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transformer question ..

Discussion in 'Electronic Basics' started by Paul, Aug 15, 2004.

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  1. Paul

    Paul Guest

    Hi

    A quick question about transformer. I read in the some book that transformer
    really only works for AC waveform. Is that true? I used to think that it works
    for DC as well? Thanks.

    V1I1=V2I2
     
  2. It'll work with short DC pulses but is generally an AC device. If a pulse
    lasts too long there's no change in magnetic field and trasnformer action
    ceases, while on AC the magnititudew and polarity is contstantly varying.
     
  3. The voltage out of a transformer is a result of a rate of change of
    the magnetic field passing through the coils. To produce DC, the
    magnetic field would have to keep changing in the same direction,
    indefinitely. Since magnetic core materials saturate at much less
    than infinite flux, no real transformer can produce DC. The general
    rule is that transformers (and any inductive component) supports an
    average of zero volts drop (the volt seconds on one direction must be
    followed by the same number of volt seconds in the opposite direction,
    each cycle). However, there is no requirement that the average
    current be zero, so inductive components, including transformers can
    pass DC current. A non zero current just implies that the average
    flux is not zero.
     
  4. Graham Knott

    Graham Knott Guest

     
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