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- Thread starter ranju
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PF depends on leakage inductance of xfm and the load itself.

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but what's the reason behind high pf??

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relatively small leakage inductance of xfm + operation near rated load pointbut what's the reason behind high pf??

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Of course, if the load will be low the p.f. could decrease more [up to 0.1 at no-load!].

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Another extreme case is a short circuit case where I>>I_{nom}. PF also low.

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jim hardy

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That's a bit ambiguous question.

I'd suggest the source from which you extracted that tidbit was suggesting that it is usual practice to use power transformers at reasonably highPF because:

Z of transformer is largely inductive

Draw your phasors..

When PF of load is unity,what is phase angle between applied voltage and I X Z drop in transformer?

When PF of load is zero, what is that angle?

At high PF your transformer I X Z drop is at right angle to applied voltage so doesn't change it much, because the hypotenuse and long side of a right triangle are nearly the same when vertex angle is small. That's elementary geometry.

At zero PF that I X Z drop Is in phase with applied voltage and subtracts or adds to it volt for volt.

So you'll get better regulation with a load having reasonably high PF.

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