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Thread: Rotary Phase Converter (Create 3-phase power from a single phase source)

  1. #161

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    Quote Originally Posted by old kodger View Post
    Paul,

    Oh, by the way, I'd have to buy the idler motor as well. Checked that one out as well, nobody wants to give one away, if it works,they want to sell it as a going concern.

    Rob.
    I have several 1/3 Hp 120 V I believe i still have them. I will sell one PM me if interested

  2. #162
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    WOW A lot of reading and arguing I don't currently have the link but there is another phase converter no one has mentioned it uses a single phase transformer with a 220 volt primary (or 240 volt as you want to call it) and a 3 wire center tapped 120-0-120 secondary and the secondary side is hooked to make a high amperage 120 volt secondary that has 1 lag tied to the primary in a way that produces about 360 volts at the open end of the 129 volt secondary and the other end of the primary that power is then fed through capacitors (calculated to the amperage requirements of the 3 phase load) the rating of the transformer to the motor HP was about 1 KVA per HP Nothing rotating and FULL rated starting torque I bought the book but have not made that type of converter yet although I have accumulated all the parts to do so I bought the book on AMAZON Gary

  3. #163

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    Quote Originally Posted by Paul Alciatore View Post
    ..........

    AND, this is a discussion about converting 240V, SINGLE phase power to run a three phase motor, not using TWO 240V phases/lines for that purpose. If, as was shown above, you connect a single, SINGLE PHASE line to two of the phase inputs (A-B and B-C for example) of a three phase motor, you will either have a short circuit (you would never actually do this) or ZERO Volts across the combination (A-C), not 480 Volts. In either case, the three phase motor will not run, even if you start it with a pony motor or rope. This is clearly not a possibility.

    .........
    Where was it "shown above" for the connections you describe?

    You would connect a single, SINGLE PHASE line to two of the motor terminals (A-B OR B-C OR A-C) of a three phase motor. It doesn't matter if it is a star wired motor or a delta wired motor as long as the applied voltage corresponds to the motor rated voltage.


    All the RPC designs I have seen are similar with respect to one thing. After the idler motor is brought up to speed they all connect a single phase voltage of an RMS amplitude that corresponds to the motor nameplate voltage rating to two out of the three idler motor terminals. If you have a 3 phase, 240 volt rated idler motor you apply a 240 volt single phase voltage and can generate a 3 phase 240 volt supply. If you want to generate a 415 volt three phase supply you would need to apply a 415 volt single phase voltage to a three phase idler motor wired for the 415 volts. If you only have a 240 volt single phase voltage available you could step the 240 volt single phase up to 415 volts single phase to generate the 415 volt three phase supply with the 415 volt three phase idler motor. For some reason old kodger and nhengineer believe the 415 volt single phase needs to be 480 volts single phase to apply to the 415 volt idler motor. You could also take the 240 volt three phase output of the 240 volt idler and use a three phase transformer to get a 415 volt three phase supply but transformers cost money, especially three phase ones or three single phase ones wired in a three phase bank.

    The first diagram I uploaded:

    Quote Originally Posted by Junker2 View Post
    Here is the vector diagram when you apply 480 volts single phase to the L1 and L2 terminals of a three phase 415 volt star wired motor.

    Attachment 16975


    Please note that you have 277 volts across each motor winding while the idler motor is running.

    It has already been suggested by Frank S that you would need 415 volts.

    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''

    Junker2
    shows the error in applying a 480 volt single phase voltage to a star wound 415 volt three phase idler motor.


    This is the post where nhengineer claims to have studied power distribution.


    Quote Originally Posted by nhengineer View Post
    Rob,

    I could not have created a better response myself. Thank you for saving me the time and effort.

