Transformers Archives - Page 6 of 13 - MCQ and Quiz for Exams

51. No-load current in a transformer

lags behind the voltage by about 75Â°

leads the voltage by about 75Â°

lags behind the voltage by about 15Â°

leads the voltage by about 15Â°

Detailed SolutionNo-load current in a transformer

52. The efficiency of two identical transformers under load conditions can be determined by

short-circuit test

back-to-back test

open circuit test

any of the above

Detailed SolutionThe efficiency of two identical transformers under load conditions can be determined by

53. Greater the secondary leakage flux

less will be the secondary induced e.m.f.

less will be the primary induced e.m.f.

less will be the primary terminal voltage

none of the above

Detailed SolutionGreater the secondary leakage flux

54. A transformer oil must be free from

sludge

odour

gases

moisture

Detailed SolutionA transformer oil must be free from

55. The highest voltage for transmitting electrical power in India is

33 kV

66 kV

132 kV

400 kV E. 765 kV

Detailed SolutionThe highest voltage for transmitting electrical power in India is

56. In an actual transformer the iron loss remains practically constant from noload to fullload because

value of transformation ratio remains constant

permeability of transformer core remains constant

core flux remains practically constant

primary voltage remains constant

Detailed SolutionIn an actual transformer the iron loss remains practically constant from noload to fullload because

57. The efficiencies of transformers compared with that of electric motors of the same power are

about the same

much smaller

much higher

somewhat smaller

Detailed SolutionThe efficiencies of transformers compared with that of electric motors of the same power are

58. The hum in a transformer is mainly attributed to

load changes

oil in the transformer

magnetostriction

mechanical vibrations

Detailed SolutionThe hum in a transformer is mainly attributed to

59. The thickness of laminations used in a transformer is usually

0.4 mm to 0.5 mm

4 mm to 5 mm

14 mm to 15 mm

25 mm to 40 mm

Detailed SolutionThe thickness of laminations used in a transformer is usually

60. Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V

Its secondary current is 5 A

Its secondary voltage is 400 V

supply is incorrect? A. Its secondary current is 5 A B. Its secondary voltage is 400 V C. Its rating is 2 kVA

Its secondary current is 20 A

Detailed SolutionWhich of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V

Page 1 Page 2 Page 3 Page 4 Page 5

Test 1 Test 2 Test 3

Exit mobile version