Help with building a Transformer Phase Converter. - Page 4
Close
Login to Your Account
Page 4 of 5 FirstFirst ... 2345 LastLast
Results 61 to 80 of 82
  1. #61
    Join Date
    Jul 2007
    Location
    Missoula Mt
    Posts
    345
    Post Thanks / Like
    Likes (Given)
    9
    Likes (Received)
    130

    Default

    Why not use the Steelman method, and call it a day?? I have done this on 50 hp, works good...Phil

  2. #62
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Quote Originally Posted by Phil in Montana View Post
    Why not use the Steelman method, and call it a day?? I have done this on 50 hp, works good...Phil
    Steelman method is the same idea in reverse.

    Instead of creating 2 phase via the 90 deg phase shift and then converting to 3 phase with the Scott connection, the motor is converted to a 2 phase motor by reconnecting the 12 leads, and capacitors are used to directly do the shift.

    If you think of the motor as having 6 coils and 12 leads, originally connected wye (for instance) with the three legs being Leg 1 (the A&B coils), Leg 2 (the C&D), and Leg 3 (the E&F), with B,D,and F joined at the wye point... then....

    The new connection puts A&C in series, B&D in series, and connects those two in parallel to form one of the two phases, and uses E&F in series as the other phase, supplied by the capacitors. In 2 phase, there is a 90 deg difference in phase, so that works out.

    It's a clever idea, and should work well. if you already have a 12 wire motor, then it is far simpler than the transformer based static converter. If your motor is 9 wire, you will have to go digging in the windings to pull out the wye point and separate wires.

    In common with pretty much all other of the "Capacitor shift" converters, they only recommend it for constant loads such as pumps. They say that right in the website in reference to the static converters they make. For other loads they manufacture and recommend rotary converters.

    The Steelman static converters also use a set of start capacitors with a contactor to cut them out. That system is common to the "Add-A-Phase" , the Steelman, and most rotary converters (for the idler).
    Last edited by JST; 03-27-2020 at 12:38 PM. Reason: Spelling/fat fingered typing

  3. #63
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Interestingly, I got a look inside a "transwave" converter (British). It appears to be a transformer only type, which surprised me. So they are in commercial production for shop use.

  4. #64
    Join Date
    Oct 2005
    Country
    UNITED STATES
    State/Province
    Pennsylvania
    Posts
    17,720
    Post Thanks / Like

    Default

    Quote Originally Posted by JST View Post
    Interestingly, I got a look inside a "transwave" converter (British). It appears to be a transformer only type, which surprised me. So they are in commercial production for shop use.
    Pix or it didn't happen......

  5. #65
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    OK, not my pic, I found it on Youtube..... video from a guy who seems to work on model steam engines, but his converter was not working right. You can ignore the chatter and just look at the stuff in the box when he has it apart.

    YouTube

  6. Likes digger doug liked this post
  7. #66
    Join Date
    Jul 2014
    Location
    MI USA
    Posts
    951
    Post Thanks / Like
    Likes (Given)
    201
    Likes (Received)
    389

    Default

    Quote Originally Posted by JST View Post
    OK, not my pic, I found it on Youtube..... video from a guy who seems to work on model steam engines, but his converter was not working right. You can ignore the chatter and just look at the stuff in the box when he has it apart.
    OMG JST, are you trying to awaken Termite again? We already suffered two pages already! He already splanied, why this is a stupid idea, and ran off the OP'er. Hardhat and earplugs at the ready...

    SAF Ω

  8. #67
    Join Date
    Mar 2008
    Location
    Marulan N.S.W. Australia
    Posts
    187
    Post Thanks / Like
    Likes (Given)
    96
    Likes (Received)
    46

    Default

    It seems to me a lot of people in the UK use static converters. That one uses a transformer to change their supply voltage from 240V to 415V and the rotary switch changes capacitor and the boost is probably bringing the start capacitors back in circuit.
    My opinion is there is nothing higher than 415V in that converter.

