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Free download in PDF Transformers Electrical Engineering Short Questions and 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.
41
Delta/star transformer works satisfactorily when
[A]
load is balanced only
[B]
load is unbalanced only
[C]
on balanced as well as unbalanced loads
[D]
none of the above
Answer: on balanced as well as unbalanced loads
42
Star/star transformers work satisfactorily when
[A]
load is unbalanced only
[B]
load is balanced only
[C]
on balanced as well as unbalanced loads
[D]
none of the above
Answer: load is balanced only
43
Which of the following property is not necessarily desirable in the material for transformer core ?
[A]
Mechanical strength
[B]
Low hysteresis loss
[C]
High thermal conductivity
[D]
High permeability
Answer: High thermal conductivity
44
Distribution transformers are generally designed for maximum efficiency around
[A]
90% load
[B]
zero load
[C]
25% load
[D]
50% load
45
The main reason for generation of harmonics in a transformer could be
[A]
fluctuating load
[B]
poor insulation
[C]
mechanical vibrations
[D]
saturation of core
Answer: saturation of core
46
Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds
[A]
50°C
[B]
80°C
[C]
100°C
[D]
150°C
47
A Buchholz relay can be installed on
[A]
auto-transformers
[B]
air-cooled transformers
[C]
welding transformers
[D]
oil cooled transformers
Answer: oil cooled transformers
48
A transformer oil must be free from
[A]
sludge
[B]
odour
[C]
gases
[D]
moisture
49
In a transformer the resistance between its primary and secondary is
[A]
zero
[B]
1 ohm
[C]
1000 ohms
[D]
infinite
50
The highest voltage for transmitting electrical power in India is
[A]
33 kV
[B]
66 kV
[C]
132 kV
[D]
400 kV
51
The function of conservator in a transformer is
[A]
to project against’internal fault
[B]
to reduce copper as well as core losses
[C]
to cool the transformer oil
[D]
to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings
Answer: to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings
52
The thickness of laminations used in a transformer is usually
[A]
0.4 mm to 0.5 mm
[B]
4 mm to 5 mm
[C]
14 mm to 15 mm
[D]
25 mm to 40 mm
53
Material used for construction of transformer core is usually
[A]
wood
[B]
copper
[C]
aluminium
[D]
silicon steel
54
Hysteresis loss in a transformer varies as CBmax = maximum flux density)
[A]
Bmax
[B]
Bmax1-6
[C]
Bmax1-83
[D]
B max
55
The noise resulting from vibrations of laminations set by magnetic forces, is termed as
[A]
magnetostrication
[B]
boo
[C]
hum
[D]
zoom
56
The transformer ratings are usually expressed in terms of
[A]
volts
[B]
amperes
[C]
kW
[D]
kVA
57
The chemical used in breather is
[A]
asbestos fiber
[B]
silica sand
[C]
sodium chloride
[D]
silica gel
58
The chemical used in breather for transformer should have the quality of
[A]
ionizing air
[B]
absorbing moisture
[C]
cleansing the transformer oil
[D]
cooling the transformer oil.
Answer: absorbing moisture
59
The use of higher flux density in the transformer design
[A]
reduces weight per kVA
[B]
reduces iron losses
[C]
reduces copper losses
[D]
increases part load efficiency
Answer: reduces weight per kVA
60
Buchholz’s relay gives warning and protection against
[A]
electrical fault inside the transformer itself
[B]
electrical fault outside the transformer in outgoing feeder
[C]
for both outside and inside faults
[D]
none of the above
Answer: electrical fault inside the transformer itself
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