Reduction of Effects of Armature Reaction & Commutation in DC Generator - MCQs with Answers

Reduction of Effects of Armature Reaction & Commutation in DC Generator - MCQs with Answers

Q1. The armature in d.c. machines are always placed on rotor

a. Otherwise commutation will not be possible
b. Otherwise there will not be any induced emf
c. Otherwise current will not flow
d. All of these

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Q2. In a d.c. machine, the commutator provides

a. Half wave rectification
b. Full wave rectification
c. Semi controlled rectification
d. Uncontrolled rectification

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Q3. To have perfect neutralization of armature mmf under the pole shoe, the ampere conductors of compensating winding must be

a. Not equal to the total armature ampere conductors under the pole shoe
b. Equal to the total armature ampere conductors under the pole shoe
c. Half of the total armature ampere conductors under the pole shoe
d. Twice of the total armature ampere conductors under the pole shoe

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Q4. Ampere turns per pole for compensating winding in d.c. machines is equal to

a. (pole arc / pole pitch) * armature ampere turns per pole
b. (pole pitch / pole arc) * armature ampere turns per pole
c. (pole arc / pole pitch) * total ampere conductors per pole
d. None of these

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Q5. The compensating windings are used to neutralize the armature reaction in d.c. machines. These windings are connected

a. Across armature
b. In series with armature
c. Either (a) or (b)
d. None of these

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Q6. The armature reaction effect in d.c. machines can be completely neutralized by using

a. Only compensating winding
b. Only interpoles
c. Both compensating winding and interpoles
d. None of these

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Q7. Practically in d.c. machines, it may happen that the emf induced in different parallel paths may not be same. This will cause inequality in brush arm currents and will give rise to copper losses. These effects can be avoided by using

a. Compensating windings
b. Interpoles
c. Equalizer rings
d. All of these

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Q8. In d.c. machines, equalizer connections are provided in

a. Only wave winding
b. Only lap winding
c. Both wave winding and lap winding
d. None of these

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Q9. If in the d.c machine, the reversal of current in the coil is faster than ideal or linear commutation then the commutation is said to be

a. Retarded commutation
b. Under commutation
c. Accelerated commutation
d. Ideal commutation

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Q10. In d.c. machines, the interpoles have tapering shape which results in

a. Simpler design
b. Reduction in the weight
c. Increase in acceleration of commutation
d. All of these

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