A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at

A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is 

(A) 86.7% (B) 88.26% (C) 88.9% (D) 87.8%
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Answer :

A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is 87.8%

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