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Homework Help: Power factor of a transformer at 80%

  1. Jun 22, 2011 #1
    PF is P / S in general. If the transformer is running at 80.1% of full load, the PF should stay the same right since

    PF = 0.801P / 0.801S
    = P / S

    since if the transformer is running at 80.1% full load, the output S and output P would both be 80.1% right? So basically, no matter what load, the PF is constant since the percentage of full load of the transformer cancels out?
  2. jcsd
  3. Jun 23, 2011 #2


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    Staff: Mentor

    The power factor not being exactly unity is due to what, exactly?

    I'm trying to understand this. The units of S , are they volt-amperes?

    Is the load considered purely resistive in all of this?

    What is the equivalent circuit model you are using for your power transformers? Does this give you a clue?
  4. Jun 23, 2011 #3


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    Science Advisor

    Hi Fred. What percentage (of it's full load value) do you think the magnetizing current would be when the transformer is running at 80% load current?
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