Question 1 of 68

1. 32. Which material is used for starting resistance of DC starters?

Eureka

Manganin

Constantine

Nichrome

Question 1 of 68

Question 2 of 68

2. 66. What is the speed, if field winding of a DC shunt motor is in open circuit?

Runs at slow speed

Motor runs normally

Runs in very high speed

Stop running

Question 2 of 68

Question 3 of 68

3. 10. What is the formula to calculate the current taken by D.C shunt motor armature?

Question 3 of 68

Question 4 of 68

4. 28. Why carbon composition brush requires in the armature circuit to operate the D.C motor?

Protects armature from over loading

Protects from armature reaction

Reduces the spark in the commutator segment

Increases the starting torque

Question 4 of 68

Question 5 of 68

5. 20. Which speed control methods offers below normal speed in DC shunt motor?

Voltage control method

Armature control method

Ward Leonard system of speed control

Field control method

Question 5 of 68

Question 6 of 68

6. 38. Why commutators are sparking heavily?

Incorrect brush position

Incorrect field connection

Incorrect direction of rotation

Incorrect armature connection

Question 6 of 68

Question 7 of 68

7. 22. Which insulating material belongs to class 'B' insulation?

Leatheroid paper

Cotton

Bamboo

Fiber glass

Question 7 of 68

Question 8 of 68

8. 48. Why the holding coil of a 3 point starter is connected in series with shunt field?

To run motor at low voltage

To protect the motor from high speed

To hold the handle plunger firmly

To limit the load current

Question 8 of 68

Question 9 of 68

9. 43. Which type of speed control of D.C series motor?

Field tapping method

Field parallel method

Field diverter method

Armature diverter method

Question 9 of 68

Question 10 of 68

10. 33. Which DC compound motor is operated at constant speed under varying load?

Differential short shunt

Differential long shunt

Cumulative long shunt

Cumulative short shunt

Question 10 of 68

Question 11 of 68

11. 37. Which speed control method is applied to obtain both below normal and above normal speed in DC motor?

Field control method

Tapped field speed control

Ward Leonard speed control

Armature control method

Question 11 of 68

Question 12 of 68

12. 58. What is the operation in the rewinding process?

Removing of wedges

Removing of winding

Cleaning of slots

Cutting of winding wire

Question 12 of 68

Question 13 of 68

13. 57. How to obtain opposite polarity in adjacent poles of a 4 pole DC motor?

Making current flow in different direction

Making parallel connection of coils

Making series connection of coils

Varying the number of turns in coil

Question 13 of 68

Question 14 of 68

14. 50. What is the purpose of NVC connected in series with the field in 3 point starter?

To prevent increase in speed

To improve the torque

Reduce the field current

To decrease the back emf

Question 14 of 68

Question 15 of 68

15. 52. Which speed control method is used in food mixture motors?

Armature diverter method

Field diverter control method

Voltage control method

Series field tapping method

Question 15 of 68

Question 16 of 68

16. 64. How the direction of rotation of a DC compound motor is changed?

By changing the direction of both field and armature current

By changing the direction of series field current

By interchanging the supply terminals

By changing the direction of armature current

Question 16 of 68

Question 17 of 68

17. 42. Why the D.C series motor field winding is wound with thick wire?

To reduce the armature reaction

To keep maximum inductance

To regulate field voltage

To carry the load current

Question 17 of 68

Question 18 of 68

18. 12. Name the type of DC motor.

Series motor

Short shunt compound motor

Shunt motor

Long shunt compound motor

Question 18 of 68

Question 19 of 68

19. 2. Which instrument is used to test armature winding for short and open circuit?

Digital multimeter

Internal Growler

External Growler

Tong Tester

Question 19 of 68

Question 20 of 68

20. 5. Which formula is used to calculate the speed of DC motor?

Question 20 of 68

Question 21 of 68

21. 11. Which rule is applied to identify the direction of flux in DC motor?

Fleming's right hand rule

Right hand grip rule

Fleming's left hand rule

Cork's screw rule

Question 21 of 68

Question 22 of 68

22. 15. What is the name of winding, if coil pitch is less than pole pitch?

Long chorded winding

Half pitch winding

Short chorded winding

Full pitch winding

Question 22 of 68

Question 23 of 68

23. 59. Which insulating material used in winding is a highly non-hygroscopic and possess good electrical strength?