    Paul,

    As with Rob, I tried of this exercise also. In addition, the time I spent learning power distribution at Franklin Institute of Boston (Massachusetts, USA) cost my parents a fortune. You could enroll there yourself ( Home - Benjamin Franklin Institute Of Technology ) or you could listen to Rob; your choice. Regardless, I do not have the time or inclination to provide free education. I have other projects to work on. Anything you would need to know regarding this subject you should be able to find using proper Google search phrases.

    Best regards,
    David Lee
    Based on nhengineer's "design calculations" so far, I wonder exactly what they teach there.

  4. #164
    smithdoor's Avatar
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    Almost ever one that has had single phase dream of just using a transformer
    The close it can get is simple three phase motor converted to single phase and using the third leg for the three phase (rotary type transformer)
    This why most MFG of converter use a simple start cap and relay The converts a three phase motor to single for few seconds now you have a rotary type transformer

    Good luck

    Dave


    Quote Originally Posted by Junker2 View Post
    Where was it "shown above" for the connections you describe?

    You would connect a single, SINGLE PHASE line to two of the motor terminals (A-B OR B-C OR A-C) of a three phase motor. It doesn't matter if it is a star wired motor or a delta wired motor as long as the applied voltage corresponds to the motor rated voltage.


    All the RPC designs I have seen are similar with respect to one thing. After the idler motor is brought up to speed they all connect a single phase voltage of an RMS amplitude that corresponds to the motor nameplate voltage rating to two out of the three idler motor terminals. If you have a 3 phase, 240 volt rated idler motor you apply a 240 volt single phase voltage and can generate a 3 phase 240 volt supply. If you want to generate a 415 volt three phase supply you would need to apply a 415 volt single phase voltage to a three phase idler motor wired for the 415 volts. If you only have a 240 volt single phase voltage available you could step the 240 volt single phase up to 415 volts single phase to generate the 415 volt three phase supply with the 415 volt three phase idler motor. For some reason old kodger and nhengineer believe the 415 volt single phase needs to be 480 volts single phase to apply to the 415 volt idler motor. You could also take the 240 volt three phase output of the 240 volt idler and use a three phase transformer to get a 415 volt three phase supply but transformers cost money, especially three phase ones or three single phase ones wired in a three phase bank.

    The first diagram I uploaded:



    shows the error in applying a 480 volt single phase voltage to a star wound 415 volt three phase idler motor.


    This is the post where nhengineer claims to have studied power distribution.




    Based on nhengineer's "design calculations" so far, I wonder exactly what they teach there.

  5. #165
    Paul Alciatore's Avatar
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    Junker2,

    I guess I was referring to the diagram in your post #146 where you clearly show two 240V phases with a ground at their common point. You show these two adding up to 480V but you do not show any transformer. And they are connected to two terminals of a three phase motor in that diagram. My point was that if a building had only single phase, 240 Volt service, as a person in Australia would typically have, then there is no way to get 480V (or was it 415V?) from that without using a transformer. And those transformers apparently are prohibitively expensive. Perhaps I misunderstood, but you seemed to be suggesting that a single 240V, single phase feed could be hooked up in that manner to produce 240V.

    I personally think this discussion is getting a bit ridiculous. We are, or at least we originally were, discussing the use of nhengineer's design in Australia. But I and apparently most of us have never even seen his plans or even a circuit diagram of the design. So we have no idea if it is or is not possible to use it there. He seems to think that it is not suitable.



    Quote Originally Posted by Junker2 View Post
    Where was it "shown above" for the connections you describe?

    You would connect a single, SINGLE PHASE line to two of the motor terminals (A-B OR B-C OR A-C) of a three phase motor. It doesn't matter if it is a star wired motor or a delta wired motor as long as the applied voltage corresponds to the motor rated voltage.


