Which type of 3 phase converter should I implement?
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    Default Which type of 3 phase converter should I implement?

    Hello,

    I've been reading a lot of posts on google and some on here about various types of 3 phase converters (e.g. vfd, rotary, etc). I had big plans a couple years back and obtained a 50 HP GE 3 phase motor. A couple years went by, my plans have changed and I need to sell that and switch to something smaller unless someone convinces me to wire it up. It seems like a 50 HP converter (GE model 5ks326ks1035d20)would be a waste of energy now that I only plan to so a couple of small things now and then.

    Ok. I have a 5.5hp Brook Hansen 3 phase motor (model w-da112mm-d) on a wet abrasive blasting cabinet I need to wire up. I don't forecast too many future 3 phase motors in my workshop, maybe a nice milling machine someday and a nice welder. At the monent, I am only concerned about wiring up this one motor.

    Here are the specs on its plate:

    brook hansen
    frame w-da112mm-d
    sf 1.15
    hp 5.5
    v 230/460
    a 12.4/6.2
    rpm 3470
    hz 60
    type TEFC
    phase 3
    diag b
    ip 55
    ic 411
    rating cont
    ins cls f
    amb 40 c
    rise k
    load rating 100%
    nom effic 87.5


    After a lot of reading my opinion right now is to go find a 10-15hp idle motor for a 3 phase rotary conversion. I'm very open to input or suggestions on this and it is why I am posting. Would anyone suggest something differently such as a VFD or a different sized motor?

    Also, I've seen a couple of good youtube videos where they are reading through a document to identify what size caps to put between which phases as they design their converter electric boxes. Are there links like that in here to PDF's or any web sites anyone recommends that I read and understand to do the same?

    Last question for now, any recommended websites for components of the electrical box stuff, caps, etc, or should I just look for the best prices and get them for what I believe would be quality parts?

    20200514_150348.jpg

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    Another thought on this wet blaster might be to just locate a single phase 5.5 hp motor that's similar and mount it but I noticed the spindle in my case is about a foot long for "mixing". I may take it apart and see if its just some shaft extension or something i could put on another single phase motor and compare price options.

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    Quote Originally Posted by homer14 View Post
    Another thought on this wet blaster might be to just locate a single phase 5.5 hp motor that's similar and mount it but I noticed the spindle in my case is about a foot long for "mixing". I may take it apart and see if its just some shaft extension or something i could put on another single phase motor and compare price options.
    Blast cabinet doesn't need reversing, single-phase should do for it.

    CAVEAT: Single-phase motors don't do as well as 3-Phase in the last 10%, or even last quartile of their load-range.

    I might even seek a 7.5 HP for the conversion if you run long and hard. It would be only trivially harder as a starting load, but run cooler, last longer, and not draw any more power than the load device demands out of it, anyway.

    An RPC is still handy. Even if a 5 HP idler will "do" a ten HP will start more loads more easily and doesn't cost a great deal more, especially if DIY'ing with used or NOS idler motor.

    Max RPC that doesn't over-stress the average residential / smallholder utility mains is closer to TEN HP than 20 HP in any case.

    Ten HP yah can cap-start off most any store-bought or DIY controller. Twenty HP yah should be looking at "pony start".

    Typical 200A mains? You'd probably not even be able to start a 50 HP RPC idler AT ALL!



    Better to peddle that to someone with a dire need who has 400A service. Even then he'll probably need to rig a way to soft-start or pony-start it.

    More than a few "commercial" RPC makers start splitting their idlers, stagger-starting, then "ganging" their RPC once up to speed in the higher HP ranges.

    Guy who MEEDS a 50 HP is generally better-off with three 20 HP, for example.

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    hi thermite:

    yes 200 amp single phase panel.

    thanks. ok I'll hunt a 7.5hp idler. the idler rpm's mean nothing right?

    yes, i plan on selling the 50hp to someone with an industrial shop need.

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    Quote Originally Posted by homer14 View Post
    hi thermite:

    yes 200 amp single phase panel.

    thanks. ok I'll hunt a 7.5hp idler. the idler rpm's mean nothing right?
    7.5 single-phase would DIRECTLY replace your 5.5 HP 3-Phase motor and live long.

