\(\eta=90 \%=0.9\)
Efficiency \(\eta=0.9=\frac{P_{s}}{P_{p}} \Rightarrow P_{s}=0.9 P_{p}\)
\(\mathrm{V}_{\mathrm{s}} \mathrm{I}_{\mathrm{s}}=0.9 \times \mathrm{V}_{\mathrm{P}} \mathrm{I}_{\mathrm{P}} \quad(\because \mathrm{P}=\mathrm{VI})\)
\({I_s} = \frac{{0.9 \times 2300 \times 5}}{{230}} = 45{\mkern 1mu} {\text{A}}\)