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  • gellfex
    replied
    Originally posted by cuemaker
    Well, I asked the seller if it would run my motor and gave them the specs, they said no....

    So much for that... Seems that the correct VFD will run me more than a new motor...

    I see that I can get a Phase-Matic static converter for about $150 and lose 1/3hp (more than fine for my needs). Do I assume correctly that the problem is starting the motor under load will be the issue?
    Hang in there and wait for your deal. I've done well on ebay vfd's, you just need to learn the ropes, download the manuals and figure out the specs. I'm thrilled to have basically retired my dynamic converter and love my vfd's. But I suppose it depends on what you're running with it, a variable speed compressor or table saw isn't that much more useful.
    Last edited by gellfex; 10-27-2008, 09:34 PM.

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  • cuemaker
    replied
    Well, I asked the seller if it would run my motor and gave them the specs, they said no....

    So much for that... Seems that the correct VFD will run me more than a new motor...

    I see that I can get a Phase-Matic static converter for about $150 and lose 1/3hp (more than fine for my needs). Do I assume correctly that the problem is starting the motor under load will be the issue?

    Leave a comment:


  • Forrest Addy
    replied
    No, you can't calculate HP directly from namplate Volts and Amps using the 746 Watt per HP conversion for AC induction motors. You also have to account for power factor, losses, service factor, etc. Plus you have to convert three phase data to sinlge phase for the watt conversion where applicable.

    The best way to estimate HP from partial nameplate data is to consult motor manufacturer catalogs for comparable motors. Anything else is guesswork.

    Another tripping point is VFD's are all foreign made for marketing in the US. They were designed for metric motors which use mechanical KW in lieu of HP. They are marketed in the US using next lowest nominal HP data for simplicity in selection. Quite often there is no convenient equivalent so the VFD is de-rated a trifle to suit the nearest merchant size US motor.

    When selecting a VFD for use from single phase neglect HP as a rating. Instead, consider the VFD's name plate volts and Amps ratings and compare them with those of the motor. Quite often a three phase rated VFD of 10 HP nominal rating VFD (for example) will serve very well if applied to a 10 HP motor. It may have been rated for a 10 KW metric motor and it's nameplate Volts and Amps will thus support a 10 HP motor to full ratings (possibly) without de-rating the VFD to the next size smaller motor. Your milage may vary; be sure to assess the VFD and the motor ratings individually and collectively before committing to a selection.
    Last edited by Forrest Addy; 10-27-2008, 01:17 PM.

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  • gellfex
    replied
    Originally posted by derekm
    The ebay listing is for a 1.4amp output VFD which is one member of a range of products that goes upto 5hp
    If that's the case then it's for a fractional, like 1/3 hp. (1.4A x 220v)/746=.41 hp

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  • derekm
    replied
    Originally posted by cuemaker
    Will this VFD run a 5 horse 3 phase motor?
    http://cgi.ebay.com/VARIABLE-FREQUENCY-DRIVE-FUJI-VFD-FVRC11-FVR-C11-1-4AMP_W0QQitemZ380068004541QQcmdZViewItem?hash=item 380068004541&_trksid=p3286.c0.m14&_trkparms=72:570 |66:2|65:12|39:1|240:1318
    The ebay listing is for a 1.4amp output VFD which is one member of a range of products that goes upto 5hp

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  • gellfex
    replied
    Originally posted by millwrong
    NO, THAT WILL NOT RUN A FIVE HP. MOTOR! You size the vfd by the motor volt/ amp nameplate ratings, at the minimum!
    So, rather than just saying NO, why don't you actually explain how you come to that conclusion, and how the OP should look for a properly sized VFD. I have 3 VFD's, and my understanding was that rating by watts was the way to go, which is what you're saying also, since Watts =Amps x Volts!

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  • cuemaker
    replied
    Here is a copy of the motor plate info...if that helps

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  • barts
    replied
    I'm using an AC-Tech SF250Y from wolfautomation.com. Works very well...

    http://www.wolfautomation.com/Config...805&x=107&y=22

    - Bart

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  • millwrong
    replied
    NO, THAT WILL NOT RUN A FIVE HP. MOTOR! You size the vfd by the motor volt/ amp nameplate ratings, at the minimum!

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  • gellfex
    replied
    Google found this using search terms: vfd horsepower watt converter

    Horsepower nameplate ratings are easily changed to watts by multiplying Hp by 746 or 0.746 to kilowatts.
    For example 5 Hp=5X746 = 3730watts.
    Kw= 3730/1000=3.73.


    So, according to the auction info,

    # Product range
    3-phase 200V : 0.1 to 3.7kW
    Single-phase 200V : 0.1 to 2.2kW

    Yes, it will run a 5hp on 3 phase input, but not single phase.

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  • cuemaker
    replied
    Hmmm,

    Here is the id number, dont think link worked
    380068004541

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  • cuemaker
    started a topic VFD Questions

    VFD Questions

    Will this VFD run a 5 horse 3 phase motor?
    http://cgi.ebay.com/VARIABLE-FREQUENCY-DRIVE-FUJI-VFD-FVRC11-FVR-C11-1-4AMP_W0QQitemZ380068004541QQcmdZViewItem?hash=item 380068004541&_trksid=p3286.c0.m14&_trkparms=72:570 |66:2|65:12|39:1|240:1318
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