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Efficiency MCQ Questions & Answers

Efficiency MCQs : This section focuses on the "Efficiency". These Multiple Choice Questions (MCQs) should be practiced to improve the Efficiency skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

A transformer having maximum efficiency at 75% full load will have ratio of iron loss and full load copper loss equal to ___________

A. 04-Mar
B. 03-Apr
C. Sep-16
D. 16-Sep

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Question 2

At which load condition maximum efficiency of a distribution transformer will be achieved?

A. At no load
B. At 60% full load
C. At 80% full load
D. At full load

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Question 3

Efficiency of a power transformer is near to the ___________

A. 100 per cent
B. 98 per cent
C. 50 per cent
D. 25 per cent

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Question 4

For a power transformer operating at full load it draws voltage and current equal to 200 V and 100 A respectively at 0.8 pf. Iron and copper losses are equal to 120 kW and 300kW. What is the efficiency?

A. 86.44%
B. 96.44%
C. 97.44%
D. 99.12%

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Question 5

For a transformer given, operating at constant load current, maximum efficiency will occur at ______

A. 0.8 leading power factor
B. 0.8 lagging power factor
C. Zero power factor
D. Unity power factor

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Question 6

On which factors transformer routine efficiency depends upon?

A. Supply frequency
B. Load current
C. Power factor of load
D. Load current and power factor of load

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Question 7

Power transformers other than distribution transformers are generally designed to have maximum efficiency around ______

A. No-load
B. Half-load
C. Near full-load
D. 10% overload

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Question 8

The efficiencies of transformers compared to electric motors of the same power are ___________

A. About the same
B. Much smaller
C. Much higher
D. Can’t comment

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Question 9

What is the correct formula of efficiency of a device?

A. Input /output
B. Output/losses
C. 1- (losses/ (output + losses))
D. Cannot be determined

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Question 10

When will be the efficiency of a transformer maximum?

A. Copper losses = hysteresis losses
B. Hysteresis losses = eddy current losses
C. Eddy current losses = copper losses
D. Copper losses = iron losses

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Question 11

Why efficiency of a transformer, under heavy loads, is comparatively low?

A. Copper loss becomes high in proportion to the output
B. Iron loss is increased considerably
C. Voltage drop both in primary and secondary becomes large
D. Secondary output is much less as compared to primary input

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