Q. A single-phase, 3-kVA, 220:110-V, 60-Hz transformer has a high-voltage winding resistance of 0.3 , a low-voltage winding resistance of 0.06 , a leakage reactance of 0.8  on its high voltage side, and a leakage reactance of 0.2 on its low-voltage side. The core loss at rated voltage is 45 W, and the copper loss at rated load is 100W. Neglect the exciting current of the transformer. Find the per-unit voltage regulation when the transformer is supplying full load at 110 V and 0.9 lagging power factor.