Empire cloth

Leatheroid paper

Triplex paper

Millinex paper

Question 23 of 68

Question 24 of 68

24. 6. How many parallel paths in duplex lap winding in the armature of 4 pole D.C Motor?

8

4

2

6

Question 24 of 68

Question 25 of 68

25. 47. Which type of instrument is used to test the armature winding?

Ohmmeter

Growler

Multimeter

Megger

Question 25 of 68

Question 26 of 68

26. 13. What is the formula to calculate back EMF in a DC motor?

Question 26 of 68

Question 27 of 68

27. 4. Which winding wire is used for DC field coil?

Double silk covered copper wire

PVC covered copper winding wire

Super enameled copper wire

Single silk covered copper wire

Question 27 of 68

Question 28 of 68

28. 67. What is the reason for reduction in speed of a D.C shunt motor from no load to full load?

Shunt field current increases

Shunt field current decreases

Armature voltage drop decreases

Armature voltage drop increases

Question 28 of 68

Question 29 of 68

29. 30. Why the series field is short circuited at the time of starting in differential compound motor?

To maintain proper direction of rotation

To increase the speed of motor

To decrease the speed of motor

To reduce the starting current

Question 29 of 68

Question 30 of 68

30. 62. Which type of test is illustrated for the armature after rewound?

Shorted coil test

Grounded coil test

Open coil test

Voltage drop test

Question 30 of 68

Question 31 of 68

31. 18. Why shunt field coil is connected in series with holding coil in D.C three point starter?

Increase the holding coil current

Protect the motor in case of open in shunt field

Decrease the holding coil current

Protect the shunt field from over current

Question 31 of 68

Question 32 of 68

32. 19. Why the direction of rotation is changed only by changing the armature current direction in a D.C compound motor?

Maintain motor characteristics

Avoid armature reaction effect

Maintain rated speed

Prevent motor from over loading

Question 32 of 68

Question 33 of 68

33. 29. Why series motor produce high torque and speed initially without load?

Load current flows through field winding

Series field winding wound with thick wire

Armature current and field current are same

Absence of back emf

Question 33 of 68

Question 34 of 68

34. 24. Which type of D.C motor is used for constant speed drives?

Differential short shunt compound motor

DC shunt motor

Differential long shunt compound motor

DC series motor

Question 34 of 68

Question 35 of 68

35. 45. Where D.C compound motors are preferred?

Constant load requirements

High starting torque requirements

Constant speed under varying load requirements

Constant speed requirements

Question 35 of 68

Question 36 of 68

36. 27. What is the effect, if a four point starter resistance is cutoff during running?

Runs at reverse direction

Runs at very high speed

Motor stopped

Runs at slow speed

Question 36 of 68

Question 37 of 68

37. 40. Which motor has this characteristics curve?

Shunt motor

Cumulative compound motor

Series motor

Differential compound motor

Question 37 of 68

Question 38 of 68

38. 8. What is the name of D.C motor?

D.C differential compound motor

D.C series motor

D.C cumulative compound motor

D.C shunt motor

Question 38 of 68

Question 39 of 68

39. 17. Which speed control method of D.C series motor is used for electric train?

Supply voltage control method

Field tapping method

Armature diverter method

Field diverter method

Question 39 of 68

Question 40 of 68

40. 34. How No volt coil is connected in a three point starter with DC shunt motor?

Connected in parallel with armature

Connected in series with shunt field

Connected in series with armature

Directly connected to supply

Question 40 of 68

Question 41 of 68

41. 31. Which is the most effective method of balancing armature?

Dynamic balancing

Static balancing

Attached with counter balancing

Plugged with lead weight balancing

Question 41 of 68

Question 42 of 68

42. 7. Which rule determines the direction of rotation of armature in D.C motor?

Right hand palm rule

Right hand grip rule

Fleming's left hand rule

Fleming's right hand rule

Question 42 of 68

Question 43 of 68

43. 25. Which type of DC motor is used in elevators?

DC differential compound motor

DC shunt motor

DC cumulative compound motor

DC series motor

Question 43 of 68

Question 44 of 68

44. 49. What is the best method to change the DOR of a compound motor without change of its characteristics?

Change series field current direction

Change the current in armature and shunt field together

Change armature current direction

Change shunt field current direction

Question 44 of 68

Question 45 of 68

45. 53. Which speed control system provides a smooth variation of speed from zero to above normal?

Field control

Ward-Leonard system control

Field diverter control

Armature control

Question 45 of 68

Question 46 of 68

46. 63. Why the newly rewound armature must be preheated before varnishing?