    Jim

  9. #68
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Quote Originally Posted by SAF View Post
    OMG JST, are you trying to awaken Termite again? We already suffered two pages already! He already splanied, why this is a stupid idea, and ran off the OP'er. Hardhat and earplugs at the ready...

    SAF Ω

    It has its issues, but it also seems to be used.

    The good news is that if you set it up to work best at full power, or near that, then the imbalance is toward the lower current/power area where it is less important.

    Not all that different from working to select the best "balance capacitor" value, which is also a losing proposition overall, but does work kinda good enough to actually get used.

  10. #69
    Join Date
    Mar 2011
    Location
    Geneva Illinois USA
    Posts
    6,439
    Post Thanks / Like
    Likes (Given)
    2817
    Likes (Received)
    2521

    Default

    Seems like an awfully small transformer for a lathe motor load.

    Tom

  11. #70
    Join Date
    Aug 2014
    Location
    bainbridge island
    Posts
    1,257
    Post Thanks / Like
    Likes (Given)
    261
    Likes (Received)
    297

    Default

    Quote Originally Posted by TDegenhart View Post
    Seems like an awfully small transformer for a lathe motor load.

    Tom
    Maybe, but if it only has to add 120vac and pass 12 amps for a 5 hp motor (240v operation) then its plausibly a 5hp box. That would be 1.5 kw and is plausible for a TX that size. (With 120C temperature rise) a more efficient TX would be larger.

  12. #71
    Join Date
    Jul 2014
    Location
    MI USA
    Posts
    951
    Post Thanks / Like
    Likes (Given)
    201
    Likes (Received)
    389

    Default

    Quote Originally Posted by JST View Post
    It has its issues, but it also seems to be used.

    The good news is that if you set it up to work best at full power, or near that, then the imbalance is toward the lower current/power area where it is less important.

    Not all that different from working to select the best "balance capacitor" value, which is also a losing proposition overall, but does work kinda good enough to actually get used.
    How do you view the RPC design that uses a autotransformer and capacitance to supply the third leg. I would think that combo would give the overall best performance, but haven't tried one yet.

    SAF

  13. Likes Jim Kennedy liked this post
  14. #72
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Quote Originally Posted by SAF View Post
    How do you view the RPC design that uses a autotransformer and capacitance to supply the third leg. I would think that combo would give the overall best performance, but haven't tried one yet.

    SAF

    Is that an "RPC"?

    If so, I do not see much need for the capacitance.

    I would suggest an autoformer that boosts the generated leg to be perhaps 5% to 10% high at no load, which will probably still be reasonable compared to the pass-thru voltage with a heavy load.

    That, so long as the autoformer does not add too much impedance (don't skimp on the VA), would seem to be the best approach. Alternately, feeding the entire idler a boosted voltage separately from the pass-through is reasonably equivalent, but may be less flexible as to the voltage.

    The actual best approach may be an idler that is wound with a few more turns on the generated leg, to bring it up to the slightly high unloaded voltage. That is the least complicated, potentially the least added impedance, but requires either a re-wind, or a custom product. And it may be limited by available wire space in the stator iron.

    Since the idler is known to be low output as far as voltage, inherently, all the various techniques come down to different ways to get a good generated leg approximation to the correct voltage/phase at a chosen load point. The phase should be inherently pretty good, but "balance capacitors " can drag it off a bit.

    The capacitor methods all suffer from sensitivity to the load. The usual way to deal with that is to set the thing up for a near-full-load situation, where you need it most. That tends to risk a wildly high voltage at low or no-load conditions, which can force a less-than-ideal compromise The phase may also shift, and the best voltage may not have as good phase or load current.

    The goodness of a transformer approach (or motor turns approach) is that it only introduces voltage boost, with minimal other effects.

  15. Likes Jim Kennedy liked this post
  16. #73
    Join Date
    Jul 2014
    Location
    MI USA
    Posts
    951
    Post Thanks / Like
    Likes (Given)
    201
    Likes (Received)
    389

    Default RPC & Auto-transformer Boost.

