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MCQ of Transformer page-3


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21. The transformer core is generally made of

a) Alumimium
b) Silicon steel
c) Copper
d) Wood

Ans: (b)

22. Which of the following is minimized by laminating the core of a transformer?

a) Hysteresis loss
b) Eddy current loss
c) Heat loss
d) All of these

Ans: (b)

23. Thickness of laminations of trans-former core is usually of the order of

a) 0.35 mm to 0.5 mm
b) 3.5 mm to 5 mm
c) 35 mm to 50 mm
d) 5mm to 10 mm

Ans: (a)

24. The size of transformer core depends on

a) Area of the core
b) Flux density of core material
c) Frequency
d) Both (b) and (c)

Ans: (d)

25. In power transformers, breather is used to

a) Provide insulation to the windings
b) Provide cooling to the windings
c) Take insulating oil from the con-servator
d) Extract moisture from the air

Ans: (d)

26. In a transformer, conservator con-sists of

a) Drum placed at the bottom of the tank
b) An air tight metal drum fixed at the top of the tank
c) Overload protection circuit
d) None of these

Ans: (b)

27. In a transformer, the resistance between its primary and secondary should be

a) Infinite
b) Zero
c) About 1 MΩ
d) About 100 MΩ

Ans: (a)

28. For large power transformer, best utilization of available core space can be made by using

a) Square core section
b) Stepped core section
c) Rectangular core section
d) None of these

Ans: (b)

29. Five limb core construction of transformer has advantage over three limb core construction that

a) Hysteresis loss is less
b) Permeability is higher
c) Magnetic reluctance of the three phases can be balanced
d) Eddy current loss is less

Ans: (c)

30. In a transformer, low voltage windings are placed nearer to the core in the case of concentric winding because it reduces

a) Eddy current loss
b) Insulation requirement
c) Leakage fluxes
d) Hysteresis loss

Ans: (b)


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