Armature Winding and EMF Equation Of Alternator - Synchronous Generator - MCQs with answers

Armature Winding And EMF Equation Of Alternator - Synchronous Generator - MCQs with answers

Q1. If coil side in one slot is connected to a coil side in another slot which is one pole pitch distance away from first slot, the winding is said to be

a. Short pitched
b. Full pitched
c. Concentrated
d. Distributed

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Q2. Among the following sentences which is/are true about short pitch coils

a. Less amount of copper is required
b. Eliminates high frequency harmonics
c. Minimizes eddy current and hysteresis losses
d. All of the above

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Q3. In practice, which combination of armature winding is preferred for the alternators?

a. Single layer, full pitched and concentrated type
b. Single layer, short pitched and distributed type
c. Double layer, full pitched and concentrated type
d. Double layer, short pitched and distributed type

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Q4. Due to short pitching, the induced emf gets

a. Reduced
b. Increased
c. Remains same
d. None of these

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Q5. In a 4 pole, 3 phase alternator, armature has 40 slots. It is using an armature winding which is short pitched by one slot. Its coil span factor is

a. 0.9
b. 0.9243
c. 0.9476
d. 0.9876

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Q6. The factor by which there is reduction in the emf due to distribution of coils is called distribution factor. It is given by

a. sin (β / 2m) / msin(β / 2)
b. sin(β / m) / msin(mβ / 2)
c. sin(m β/2) / msin(β / 2)
d. msin(β / 2) / sin(m β / 2)

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Q7. The generalized expression for emf equation of an alternator is

a. E_ph = 4.44f φ T_ph
b. E_ph = 4.44 K_cK_df φ E
c. E_ph = 4.44 K_cK_dfφT_ph
d. E_ph =4 K_cK_df φ T_ph

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Q8. For a short pitch and distributed winding, the value of coil span factor and distributed factor

a. Both are less than unity
b. Less than unity, greater than unity
c. Greater then unity, less than unity
d. Both are greater than unity

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Q9. An armature of a three phase, 8 pole alternators has 120 slots. The distribution factor is equal to

a. 0.897
b. 0.946
c. 0.957
d. 1

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Q10. A 3 phase, 50 Hz, 8 pole, star connected alternator has 120 slots having 10 conductors per slot. The flux per pole is 0.02 Wb and distributed sinusoidally. The induced emf per phase for full pitch winding is

a. 849.816 V
b. 956.782 V
c. 1046.812 V
d. None of these

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