gate 2017 EE(Set-B) q44-solution

25KVA, Y -D, 3.3kV-$$\Delta$$\\
$$N_1:N_2=5:1$$\\
$$I_{st}=\frac{25\times 10^3}{\sqrt{3}\times 3.3\times10^3}$$\\
$$I_L=I_{ph}=4.374Amps$$
Transformer is a constant-Power device
$$E_2I_2=E_1I_1$$\\
$$N_2I_2=N_1I_1\Rightarrow I_2=\frac{N_1}{N_2}.I_1=\frac{5}{1}\times 4.374$$\\
$$I_{ph}=I_2=21.869Amps \leftarrow \Delta – side$$\\
$$I_L=\sqrt{3}\times I_2=\sqrt{3}\times21.869=37.879Amps$$