Is an inverter duty electric motor suitable for a rotary phase converter?
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    Default Is an inverter duty electric motor suitable for a rotary phase converter?

    Im in need of 3 phase power. 7.5 hp leblond lathe wants back to life in my new home shop. I found a 15hp inverter duty marathon brand 3 phase motor for 150 dollars near me. Looks in good condition. My research on this topic is not very thorough as time is hard for me to come by. 3 kids, good job etc. Can anyone answer if this is a good starting point for an rpc? Also mention your experiences with ebay capacitor kits.

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    Google is your friend, at least regarding this issue. .

    inverter duty motor - Google Search

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    Motors are motors. If it works as a motor it works as an idler.

    I tend to prefer an older motor with more iron, but a newer "efficient" motor can have some advantages. But no need to pay more for it. Your price is not bad at all.

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    Quote Originally Posted by Goerger View Post
    Im in need of 3 phase power. 7.5 hp leblond lathe wants back to life in my new home shop. I found a 15hp inverter duty marathon brand 3 phase motor for 150 dollars near me. Looks in good condition. My research on this topic is not very thorough as time is hard for me to come by. 3 kids, good job etc. Can anyone answer if this is a good starting point for an rpc? Also mention your experiences with ebay capacitor kits.
    GREAT price .. if it is in decent condition electrically. Bearings are cheap and easy, scarred shaft, buggered keyway or splines, damaged face or foot mount are all "don't care" for an idler.

    I'd grab it, even though I already HAVE what I need!


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    Quote Originally Posted by Goerger View Post
    Im in need of 3 phase power. 7.5 hp leblond lathe wants back to life in my new home shop. I found a 15hp inverter duty marathon brand 3 phase motor for 150 dollars near me.
    The price of $10 per Hp is not much lower until you go get a scrap yard piece.

    The inverter duty class might come in useful if you ever use the motor with a VFD.

    I would rather get capacitors from Grainger than ebay...

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    Quote Originally Posted by rons View Post
    TI would rather get capacitors from Grainger than ebay...
    You and Ganymede? Cup-bearer to the Gods was a notorious anal-receptive.

    You'd have to know Grainger's pricing!


    Try the major online commercial HVAC suppliers instead, Florida and gulf coast. Techs doing rooftops full of serious HVAC gear use more caps than RPC DIY'ers do.

    Some DO list on eBay, but wot the hey - seriously competitive bizness, so they have websites, too.

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    $10 dollars per hp has been my target price on used three phase motors. If you don't have a lot of time to scrounge for something cheaper I would go for it.

    An as stated, you just may find a reason to repurpose it later.

    I hold no grudge against Grainger as they are very upfront about their prices and have needed to use them more than once BUT, I always look elsewhere first. Buy new start caps (unless you make this a pony start) but run caps are so long lived I have no problem using used from about any source.

    You didn't ask but you will probably need a motor starter for that RPC. I always bought used on Ebay with good results but the prices have gone almost retail in recent years. The Chinese have flooded the market with starters and contactors at incredibly low prices, much less than used name brands, but I have not used them and therefore can not attest to their quality.

    Bill

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    Quote Originally Posted by Bill Simmons View Post
    I hold no grudge against Grainger as they are very upfront about their prices and have needed to use them more than once BUT, I always look elsewhere first.
    Not bad prices IF.. one has a major account with its discounts - as several of my old NOVA area Day Job employers had. Two of those, I was "the guy" who hooked them up with Grainger more to reduce facility management outages and delays than shave costs. See also Zoro - their own online arm.

    On my own for years, now - I treat Grainger like the local paramedic Rescue Squad or a hospital emergency room.

    The brick-and-mortar local outlet usually got what you need when you need it, at once, or next-day, but it wasn't in the first-choice column on the menu, budget-wise!

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    I bought it. 9 wires inside. Nicely marked. Tested with multimeter. No ground faults. 5.. maybe .5 ohms or no line between every wire combination. I built a stand so its spindle points down so i can easily perform an easy repair to the fan shield. Now what? ?? Do i put a pulley or flywheel on it? Am i supposed to have it on its side or?? Start watching youtube? What gauge wire do i buy? Lol. Im supposed to be working on framing my addition but this is an important part of how im supposed to pay for the addition.

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    Quote Originally Posted by Goerger View Post
    I bought it. 9 wires inside. Nicely marked. Tested with multimeter. No ground faults. 5.. maybe .5 ohms or no line between every wire combination. I built a stand so its spindle points down so i can easily perform an easy repair to the fan shield. Now what? ?? Do i put a pulley or flywheel on it? Am i supposed to have it on its side or?? Start watching youtube? What gauge wire do i buy? Lol. Im supposed to be working on framing my addition but this is an important part of how im supposed to pay for the addition.
    Ermmm.. dunno.. I suspect all that has only been covered a few thousand times....
    just in this forum.

    I think you should paint it puce. With yellow polka-dots. And glitter.

    Then epoxy a feather to its shaft. Off-center, even.

    THAT may not have been covered yet? ISTR we already have a shark mouth?

    I could be wrong. I've been wrong before.....

    Start with the "stickies", top of this forum? They are there for a reason.

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    Quote Originally Posted by Goerger View Post
    Now what? ??
    Build a rpc from scratch and enjoy, or buy a cheap ChiComm panel and enjoy a little less.

    Quote Originally Posted by Goerger View Post
    Do i put a pulley or flywheel on it?
    No. Unless you are going to spin the 15Hp up with a smaller motor for initial starting.

    Quote Originally Posted by Goerger View Post
    Am i supposed to have it on its side or??
    On it's welded on skids.

    Quote Originally Posted by Goerger View Post
    Start watching youtube?
    Couldn't hurt. Beware of phony EE's that have bum advice.... (who am I thinking of )

    Quote Originally Posted by Goerger View Post
    What gauge wire do i buy?
    Depends of current requirements. Start with the motor nameplate parameters.

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    Quote Originally Posted by thermite View Post
    You and Ganymede? Cup-bearer to the Gods was a notorious anal-receptive.

    You'd have to know Grainger's pricing!


    Try the major online commercial HVAC suppliers instead, Florida and gulf coast. Techs doing rooftops full of serious HVAC gear use more caps than RPC DIY'ers do.

    Some DO list on eBay, but wot the hey - seriously competitive bizness, so they have websites, too.

    I bought all of my capacitors for two different RPC's on eBay and probably spent no more than $75 on the lot.

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    Quote Originally Posted by Newman109 View Post
    I bought all of my capacitors for two different RPC's on eBay and probably spent no more than $75 on the lot.
    For me.. eBay "identified a source". Sources with "regular businesses" behind them are many on eBay, Most list only a tiny fraction of what they have. Source had their own website.

    Through which website I was able to find US-Made, brand-new, not stale stock capacitors with a higher Voltage and ripple rating. Cheaply.

    And then? Time never seeming in surplus, rather than lay-out parts, drill holes, fasten, cut wire, crimp terminals, run wire, check and double check my work..etc.. none of that new ground....

    Figured if I had no plan to get into the bizness of making "many" RPC controllers, nor even TWO, then why make even ONE?

    ..just went and BOUGHT one of Jim Gorman's "Phase-Craft" well proven RPC controllers.

    There are others out there. I don't know if even any of them are "Chinese".

    They are simple enough they can even be made in California, prevent-everything regulations and all. Just add the usual "known to cause cancer in the State of California" sticker and carry-on.



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