Electrical Machines Questions and Answers – Constructional Features of Rotating Electrical Machines-1

This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Constructional Features of Rotating Electrical Machines-1”.

1. Which of the following two windings produces/induces the working flux and working EMF respectively?
a) field winding and armature winding
b) armature winding and field winding
c) both are produced in field winding
d) both are produced in armature winding
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2. Armature winding carries which of the following current?
a) magnetizing current only
b) load current only
c) both magnetizing current and load current
d) none of the mentioned
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3. Field winding carries which of the following current?
a) exciting current only
b) load current only
c) both exciting current and load current
d) none of the mentioned
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4. Which of the following statements are correct regarding exciting current?

(i) exciting current varies with the load
(ii) exciting current doesn't vary with load
(iii) exciting current produces only a working magnetic flux
(iv) exciting current is not responsible for the production of working  magnetic flux

a) (i) & (iv)
b) (ii) & (iii)
c) (i) & (iii)
d) (ii) & (iv)
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5. Current in the field winding is ___________
a) AC always
b) DC always
c) Both AC and DC
d) Either AC or DC
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6. The rating of the armature winding is ___________
a) 1/2 to 2% of the rated power of the machine
b) less than the power rating of the machine
c) greater than the power rating of the machine
d) equal to the power rating of the machine
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7. The power rating of the field winding is ___________
a) equal to the power rating of the machine
b) 1/2 to 2% of the rated power of the machine
c) greater than the power rating of the machine
d) less than the power rating of the machine
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8. What is the reason behind armature structure for both DC and AC machines being laminated?
a) reduce i²R losses
b) reduce the leakage flux
c) reduce the eddy current losses
d) for better operating power factor
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9. Armature winding is one in which working ___________
a) flux is produced by field current
b) flux is produced by the working emf
c) emf is produced by the working flux
d) emf is produced by the leakage flux
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10. Why is the air gap between stator and rotor should be kept as small as mechanically possible in induction motor?
a) to reduce the leakage flux between stator and rotor
b) as it leads to better operating power factor of the induction motor
c) reduce the eddy current losses
d) both, to reduce leakage flux between stator and rotor, and also for better operating power factor
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Sanfoundry Global Education & Learning Series – Electrical Machines.

To practice all areas of Electrical Machines, here is complete set of 1000+ Multiple Choice Questions and Answers.