    As an idler for it? It may or may not "easily" start a 5.5 HP load. "Probably", though.

    Two pole, nominal 3600 RPM, are cheapest. Four pole, nominal 1800 RPM, are less annoying as to audible noise, prolly the most common.

    Six and 8 pole are quieter yet, will work OK, but are not as common when yer searching for a bargain.

    On which count PAY ATTENTION to the VOLTAGE! Some bargains are 500 Volters or above and NOT strappable for less!

    Six and eight pole are also getting into "diminishing returns", efficiency-wise, so are not as often utilized for idlers.

    "In theory" it doesn't matter, and yah can even mix and match when going for one or more "supplementary" idlers.

    All three idlers in my "selectable" rig are 4-pole, though.

    10 HP & 7.5 HP, "dedicated" arredy, the 5 HP one still "borrowed" out of a machine-tool (wire is neat s**t, ain't it?)... whilst I get a "permanent" 5 HP I like bought and delivered.

    I have 3-P loads from down around 1 HP clear up to 8 HP or so and hard-starting, but can pick and chose any given tasking period, so "works for me".

    CAVEAT #2: Even at same-same line Hz, and even IF yah THINK yah have the same "slip" and RPM?

    An(y) array with more than one idler WILL also produce a hetrodyne or "beat" acoustic sound at two, minimum, detectable Hz and a few more yah might not notice.

    That can be annoying. Low Hz "subsonic", are wired into human psyche as warnings - can be debilitating - lead to loss of productivity, depression, and worse. Meant for earthquake detection, mayhap? I wasn't on the design team.

    In general, RPC's should live somewhere other than right in the shop. "Doghouse" or out under the carport.

    I did say Copper wire was kinda neat stuff?


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    oh my bad, were you suggesting I dont do a phase converter? i may have misread your 1st reply where I thought you were mentioning a 7.5 hp 3 phase would be a good choice for an idler.

    my problem is i either need to convert the three phase 5.5 hp (with some 1ft long spindle) to a 5.5 hp single phase that will work the same mechanically with the weird mixer attachments and mount it on. ive googled a bunch on the model in my photo and dont quite understand the frame comparisons to see if i could just swap it with a single phase 5.5 hp yet.

    or

    build a phase converter and have some room for future small 3 phase toys. if i went this route i'll probably put it on wheels i was thinking.

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    Quote Originally Posted by homer14 View Post
    oh my bad, were you suggesting I dont do a phase converter? i may have misread your 1st reply where I thought you were mentioning a 7.5 hp 3 phase would be a good choice for an idler.

    my problem is i either need to convert the three phase 5.5 hp (with some 1ft long spindle) to a 5.5 hp single phase that will work the same mechanically with the weird mixer attachments and mount it on. ive googled a bunch on the model in my photo and dont quite understand the frame comparisons to see if i could just swap it with a single phase 5.5 hp yet.

    or

    build a phase converter and have some room for future small 3 phase toys. if i went this route i'll probably put it on wheels i was thinking.
    Long shaft is a pain in the ass. Re-engineering anything that ain't broke is usually a waste of scarce time.

    Just build the RPC.

    I'd do (and DID do..) a 10 HP idler "first". Your case, that should be the end of it, and just go do other stuff.


    Not big or heavy enough to justify a pallet-jack.

    If ya make it mobile, simplest is to set it up for easy access and use of an ignorant hand-truck or reefer-dolly. Or even build it ONTO one, cheap as they can be. Hubbell twist lock or several, and movement gets easier. Have a look at the "kit" most Big Box stock for gen sets & SO cord.

    Otherwise, use solid-iron casters, not insulated elastomeric wheels.
    Add a PAIR of short drag chains so the rig is at least half-assed frame-grounded at all times. Make sure it has a "proper" PE (Protective Earth) AKA frame ground as well, of course.

    You HAVE NO usable "Neutral". RPC are inherently Delta-out AND phase offset from the spit-phase mains as feed em.

    I don't like high-leg or corner-grounded delta, so...

    My rig feeds a 27 KVA Delta-in, Wye-out EGS Hevi-Duty "drive isolation" transformer, then an overly large ('coz it was cheaper than small ones) Square-D 3-Phase load center with 3-Pole common-trip breakers for the loads.

