transformers MCQs – Page 5

Practise focused transformers questions with marked answers for exam preparation and subject revision.

transformers Mcqs
81. If the percentage impedances of the two transformers working in parallel are different, then______________________?
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A. transformers will be overheated

B. power factors of both the transformers will be same

C. parallel operation will be not possible

D. parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load
82. A transformer transforms__________________?
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A. power

B. current

C. voltage

D. frequency

83. An ideal transformer will have maximum efficiency at a load such that?
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A. copper loss iron loss

B. copper loss = iron loss

C. none of the above

84. In a transformer the resistance between its primary and secondary is____________?
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A. 1 ohm

B. 1000 ohms

C. zero

D. infinite
85. N atural air coo ling is generally restricted for transformers up to__________?
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A. 15 MVA

B. 1.5 MVA

C. 5 MVA

D. 50 MVA

86. An open-circuit test on a transformer is conducted primarily to measure______________?
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A. total loss

B. none of the above

C. core loss

D. copper loss

E. efficiency

F. insulation resistance

87. Efficiency of a power transformer is of the order of________________?
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A. 100 per cent

B. 25 per cent

C. 98 per cent

D. 50 per cent

88. Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?
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A. 80C

B. 50C

C. 150C

D. 100C

89. The noise produced by a transformer is termed as_______________________?
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A. hum

B. zoom

C. ringing

D. buzz

90. Which of the following loss in a transformer is zero even at full load ____________?
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A. Eddy current loss

B. Friction loss

C. Core loss

D. Hysteresis loss

91. An ideal transformer is one which has_____________?
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A. none of the above

B. interleaved primary and secondary windings

C. no losses and magnetic leakage

D. a common core for its primary and secondary windings

E. core of stainless steel and winding of pure copper metal

92. A transformer oil must be free from________________?
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A. gases

B. moisture

C. odour

D. sludge

93. In a transformer the tappings are generally provided on_____________?
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A. secondary side

B. primary side

C. high voltage side

D. low voltage side

94. Material used for construction of transformer core is usually___________________?
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A. copper

B. aluminium

C. silicon steel

D. wood

95. The maximum efficiency of a distribution transformer is____________?
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A. at no load

B. at full load

C. at 80% full load

D. at 50% full load
96. A shell-type transformer has_________?
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A. negligibly hysteresis losses

B. none of the above

C. high eddy current losses

D. reduced magnetic leakage
97. The size of a transformer core will depend on__________?
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A. frequency

B. flux density of the core material

C. A. and B. both

D. area of the core

98. For the parallel operation of single phase transformers it is necessary that they should have___________?
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A. same efficiency

B. same polarity

C. same kVA rating

D. same number of turns on the secondary side.

99. Primary winding of a transformer________________?
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A. is always a low voltage winding

B. could either be a low voltage or high voltage winding

C. is always a high voltage winding

D. none of the above

100. The maximum load that a power transformer can carry is limited by its________________?
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A. voltage ratio

B. dielectric strength of oil

C. copper loss

D. temperature rise