Questions
61
The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and
night is taken care of by which part of transformer
Answer: Conservator
62
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
Answer: loading of the transformers not in proportion to their kVA ratings
63
During short circuit test iron losses are negligible because
Answer: the voltage applied on primary side is low
64
Which of the following is the main advantage of an auto-transformer over a two winding transformer ?
Answer: Saving in winding material
65
Power transformers are generally designed to have maximum efficiency around
Answer: near full-load
66
Which winding of the transformer has less cross-sectional area ?
Answer: High voltage winding
68
The value of flux involved m the e.m.f. equation of a transformer is
Answer: maximum value
69
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be
Answer: 400 W
72
Helical coils can be used on
Answer: low voltage side of high kVA transformers
73
A transformer can have zero voltage regulation at
Answer: leading power factor
74
Which of the following is not a routine test on transformers ?
Answer: Radio interference test
76
The path of the magnetic flux in transformer should have
Answer: low reactance
78
Which of the following properties is not necessarily desirable for the material for transformer core ?
Answer: High thermal conductivity
79
Which of the following does not change in an ordinary transformer ?
Answer: Frequency
80
The magnetising current of a transformer is usually small because it has
Answer: small air gap
