Converting 110 volt to 220 v (single phase) with transformer .... ok idea ?
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    Question Converting 110 volt to 220 v (single phase) with transformer .... ok idea ?

    This for a tiny motor that doesn't actually need 220 volt input but just happens to be wired that way. A transformer in the 3000 VA range like this -

    3000W WATT Voltage Converter Transformer 220V to 110V 110V to 220V Step Up/ Down | eBay

    Mostly curious if the output from a transformer like this would be just as clean as running the motor from 220v directly ?

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    Seems rather low cost for what it is rated at, but the principle is sound.

    Done it many times myself.

    If that "box" is rated accurately, the only problem you would expect to have is if the surge from powering up the transformer pops the breaker. That can happen, I have had trouble with variacs doing that.

    I'm a bit skeptical about the rating, given the weight, however.

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    I have a very similar one running a little water cooler thing for my chemistry projects. They work fine. I trust them to maybe 70% of their rated load continuous. I feel like 3kva is more a peak rating for that.

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    Should be fine if the conversion method is just a transformer. The output should be as clean as the input.

    In my job I used step up and step down transformers often to test products. Never once saw anything alarming although we always used quality products and that ebay item seems very cheap so I would wonder how good the quality of the core and windings are. If it were me I would simply buy a 120v primary, 240v secondary transformer and wire it myself. For single phase you are only dealing with 4 wires.

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    Quote Originally Posted by JST View Post
    Seems rather low cost for what it is rated at, but the principle is sound.

    Done it many times myself.

    If that "box" is rated accurately, the only problem you would expect to have is if the surge from powering up the transformer pops the breaker. That can happen, I have had trouble with variacs doing that.

    I'm a bit skeptical about the rating, given the weight, however.
    The issue of breaker tripping on inrush is common due to core materials (such as grain-oriented silicon steel) that have significant magnetic hysteresis. If power is reapplied at nearly the same phase angle at which it was interrupted you can get huge inrush. The cure is usually specifying more input turns.

    I suspect that probably China made unit might be of minimal construction.

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    Quote Originally Posted by Scottl View Post
    I suspect that probably China made unit might be of minimal construction.
    Got any sources of these made in USA, Europe or Japan ?

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    Quote Originally Posted by Milacron View Post
    Got any sources of these made in USA, Europe or Japan ?
    Looking now. So far I haven't found reasonably priced 3000 va units for indoor use.

    Update: Sorry, but I'm striking out here. Can't seem to find much with 120v in/240v out in that power range. Search engines lately seem almost useless. Even Boolean searches are being overridden by false hits from advertisers.

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    In a pinch, you can run one of those travel-transformers backwards. They are 220v-110v but will operate in reverse. At least every one I ever tried ...

    Quote Originally Posted by Scottl View Post
    Even Boolean searches are being overridden by false hits from advertisers.
    Absolutely. The web seems to have eaten itself.

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    IIRC reputable transformer manufacturers often make transformers that size, especially if they also make buck boost transformers.

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    I've had a few of those cheapies, seem ok, 1 had an audible and irritating hum but still worked. I used them for running kitchen gadgets and stuff when I moved over here. They've made their way to the trash as I replaced them with European made good ones from flea markets. If it's for non-critical occasional use should be fine, otherwise source a real one.

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    Is 3kVA really needed? It was described as a "tiny motor", which I suppose, is relative.... Dunno what is considered tiny in this thread.

    There are beaucoup "4-way" transformers made, you could even start at Digikey..... Often those are available down to around 500VA, if the motor really is "tiny".

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    Quote Originally Posted by Milacron View Post
    Got any sources of these made in USA, Europe or Japan ?
    White-bread commodity goods, Boss. 120 <=> 240 more than most.

    Acme

    Jefferson Electric

    Temco.

    Hammond

    Schneider / Square-D (and not only)

    Emerson / SOLA

    EGS / Hevi-Duty


    Even R.E. Uptegraff Manufacturing Company, Scottsdale, Pennsyltucky ..
    .. if you need the transformer-equivalent of a Bugatti Royale or a Nimitz class carrier engineered for a specific purpose.