    It is an RPC, with an addition such as this example. Has boost transformer and balance caps. Richardson model.

    rpc-autoformerboost.jpg

    rpc-autoformerboost-diagram208-24.jpg

    SAF Ω

  17. Likes Jim Kennedy liked this post
  18. #74
    Join Date
    Mar 2008
    Location
    Marulan N.S.W. Australia
    Posts
    187
    Post Thanks / Like
    Likes (Given)
    96
    Likes (Received)
    46

    Default

    Now after 72 posts we finally get to the good stuff.

    Jim

  19. #75
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Quote Originally Posted by SAF View Post
    It is an RPC, with an addition such as this example. Has boost transformer and balance caps. Richardson model.
    .........
    SAF Ω
    Yeah, that's the idea. The capacitors, are a maybe, to me, but they could be a bit of a help.

    I like the extra winding in the idler the best, but that's harder to do.

    You need the boost because the back EMF is inherently lower than line volts, and the back EMF is what makes the generated leg. So a boost transformer gives you the volts with the least dependency of voltage on load.

    It just makes sense.

    I'd seen the transformer in the "Transwave" converters before, but at that time I thought there was an idler also, and that they were doing the transformer boost. Actually, I believe they make all flavors, static, rotary, and inverter based, and the rotary ones may in fact have the boost feature.

  20. #76
    Join Date
    Nov 2004
    Location
    Webster Groves, MO
    Posts
    7,610
    Post Thanks / Like
    Likes (Given)
    1938
    Likes (Received)
    3632

    Default

    The problem with the Transwave is likely that it uses a potential relay that isn't getting a high enough voltage to hold it in. Another video of limited value by someone who has no idea what he is talking about but goes on and on about it. These clowns seem to be in love with their own voices, like the ones about how to wind your own springs by someone who doesn't even know they have to be stress relieved but thinks he is an authority.

    Bill

  21. #77
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,423
    Post Thanks / Like
    Likes (Given)
    2042
    Likes (Received)
    3217

    Default

    Eh, the only value in it was seeing what is, and what is not, in that device.

    The makers advised him to adjust what may be the potential relay to solve his problem.

  22. #78
    Join Date
    Mar 2008
    Location
    Marulan N.S.W. Australia
    Posts
    187
    Post Thanks / Like
    Likes (Given)
    96
    Likes (Received)
    46

    Default Richardson Induction Phase Converter

    This is a copy of the text of the scans SAF posted in post 73.
    It's from the book Rotating Electric Machinery and Transformer Technology by Donald V Richardson 1978.

    I am sorry I could not get the images to stay in portrait. Maybe admin can change them.

    Jim
    Attached Thumbnails Attached Thumbnails 1.jpg   2.jpg   3.jpg  

  23. #79
    Join Date
    Nov 2004
    Location
    Webster Groves, MO
    Posts
    7,610
    Post Thanks / Like
    Likes (Given)
    1938
    Likes (Received)
    3632

    Default

    I photo shopped the images and rotated them as well as tinkering with brightness and contrast. On my screen the letters appear chopped up but they print fine. In case anyone notices that picture 3 is now 5, it is because in the interaction between the computer I use on the net and the one with Photo Shop, something got corrupted and I could only get around it by changing the designation of the file. That's the modern age- worry about Corona virus and computer failure.

    1.jpg2.jpg5.jpg

    Bill

  24. #80
    Join Date
    Jul 2014
    Location
    MI USA
    Posts
    951
    Post Thanks / Like
    Likes (Given)
    201
    Likes (Received)
    389

    Default RPC, Induction Boosted 3rd Leg

    A link to a more readable PDF copy of the Richardson article.

    I have sourced a transformer to try this method, on a 480V prototype RPC I have, but haven't made time to try that feature out yet.

    SAF Ω


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •