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Free download in PDF Transformers Electrical Engineering MCQs 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.
81
A shell-type transformer has
[A]
high eddy current losses
[B]
reduced magnetic leakage
[C]
negligibly hysteresis losses
[D]
none of the above
Answer: reduced magnetic leakage
82
N atural air coo ling is generally restricted for transformers up to
[A]
1.5 MVA
[B]
5 MVA
[C]
15 MVA
[D]
50 MVA
83
The size of a transformer core will depend on
[A]
frequency
[B]
area of the core
[C]
flux density of the core material
[D]
(a) and (b) both
84
The secondary winding of which of the following transformers is always kept closed ?
[A]
Step-up transformer
[B]
Step-down transformer
[C]
Potential transformer
[D]
Current transformer
Answer: Current transformer
85
The function of breather in a transformer is
[A]
to provide oxygen inside the tank
[B]
to cool the coils during reduced load
[C]
to cool the transformer oil
[D]
to arrest flow of moisture when outside air enters the transformer
Answer: to arrest flow of moisture when outside air enters the transformer
86
The transformer oil should have _____ volatility and _____ viscosity.
[A]
low,low
[B]
high,high
[C]
low,high
[D]
high,low
87
For the parallel operation of single phase transformers it is necessary that they should have
[A]
same efficiency
[B]
same polarity
[C]
same kVA rating
[D]
same number of turns on the secondary side.
88
Short circuit test on transformers is conducted to determine
[A]
hysteresis losses
[B]
copper losses
[C]
core losses
[D]
eddy current losses
89
Open circuit test on transformers is conducted to determine
[A]
hysteresis losses
[B]
copper losses
[C]
core losses
[D]
eddy current losses
90
During open circuit test of a transformer
[A]
primary is supplied rated voltage
[B]
primary is supplied full-load current
[C]
primary is supplied current at reduced voltage
[D]
primary is supplied rated kVA
Answer: primary is supplied rated voltage
91
Which type of winding is used in 3phase shell-type transformer ?
[A]
Circular type
[B]
Sandwich type
[C]
Cylindrical type
[D]
Rectangular type
92
The transformer laminations are insulated from each other by
[A]
mica strip
[B]
thin coat of varnish
[C]
paper
[D]
any of the above
Answer: thin coat of varnish
93
When secondary of a current transformer is open-circuited its iron core will be
[A]
hot because of heavy iron losses taking place in it due to high flux density
[B]
hot because primary will carry heavy current
[C]
cool as there is no secondary current
[D]
none of above will happen
Answer: hot because of heavy iron losses taking place in it due to high flux density
94
Iron loss of a transformer can be measured by
[A]
low power factor wattmeter
[B]
unity power factor wattmeter
[C]
frequency meter
[D]
any type of wattmeter
Answer: low power factor wattmeter
95
Negative voltage regulation is indicative that the load is
[A]
capacitive only
[B]
inductive only
[C]
inductive or resistive
[D]
none of the above
96
If the supply frequency to the transformer is increased,”the iron loss will
[A]
not change
[B]
decrease
[C]
increase
[D]
any of the above
97
An ideal transformer will have maximum efficiency at a load such that
[A]
copper loss = iron loss
[B]
copper loss < iron loss
[C]
copper loss > iron loss
[D]
none of the above
Answer: copper loss = iron loss
98
In an actual transformer the iron loss remains practically constant from noload to fullload because
[A]
value of transformation ratio remains constant
[B]
permeability of transformer core remains constant
[C]
core flux remains practically constant
[D]
primary voltage remains constant
Answer: core flux remains practically constant
99
When a given transformer is run at its rated voltage but reduced frequency, its
[A]
flux density remains unaffected
[B]
iron losses are reduced
[C]
core flux density is reduced
[D]
core flux density is increased
Answer: core flux density is increased
100
An ideal transformer is one which has
[A]
no losses and magnetic leakage
[B]
interleaved primary and secondary windings
[C]
a common core for its primary and secondary windings
[D]
core of stainless steel and winding of pure copper metal
Answer: no losses and magnetic leakage
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