A $220/110$ V$,$ single$-$phase transformer has the following parameters: X$=0\mathrm{.}6$ X$=0\mathrm{.}10$ R$=10$ R$=0\mathrm{.}2($referred to primary$)($referred to secondary$)$ The transformer is supplied from a source of $220$ V from the primary side. Ignore magnetizing branch. a$)$ With a load impedance ZLoad $=2+$ j$52($referred to secondary$)$ is connected to the secondary side, find the current supplied to the load $(7).$ b$)$ Find the efficiency of the transformer when rated secondary voltage appears across a load of $1\mathrm{.}7$ kVA with $0\mathrm{.}316$ power factor lagging, and core loss is $13$ W$.$ c$)$ Calculate the phase angle at which regulation is zero for this transformer.