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Q5. a) What is leakage flux as it applies to the iron-core transformer? How is it taken into account in the analysis of the transformer? (6)

b) The following results were obtained on a 50 kVA transformer: open circuit test-primary voltage, 3300 V; Second voltage, 415 V: primary power, 430 W. Short circuit test-primary voltage, 124 V: primary current, 15.3 A; primary power, 525 W; secondary current, to be assumed at full load value. Calculate:

(i) The efficiencies at full load and at half load for 0.7 power factor.

(ii) The voltage regulations for power factor 0.7 (i) lagging, (ii) leading

(iii) The secondary terminal voltages corresponding to (i) and (ii) (10)

Q4.a) List the factors that determine the starting torque of the three-phase induction motor. How does this torque generally compare with the value of the rated torque (6)

b) An 18.65 KW, 6 Pole, 50 Hz, 3 phase slip ring induction motor runs at 960 rpm on full load with a rotor current per phase of 35 A allowing 1 KW for mechanical losses, find the resistance /phase of three-phase winding. (10)

Q8. The half-ordinates of a ship’s water-plane, which is 80 m long, commencing from forward at equal intervals, are as follows: 0.2, 4.0, 5.0, 5.2, 5.0, 4.0 and 0.2 m respectively. Calculate the area of the water-plane using Simpson’s First Rule.