    "Wye" last-leg service gave me back a "local Neutral" in addition to PE, so no single leg is more than about 135 VAC above Earth.

    Overkill?

    Dambetcha!

    Rare, even. Most folk just do the corner-grounding.

    But I didn't reach 76th year by accident.
    Avoidance-of, rather!

    Which needs more in the way of HELP and crutches as yah age and become more accident-prone than the youngsters. So yah cheat and "stack the deck" in yer own favour.


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    I would agree with thermite to build an RPC and be done with it.

    As far as starting the 5.5, is the motor unloaded or does it start driving something like a pump. An unloaded 5.5 should have no problem starting from a 7.5 idler, a loaded one might.

    Tom

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    tom and thermite:

    i can score a 7.5 3ph baldor for $100 if i act fast. i "think" that's a good deal?

    i havent turned on the 5.5 yet but i believe it will instantly start stirring a slurry of abrasive and water for my wet blaster so i guess "loaded" lightly?

    ive seen videos of people using a start cap that switches off as soon as an emf return occurs on the 3rd leg, would that start the 5.5 if loaded?

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    Quote Originally Posted by homer14 View Post
    tom and thermite:

    i can score a 7.5 3ph baldor for $100 if i act fast. i "think" that's a good deal?
    Only if it was made fifty years ago. There are better motors than modern economized "pretty on the outside, ugly on the inside" Baldors.

    MOST of them, actually.

    Loaded slurry stirrer might be just enough to cause starting pain. 10 HP idler should cost about the same as a 7.5 HP. Closer to $300-$400 than $100 if yah want a new or nearly new one. Freight cost matters.

    If you buy old, used? Test it first.

    No obvious stink, soot, nor other show-stoppers? THEN open it up. Blast the rocks and dog-hair out of it, replace the bearings (they are cheap).

    For the roughly $200 - $250 saved? I could not be bothered with the mess or work, either one.

    I just kept looking until I could find NEW or "NOS".

    ...seen videos of people using a start cap that switches off as soon as an emf return occurs on the 3rd leg, would that start the 5.5 if loaded?
    Don't waste yer time looking for free "magic" nor re-inventing the wheel.
    RPC have all been "done to death", right here, on PM. And not-only.

    Either purchase a decent store-bought starter/controller, (mine is one of Jim's "Phase-Craft" bought before he retired).

    Or build the Fitch Williams one off the .pdf he left us on PM.

    It JFW. At 10 HP? Nothing to even change. He used that size as the basis for "scaling".

    Digi-key, Mouser, Newark have the parts. Zoro and others have nice "Weigmann" boxes.

    I order the "NK" (No Knockout) ones and make my own "few" hole(s). Bigger and deeper the better. Cleaner and easier that way.

    No need to make a new project of it. Just go and copy what has been done so many times already.

    "Right here, on PM".


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    the 7.5 for $100 appears to be an older one but who knows...

    baldor M3311T discontinued... pic attached. should i still go for a 10hp instead?

    baldor75.jpg

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    Quote Originally Posted by homer14 View Post
    the 7.5 for $100 appears to be an older one but who knows...

    baldor M3311T discontinued... pic attached. should i still go for a 10hp instead?

    baldor75.jpg
    $100 - cheaper than used Chinese - and you don't smell at least a HINT of trouble?

    What part of "you can do better" did you miss?

    My idea of a decent 7.5 HP, not an example - THIS very one is "here, now":

    https://www.ebay.com/itm/NEW-RELIANC...72.m2749.l2648

    US $450.63 with shipping. Then still a "go fetch" to the terminal, so a bit over $530, end of the day.

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    hah.

    what do you think of the US motors brand?

    usmotors.jpg

    any tips on testing these with a multi-meter in regard to windings? i see stuff on google but might as well ask the experts. i want to be confident with my own testing not being able to see one run when purchasing im expecting.

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    Quote Originally Posted by homer14 View Post
    hah.

    what do you think of the US motors brand?

    usmotors.jpg
    They actually work. So do A.O. Smith/Century. And Dayton. Not my favorites.

