3 phase electric question

Discussion in 'Shop Talk' started by Mike in Ohio, Aug 10, 2004.

  1. Mike in Ohio

    Mike in Ohio Well-Known Member

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    Well, no 3 phase available to my farm. The fellow at the electric cooperative mentioned that there is a way to make 3 phase from single phase but he didn't have any details. We have a 200 amp feed and a 100 amp feed so the amount of power isn't an issue...it's the type.

    I have a piece of equipment (nut huller) which is 220v 3 phase 5 hp motor. My options would appear to be:

    1) change the 3 phase motor for a single phase motor;
    2) rent a generator for the 2-3 weeks I would need to run the huller (to get through this season)
    3) install one of these single phase to 3 phase doohickeys.

    Anyone have any input that might be useful?

    Thanks in advance.

    Mike
     
  2. daeve

    daeve Well-Known Member

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    Here's a link to a page on building a rotary converter: http://www.metalwebnews.com/howto/phase-converter/phase-converter.html that I bookmarked a while back. Haven't tried it yet so no personal recommendation here. Was looking cause I bought a drill press at auction a while back that is 3 phase. None here on the farm either though I may put it in when I get the shop built. In another load of junk I got an old 5 hp 3 phase motor and am planning to try building one out of. Course that's after I get the dozers fixed and work shop built and trailers moved in and... One more round tuit project I suspect.

    HTH
     

  3. Ross

    Ross Moderator Staff Member Supporter

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    Arn't they called roto-phasers too? I know a fellow who uses one to run milling machines. It works quite well but he uses it alot so perhaps cost wasn't an issue. I have a large 3 phase table saw so I have the same problem when i go to get it rigged up. I was thinking of a genset to power it.
     
  4. rambler

    rambler Well-Known Member Supporter

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    There are several folks advertising phase converters in the farm publications I get. I understand you can build your own from a 3 phase motor - I think.

    Three phase is really expensive to get brought in, but 3 phase motors are a lot cheaper to buy, so the big electric power users do it, as it's cheaper overall. For a single task or part-time use, it really doesn't pay.

    A used or cobbled phase converter might be your best bet.

    --->Paul
     
  5. Tractorman

    Tractorman Well-Known Member

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    If you want it too last oversize the converter!
     
  6. mary,tx

    mary,tx Well-Known Member Supporter

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    Just thinking out loud...

    It seems to me that the whole reason one runs three-phase motors is that it is more efficient than single phase. It also seems to me that to get three-phase power by converting single phase is a loss in efficiency, perhaps a greater loss than the loss of single-phase AC motors. Therefore it seems to me that perhaps you may want to simply look into using a 220/240VAC or even a 120VAC single phase motor if the conversion cost is less than the three-phase converter cost plus the loss of efficiency in power conversion--especially if you can run your nut huller on a smaller HP motor than 5HP. How much power do you really need for this nut huller thing? I don't really know the answers, but perhaps a real electrician can chime in on this. I am curious.
    Dale (DH of mary, tx)
     
  7. Stush

    Stush Well-Known Member

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    Your #1 option is your best bet. We picked up a rockwell metal lathe years ago that came with 3 phase motor and looked at options 1 and 3. #1 was the better option for several reasons. I can't believe that renting a generator would be less expensive that a single phase motor to replace the existing one.
     
  8. Mike in Ohio

    Mike in Ohio Well-Known Member

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    Just want to thank everyone for their input. I think option #1 seems to make the most sense.

    Mike
     
  9. agmantoo

    agmantoo agmantoo Supporter

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  10. Tracy

    Tracy Well-Known Member

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    I have a 15 hp roto phase converter that runs two compressors for walk in freezers as well as 2 meat grinders, a 10 hp the other a 5 hp. The phase converter cost over $1000.00 installed.

    The reason I did this instead of having the 3 phase ran from the power company was 1] in this area if tyou have 3 phase you are billed at a business rate and not residential and it is more costly. 2] the cost for the power company to hook up 3 phase would ahve been over $3,000.

    The phase convertor has to run constantly though to keep the compressors running on the freezers. The cost of my electric bill runs around $500.00 per month so in retrospect I am not sure if this is a savings by doing it this way or if I would have been better off just having it ran from the power company.

    If you are looking for something that is not running constantly [like a compressor] then a converter would not need to run all the time.

    There is also 2 types of converters. A roto phase which alows you to run at full power but much more expensive or a static converter. A static converter is a LOT cheaper but you will loose about 1/3 of your power. You can find static converters on ebay reasonably priced.