Transformers MCQS

This set of Electrical engineering Multiple Choice Questions & Answers (MCQs) focuses on “ Transformers ”. These questions are chosen from a collection of most authoritative and best reference books on Electrical engineering. Our aim is to prepare an individual for competitive exams like NTS, GAT, ECAT, University and College entrance exams, Jobs and interviews. One should practice our MCQS to assimilate Transformers in Electrical engineering comprehensively.

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 A.C. supply is incorrect?

Its secondary current is 5 A

Its secondary voltage is 400 V

Its rating is 2 kVA

Its secondary current is 20 A

In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are__________?

Hysteresis and eddy current losses

Friction and windage losses

Copper losses

None of the above

Losses which occur in rotating electric machines and do not occur in transformers are___________?

Friction and windage losses

Magnetic losses

Hysteresis and eddy current losses

Copper losses

For given applied voltage, with the increase in frequency of the applied voltage?

Eddy current loss will decrease

Eddy current loss will increase

Eddy current loss will remain unchanged

None of the above

In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?

To withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns

To absorb the line surge voltage and save the winding of transformer from damage

To reflect the line surge and save the winding of a transformer from damage

None of the above

Reduction in core losses and increase in permeability are obtained with transformer employing__________?

Core built-up of laminations of cold rolled grain oriented steel

Core built-up of laminations of hot rolled sheet

Either of the above

None of the above

Which of the following parts of a transformer is visible from outside ?



Primary winding

Secondary winding

Which of the following insulating materials can withstand the highest temperature safely ?




Glass fibre

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

Which of the following acts as a protection against high voltage surges due to lightning and switching ?

Horn gaps

Thermal overload relays



A good voltage regulation of a transformer means________________?

Ood voltage regulation of a transformer means

Output voltage fluctuation from no load to full load is least

Output voltage fluctuation with power factor is least

Difference between primary and secondary voltage is least

Which of the following protection is normally not provided on small distribution transformers ?

Overfluxing protection

Buchholz relay

Overcurrent protection

All of the above

For a transformer, operating at constant load current, maximum efficiency will occur at______________?

0.8 leading power factor

0.8 lagging power factor

Zero power factor

Unity power factor

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