Armature Reaction in DC Generator - MCQs with Answers

Armature Reaction in DC Generator - MCQs with Answers

Q1. In a d.c. machine, the form of armature reaction mmf is

a. Triangular
b. Sinusoidal
c. Saw tooth
d. Rectangular

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Q2. For low reluctance path for the flux in armature, the permeability of the material should be

a. High
b. Low
c. Doesn't depend upon the permeability


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Q3. In a d.c. machine, the eddy current losses mainly occurs in

a. Armature
b. Windings
c. Yoke
d. At brush contact

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Q4. The conductors which will cause distortion in the main field flux of d.c. machine is

a. Demagnetizing armature conductors
b. Cross magnetizing armature conductors
c. Both (a) and (b)
d. None of these

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Q5. If the brush shift angle is given in electrical degrees then for converting it into mechanical degree by using the relation

a. θ _electrical / P
b. 2 θ _electrical / P
c. θ _electrical / 2P
d. 2P / θ _electrical

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Q6. A 6 pole wave wound d.c. generator has 460 armature conductors carrying armature current of 180 A. The armature reaction demagnetizing and cross magnetizing ampere turns per pole if brushes are shifted by 6 degree electrical from G.N.A are

a. 3220, 230
b. 3220, 260
c. 260, 3220
d. 230, 3220

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Q7. For neutralizing the demagnetizing effect of armature reaction, an extra number of winding turns are provided on each pole. To calculate number of extra turns per pole the equation used is

a. (AT_d / I) * leakage coefficient
b. (AT_d / I) / leakage coefficient
c. Leakage coefficient / (AT_d / I)
d. (AT_d / I)

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Q8. Due to the effect of armature reaction in d.c. machine, the value of generated voltage and flux per pole

a. Increases, decreases
b. Decreases, decreases
c. Decreases, increases
d. Increases, increases

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Q9. The armature reaction in d.c. machine causes distortion in the main field flux. This effect of armature reaction can be reduced by

a. Increasing the length of air gap
b. Decreasing the length of air gap
c. Increasing the number of poles
d. Decreasing the number of poles

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Q10. Two 4 pole d.c. machines of identical armature, one with wave winding and other with lap winding are wound. Then

a. The lap wound machine will have more generated voltage
b. Wave wound machine will have more generated voltage
c. Both will have same generated voltage
d. None of these

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