A $8000VA,\frac{620}{120}V$ transformer has been tested to determine its equivalent circuit. The results of the :tests are

:open circuit test on the low voltage side

VOC$=120V,$loC$=0\mathrm{.}5A,$POC$=8W$

:short circuit test on the high voltage side

$VsC=20V,$ISC$=10A,PsC=50W$

:The equivalent circuit of this transformer referred to the low$-$voltage side of the transformer as follows

$\%$ voltage regulation of the transformer at rated conditions and $0\mathrm{.}5$ PF lagging is $(5$

Pin $($transformer input power$)$ at rated condition is

$W16$

$\%$

Transformer efficiency at rated conditions and $0\mathrm{.}5$ PF lagging is $(7$