Task 4.3 = (a) A 250 kVA, ...

Task 4.3 = (a) A 250 kVA, 11 000 V/400 V, 50 Hz single-phase transformer has 80 turns on the secondary. Calculate: (i) the approximate values of the primary and secondary currents; and (ii) the approximate number of primary turns; (b) The primary and secondary windings of a 500 kVA transformer have resistances of 0.42 Ω and 0.0019 Ω respectively. The primary and secondary voltages are 11 000 V and 400 V respectively and the core loss is 2.9 kW, assuming the power factor of the load to be 0.8. Calculate the efficiency on (i) full load; and (ii) half load.