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MCQ of Transformer page-14

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31. In a transformer if peak voltage is fed to primary

A) the windage losses will be more
B) the copper losses will be less
C) the iron losses will be less
D) the iron losses will be more.

Ans : (D)

32. The value of flux involved in emf equation is.

B) Average
C) Maximum
D) Instantaneous.

Ans : (C)

33. Buchholz relay is generally not provided on transformers below

A) 1 kVA
B) 5 kVA
C) 50 kVA
D) 500 kVA.

Ans : (B)

34. The phase difference between the primary and secondary voltage of a transformer is

A) 0°
B) 90°
C) 180°
D) Between 30° and 60°.

Ans : (C)

35. In a transformer, the copper loss at half load compared to the at full load will be

A) One fourth
B) Half
C) 2 times
D) 4 times.

Ans : (A)

36. In a distribution transformer, normally

A) core losses are equal to copper losses
B) core losses are more than copper losses
C) core losses are less than copper losses
D) core losses are half of the copper losses

Ans : (C)

37. Core losses in a transformer

A) depend only on the supply voltage
B) decreases as the load on transformer increases
C) vary from 10% to 50% between no load and full load
D) vary from 1% to 3% between no load and full load.

Ans : (A)

38. The function of transformer oil in a transformer is

A) to lubricate the moving parts
B) to provide protection against short circuiting
C) to provide protection against lightning
D) to provide insulation and cooling.

Ans : (D)

39. In a transformer

A) open circuit test is conducted on high voltage side and short circuit test on low voltage side
B) open circuit test is conducted on low voltage side and short circuit test on high voltage side
C) open circuit and short circuit tests are conducted on high voltage side
D) open circuit and short circuit tests are conducted on low voltage side.

And : (B)

40. For a transformer, operating at constant load current, maximum efficiency will occur at

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

Ans : (C)

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