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  1. #31
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by .RC. View Post
    Yes it is a 4KW version. I hooked it up to the 10EE and runs the MG fine off a 10amp power point .

    The unit indicates at idle the MG draws 1.8A, which I suspect is per phase on the three phase side. Running the lathe no load at 2500rpm it goes up to 6amps.

    These units if reliable and long lasting are bits of game changers for your older machinery with just a single motor to run everything.
    ,

    VFDs usually show per phase current so x sqrt(3) to get total current.
    That means 6A per phase = 10.49A total
    But are those currents @240V or 415V?
    If its at 415V you are going to be well over the 10A/240V limit.

  2. #32
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    I just put a clamp meter on mine.
    240v input was 3.9A, the VFD was showing 2.7A

    I tried putting the meter on the motor side, but it was showing 10A - obviously not right. Itís only a cheap meter so Iím picking itís struggling with the VFD output waveform. I had the same issue originally when I tried to measure the voltage with the same meter and had to resort to my analogue meter.

    Steve

  3. #33
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by OxxAndBert View Post
    I just put a clamp meter on mine.
    240v input was 3.9A, the VFD was showing 2.7A
    To compare those two you need to multiply the 2.7 by SQRT 3 so then it comes to 4.7A?
    Unless those VFD display amps are @415V

    I tried putting the meter on the motor side, but it was showing 10A - obviously not right. Itís only a cheap meter so Iím picking itís struggling with the VFD output waveform. I had the same issue originally when I tried to measure the voltage with the same meter and had to resort to my analogue meter.
    Steve
    Yeah could be the meter but maybe not the wave form - more likely from the VFD noise.

    I did a bunch of simultaneous current measurements on a VFD powered compressor motor during compressor recharge cycles between 10 and 16A.
    I compared the VFD input and output currents using Fluke current clamps and they all agreed within 10% (most within 2%) but few of these measurements came close to the VFD display.
    The VFD display currents were usually a lot less than the inout and output currents.

  4. #34
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    Quote Originally Posted by .RC. View Post

    I wonder if the big capacitors are the main components in the increased voltage.
    I presume these drives have a voltage doubling circuit as the input rectifier. This does place heavy stress on the filter capacitors, requiring more to share the load.

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