    North America or Europe ONLY? Some are. See also Canada & Mexico.

    Sheer MASS vs value of a transformer makes even cheap sea-freight and the delay-en-route hit vs annual "turns" of mostly-materials goods enough of a drag that local makers CAN still compete on "just in time" economics.

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    Bear in mind that the transformer only changes the voltage. If your motor is intended for 60Hz and you're running it in a 60Hz location, sweet. If the motor is European, you may need to do some further investigation.

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    Quote Originally Posted by SomeoneSomewhere View Post
    Bear in mind that the transformer only changes the voltage. If your motor is intended for 60Hz and you're running it in a 60Hz location, sweet. If the motor is European, you may need to do some further investigation.
    50 Hz?

    "Nameplate" might fib, but motor won't much care. "Many" are actually optimized for 55 Hz to keep global logistics cheap.

    Couldn't sell a VFD with more than 5 Hz range either way of mains freq. if motors were THAT picky!


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    Whoops...

    Most I see fairly explicitly call it out or give different voltage ratings for the different frequencies.

    Universal tends to be happy.

    VFDs alter the voltage and frequency (AKA 'VVVF drive') - if you try feeding a motor with 30Hz 480V it's not going to be happy.

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    Quote Originally Posted by SomeoneSomewhere View Post
    Whoops...

    Most I see fairly explicitly call it out or give different voltage ratings for the different frequencies.

    Universal tends to be happy.

    VFDs alter the voltage and frequency (AKA 'VVVF drive') - if you try feeding a motor with 30Hz 480V it's not going to be happy.
    LOL

    What? Are you smoking?

    An ignorant 2:1 || 1:2 is as common as housefly-poop, North of the equator..

    So if we are to throw irrelevant s**t into this game, could you export some NZ SHEEP s**t, just so it is less boring?

    Oh.. and I need a new one of those neat Kiwi folding leather "rain hats" you can stash so easily. Too DAMNED easily! That's why I cannot FIND my one!

    Hopfully Don got his transformer "a while ago".

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    Ah, I meant the motor expected 60Hz or 50hz specifically. Not the transformer. I agree that transformers generally don't care.

    I just mean that a VFD doesn't just throw a different frequency at the same voltage; it varies both voltage and speed together. So saying "well, a VFD can make the motor run at 30Hz just fine, so running a 60Hz 230V motor at 50Hz 230V must be fine" is a bit of a false equivalence.

    When a VFD is programmed for a 230V 60Hz motor, and told to drive it at 30Hz, it will reduce the voltage proportionately down to 115V; hence the term 'V/Hz' - the ratio of voltage to frequency remains constant. Special modes like low-end torque boost, parabolic V/Hz, and vector modes are different but you will still see less voltage at lower speed. I'm pretty sure you already know that, though.

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    Transformers have the same V/Hz requirement as motors.

    Yes, you can fudge the numbers or reverse engineer it for different conditions than it was designed for.

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    Pricing seems out of line. Claims to be made in USA and rated at 2500W

    2500 Tru-Watts™ Step Up Transformer Converter - Use 220 Volts applianc – ACUPWR

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    Quote Originally Posted by SomeoneSomewhere View Post
    Ah, I meant the motor expected 60Hz or 50hz specifically. Not the transformer. I agree that transformers generally don't care.

    I just mean that a VFD doesn't just throw a different frequency at the same voltage; it varies both voltage and speed together. So saying "well, a VFD can make the motor run at 30Hz just fine, so running a 60Hz 230V motor at 50Hz 230V must be fine" is a bit of a false equivalence.

    When a VFD is programmed for a 230V 60Hz motor, and told to drive it at 30Hz, it will reduce the voltage proportionately down to 115V; hence the term 'V/Hz' - the ratio of voltage to frequency remains constant. Special modes like low-end torque boost, parabolic V/Hz, and vector modes are different but you will still see less voltage at lower speed. I'm pretty sure you already know that, though.
    This is easily taken care of for 50 Hz motors by the parameters that specify the motor Hz and motor voltage. Whatever you put in those will be the base from which the V/Hz operates.

    You DO need to have the available current from the VFD to drive the motor at the Hz and Volts, of course.


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