Transformers Archives - Page 3 of 13 - MCQ and Quiz for Exams

21. 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

Conservator

Breather

Bushings

Buchholz relay

Detailed SolutionThe 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

22. The magnetising current of a transformer is usually small because it has

small air gap

large leakage flux

laminated silicon steel core

fewer rotating parts

Detailed SolutionThe magnetising current of a transformer is usually small because it has

23. Power transformers are generally designed to have maximum efficiency around

no-load

half-load

near full-load

10% overload

Detailed SolutionPower transformers are generally designed to have maximum efficiency around

24. Efficiency of a power transformer is of the order of

100 per cent

98 per cent

50 per cent

25 per cent

Detailed SolutionEfficiency of a power transformer is of the order of

25. Which winding in a transformer has more number of turns?

Low voltage winding

High voltage winding

Primary winding

Secondary winding

Detailed SolutionWhich winding in a transformer has more number of turns?

26. Which of the following properties is not necessarily desirable for the material for transformer core?

Low hysteresis loss

High permeability

High thermal conductivity

Adequate mechanical strength

Detailed SolutionWhich of the following properties is not necessarily desirable for the material for transformer core?

27. Noise level test in a transformer is a

special test

routine test

type test

none of the above

Detailed SolutionNoise level test in a transformer is a

28. In a transformer routine efficiency depends upon

supply frequency

load current

power factor of load

both (B) and (C)

Detailed SolutionIn a transformer routine efficiency depends upon

29. Star/star transformers work satisfactorily when

load is unbalanced only

load is balanced only

on balanced as well as unbalanced loads

none of the above

Detailed SolutionStar/star transformers work satisfactorily when

30. When secondary of a current transformer is open-circuited its iron core will be

hot because of heavy iron losses taking place in it due to high flux density

hot because primary will carry heavy current

cool as there is no secondary current

none of above will happen

Detailed SolutionWhen secondary of a current transformer is open-circuited its iron core will be

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