Power Electronic Controlled Drives 4

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Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Power Electronic Controlled Drives 4

Part 3: List for questions and answers of Power Electronic Controlled Drives

 

Q1. If field current is decreased in shunt dc motor, the speed of the motor

a) Remains same

b) Increases

c) Decreases

d) None of the above

 

Q2. What is the mechanical power developed by a DC series motor is maximum?

a) Back emf is equal to half the applied voltage

b) Back emf is equal to applied voltage

c) Back emf is equal to zero

d) None of above

 

Q3. In Ward-Leonard system, the lower limit of the speed imposed by

a) Field resistance

b) Armature resistance

c) Residual magnetism of the generator

d) None of above

 

Q4. Ward-Leonard control is basically a ___________ control method

a) Field control

b) Armature resistance control

c) Armature voltage control

d) Field diverter control

 

Q5. For very sensitive and wide speed control, the preferable control method is

a) Armature control

b) Ward-Leonard control

c) Multiple voltage control

d) Field control

 

Q6. Commutator pitches of duplex and simplex lap windings are respectively

a) 4 and 2

b) 2 and 1

c) 4 ang 1

d) 2 and 2 

 

Q7. In DC machine yoke offers

a) Mechanical protection to the machine

b) Flux path completion

c) Produce working flux

d) Both A and B

 

Q8. In a dc machine 72 number of coils are used. Find the number of commutator segments required?

a) 36

b) 37

c) 72

d) 74

 

Q9. Which of the following type of brush and their application is/are correct

a) Carbon brush –>   normal ratings

b) Electro graphite —>  large ratings

c) Copper graphite  ->  low voltage high current density

d) All of the above

 

Q10. Which of the following windings are necessary in case of all dc machines?

a) Closed winding

b) Lap winding

c) Wave winding

d) Open type winding

 

Q11. DC machine windings are

a) Full pitched

b) Short piched

c) Either of these

d) None of the above

 

Q12. Which of the following represents the commutator pitch?

a) Number of conductors spanned by one coil at the back end of the armature

b) Number of conductors spanned by one coil at the front end of the armature

c) The distance between the staring of first coil and its next successive coil

d) Number of commutator segments between two successive coils 

 

Q13. In a dc machine 4 pole lap winding is used. The number of parallel paths are?

a) 2

b) 4

c) 1

d) 8

 

Q14. In a dc machine 6 pole wave winding is used. The number of parallel paths are?

a) 6

b) 4

c) 2

d) 1

 

Q15. Inter pole winding is connected in———?

a) Series with armature

b) Series with main poles

c) Parallel with armature

d) Parallel with main poles

 

Q16. In a lap winding dc machine number of conductors are 100 and number of parallel paths are 10. Find the average pitch

a) 10

b) 100

c) 50

d) 1

 

Q17. In a 2 pole lap winding dc machine , the resistance of one conductor is 2? and total number of conductors is 100. Find the total resistance

a) 200 ohm

b) 100 ohm

c) 50 ohm

d) 10 ohm 

 

Q18. Dummy coils are used for

a) Increasing efficiency

b) Reducing armature reaction

c) Mechanical balancing

d) All of the above 

 

Q19. Which of the following is/are the advantages of carbon brush over the copper brush?

a) They are not hard as copper brush

b) They are self lubricating in nature

c) In case of any sparking they will be less damaged than copper brushes

d) All of the above

 

Q20. Maximum power will be developed when back ems is

a) equals to supply voltage

b) half of the supply voltage

c) doubles the supply voltage

d) all of the above 

 

Part 3: List for questions and answers of Power Electronic Controlled Drives

 

Q1. Answer: b

 

Q2. Answer: a

 

Q3. Answer: c

 

Q4. Answer: c

 

Q5. Answer: b

 

Q6. Answer: b

 

Q7. Answer: d

 

Q8. Answer: c

 

Q9. Answer: d

 

Q10. Answer: a

 

Q11. Answer: a

 

Q12. Answer: d

 

Q13. Answer: b

 

Q14. Answer: c

 

Q15. Answer: a

 

Q16. Answer: a

 

Q17. Answer: c

 

Q18. Answer: c

 

Q19. Answer: d

 

Q20. Answer: b