    All the RPC designs I have seen are similar with respect to one thing. After the idler motor is brought up to speed they all connect a single phase voltage of an RMS amplitude that corresponds to the motor nameplate voltage rating to two out of the three idler motor terminals. If you have a 3 phase, 240 volt rated idler motor you apply a 240 volt single phase voltage and can generate a 3 phase 240 volt supply. If you want to generate a 415 volt three phase supply you would need to apply a 415 volt single phase voltage to a three phase idler motor wired for the 415 volts. If you only have a 240 volt single phase voltage available you could step the 240 volt single phase up to 415 volts single phase to generate the 415 volt three phase supply with the 415 volt three phase idler motor. For some reason old kodger and nhengineer believe the 415 volt single phase needs to be 480 volts single phase to apply to the 415 volt idler motor. You could also take the 240 volt three phase output of the 240 volt idler and use a three phase transformer to get a 415 volt three phase supply but transformers cost money, especially three phase ones or three single phase ones wired in a three phase bank.

    The first diagram I uploaded:



    shows the error in applying a 480 volt single phase voltage to a star wound 415 volt three phase idler motor.


    This is the post where nhengineer claims to have studied power distribution.




    Based on nhengineer's "design calculations" so far, I wonder exactly what they teach there.
    Paul A.

  6. #166

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    Here is where nhengineer realized there needs to be two hot leads (out of phase with each other) with reference to earth ground for his present design to work.

    Quote Originally Posted by nhengineer View Post
    If the idler motor is 50Hz then its output will also be 50Hz. By the way, a 3-phase 50Hz motor is quite happy to run on 60Hz 3-phase. It will turn about 1.2 * faster than that which is written on its nameplate however.

    I'm wondering, Dave, what will be accomplished with a buck/boost transformer? The issue here is most former United Kingdom locations are 220 (230 now actually) with a single hot lead and a neutral. In order for my present design to work, there needs to be two hot leads (out of phase with each other) with reference to earth ground.


    Somewhere around here is where old kodger suggested using two phases of 230 volts 180 degrees apart.

    Quote Originally Posted by old kodger View Post
    Hi David,
    Yeh, I'm with you on that one, the only way I could see of getting plus 230-0-minus 230 would be to get a big old 450volt output tranny with a center tap and use the center tap as the ground reference.
    With two trannys working in tandem you'd still only get two lots of 230 IN phase.

    I got this far and suddenly realized that if the two were tied in the middle and that junction grounded, you may very well get plus 230 and minus 230 at the other ends of the transformers, though whether they would be out of phase is still questionable.

    Any thoughts on this?

    Rob.



    And here is where nhengineer confirmed that old kodger would need two phases of 230 volts 180 degrees apart.






    Quote Originally Posted by nhengineer View Post
    Rob,


    Answer = Yes. Sorry.

    .............

    David Lee
    (NHEngineer)
    Quote Originally Posted by nhengineer View Post
    ........................

    You don't need a 3-phase transformer. Single phase boost transformer ANSI schematic below:

    Attachment 16191 Sorry, I've not yet been able to finger out those ISO symbols.

    The output section is configured so that there is a 180° phase shift from one output to the other. That will give you two 230V outputs a half phase apart. That is what we have for residential high voltage here in the USA (except it's 240-250V). With that you can use that at the input to my design and create (kind of) a 230V 3-phase suitable to run your 230V, 3-phase motors with reduced horsepower output (83.3% of the nameplate rating)

    ...........................

    Now why would you want to buy an expensive transformer to get the two 230V outputs a half phase apart that would create (kind of) a 230V 3-phase (supply) suitable to run your 230V, 3-phase motors with reduced horsepower output (83.3% of the nameplate rating) when all the other RPC designs use a 230 volt (240 volt) idler motor to generate a "full" power 240 volt 3 phase supply?


    I assumed they wanted the "480" volts to generate a 415 volt supply from a 415 volt star wired idler motor.



