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MCQ of Transformer page-12


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11. Primary winding of a transformer is

A) Connected to the load
B) Connected to supply mains
C) Always high voltage winding
D) Always low voltage winding.

Ans : (B)

12. Which test on a transformer provides information about regulation, efficiency and heading under load conditions ?

A) Short circuit test
B) Hopkinson test
C) Back to back test
D) Open circuit test.

Ans : (C)

13. Which of the following transformer will be smallest in size

A) 10 kVA, 200 Hz
B) 10 kVA, 100 Hz
C) 10 kVA, 60 Hz
D) 10 kVA, 50 Hz.

Ans : (A)

14. For a transformer, the condition for maximum efficiency is

A) copper loss = iron loss
B) hysteresis loss = eddy current loss
C) core loss = hysteresis loss
D) total loss = 2/3 x copper loss.

Ans : (A)

15. Eddy current losses in a transformer core can be reduced by

A) reducing the airgap in the magnetic circuit
B) increasing the airgap in the magnetic circuit
C) increasing the thickness of lamination
D) reducing the thickness of lamination.

Ans : (D)

16. A short circuit test on a transformer gives

A) copper losses at half load
B) copper losses at full load
C) sum of iron losses and copper losses.
D) iron losses at any load.

Ans : (B)

17. Iron losses of a transformer can be approximately calculated if

A) the shape of core and yoke is know
B) the weight of core and yoke is known
C) the material of core and yoke is known
D) the gauge of sheet used in core is known.

Ans : (B)

18. Leakage fluxes in a transformer may be minimized by

A) under rating the transformer
B) reducing the reluctance of the iron core to the minimum
C) constantly cooling the core
D) sectionizing and interleaving the primary and secondary windings.

Ans : (D)

19. Essential condition for the parallel operation of transformer is

A) their ratio of transformation must be in proportion to the load shared
B) they must operate at the same frequency
C) their voltage rating must be in proportional to the load shared
D) they must have equal kVA ratings.

Ans : (B)

20. Which of the following transformer will be largest in size ?

A) 1 kVA, 100 Hz
B) 1 kVA, 60 Hz
C) 1 kVA, 50 Hz
D) 1kVA, 25 Hz.

Ans : (D)


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