Power Transformer MCQs Part 05

41. The phase difference between the primary and secondary voltage of a transformer is
a. o
b. 90
c. 180
d. between 30 and 60

42. In a transformer the copper loss at half load as compared to that at full load will be
a. 4 times
b. 2 times
c. half
d. one fourth

43. The path of the magnetic flux in transformer should have
a. low reluctance
b. low resistance
c. high reluctance
d. high resistance

44. The desirable properties of transformer core material are
a. low permeability and low hysteresis loss
b. high permeability and high hysteresis loss
c. high permeability and low hysteresis loss
d. low permeability and high hysteresis loss

45. Core losses in a transformer
a. vary from 1% to 3% between no load and full load
b. vary form 10% to 50% between no load and full load
c. decrease as the load on transformer increases
d. depends only on the supply voltage

46. The function of transformer oil in a transformer is
a. to provide insulation and cooling
b. to provided protection against lightning
c. to provide protection against short circuiting
d. to lubricate the moving parts

47. Full load copper loss in a transformer is 1600 watts . At half load the loss will be
a. 6400 W
b. 1600 W
c. 800 W
d. 400 W

48. Iron loss for transformer is 400 watt If the transformer is working at its maximum efficiency then copper loss will be
a. 1600 W
b. 400 W
c. 200 W
d. 100 W

49. A transformer working under the conditions of maximum efficiency has total losses of 1600 W While operating at half load, the copper loss will be
a. 800 W
b. 400 W
c. 200 W
d. 100 W

50. A transformer has full load copper loss of 800 W and core loss of 600 W . Total losses at no load will be approximately
a. 1400 W
b. 1100 W
c. 1000 W
d. 600 W

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