Rotary Phase Converter Designs and Plans - Page 3
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  1. #41
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    "... put me in touch with the Fitch Williams design ..."

    Fitch is more-or-less permanently retired.

    His design lives on, on the web.

    And, of course, here, with his desciples.

  2. #42
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    This is the Fitch posting in the Metalworking drop box from 1998.
    http://www.metalworking.com/dropbox/...retired_files/
    Look for FRW files.
    M.

  3. #43
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  4. #44
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    I am new to the forum and have been reading the plans and the postings with great interest.
    I have two questions that come to mind from all the searching I have been doing:
    1) How can the phase converter manufacturers, on their site, even begin to claim that these home built converters don't work, or are unsafe? It makes me angry to see them using this type of fear mongering.
    2) The second question accounts for the reason I found this wonderful site. I acquired a very sophisticated Miller Dimension 400 amp welder at an auction, and I want to hook it up to an RPC. I am worried that I could possibly damage the unit and for that reason, I have not gone ahead with building a larger RPC. Is there any reason I should be so concerned about using a high end welder with an RPC? Even if I felt safe enough to start up the welder without using it, so that I could put a scope on the lines would be very informative.
    I do not have any need to run the welder at more than 225 amps and was planning to build a 10hp RPC.
    3) The third (second ) question is, what would be the matter with running 2 five hp idlers in parallel instead of running a 10 hp idler? I would like to find a 10, but I have the two 5's ready to go.

    Thanks for all the great information.
    Bob

  5. #45
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    No problem running multiple idlers.

    If you design your system right, you can use one 5 HP idler to start additional idlers, so only the first needs a starting circuit.

  6. #46
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    hello
    I'm new this forum and was interested in building a phase converter
    my question is I have a 5hp 220v lathe motor what size motor do I need to use to build the PH Converter and I will be on the look out for a Mill also so I want to build one large enough for both. any help would be greatly appreciated
    Thanks in advance Jeff

  7. #47
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    Some time ago I began to rethink topologies for RPCs using a potential relay.

    This was in part because some early efforts required modifications to the potential relay itself, in order to control a larger contactor, for RPCs which exceeded the 5 HP rating of the Steveco 90-66, or the 3 HP rating of the equivalent General Electric potential relay (PR).

    I soon discovered that modification of the PR was not required at all, provided the PR's coil terminals were interchanged without affecting its operation.

    Thereafter, I came up with two topologies, the first of which was for large RPCs.

    I drew this preliminary schematic for the general case of multiple paralleled capacitors, specifically for for the run caps, Cab and Ccb, and also for the start cap, Cs. For the power factor correcting cap, I did not parallel the caps on the schematic for lack of space, but it is understood that Cpf may indeed consist of multiple caps.

    (Bleeder resistors are not shown paralleling the caps, but are highly recommended as a safety measure for each cap which is not shunted by a motor winding).

    This schematic immediately suggested breaking the RPC into five distinct sections:

    1) Start Section,

    2) Sense Section,

    3) Run Section,

    4) Idler Section, and

    5) Power Factor Correction Section,

    and in the general case, all of these Sections may be present.

    However, in special cases, one or more Sections may be omitted without sacrificing functionality. It is, of course, up to the implementor to evaluate each change on a case by case basis.

    The 5 HP or less topology is a special case of the greater than 5 HP topology.

    Note that the PRs are shown as having two (2) terminals. This is not a misprint as a PR does indeed have two (2) terminals, which are connected externally.

    (It should be apparent that a small RPC may be very easily increased beyond 5 HP with the appropriate changes and additions, most particularly exchanging the terminals to the PR's coil).

    As is customary, the manufactured phase is shown as the B phase, while the single-phase line is shown as L1 (also the A phase) and L2 (also the C phase) and the RPC's three-phase output is taken from T1 (A), T2 (C) and T3 (B).

    Protective devices are not shown, and may range from a double-pole breaker in a panelboard for small RPCs to a magnetic motor starter for large RPCs.

