(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. 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.