The core flux of a practical transformer with a resistive load

A 3-phase transformer has rating of 20 MVA, 220 kV (star) / 33 kV (delta) with leakage reactance of 12%. The transformer reactance (in ohms) referred to each phase of the L.V. delta-connected side is

The hysteresis loop of a magnetic material has an area of 5 cm² with the scales given as 1 cm = 2 AT and 1 cm = 50 mWb. At 50 Hz, the total hysteresis loss is

It is desirable to eliminate 5^th harmonic voltage from the phase voltage of an alternator. The coils should be short-pitched by an electrical angle of