    "We sting houses" went onto US Federal procurement tenders in the 1950's with:

    "bidder may specify any leading make of motor except Westinghouse", and I knew WHY, so those never agan darkened my door - nor ever will.

    GE are OK. So, too Marathon, Leeson, Lincoln. My 10 HP is a Weg ODP.
    Budget was tighter then. It was lower-cost with free delivery than Chinese ones with free delivery, same distributor. Mind - the Chinese ones were fifty percent heavier as to the housing, just not as well-built on the inside as Weg.

    The 10 HP Weg weighs about 40% of what the 7.5 HP Reliance does and was $150 cheaper, brand new, not "NOS", delivered to my kerb than the Reliance!

    Michigan is "rust belt". Parts of it were once paved with old motors from failed factories.

    Give yer air-head Governator another month practicing at channeling Benito Mussolini, 1922, instead of Margherita Grassini, 1945, ("My Fault") it soon will be again.


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    the stay at home orders here are why im actually getting shit done!

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    Quote Originally Posted by thermite View Post
    They actually work. So do A.O. Smith/Century. And Dayton. Not my favorites.

    "We sting houses" went onto US Federal procurement tenders in the 1950's with:

    "bidder may specify any leading make of motor except Westinghouse", and I knew WHY, so those never agan darkened my door - nor ever will.

    GE are OK. So, too Marathon, Leeson, Lincoln. My 10 HP is a Weg ODP.
    Budget was tighter then. It was lower-cost with free delivery than Chinese ones with free delivery, same distributor. Mind - the Chinese ones were fifty percent heavier as to the housing, just not as well-built on the inside as Weg.

    The 10 HP Weg weighs about 40% of what the 7.5 HP Reliance does and was $150 cheaper, brand new, not "NOS", delivered to my kerb than the Reliance!

    Michigan is "rust belt". Parts of it were once paved with old motors from failed factories. Give yer air-head Governator another month practicing at channeling Benito Mussolini, 1922, instead of Margherita Grassini, it soon will be again.

    Why not Westinghouse?

    Tom

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    Quote Originally Posted by TDegenhart View Post
    Why not Westinghouse?

    Tom
    The massive price fixing scandal. Turbines & major motors & such. The 1950's is when the spotlight was put onto it. It played out in the courts for another ten years:

    The Great Electrical Equipment Conspiracy – Reason.com

    Basically, everyone else rolled-over, paid fines.

    Westinghouse was so arrogant they thought their lawyers could win, fought it, lost the most, got hammered the hardest for their sins. Brands ended up under Asian ownership.

    But the arseholes had actually started fixing prices during and right after World War ONE, not War TWO or Korean War!

    Check Reliance history, they saw it coming, dodged TF out of "commodity" motor making GE and Circle-W were tidily divvying-up, and went off to do only "the hard stuff", premium, and custom solutions "too much like work" for GE/Westinghouse, and too HARD for players with fewer top-skilled Engineers.

    Reliance didn't have "salesmen" back in the day. They put a Degreed Engineer on the train, fixed yer problem, made yet-another "niche solution" motor off the back of what was learnt until the time came their "stock items" fixed MOST problems.

    As did Ward-Leonard. All W-L do, present-day, is severe-duty high-power for oil drilling platforms and submarine electric motors.

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    thanks for all the input today! including the history of price fixing.

    im going to hunt a 10hp motor for a bit and then ill check back in and locate the specs suggested on the components and design of the 3 phase converter complete system. i think i found a 10 hp motor but cant check it out for several days.

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    Quote Originally Posted by homer14 View Post
    thanks for all the input today! including the history of price fixing.

    im going to hunt a 10hp motor for a bit and then ill check back in and locate the specs suggested on the components and design of the 3 phase converter complete system. i think i found a 10 hp motor but cant check it out for several days.
    There's a "livable" shipping cost on this one - claims "New, No Box":

    10 hp electric motor 3 phase 215T Frame Motor | eBay

    It's an auction, but with a "make offer" as if it was a BIN???

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    ill keep my eye on it. a weg eh? sensing a pattern here...

    weird it has an alternate 7.5 hp marking?

    -----

    saw this GE 10 hp not too far away for about $120 too...

    ge.jpg


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