load of all machines, if they were all running simultaneously, would be 25A on 240V three phase.

    A google search turns up a lot of 'plug and pray' magic looking equipment, makes me skeptical. I figured the fine people from the PM forum could set me in the right direction!


    Thank you

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    What kind of machines? Drill presses and belt grinders? Engine lathes? Seven axis cnc swiss?

    What is your end goal? Testing out the equipment? Starting a for profit machine shop?

    The procedure needed to wire a single outlet for a toaster varies a tad from what is needed for a commercial kitchen.

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    Quote Originally Posted by GENERALDISARRAY View Post
    What kind of machines? Drill presses and belt grinders? Engine lathes? Seven axis cnc swiss?

    What is your end goal? Testing out the equipment? Starting a for profit machine shop?

    The procedure needed to wire a single outlet for a toaster varies a tad from what is needed for a commercial kitchen.
    Mostly drills, mills, and grinders. End goal for him is to use these for personal use, hobby level... somewhere in between a for-profit machine shop and testing them out.

    Sent from my Pixel 2 XL using Tapatalk

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    With multiple equipment the best is to get a rotary phase converter or RPC. This will allow some or all of the equip to be run at the same time. Rpc is also easy and cheap.
    I have a spare one that I am not using that would probably work for you guys but shipping it might be $$$

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    For a 25A multi-machine load, there are two basic routes: rotary phase converter or electronic phase converter. Phase Perfect rules the electronic phase converter market at this (low) end of the market. Rotary phase converters can be bought pre-packaged and pre-assembled, or as control boxes to which you add a motor, to DIY installations based on any number of published recipes/designs. (There are also static phase converters, which would not be applicable in this situation.)

    The other option, which is decreasingly expensive every year, is to install variable frequency drives (VFD) on each piece of three phase equipment. Most modern VFDs can be fed from single-phase power, with appropriate derating of the VFD, and will output three-phase power. This is especially useful when the individual machine can benefit from slower- or faster-than-normal motor speed.

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    +1 on what sfriedberg has written.

    A phone call or email to Phase Perfect or to American Rotary will set you in the right direction. VFDs are another good option.



    >>converting single phase 120/240 to three phase 120/240

    To speak in generalities: when thinking of 3 phase power, 120v is not a standard 3 phase power voltage.

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    Quote Originally Posted by medsar View Post
    +1 on what sfriedberg has written.

    A phone call or email to Phase Perfect or to American Rotary will set you in the right direction. VFDs are another good option.

    Ok, one of my local vendors sells North America Phase Converter Co brand. Any feedback on those? Good, bad, or ugly. Thanks!

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    I have not used that brand, sorry.

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    Quote Originally Posted by medsar View Post
    I have not used that brand, sorry.
    No worries. Thanks for your input!

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    I have a 30hp american rotary and it is very good. All I have ever read about them is good too. They and others also sell just the control box now (check ebay) or you can buy with the motor. If you can source a motor locally that might be a good option.

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    All I can say is do lots of reading! If you don't know what a DMM is or how to use ALL the functions on one, you probably should get help. Easy to toast good equipment.

    When you stumble into the term "static converter", RUN the other way! You will see a low price and think SOLD! Do not be fooled. It is crap that needs uninvented. It is NOT a good way to run a 3P load and in fact, they WON'T run anything but a motor because the 3rd leg doesn't even exist.

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    Quote Originally Posted by huleo View Post
    All I can say is do lots of reading! If you don't know what a DMM is or how to use ALL the functions on one, you probably should get help. Easy to toast good equipment.

    When you stumble into the term "static converter", RUN the other way! You will see a low price and think SOLD! Do not be fooled. It is crap that needs uninvented. It is NOT a good way to run a 3P load and in fact, they WON'T run anything but a motor because the 3rd leg doesn't even exist.
    Thanks! I have heard exactly that about the static converters, stay away. When you say DMM - you do mean a Digital Multimeter right? If so, I am covered.

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    You said all the machines running simultaniously will pull 25A at 240v 3ph?

    that's not much power... under 8hp or so... is that correct?

    If you're safe with connecting wires and the voltmeter, willing to invest a little effort in a project, a 10hp 3-phase 230v motor, a couple of contactors, a pushbutton and some capacitors, you'll have a really nice little homemade rotary converter...

    Or if you're dirt-poor and need something crude, just a knife switch, a 10hp 3ph motor, and a piece of string...

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    If deciding to build an RPC do get the high speed 2 pole motors (those above 3000RPM) The faster motors are cheaper but much harder to start especially pull starting with a rope("string") However they are easy to build, I have been using mine for 8 years. I have also built many for friends that also work great.

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    Quote Originally Posted by medsar View Post
    +1 on what sfriedberg has written.

    A phone call or email to Phase Perfect or to American Rotary will set you in the right direction. VFDs are another good option.



    >>converting single phase 120/240 to three phase 120/240

    To speak in generalities: when thinking of 3 phase power, 120v is not a standard 3 phase power voltage.
    American Rotary has outstanding customer service! They answered the phone at 6 am on a Sunday morning and walked me through all of my questions. If I were buying another one this is the company I would be buying from. Hands down.


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