Questions and answers for exam Preparation

MCQs

Total Questions : 631 | Page 9 of 64 pages

Question 81. The no-load current drawn by transformer is usually what per cent of the full-load current?

0.2 to 0.5 per cent
2 to 5 per cent
12 to 15 per cent
20 to 30 per cent

Discuss Question

Answer: Option B. -> 2 to 5 per cent

Question 82. The chemical used in breather for transformer should have the quality of

ionizing air
absorbing moisture
cleansing the transformer oil
cooling the transformer oil

Discuss Question

Answer: Option B. -> absorbing moisture

Question 83. The function of conservator in a transformer is

to project against internal fault
to reduce copper as well as core losses
to cool the transformer oil
to take care of the expansion and contraction of transformer oil due to variation of temper-ature of sur-roundings

Discuss Question

Answer: Option D. -> to take care of the expansion and contraction of transformer oil due to variation of temper-ature of sur-roundings

Question 84. The function of breather in a transformer is

to provide oxygen inside the tank
to cool the coils during reduced load
to cool the transformer oil
to arrest flow of moisture when outside air enters the transformer

Discuss Question

Answer: Option D. -> to arrest flow of moisture when outside air enters the transformer

Question 85. Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in

short-circuiting of the secondaries
power factor of one of the transformers is leading while that of the other lagging
transformers having higher copper losses will have negligible core losses
loading of the transformers not in proportion to their kVA ratings

Discuss Question

Answer: Option D. -> loading of the transformers not in proportion to their kVA ratings

Question 86. The value of flux involved m the e.m.f. equation of a transformer is

average value
r.m.s. value
maximum value
instantaneous value

Discuss Question

Answer: Option C. -> maximum value

Question 87. In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are

friction and windage losses
copper losses
hysteresis and eddy current losses
none of the above

Discuss Question

Answer: Option C. -> hysteresis and eddy current losses

Question 88. The changes in volume of transformer cooling oil due to variation of atmospheric tem-perature during day and night is taken care of by which part of transformer