Hi friends, this post is about objectives of synchronous machine. Mcq's on synchronous machines which are asked recently in various competitive exams like Gate , Upsc exams and so on. check out and comment if you have any doubts regarding this bits..
1) In an alternator, the armature mmf will be in phase with the main field flux only when the load is purely
A) resistive
B) inductive
C) capacitive
Ans:C
2) A synchronous generator is feeding a zero power factor (lagging) load at rated current. The armature reaction is
A) magnetizing
B) demagnetizing
C) cross-magnetizing
D) ineffective
Ans:B
3) The synchronous reactance is the
A) reaction due to armature reaction of the machine
B) reactance due to leakage flux
C) combined reactance due to leakage flux and armature reaction
D) reactance either due to armature reaction or leakage flux
Ans:C
4) Drop in terminal voltage of an alternator due to armature reaction is countered by
A) damper winding
B) effect of saliency
C) increased prime-mover output
D) automatic voltage regulator
Ans:D
5) The saturated synchronous reactance of an alternator is ......... its unsaturated synchronous reactance
A) more than
B) less than
C) equal to
D) none of these
Ans:B
6) In an alternator, short-circuit current is limited by the
A) saturated synchronous impedance
B) unsaturated synchronous impedance
C) either of the above
D) none of these
Ans:B
7) The power factor on which an alternator operates depends on the
A) speed of the prime-mover
B) nature of the load being supplied
C) armature losses
D) copper losses
Ans:B
8) Unbalanced 3-phase stator currents cause
A) vibrations
B) heating of rotor
C) double frequency currents in the rotor
D) all of the above
Ans:D
9) When the load (inductive) is thrown off, the terminal voltage will
A) increase
B) decrease
C) remains unchanged
D) none of these
Ans:A
10) As the leading factor of the load of an alternator decreases, the magnitude of generated voltage required to give rated terminal voltage
A) increases
B) decreases
C) remains unchanged
Ans:B
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1) In an alternator, the armature mmf will be in phase with the main field flux only when the load is purely
A) resistive
B) inductive
C) capacitive
Ans:C
2) A synchronous generator is feeding a zero power factor (lagging) load at rated current. The armature reaction is
A) magnetizing
B) demagnetizing
C) cross-magnetizing
D) ineffective
Ans:B
3) The synchronous reactance is the
A) reaction due to armature reaction of the machine
B) reactance due to leakage flux
C) combined reactance due to leakage flux and armature reaction
D) reactance either due to armature reaction or leakage flux
Ans:C
4) Drop in terminal voltage of an alternator due to armature reaction is countered by
A) damper winding
B) effect of saliency
C) increased prime-mover output
D) automatic voltage regulator
Ans:D
5) The saturated synchronous reactance of an alternator is ......... its unsaturated synchronous reactance
A) more than
B) less than
C) equal to
D) none of these
Ans:B
6) In an alternator, short-circuit current is limited by the
A) saturated synchronous impedance
B) unsaturated synchronous impedance
C) either of the above
D) none of these
Ans:B
7) The power factor on which an alternator operates depends on the
A) speed of the prime-mover
B) nature of the load being supplied
C) armature losses
D) copper losses
Ans:B
8) Unbalanced 3-phase stator currents cause
A) vibrations
B) heating of rotor
C) double frequency currents in the rotor
D) all of the above
Ans:D
9) When the load (inductive) is thrown off, the terminal voltage will
A) increase
B) decrease
C) remains unchanged
D) none of these
Ans:A
10) As the leading factor of the load of an alternator decreases, the magnitude of generated voltage required to give rated terminal voltage
A) increases
B) decreases
C) remains unchanged
Ans:B
If you like my post please share it with your friends and subscribe to latest updates.. If you have doubts you can start new topic on forum and start discussion with our readers..
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