Drive out the moisture from it

Make easy to penetrate varnish inside

Maintain uniform spreading of varnishing

Help for quick drying of varnish

Question 46 of 68

Question 47 of 68

47. 68. Which winding fault is determined by the test?

Grounded core fault

Short coil fault

Grounded coil fault

Open coil fault

Question 47 of 68

Question 48 of 68

48. 51. Which type of DC motor is used for sudden application of heavy loads?

Shunt motor

Cumulative compound motor

Differential compound motor

Series motor

Question 48 of 68

Question 49 of 68

49. 35. Which type of armature winding is illustrated?

Simplex lap winding

Duplex lap winding

Triplex lap winding

Quadruplex lap winding

Question 49 of 68

Question 50 of 68

50. 55. Which type of DC armature winding the front pitch (YF) is greater than back pitch (YB)?

Wave winding

Progressive winding

Retrogressive winding

Lap winding

Question 50 of 68

Question 51 of 68

51. 46. What is the necessity of starter for D.C motor?

Control the motor speed

Limit the armature current

Limit the field current

Limit the field voltage

Question 51 of 68

Question 52 of 68

52. 1. Which instrument is used to measure armature winding resistance?

Series type Ohm meter

Multimeter

Megger

Kelvin bridge

Question 52 of 68

Question 53 of 68

53. 3. What is the name of the speed control method of DC motor?

Armature diverter method

Field tapping method

Field diverter method

Voltage control method

Question 53 of 68

Question 54 of 68

54. 14. What is the name of the equipment?

External growler

Megger

Internal growler

Earth resistance tester

Question 54 of 68

Question 55 of 68

55. 61. Calculate the average pitch (Y_A ) for retrogressive wave winding, if No. of armature conductor = 14, No. of slots = 7, No. of poles = 2

14

8

4

6

Question 55 of 68

Question 56 of 68

56. 21. Why starters are required to start D.C motors in industries?

Control the armature reaction

Reduce the armature current

Regulate the field voltage

Smooth operation of motors

Question 56 of 68

Question 57 of 68

57. 36. Which growler test for armature is illustrated?

Shorted coil test

Shorted commutator test

Open coil test

Grounded coil test

Question 57 of 68

Question 58 of 68

58. 56. What reduces the cross sectional area of core material for VA rating?

Dynamo sheet

Low alloy sheet

High alloy sheet

Normal steel sheet

Question 58 of 68

Question 59 of 68

59. 16. What is the purpose of series resistor connected with holding coil in a D.C four point starter?

Limit the current in holding coil

Increase the current in holding coil

Decrease the voltage in holding coil

Increase the voltage in holding coil

Question 59 of 68

Question 60 of 68

60. 26. Which method of speed control gives below the rated speed in DC series motor?

Voltage control method

Tapped field method

Field diverter method

Armature diverter method

Question 60 of 68

Question 61 of 68

61. 65. What is the effect in a D.C shunt motor, if its supply terminals are interchanged?

Runs in the same direction

Runs in high speed

Runs in slow speed

Runs in the reverse direction

Question 61 of 68

Question 62 of 68

62. 60. Which type of armature winding is illustrated?

Retrogressive lap winding

Triplex wave winding

Progressive lap winding

Duplex wave winding

Question 62 of 68

Question 63 of 68

63. 39. What is the action of the induced emf in a running D.C motor?

Opposes the applied voltage

Increases the armature current

Assists the applied voltage

Decreases the armature current

Question 63 of 68

Question 64 of 68

64. 23. What is the temperature value of class 'F' insulation?

120°C

155°C

105°C

90°C

Question 64 of 68

Question 65 of 68

65. 54. What is the purpose of tapes in winding?

Bind the coils

Insulate slots

Wrap the conductor

Insulate exposed conductors

Question 65 of 68

Question 66 of 68

66. 9. Which rule determines the direction of current in D.C motor?

Right hand palm rule

Fleming's right hand rule

Right hand grip rule

Fleming's left hand rule

Question 66 of 68

Question 67 of 68

67. 44. Which type of D.C motor is suitable for shearing machines?

Differential compound motor

Series motor

Shunt motor

Cumulative compound motor

Question 67 of 68

Question 68 of 68

68. 41. What is the purpose of resistor connected with holding coil in 4 point starter?

Protect the motor from overload

Protect the coil from short circuit

Protect the armature from short circuit

Limit current in NVC

Question 68 of 68