The resistance and reactance of a 100 kVA 11000|400 V, $$\triangle$$ - Y distribution transformer are 0.02 and 0.07 pu respectively. The phase impedance of the transformer referred to the primary is

A 50 kVA, 3300/230 V single-phase transformers is connected as an autotransformer shown in figure. The nominal rating of the autotransformer will be

A 500 kVA, 3-phase transformer has iron loses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is

Figure shows an ideal three-winding transformer. The three windings 1,2,3 of the transformer are wound on the same core as shown. The turn's ratio N₁:N₂:N₃ is 4:2:1. A resistor of 10 Ω is connected across winding-2. A capacitor of reactance 2.5 Ω is connected across winding-3. Winding-1 is connected across a 400 V, ac supply. If the supply voltage phasor $$\overline V=400\angle0^\circ$$, the supply current phasor $${\overline I}_1$$ is given by