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) The angle between induced emf and terminal voltage on no-load for a single phase alternator is
A) 180°
B) 90°
C) 0°
D) none of these
Ans:C
2) The 5th space harmonics in the mmf developed by balanced fundamental frequency armature currents rotate at .......... times the synchronous speed with respect to the field
A) 5/6
B) 6/5
C) 5/4
D) 5/7
Ans:B
3) The seventh space harmonics in the mmf produced by balanced fundamental frequency armature currents rotate at ............ times the synchronous speed with respect to the field.
A) 5/7
B) 8/7
C) 6/7
D) 7/6
Ans:C
4) The phase sequence of a three-phase alternator will reverse if
A) the field current is reversed keeping the direction of rotation same
B) the field current remains the same but the direction of rotation is reversed
C) the field current is reversed and the number of poles is doubled
D) the number of poles is doubled without reversing the field current
Ans:B
5) A 500 MW 3-phase Y-connected synchronous generator has a rated voltage of 21.5 Kv at 0.85 pf. The line current when operating at full load rated conditions will be
A) 13.43 KA
B) 15.79 KA
C) 23.25 KA
D) 27.36 KA
Ans:B
6) The rating of a synchronous machine is usually governed by its
A) speed
B) temperature rise
C) weight
D) none of these
Ans:B
7) How can the reactive power delivered by a synchronous generator be controlled?
A) By changing the prime mover input
B) By changing the excitation
C) By changing the direction of rotation
D) By changing the prime mover speed
Ans:B
8) The rating of the prime-mover driving an alternator is determined entirely by its ....... rating
A) volatge
B) current
C) Kw output
D) speed
Ans:C
9) When an alternator designed for operation at 60 Hz is operated at 50 Hz
A) kVA rating will increase in the ratio of 1.2
B) operating voltage will reduce in the ratio of 5/6
C) operating voltage will increase in the ratio of 1.2
D) operating voltage will reduce in the ratio of (5/6)^2
Ans:B
10) The flux setup by the armature current, which does not cross the air-gap and takes a different path is called the ............... flux
A) leakage
B) main
C) cross-magnetizing
D) demagnetizing
Ans:A
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1) The angle between induced emf and terminal voltage on no-load for a single phase alternator is
A) 180°
B) 90°
C) 0°
D) none of these
Ans:C
2) The 5th space harmonics in the mmf developed by balanced fundamental frequency armature currents rotate at .......... times the synchronous speed with respect to the field
A) 5/6
B) 6/5
C) 5/4
D) 5/7
Ans:B
3) The seventh space harmonics in the mmf produced by balanced fundamental frequency armature currents rotate at ............ times the synchronous speed with respect to the field.
A) 5/7
B) 8/7
C) 6/7
D) 7/6
Ans:C
4) The phase sequence of a three-phase alternator will reverse if
A) the field current is reversed keeping the direction of rotation same
B) the field current remains the same but the direction of rotation is reversed
C) the field current is reversed and the number of poles is doubled
D) the number of poles is doubled without reversing the field current
Ans:B
5) A 500 MW 3-phase Y-connected synchronous generator has a rated voltage of 21.5 Kv at 0.85 pf. The line current when operating at full load rated conditions will be
A) 13.43 KA
B) 15.79 KA
C) 23.25 KA
D) 27.36 KA
Ans:B
6) The rating of a synchronous machine is usually governed by its
A) speed
B) temperature rise
C) weight
D) none of these
Ans:B
7) How can the reactive power delivered by a synchronous generator be controlled?
A) By changing the prime mover input
B) By changing the excitation
C) By changing the direction of rotation
D) By changing the prime mover speed
Ans:B
8) The rating of the prime-mover driving an alternator is determined entirely by its ....... rating
A) volatge
B) current
C) Kw output
D) speed
Ans:C
9) When an alternator designed for operation at 60 Hz is operated at 50 Hz
A) kVA rating will increase in the ratio of 1.2
B) operating voltage will reduce in the ratio of 5/6
C) operating voltage will increase in the ratio of 1.2
D) operating voltage will reduce in the ratio of (5/6)^2
Ans:B
10) The flux setup by the armature current, which does not cross the air-gap and takes a different path is called the ............... flux
A) leakage
B) main
C) cross-magnetizing
D) demagnetizing
Ans:A
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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