    Quote Originally Posted by Paul Alciatore View Post
    Junker2,

    I guess I was referring to the diagram in your post #146 where you clearly show two 240V phases with a ground at their common point. You show these two adding up to 480V but you do not show any transformer. And they are connected to two terminals of a three phase motor in that diagram. My point was that if a building had only single phase, 240 Volt service, as a person in Australia would typically have, then there is no way to get 480V (or was it 415V?) from that without using a transformer. And those transformers apparently are prohibitively expensive. Perhaps I misunderstood, but you seemed to be suggesting that a single 240V, single phase feed could be hooked up in that manner to produce 240V.

    '''''''

    Paul,

    Yes, the 480 volts is generated from a transformer configured as they are discussing above. I uploaded the diagram in post #146 to show that if the 480 volts was connected as shown in the diagram the actual voltage across the motor winding would be 277 volts, NOT the 240 volts that the motor windings are rated for.

    This post:

    Quote Originally Posted by Junker2 View Post
    To Rob AKA: old kodger,

    ........

    For your enjoyment I have attached a diagram for a 240 volt delta connected idler motor setup. The magenta colors show the "virtual" neutral point that does not actually physically exist (this was explained by Paul Alciatore assuming you can understand the electromagnetic theory involved).

    Attachment 17004

    Good Luck
    Junker2

    shows how to connect a 240 volt single phase system to generate a 240 volt three phase supply WITHOUT THE NEED FOR ANY TRANSFORMERS.

    I agree Paul, At this point, this thread appears to be a big circle jerk.

  7. #167
    Frank S's Avatar
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    The one thing that caused this thread to travel down the road top perdition is the fact that there are folks all around the globe with differing electrical power services available to them, plus the fact that not everyone understands that when something is written up or explained it can mean the nominal voltage, as with the term of single phase. In the USA single phase 220/240 volts requires 2 hot lines of 120 volts (nominal) in other places this is done by a single hot leg and the neutral. In many places such as Europe or in particular the Middle east 3 phase power is supplied to many homes in the form of 415v across any 2 of the phases
    While I was working in Kuwait we often installed overhead doors made in Denmark that were powered by small 3 ph motors but only used a single hot leg and the common. this was accomplished via a very compact box which contained a small center tapped transformer and a couple of capacitors and not a whole lot else except for maybe a few resistors and a 5 amp fuse and a reversing switch.
    I do onw a set of rhengineer's rotary phase converter plans and although his method of construction differs from the way I made my RPC years ago they are a valid set of plans. But no as they are written up they do not address differing voltages or energy production methods around the world. any more than a friend of mine who lives in New Zealand on another form who a long time ago made his own buck and boost transformer would have worked as made in the USA However he later created a spread sheet calculator which if a person understood enough about how electromagnetic currents are created could build their own
    I've posted a few times on this thread of how a solution to achieving 3 ph from 1 ph could be accomplished, as wqell as a couple of others who have posted as well. This is not to say that my way or another's way is better or the only way they are simply a means to reach a suitable outcome.
    When it comes to a RPC for small ones I prefer to simply add the required amount of capacitors to the idler motor when the become larger say over 7.5 HP the addition of a pony motor to serve as a means to start the idler motor turning reduces the inrush current of the locked rotor condition call it reducing amperage spike. However I still prefer to have a bank of capacitors across the phases of the idler motor to smooth out the 120° 3 ph offset from the 180° of a 2 hot line single phase.
    You still need a way of creating 2 hot legs though in order for any 3 ph motor to be started and run even with the addition of capacitors or a pony motor, no matter what the desired output voltage is to be. The 1 exception might be and I say this only becaus I have never had the opportunity to try it, would be a motor with 12 or 18 wires, instead of the more common 9 wire motors
    Last edited by Frank S; 03-20-2017 at 03:01 PM.
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  8. #168
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    Quote Originally Posted by Frank S View Post
    The one thing that caused this thread to travel down the road top perdition is the fact that there are folks all around the globe with differing electrical power services available to them, plus the fact that not everyone understands that when something is written up or explained it can mean the nominal voltage, as with the term of single phase. In the USA single phase 220/240 volts requires 2 hot lines of 120 volts (nominal) in other places this is done by a single hot leg and the neutral. In many places such as Europe or in particular the Middle east 3 phase power is supplied to many homes in the form of 415v across any 2 of the phases
    While I was working in Kuwait we often installed overhead doors made in Denmark that were powered by small 3 ph motors but only used a single hot leg and the common. this was accomplished via a very compact box which contained a small center tapped transformer and a couple of capacitors and not a whole lot else except for maybe a few resistors and a 5 amp fuse and a reversing switch.
    I do onw a set of rhengineer's rotary phase converter plans and although his method of construction differs from the way I made my RPC years ago they are a valid set of plans. But no as they are written up they do not address differing voltages or energy production methods around the world. any more than a friend of mine who lives in New Zealand on another form who a long time ago made his own buck and boost transformer would have worked as made in the USA However he later created a spread sheet calculator which if a person understood enough about how electromagnetic currents are created could build their own
    I've posted a few times on this thread of how a solution to achieving 3 ph from 1 ph could be accomplished, as wqell as a couple of others who have posted as well. This is not to say that my way or another's way is better or the only way they are simply a means to reach a suitable outcome.
    When it comes to a RPC for small ones I prefer to simply add the required amount of capacitors to the idler motor when the become larger say over 7.5 HP the addition of a pony motor to serve as a means to start the idler motor turning reduces the inrush current of the locked rotor condition call it reducing amperage spike. However I still prefer to have a bank of capacitors across the phases of the idler motor to smooth out the 120° 3 ph offset from the 180° of a 2 hot line single phase.
    You still need a way of creating 2 hot legs though in order for any 3 ph motor to be started and run even with the addition of capacitors or a pony motor, no matter what the desired output voltage is to be. The 1 exception might be and I say this only because I have never had the opportunity to try it, would be a motor with 12 or 18 wires, instead of the more common 9 wire motors
    Hi Frank S,

