Hi friends, these are objectives on electrical engineering emphasis on dc generator check out and comment if you have any doubts......
1) In a dc machine, the armature winding is made up of number of coils distributed in large number of armature slots instead of placing all the coils into two slots to
A) have maximum emf at the output terminals
B) have maximum emf generated in the armature
C) have minimum heat dissipation from the armature
D) make the armature dynamically balanced
Ans:D
2) with the increase in field excitation of a dc generator, its generator emf
A) increases
B) decreases
C) remains constant
D) goes on increasing proportionately
E) increases up to a limit and then remains almost constant
Ans:E
3) The slight curvature at the lower end of the OCC of a self excited dc generator is due to
A) magnetic inertia
B) residual flux
C) high speed
D) high field resistance
Ans:B
4) The fall in speed of a dc generator due to increase in load can be corrected by
A) cooling the armature
B) increasing the excitation
C) reducing the load voltage
D) increasing the input to the prime mover
Ans:D
5) A dc series generator is provided with divertor and is delivering its rated current. If the divertor switch is opened, the terminal voltage will
A) remain constant
B) decrease
C) increase
D) none of these
Ans:C
6) A dc shunt generator is supplying a load of 1.8 KW at 200 V. Its armature and field resistances are 0.4Ω and 200Ω respectively. what is generated emf?
A) 190 V
B) 196 V
C) 204 V
D) 210 V
Ans:C
7) In a dc compound generator, "flat compound" characteristic, required for certain applications, may be obtained by connecting a variable resistance
A) across the series field
B) in series with the series field
C) in parallel with the shunt field
D) in series with the shunt field
Ans:A
8) A cumulatively compounded dc generator is supplying 20 A at 200 V. Now if the series field winding is short circuited, the terminal voltage
A) will remain unaltered at 200 V
B) will rise to 220 V
C) will shoot up to a very high value
D) will become less than 200 V
Ans:D
9) For a specified open circuit voltage of a dc generator, the short circuit current will be maximum when it is
A) separately excited
B) shunt connected
C) cumulatively compounded
D) differentially compounded
Ans:C
10) A shunt generator has a critical field resistance of 200 Ω at a speed of 800 rpm. If the speed of the generator is increased to 1000 rpm, what is the change in the critical field resistance of the generator?
A) Decrease to 160 Ω
B) Remains the same at 200 Ω
C) Increase to 250 Ω
D) Increase to 312.5 Ω
Ans:C
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1) In a dc machine, the armature winding is made up of number of coils distributed in large number of armature slots instead of placing all the coils into two slots to
A) have maximum emf at the output terminals
B) have maximum emf generated in the armature
C) have minimum heat dissipation from the armature
D) make the armature dynamically balanced
Ans:D
2) with the increase in field excitation of a dc generator, its generator emf
A) increases
B) decreases
C) remains constant
D) goes on increasing proportionately
E) increases up to a limit and then remains almost constant
Ans:E
3) The slight curvature at the lower end of the OCC of a self excited dc generator is due to
A) magnetic inertia
B) residual flux
C) high speed
D) high field resistance
Ans:B
4) The fall in speed of a dc generator due to increase in load can be corrected by
A) cooling the armature
B) increasing the excitation
C) reducing the load voltage
D) increasing the input to the prime mover
Ans:D
5) A dc series generator is provided with divertor and is delivering its rated current. If the divertor switch is opened, the terminal voltage will
A) remain constant
B) decrease
C) increase
D) none of these
Ans:C
6) A dc shunt generator is supplying a load of 1.8 KW at 200 V. Its armature and field resistances are 0.4Ω and 200Ω respectively. what is generated emf?
A) 190 V
B) 196 V
C) 204 V
D) 210 V
Ans:C
7) In a dc compound generator, "flat compound" characteristic, required for certain applications, may be obtained by connecting a variable resistance
A) across the series field
B) in series with the series field
C) in parallel with the shunt field
D) in series with the shunt field
Ans:A
8) A cumulatively compounded dc generator is supplying 20 A at 200 V. Now if the series field winding is short circuited, the terminal voltage
A) will remain unaltered at 200 V
B) will rise to 220 V
C) will shoot up to a very high value
D) will become less than 200 V
Ans:D
9) For a specified open circuit voltage of a dc generator, the short circuit current will be maximum when it is
A) separately excited
B) shunt connected
C) cumulatively compounded
D) differentially compounded
Ans:C
10) A shunt generator has a critical field resistance of 200 Ω at a speed of 800 rpm. If the speed of the generator is increased to 1000 rpm, what is the change in the critical field resistance of the generator?
A) Decrease to 160 Ω
B) Remains the same at 200 Ω
C) Increase to 250 Ω
D) Increase to 312.5 Ω
Ans:C
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