Frequency - Temperature characteristics of transformer winding

  1. Dear Sir,
    The rating of a single phase transformer is 230V / 230V (1:1), 5A, 50 hz, 1200W.
    When this transformer is operated at 230V, 5A, and 50 hz the transformer winding saturated temperature may be some value. Now when the same transformer is operated at 230V, 5A and 40 hz (reduced frequency), what will happen to winding temperature? will temperature decrease or increase? what can be the reasons for temperature change?
    is there any relation between frequency and winding temperature of transformer?

    Thank you
     
    Last edited: Jul 25, 2014
  2. jcsd
  3. jim hardy

    jim hardy 5,356
    Science Advisor
    Gold Member
    2014 Award

    The transformer will probably burn up.
    Its core will overheat from too much magnetic flux
    and its windings will overheat from the high current required to create that flux.

    Go back to your very basics:

    Since voltage is derivative of flux,
    flux must be integral of voltage

    ∫sin(ωt) = -(1/ω) X cos(ωt) + C.... and since it's AC we'll ignore the constant of integration C.

    ω is in the denominator
    so as ω gets smaller the result gets bigger
    and that's why for a constant voltage, as frequency goes down flux goes up .

    look up "volts per hertz";

    see
    http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/transf.html

    and
    http://www.allaboutcircuits.com/vol_1/chpt_14/4.html

    and here's a brief summary:


    https://www.gedigitalenergy.com/smartgrid/Mar07/article5.pdf

    old jim
     
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