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  1. #81
    smithdoor's Avatar
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    This why you use star wound motor.
    The power for the rotor come from one side of the motor windings. I do know the first told it was hard to see how works BUT it does work. This true with Star wound motor. Any time I see motor with delta will not work. Today you can find some power plants using this same technology. They have to have power going the generator be it starts generating power.

    The AVR ( automatic voltage regulator) as the name implies for voltage regulating note some will use buck and boost transform. Most are 12 or 16 volts steps.

    The Hz is sync to your power and will stay the same

    I have chart from my power company see the red box the left side show 120 volts and the right is for 240 volts.

    FYI this voltage at the meter after inside shop it can drop ever more as most spec 5 volt drop on some location I have for over a 20 volt drop to water pumps This where a buck and boost transform works great so pump work good

    Dave



    Quote Originally Posted by Frank S View Post
    What you would be doing there is building a generator then you would need an AVR ( automatic voltage regulator) to hold it at the correct HZ
    Also without line voltage to the motor now being used as a generator it would require a source excite the field winding.
    Attached Files Attached Files
    Last edited by smithdoor; 01-18-2017 at 06:54 AM.

  2. #82
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    Rob,

    Quote Originally Posted by old kodger View Post
    The transformer thing will likely work, but would it not have to be 1:2 in order to input 230volts and get two lots of 230 volts (center tapped) 180 degrees out of phase?
    Answer = Yes. Sorry.

    Quote Originally Posted by old kodger View Post
    Also, each time an idea (opinion) has been postulated on this thread, I've gone and done whatever research I could, and in every case IN AUSTRALIA the cost has not been justifiable.
    Why? A scrapper's 3-phase idler motor I would not expect to be expensive. The transformer would be another story perhaps but what would be the cost of refitting your equipment with single phase motors?

    Quote Originally Posted by old kodger View Post
    Now to throw another consideration into the fray, since the acquisition of an idler motor is mandatory in all instances, if one were to forcibly drive an idler motor with say, a diesel motor, (motors from old banged up utes are not so hard to get), would it produce all three phases?
    I do not think so but I'm not 100% sure. I think you would need an external source of power. My converter design depends on a two hot wire input in order to function. The third output leg does not conduct electricity that I can detect on my Amp Probe. I found this LINK (click on the word 'link') to be quite informative.

    David Lee
    (NHEngineer)

  3. #83
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    Quote Originally Posted by smithdoor View Post
    I just look at your drawing on the first page
    I like using a simple way capacitor and potential relay
    Low cost an time proven Today it use for AC and water well pumps on single phase
    I have seen the pony type with no more than a lawn mover pulley and rope for starting it works and simple
    The one I saw the guy raped the rope around the pulley mounted on the idler motor, pulled the rope and switch the motor on it work. I could not use with employs. so I used capacitor and potential relay it is automatic
    Dave,

    I have serious misgivings regarding the morality of anyone who would rape a rope. Seriously, yes, it is true. The pony motor is only needed to start the idler motor turning and can (and should) be switched out of the circuit once the idler is turning.

    DSLee

  4. #84
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    FYI I have never did this rape rope and pull I just pitcher the rope not letting go. NO WAY for me
    I have seen done and worked it is just one those thing you in your life.
    Like watching some jump out off a cliff hoping the shoot will open on time. NO WAY for me

    I did think of using a model airplane starter after I saw rope being used.
    Yes used starter for model planes after a few sore fingers.


    Dave


    Quote Originally Posted by nhengineer View Post
    Dave,

    I have serious misgivings regarding the morality of anyone who would rape a rope. Seriously, yes, it is true. The pony motor is only needed to start the idler motor turning and can (and should) be switched out of the circuit once the idler is turning.

    DSLee
    Last edited by smithdoor; 01-18-2017 at 09:31 AM.