    In many cases a three-phase fusible safety switch may be used for the RPC's controller, with the B phase being back-fed. The single-phase line would then be on the top of the safety switch (line side), and the three-phase loads would then be on the bottom of the switch (load side).

    (Backfeeding may also be employed with a motor starter, in some cases).

    In the following screen images, click on the image itself to obtain a page-sized version of the screen-sized image. You may then save the resulting image to your disk for later printout to 8-1/2"x11" paper.


    For > 5 HP ...




    For <= 5 HP ...




    Enjoy.

    Peter

  8. #48
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    I built this ugly 2HP converter about 6 years ago to run my 10" South Bend (3/4 HP):

    http://tinyurl.com/33ej64

    To explain the substandard appearance, everything you see was free surplus, except the two 30 uF caps. The idler motor came from a buddy who converted his Asian lathe to single phase. The 3-phase contactor with overloads came off a siezed 2HP vacuum pump. It runs off a 4-wire 240V 30A dryer circuit (I brought in the house neutral because I only had a 120V control coil for the starter).

    I lucked into a cool simplification. No start circuit, pony, delay or potential relay is needed. The two small 30 uF run caps across one generated leg (and NOT the other) are big enough to start the idler on their own, within about a quarter second. They also do a fair job balancing phases under load, which was a surprise. I have not fussed about power factor at this size, since I only run the converter with the tool. Phase balance under load is as good as the power company would provide.

    I suspect I couldn't get away with this cheat on a bigger idler, but the biggest thing in my future is probably a Bridgeport, so I think I'm done for now.

    Cheers,

    Mike

  9. #49
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    "... I lucked into a cool simplification. No start circuit ..."

    The self-starting RPC, first published in the "peer reviewed" literature by Habermann, and available in the archives of this site, dates back at least fifty years.

    But, way before Habermann published his results, a capacitorless RPC, of sorts, was being employed in electrified railways, where the catenary was 11 kV single-phase, and the traction motors were 600 V, three-phase.

  10. #50
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    Well.. I finally finished my dual motor RPC. It took me WAY too long.

    The smaller motor is a 7.5HP and the large motor is a 20HP for a combined rating of 27.5HP.

    After all of the final wiring was done, I ended up with 248.3-241.2-247.8 volts with 7.3A of current draw with both motors idling. It was actually possible to get all 3 voltages to within a few volts of each other, but I decided to run them a bit higher to give more overhead for the load. See my post HERE for info on what capacitance I ended up using.

    Most of the parts for this project were purchased at Hardware Specialties in Seattle or at Boeing Surplus. A friend let me raid some scrapped motor control panels for the indicator lights, push buttons and labels. The cabinet for the motor controller was some type of control cabinet. The On-Off switch and the muffin fan were already there so I decided to use them. The farthest left LARGE contactor is the main run contactor. The center contactor is the start contactor. It happened to come with the handy timer unit on the right of it so I used that instead of a potential relay. A little fine tuning and it works perfect. The contactor on the far right is the 20HP contactor. The motor control box is wired so that when the 20HP idler is switched on, additional capacitors are brought into the circuit to rebalance the power.

    You may be wondering how I insulated the wiring terminal strips. I used nylon spacers on the top and bottom and a nylon sleeve over the screw.

    Many pictures below with a link to the larger version under it.

    If requested, I'll take the time to draw up the schematics for it. There were a couple of pitfalls I ran into using the contactors, but I figured it out.

    General view of main breaker switch box and Motor control panel:

    Large Pic


    Inside breaker panel. The small 10A breaker was salvaged from a Takahashi Microstar I scrapped. It's for the 110V control circuits.

