All changes in the state of matter of a substance requires a change in
mass
temperature
permission
energy
Q.2.
Identify the correct order for the voltage transformation for the three-phase transformers.
D-Y > D-D = Y-Y > Y-D
D-Y > D-D > Y-Y > Y-D
D-Y > D-D = Y-Y < Y-D
D-Y > D-D < Y-Y < Y-D
Q.3.
For a star-delta three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be?
73%
57%
173%
157%
Q.4.
For a delta-star three phase transformer, if the transformation ratio is ‘x:1’, then how much percent of output will be improved?
73%
57%
173%
157%
Q.5.
In three phase supply, the voltage phases are displaced by ________ and in two phase by ___________
120°, 90°
180°, 90°
120, 120°
120°, 180°
Q.6.
Operating transformers in parallel gives the advantage of ___________
reliable loading
increased capacity of power system
reducing the capacity of substation
all of the mentioned
Q.7.
Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal and xa > xb. Then?
A has poorer pf than B
B has poorer pf than B
lesser power factor angle
both operate at same power factor
Q.8.
Two single phase transformers A and B are operating in parallel having same impedance. But the x/r ratio of them are not equal. Then total kVA output of the output will be ___________
less than sum of kVA of A and B
more than sum of kVA of A and B
equal to sum of kVA of A and B
any of the mentioned
Q.9.
Which of the following is the correct matching made for the harmonics and the associated harmonic component?A. Positive sequence components - 5th harmonic componentB. Negative sequence components - 7th harmonic componentC. Zero sequence components - 3rd harmonic component
A, B, C
C
A, B
B, C
Q.10.
Which if the conditions is must be fulfilled for satisfactory parallel operation of transformers?
Same voltage ratio
Leakage impedances should be inversely proportional to kVA of the transformer
Same pu impedance
Correct polarity
Q.11.
A 2000/1000/three winding transformer is to be used as auto transformer with supply ofV. Two loads ofkVA atand other one atkVA at 1000V. The total kVA supplied will be?
1230 kVA
1440 kVA
1680 kVA
1150 kVA
Q.12.
Transformer operating in parallel will share a common load in the best possible manner if ____________
leakage impedances are proportional to their kVA rating
pu leakage impedances are equal
leakage impedances are equal
any of the mentioned
Q.13.
What is the phase change of a solid to a liquid?
freezing
melting
boiling
condensation
Q.14.
What is it called when a solid turns directly into a gas?
Sublimation
Condensation
Liquid
deposition
Q.15.
Change from gas to liquid...
condensation
evaporation
expansion
movement
Q.16.
Change from Liquid to Solid is call......
fusion
Freezing
sublimation
evaporation
Q.17.
What is deposition?
Phase change from gas to solid
phase change from liquid to solid
Phase change from solid to gas
Phase change from liquid to gas
Q.18.
Change from liquid to gas is called....
expansion
evaporation
condensation
sublimation
Q.19.
During a phase change what happens to temperature?
it increases
it decreases
depends; if being heated it increases, if being cooled it decreases
stays constant
Q.20.
What is sublimation?
phase change between solid and liquid
pahse change from gas to solid
phase change from solid to gas
phase change from solid to solid
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