Design of Electrical Machines Questions and Answers – Single Phase Induction Motor Construction

This set of Design of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Single Phase Induction Motor Construction”.

1. How many steps are involved in the construction of single phase induction motor?
a) 3
b) 4
c) 5
d) 6
View Answer

Answer: c
Explanation: There are 5 steps in the construction of the single phase induction motor. They are stator, stator windings, rotor, starting switches, electrolytic capacitor.

2. What is the lamination used for the stator?
a) cast iron
b) die cast aluminium alloy frame
c) cast iron or die cast aluminium alloy frame
d) cast iron and die cast aluminium alloy frame
View Answer

Answer: c
Explanation: The stator is made up of a block of laminations. The block of laminations are made up of cast iron or die cast aluminium alloy frame.

3. What type of coils are used for winding the single phase induction motor generally?
a) rectangular coils
b) square coils
c) cruciform coils
d) circular coils
View Answer

Answer: d
Explanation: The slots house the starting and running windings. The single phase induction motors are generally wound with concentric coils.
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4. How many kinds of single phase windings are present?
a) 2
b) 3
c) 4
d) 5
View Answer

Answer: b
Explanation: There are basically 3 kinds of single phase windings. They are concentric, progressive and skein.

5. How are the poles and pitches in the concentric windings?
a) single pole, different pitches
b) different pole, different pitches
c) different pole, single pitch
d) single pole, single pitch
View Answer

Answer: a
Explanation: The concentric windings have a single pole for a common centre. They have different pitches for each individual coil.
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6. What is the form of the progressive windings?
a) double layer diamond coil windings
b) single layer diamond coil windings
c) multi layer diamond coil windings
d) three layer diamond coil windings
View Answer

Answer: b
Explanation: The progressive windings is one kind of the stator windings. They are in the form of the single layer diamond coil windings.

7. When is the skein winding made use of?
a) when small amount of relatively small size wire is used
b) when large amount of relatively small size wire is used
c) when large amount of relatively large size wire is used
d) when small amount of relatively large size wire is used
View Answer

Answer: a
Explanation: Skein winding is one of the 3 kinds of single phase windings used. It is used when small amount of relatively small size wire is used.
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8. What kind of motor employs the skein winding made use of?
a) maximum horse power single phase induction motor
b) fractional horse power single phase induction motor
c) minimum horse power single phase induction motor
d) zero horse power single phase induction motor
View Answer

Answer: b
Explanation: The skein winding is one of the 3 kinds of single phase induction motor. The skein winding is used when fractional horse power single phase induction motor is used.

9. Which winding is mostly used winding in the single phase induction motor?
a) circular winding
b) concentric winding
c) progressive winding
d) skein winding
View Answer

Answer: b
Explanation: The concentric winding is the most widely used winding. It is also the most flexible winding of the windings used in the single phase induction motor.
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10. What is/are the advantages of the skein winding?
a) low cost to wind
b) low cost to insert
c) permits some freedom of choice of distribution
d) low cost to wind, low cost to insert, permits some freedom of choice of distribution
View Answer

Answer: d
Explanation: The skein winding is the low cost to wind and to insert. It also permits some freedom of choice of distribution.

11. What material is used in the tunnel of the rotor of the single phase induction motor?
a) aluminium
b) copper
c) steel
d) wood
View Answer

Answer: a
Explanation: The rotor consists of a block of slotted laminations. The slots form a series of tunnels that are filled with aluminium in its molten state.

12. What type of operations are used in the starting switches?
a) mechanical operation
b) electrical operation
c) centrifugal operation and mechanical operation
d) centrifugal operation
View Answer

Answer: c
Explanation: The starting switch is used to cut the auxillary winding when the motor attains 75% of the full load speed. The switches operate in both the centrifugal as well as mechanical operation.

13. The ac electrolytic capacitor is formed by winding two sheets of etched aluminium foil.
a) true
b) false
View Answer

Answer: a
Explanation: Modern capacitor start motors employ ac electrolytic capacitors. The ac electrolytic capacitor is formed by winding two sheets of etched aluminium foil, separated by two layers of insulating paper, into a cylindrical shape.

14. The electrolytic capacitor and insulator unit is impregnated using ethylene glycol or a derivative.
a) true
b) false
View Answer

Answer: a
Explanation: The electrolytic capacitor and insulator unit is impregnated using the ethylene glycol. It is also impregnated using the derivative of ethylene glycol.

15. What is the range of the power factor of electrolytic capacitors?
a) 2-4
b) 4-6
c) 6-8
d) 7-9
View Answer

Answer: c
Explanation: The minimum power factor of the electrolytic capacitor is 6. The maximum power factor of the electrolytic capacitor is 8.

Sanfoundry Global Education & Learning Series – Design of Electrical Machines.

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

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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