    Large Pic


    Inside motor control panel:

    Large Pic


    Close up of contactors and wiring:

    Large Pic


    Close up of capacitor bank. I bought 2 huge racks of capacitors for this project from Hardware Specialties. I have tons extra that will be hitting ebay unless someone else here wants them. They are all 600VAC rated except for the starting caps. Those are 220VAC rated. I figured they are used so little plus I'm under the 10% overvoltage threshold I was safe to use these.

    Large Pic


    Inside of front door:

    Large Pic


    Outside motor box. This thing is pretty cool. A friend gave it to me. Apparently it's original purpose was to transport camera equipment, etc. It's a waterproofd fiberglass box with an aluminum structure inside supported by 8 vibration/shock damping rubber mounts.

    Large Pic


    Inside of motor box: This thing was a total pain in the butt to get put together. I hope I NEVER have to disassemble it. Notice the stacked washers? I absolutely hated to do that but I didn't have a choice. I had no way to power my lathe to make up some spacers! If you look at the large pic you can see the rubber isolators.

    Large Pic

    More pics coming in next post

  11. #51
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    Here are the rest of the pics.


    General view of motor control panel with both idlers running. You can just barely make out the needles on the voltmeters in this pic:

    Large Pic


    Inside of 3 phase breaker panel. I mounted the panel about 10 feet farther down the wall. I just didn't have room for everything to be right next to each other.

    Large Pic


    Junction box for manual lathe plus "power on reminder" indicator. This is located just above the light switch for the garage:

    Large Pic

    I have more but you guys have probably seen enough. [img]smile.gif[/img]

    Let me know what you guys think.

    Thanks,
    Michael

  12. #52
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    I love the voltage readouts. That's a great idea I haven't seen before and it never occurred to me to do it either.

  13. #53
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    Thanks Jim.

    Unfortunately I can't claim credit for the idea.

    I got the idea from a post by mjk. Look on the first page of this thread. 3rd post from the bottom.

    Michael

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    Michael,
    I'm interested in your extra caps.
    PM me with your price and size of caps.
    Thanks,
    Mick

  15. #55
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    Default

    Peter-

    Quote Originally Posted by peterh5322 View Post
    "
    The self-starting RPC, first published in the "peer reviewed" literature by Habermann, and available in the archives of this site, dates back at least fifty years."
    Very interested to read this ref, internal PM search and Google apparently could not find it- do you have a pointer to share? Related bibliographies show a 1954 Habermann paper in AIEE Transactions, is that the one?

    Alas, I did all this playing around ~8-9 years ago, and this great online support community wasn't known to me then (if indeed it existed). Just discovered this thread recently and figured "better late than never."

    Thanks for your help,

    Mike

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  17. #56
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    "Related bibliographies show a 1954 Habermann paper in AIEE Transactions, is that the one?"

    The very one!

    NEMA codified most motors beginning in 1952, or there-abouts, and pre-NEMA motors, which is what I believe Habermann worked with, early NEMA motors, late NEMA motors, and post-1999 "high efficiency" motors, each have separate rules-of-thumb. Which is why Habermann's recommendations differ considerably from the much later recommendations of Richardson, and the still later recommendations of Hanrahan.

    All can be employed as "bare" RPCs, as self-starting RPCs, or as fully compensated Fitch-type RPCs, although the capacitance required to achieve the best performance will vary significantly.

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    Default Moteur Pilote

    Bonjour A Tous Nouveau Venu Sur Le Forum
    Je Suis Interresser Par Le Moteur Pilote Mais J'ai Peur De N'avoir Pas Tout Saisi Car Je Ne Parle Pas Anglais.
    Ce Montage Me Permettre De Faire Fonctionner Un Vieux Tour A Metaux Ernault Tri
    Si Quelqu'un Parle Francais Je Suis Preneur
    Merci D'avance

  19. #58
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    Please refer to ...

    http://www.practicalmachinist.com/vb...9&postcount=47

    It's "en Englaise", but the schematics are self-describing.

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    Default

    Think You But In French Please Please Please

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    Smile

    Sorry To Run A 2hp Please
    Think's A Lot


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