(a) Explain how excitation of the rotor is produced and supplied. (6)

(b) A 25 kVA, single phase transformer has 250 turns on the primary and 40 turns on the secondary winding. The primary is connected to 1500 V, 50 Hz mains calculate (10)

(i) secondary emf

(ii) primary and secondary current on full load

(iii) maximum flux in the core.