Question $3[14]$

Test data obtained on a $30-$kVA,$\frac{3000}{110}-V,$ single$-$phase transformer is as follows:

Calculate:

$3\mathrm{.}1$ The full$-$load efficiency of the transformer at $0\mathrm{.}8$ pf lagging $q,[7)$

$3\mathrm{.}2$ The efficiency of the transformer at half$-$load for unity pf$.q,[2]$

$3\mathrm{.}3$ The load in KW for maximum efficiency when pf is $0\mathrm{.}8$ lagging $q,(5)$