50. If a 1000 kVA, 200 Hz transformer is operated at 50 Hz, its kVA rating is

A. 100 kVA

B. 250 kVA

C. 4000 kVA

D. 500 kVA

51. In a three-phase transformer, the turns ratio k is given by

A. k = line voltage ratio

B. k =x line voltage ratio

C. k = phase voltage ratio

D. k = 43- x phase voltage ratio

52. For getting minimum weight of a transformer, the weight of iron should be

A. less than the weight of copper

B. greater than the weight of copper

C. equal to the weight of copper

D. none of these

53. A constant current transformer should not have

A. high value of reactance

B. i movable secondary winding

C. a high value of resistance

D. primary and secondary windings sun-oun-ding the core

54. When the secondary of the transformer is loaded, the primary current will

A. not be effected

B. increase

C. be less than the secondary current

D. be the vector sum of no load current and additional current drawn due to the secondary current

55. A single phase transformer has turn ratio of 10. The primary winding has resistance of 2.2 ohms and the secondary winding has resistance of 0.030. The total resistance as referred to the primary is

A. 2.5 S2

B. 5.2 S2

C. 2.23 CI

D. 2.203 CI

56. At full load, the copper loss in a transformer is 600 watts. At half load, the copper load will be

A. 300 watts

B. 150 watts

C. 75 watts

D. 600 watts

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