Answer লেখা ইমেজে ক্লিক করলে উত্তর অপশন দেখাবে।
1) When speed change of an alternator is changed from 3600 rpm to 1800 rpm, the generated voltage/phase will become-
A) twice
B) one-half
C) one fourth
D) none of this options
2) If an alternator winding has a fractional pitch of 5/6 , the coil span is…..degrees.
A) 130
B) 150
C) 180
D) 320
3) A 50 Hz alternator will run at the greatest possible speed if it is wound for…..poles.
A) 8
B) 6
C) 4
D) 2
4) The frequency of alternator having 4-poles and rotating speed at 1500 rpm is ..... Hz
A) 150
B) 25
C) 60
D) 50
5) Armature reaction in an alternator primarily affects
A) frequency of armature current
B) generated voltage per phase
C) rotor speed
D) None of above.
6) Under no load condition , power drawn by the prime mover of an alternator goes to
A) meet no-load losses.
B) meet cu losses
C) produce power in armature
D) meet induced emf in armature winding
7) The power factor of an alternator is determined by its–
A) excitation
B) speed
C) frequency
D) load
8) At lagging load , armature reaction in an alternator is.
A) cross-magnetising
B) demagnetising
C) magnetising
D) None of above
9) Zero power factor method of an alternator is used to find its–
A) voltage regulation
B) efficiency
C) impedance
D) armature resistance
10) As load power factor of an alternator becomes more leading , the value of generated voltage required to give rated terminal voltage–
A) increase
B) decrease
C) unchange
D) none of above
11) When a coil rotated in magnetic field induced current in it
A) becomes maximum
B) remains same
C) becomes zero
D) continuously changes
12) EMF developed by generator depends upon
A) length of rotating wire
B) area of rotating wire
C) size of magnet
D) radius of wire
13) Squirrel cage bars placed in the rotor pole facts of an alternator help reduce hunting
A) above and below synchronus speed
B) Below synchronus speed
C) above synchronus speed
D) none above
14) At leading power factor , the armature flux in an alternator …..the rotor flux
A) aids.
B) opposes
C) distors
D) does not effect
15) For proper parallel operation, a.c polyphase alternator must have the same–
A) Speed
B) Voltage rating
C) Excitation
D) KVA Rating
See more 50 MCQ of AC Generator
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