EE SHORT NOTES(ONE LINER)-TRANSFORMERS PART 2

21
Gas is usually not
liberated due to dissociation of transformer oil unless the oil temperature
exceeds
150°C
22
The noise resulting from
vibrations of laminations set by magnetic forces, is termed as
hum
23
If R2 is the resistance
of secondary winding of the transformer and K is the transformation ratio
then the equivalent secondary resistance referred to primary will be
R2/K2
24
Power transformers are
designed to have maximum efficiency at
nearly full load
25
Primary winding of a
transformer
could either be a low
voltage or high voltage winding
26
The permissible flux
density in case of cold rolled grain oriented steel is around
1.7 Wb/m2
27
Which of the following
does not change in a transformer ?
Frequency
28
In a transformer maximum
voltage regulation occurs when the power factor of the load is
lagging
29
Which of the following
statement concerning parallel operation of transformers is incorrect ?
Transformers must have
equal kVA
30
Dust should never be
allowed to accumulate on the windings and core of a drytype transformer
because it
reduces dissipation of
heat
31
The transformation ratio
of a transformer, for a given application
is fixed but not
constant
32
Which of the following
can be reduced when the flux density in the transformer core is increased ?
Size of the
transformer
33
Buchholz relay is used
in
transformer protection
34
In core-type
transformers, the concentric windings are used with
low voltage winding
placed next to core
35
A sinusoidal e.m.f.
lags the flux inducing
it by 90°
36
A distribution
transformer has low flux denSity because
it is constantly
connected to the supply
37
The kVA rating ratio of
transformers operating in parallel, as a general rule, should be within
3 : 1
38
H.R.C. fuses on a
transformer provide protection against
external faults
39
Which of the following:
statements about a transformer having a small short-circuit voltage is true ?
A high short-circuit
current flows through the transformer
40
A transformer is working
at its full load and its efficiency is also maximum. Its iron loss is 1 kW,
its copper loss at half load will be
0.25 kW
MAHATRANSCO Exam Pattern & Syllabus(Electrical ,Civil,Electronics & Telecommunication) Engineering 2017
EE SHORT NOTES(ONE LINER)-TRANSFORMERS PART 1

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