Download PDF
Free download in PDF Transformers Electrical Engineering Multiple Choice Questions with Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
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
[A]
Conservator
[B]
Breather
[C]
Bushings
[D]
Buchholz relay
62
Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in
[A]
short-circuiting of the secondaries
[B]
power factor of one of the transformers is leading while that of the other lagging
[C]
transformers having higher copper losses will have negligible core losses
[D]
loading of the transformers not in proportion to their kVA ratings
Answer: loading of the transformers not in proportion to their kVA ratings
63
During short circuit test iron losses are negligible because
[A]
the current on secondary side is negligible
[B]
the voltage on secondary side does not vary
[C]
the voltage applied on primary side is low
[D]
full-load current is not supplied to the transformer
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 ?
[A]
Hysteresis losses are reduced
[B]
Saving in winding material
[C]
Copper losses are negligible
[D]
Eddy losses are totally eliminated
Answer: Saving in winding material
65
Power transformers are generally designed to have maximum efficiency around
[A]
no-load
[B]
half-load
[C]
near full-load
[D]
10% overload
66
Which winding of the transformer has less cross-sectional area ?
[A]
Primary winding
[B]
Secondary winding
[C]
Low voltage winding
[D]
High voltage winding
Answer: High voltage winding
67
Silicon steel used in laminations mainly reduces
[A]
hysteresis loss
[B]
eddy current losses
[C]
copper losses
[D]
all of the above
68
The value of flux involved m the e.m.f. equation of a transformer is
[A]
average value
[B]
r.m.s. value
[C]
maximum value
[D]
instantaneous value
69
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be
[A]
6400 W
[B]
1600 W
[C]
800 W
[D]
400 W
70
The core used in high frequency transformer is usually
[A]
copper core
[B]
cost iron core
[C]
air core
[D]
mild steel core
71
Harmonics in transformer result in
[A]
increased core losses
[B]
increased I2R losses
[C]
magnetic interference with communication circuits
[D]
all of the above
72
Helical coils can be used on
[A]
low voltage side of high kVA transformers
[B]
high frequency transformers
[C]
high voltage side of small capacity transformers
[D]
high voltage side of high kVA rating transformers
Answer: low voltage side of high kVA transformers
73
A transformer can have zero voltage regulation at
[A]
leading power factor
[B]
lagging power factor
[C]
unity power factor
[D]
zero power factor
Answer: leading power factor
74
Which of the following is not a routine test on transformers ?
[A]
Core insulation voltage test
[B]
Impedance test
[C]
Radio interference test
[D]
Polarity test
Answer: Radio interference test
75
Noise level test in a transformer is a
[A]
special test
[B]
routine test
[C]
type test
[D]
none of the above
76
The path of the magnetic flux in transformer should have
[A]
high reluctance
[B]
low reactance
[C]
high resistance
[D]
low resistance
77
The leakage flux in a transformer depends upon
[A]
load current
[B]
load current and voltage
[C]
load current, voltage and frequency
[D]
load current, voltage, frequency and power factor
78
Which of the following properties is not necessarily desirable for the material for transformer core ?
[A]
Low hysteresis loss
[B]
High permeability
[C]
High thermal conductivity
[D]
Adequate mechanical strength
Answer: High thermal conductivity
79
Which of the following does not change in an ordinary transformer ?
[A]
Frequency
[B]
Voltage
[C]
Current
[D]
Any of the above
80
The magnetising current of a transformer is usually small because it has
[A]
small air gap
[B]
large leakage flux
[C]
laminated silicon steel core
[D]
fewer rotating parts
Please share this page