Q.23- A 200 KVA, 66000/400 V, 50 HZ, single phase transformer has 80 turns on the secondary side and cross sectional area of the core is 80 sq.cm. Neglecting losses, calculate: (i) The full load primary and secondary currents. (ii) The number of primary turns. (iii) The maximum value of the flux. Q.24 A 230/110 V,single phase transformer takes an input of 350 VA at no load and rated voltage. The core loss is 110W. Find (i) no- load power factor (ii) the iron loss component of no- load current, and (iii) magnetize component of no- load current. Q.25- A 30 KVA, 2400/120 V, 50 HZ, transformer has a high voltage winding resistance of 0.1 and leakage reactance of 0.22 2. The low voltage winding resistance is 0.03502 and leakage reactance of 0.012 2. Calculate for the transformer: (i) Equivalent resistance as referred to both primary and secondary. (ii) Equivalent reactance as referred to both primary and secondary. (iii) Equivalent impedance as referred to both primary and secondary. (iv) Copper loss at full load. Q.26- A 600 KVA, single phase transformer has an efficiency of 92% at full load and also at half load, working at unity pf. Calculate the efficiency of the transformer at 60% full load and unity pf. Q.27-A 240 V, DC shunt motor with an armature resistance of 0.50 has a full load current of 40 A. Find a ratio of the stalling torque to the full load torque when a resistance of 1 is connected in series with the armature? (a) 4 (b) 12 (c) 6 (d) none of the above. (Gate EE 1998)