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VFD Outputs

Discussion in 'Electrical Engineering' started by Rob Hammond, Aug 31, 2003.

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  1. Rob Hammond

    Rob Hammond Guest

    Hi all

    Are there any VFDs that provide a near-pure sine wave output that could
    be used as a source for other electrical equipment?
    Alternatively, provided the output of a 3ph variable frequency drive is
    maintained at 50-60Hz is it permissible to connect a transformer to one
    of the output phases to provide a 'smoothed' secondary output voltage?

    Rob Hammond
  2. albown

    albown Guest

    VFD's as far as I know are basically pulsed DC to look like a sine wave for
    the motor. Most today are PWM, pulse width modulation. Some companies call
    it another name.

    If the drive is at a set speed, i.e. 60 hz then there should not be much
    more variance in the voltages than the utility feed.

    Seems to me your trying to make something more complicated than it needs to
    be. Remember if your using the output to two sources, i.e. motor and then
    your transformer. The VFD will have to be sized for the job. I have seen
    one 40 hp drive running 2 10 hp motors. I doubt that you will be able to
    connect a single phased transformer with out frying the drive sooner than

    Just my opinion.
  3. Connecting a single phase transformer will show the drive a load imbalance
    and it will most likely fault out. Those drives assume a motor load that
    should be balanced within a certain %.
  4. Elettronica

    Elettronica Guest

    You have to look at Frequency inverter with all pole sine filter integrated.
    Much expensive, large and heavy but sine wave output.
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