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Thread: Single Phase current draw for a 3 phase output VFD: technical discussion

  1. #141
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    Quote Originally Posted by GoldDigger View Post
    Labels R as in Red, B as in Blue and G as in Green.
    No reference to "ground" except perhaps implied in the fact that the three AC lines are the voltages with respect to some common fixed point.

    And when the voltages plotted are line to line voltages, even that implicit reference is gone.
    Exactly that. With respect to each other. Line to line as you say. No common ground, fixed point, neutral, or reference required, inferred or implied.
    It would have been red, yellow (not green) and blue but yellow didn't show up too well so I picked another colour. Just so happened.........water under the bridge.......no pun intended.
    Si hoc legere scis nimium eruditionis habes.

  2. #142
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    Quote Originally Posted by Besoeker View Post
    ... Just so happened.........water under the bridge.......no pun intended.
    That's alright. None taken.



    Sent from my XT1585 using Tapatalk

  3. #143
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    Quote Originally Posted by GoldDigger View Post
    That's alright. None taken.
    Rectified then.............
    Si hoc legere scis nimium eruditionis habes.

  4. #144
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    170522-0907 EDT

    Smart $:

    G is just one of the three input lines along with R and B. The letters correspond with the colors of the plotted curves. Others have pointed this out.

    For convenience I would pick -DC output as the reference point, but note the AC input line that connects to -DC changes three times per cycle, and corresponds to the plotted waveform that is most negative.

    If you go to 12 diodes, 6 transformers, and appropriately connected primaries, then you may need virtually no output capacitor, and ripple will be small. About 1/2 of the 6 diode bridge.

    .

  5. #145
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    Quote Originally Posted by gar View Post
    170522-0907 EDT

    Smart $:

    G is just one of the three input lines along with R and B. The letters correspond with the colors of the plotted curves. Others have pointed this out.

    For convenience I would pick -DC output as the reference point, but note the AC input line that connects to -DC changes three times per cycle, and corresponds to the plotted waveform that is most negative.

    If you go to 12 diodes, 6 transformers, and appropriately connected primaries, then you may need virtually no output capacitor, and ripple will be small. About 1/2 of the 6 diode bridge.

    .
    This is something we have quite often done but with one transformer. Delta primary and two secondaries, one star (wye), the other being delta. Ddyn11. So called 12-pulse.
    It was for supply harmonic mitigation the lowest being 11th. But yes, it does reduce the ripple also.
    Si hoc legere scis nimium eruditionis habes.

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