  5. #85
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    Quote Originally Posted by smithdoor View Post
    FYI I have never did this rape rope and pull I just pitcher the rope not letting go. NO WAY for me
    I have seen done and worked it is just one those thing you in your life.
    Like watching some jump out off a cliff hoping the shoot will open on time. NO WAY for me

    I did think of using a model airplane starter after I saw rope being used.
    Yes used starter for model planes after a few sore fingers.


    Dave

  6. #86
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    You find more information on why this does not work from the book publish by Lindsay Publications (How to run three phase motor) I can not post it here as has copyright of 1977 and 1987.
    You find this book on the web see pages 4 5 & 6 It does not have any charts for making one. Try this site https://groups.yahoo.com/neo/groups/...ndlathe9/files

    Dave


    Quote Originally Posted by Frank S View Post
    Split phase is also the type of current here in the USA When talking about 220 v single phase
    some mistakenly say there are 2 phases of 120v to get the 220 volt when actually it is only 1 phase split in the transformer to achieve 220v
    Split phase is also used in rule Australia to get 480v

  7. #87
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    Quote Originally Posted by smithdoor View Post
    You find more information on why this does not work from the book publish by Lindsay Publications (How to run three phase motor) I can not post it here as has copyright of 1977 and 1987.
    You find this book on the web see pages 4 5 & 6 It does not have any charts for making one. Try this site https://groups.yahoo.com/neo/groups/...ndlathe9/files

    Dave
    I can't get into YAHOO groups anymore without giving up my cell number and that's not going to happen; not to YAHOO. How about you, Smithdoor, upload that file to your PC and then download here?

    DSLee

  8. #88
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    FYI do have info on Home Model Engine Machinist for single to three phase
    Rotary / Static Three Phase Converter update Dec 27 2012

    Dave

    Quote Originally Posted by nhengineer View Post
    I can't get into YAHOO groups anymore without giving up my cell number and that's not going to happen; not to YAHOO. How about you, Smithdoor, upload that file to your PC and then download here?

    DSLee

  9. #89
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    Quote Originally Posted by smithdoor View Post
    Yes it say split phase so NOW it on the internet it must be true

    But when make drawing for the city or county That is a 3 wire single phase
    That will not start a 3 phase motor with additional caps for starting and last I heard We are taking about 3 phase

    Good luck with internet

    Dave
    Smithdoor, your comments questioning the integrity of the Internet are not groundless. However, I have found yet another text and drawing NOT from the internet but from a 40-year-old publication that is in FULL agreement with the previous text and drawing that I submitted a few days ago.

    Rotary Phase Converter (Create 3-phase power from a single phase source)-lindsayschematic.jpg

    What say you now?

  10. #90
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    Quote Originally Posted by old kodger View Post
    Hi Rhengineer,
    The transformer thing will likely work, but would it not have to be 1:2 in order to input 230volts and get two lots of 230 volts (center tapped) 180 degrees out of phase?
    Also, each time an idea (opinion) has been postulated on this thread, I've gone and done whatever research I could, and in every case IN AUSTRALIA the cost has not been justifiable.

    Rob.
    Mr. Kodger,

    After sleeping on it for a bit, I believe an isolation transformer transformer may (or may not) be your wisest choice. Immediately below is a watts to HP chart which should be useful in sourcing a proper transformer.

    Rotary Phase Converter (Create 3-phase power from a single phase source)-wattstohpchart.jpg

    Next is finding a transformer with the proper KVA rating. For 3HP you'd need about 2400Watts so I quickly looked at the Newark catalog.

    http://www.farnell.com/datasheets/18...440.1484843408

    Rotary Phase Converter (Create 3-phase power from a single phase source)-nawarkisolationtransformer.jpg

    The cost is around $450 US plus shipping. The transformer above is NOT the exact one but it is representative of the device you'd need for 3.0HP. If you'd like for me to try and find the exact one let me know. It is not totally unlikely that you may need two transformers to do what you need to do.
    Attached Thumbnails Attached Thumbnails Rotary Phase Converter (Create 3-phase power from a single phase source)-wattstohpchart.jpg  
    Last edited by nhengineer; 01-19-2017 at 09:53 AM.

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