    Thank you for your input. Everything you have written is correct. I have never implied it was the ONLY way to run a 3-phase motor from 2-phase service but my RPC design has worked for me running my Bridgeport, lathe and 7-1/2 HP compressor since 2012.

    I have refused to get into a urinating contest with the trolls patrolling this thread and, by your writing, "...I do own a set of nhengineer's rotary phase converter plans and although his method of construction differs from the way I made my RPC years ago they are a valid set of plans..." you may now be a victim of their venom as well. Honestly, I've found their exchanges quite entertaining. It is interesting to note that they have never even seen my plans yet they freely criticize them.

    For your edification, the edification of sincere contributors here and the edification of prospective owners of my plans, at the time I created them, I had no consideration of helping builders other than those in the western hemisphere. It simply did not occur to me. Now that there have been international inquiries, I intend to amend the booklet to include possible uses in former British Crown colonies (India, Japan, New Zealand and others) with the help of our Rob Candy (Australia).

    In Rob's case, my research so far indicates that just the addition of a properly configured transformer would provide the required 2-phase service to the idler motor but presently I have been too busy designing and building a lift table to devote my resources to that endeavor.

    Thank you again for your valued contributions here.

    Best regards,
    David Lee

  9. #169

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    Frank S

    BRAVO!!
    Rob

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    homemade phase converters

    Quote Originally Posted by Jon View Post
    When I search, I see plenty at that price point. From Amazon.com: https://www.amazon.com/Pentair-35706...dp/B008GTWJZ6/. Similar results from Google Shopping.

    Aren't you the same guy who said that you have Rotary Phase Converter plans that you'll send out for free, in this post? Can you post them?

    So far, these Phase Converter Plans have the highest 1st-month sales total of all of our plans.
    I made a phase converter 20 years from plans I found on eBay, I used a 50 dollar 10 HP motor it worked for 10 years then I started adding bigger machines 15 HP and 10 HP. I bought a larger one with about 8 capacitors and have been very satisfied. If this book covers larger motors it is a steal at 12.50.

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