Question 1 of 68

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

Limit current in NVC

Protect the motor from overload

Protect the coil from short circuit

Protect the armature from short circuit

Question 1 of 68

Question 2 of 68

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

Nichrome

Manganin

Constantine

Eureka

Question 2 of 68

Question 3 of 68

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

Empire cloth

Millinex paper

Leatheroid paper

Triplex paper

Question 3 of 68

Question 4 of 68

4. 12. Name the type of DC motor.

Shunt motor

Short shunt compound motor

Series motor

Long shunt compound motor

Question 4 of 68

Question 5 of 68

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

Limit the field voltage

Limit the field current

Limit the armature current

Control the motor speed

Question 5 of 68

Question 6 of 68

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

DC shunt motor

DC series motor

DC differential compound motor

DC cumulative compound motor

Question 6 of 68

Question 7 of 68

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

Armature diverter method

Field diverter method

Voltage control method

Tapped field method

Question 7 of 68

Question 8 of 68

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

Armature voltage drop decreases

Shunt field current increases

Shunt field current decreases

Armature voltage drop increases

Question 8 of 68

Question 9 of 68

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

Drive out the moisture from it

Maintain uniform spreading of varnishing

Make easy to penetrate varnish inside

Help for quick drying of varnish

Question 9 of 68

Question 10 of 68

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

4

2

8

6

Question 10 of 68

Question 11 of 68

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

Voltage control method

Field diverter method

Field tapping method

Armature diverter method

Question 11 of 68

Question 12 of 68

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

Field control method

Ward Leonard system of speed control

Voltage control method

Armature control method

Question 12 of 68

Question 13 of 68

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

To prevent increase in speed

To decrease the back emf

Reduce the field current

To improve the torque

Question 13 of 68

Question 14 of 68

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

Bamboo

Leatheroid paper

Cotton

Fiber glass

Question 14 of 68

Question 15 of 68

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

Cumulative compound motor

Differential compound motor

Series motor

Shunt motor

Question 15 of 68

Question 16 of 68

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

Motor stopped

Runs at slow speed

Runs at reverse direction

Runs at very high speed

Question 16 of 68

Question 17 of 68

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

Low alloy sheet

Dynamo sheet

Normal steel sheet

High alloy sheet

Question 17 of 68

Question 18 of 68

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

To maintain proper direction of rotation

To reduce the starting current

To decrease the speed of motor

To increase the speed of 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

External Growler

Internal Growler

Tong Tester

Question 19 of 68

Question 20 of 68

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

Constant speed under varying load requirements

Constant speed requirements

High starting torque requirements

Constant load requirements

Question 20 of 68

Question 21 of 68

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

Megger

Ohmmeter

Multimeter

Growler

Question 21 of 68

Question 22 of 68

22. 40. Which motor has this characteristics curve?

Shunt motor

Differential compound motor

Series motor

Cumulative compound motor

Question 22 of 68

Question 23 of 68

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

Decrease the voltage in holding coil

Increase the voltage in holding coil

Limit the current in holding coil

Increase the current in holding coil

Question 23 of 68

Question 24 of 68

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

Protect the motor in case of open in shunt field

Increase the holding coil current

Decrease the holding coil current

Protect the shunt field from over current

Question 24 of 68

Question 25 of 68

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

120°C

155°C

90°C

105°C

Question 25 of 68

Question 26 of 68

26. 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

8

14

4

6

Question 26 of 68

Question 27 of 68

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

Triplex lap winding

Simplex lap winding

Duplex lap winding

Quadruplex lap winding

Question 27 of 68

Question 28 of 68

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

Short chorded winding

Full pitch winding

Long chorded winding

Half pitch winding

Question 28 of 68

Question 29 of 68

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

Avoid armature reaction effect

Maintain rated speed

Maintain motor characteristics

Prevent motor from over loading

Question 29 of 68

Question 30 of 68

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

DC shunt motor

Differential long shunt compound motor

DC series motor

Differential short shunt compound motor

Question 30 of 68

Question 31 of 68

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

Field diverter control

Armature control

Field control

Ward-Leonard system control

Question 31 of 68

Question 32 of 68

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

Duplex wave winding

Progressive lap winding

Retrogressive lap winding

Triplex wave winding

Question 32 of 68

Question 33 of 68

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

Field tapping method

Supply voltage control method

Armature diverter method

Field diverter method

Question 33 of 68

Question 34 of 68

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

Directly connected to supply

Connected in series with armature

Connected in parallel with armature

Connected in series with shunt field

Question 34 of 68

Question 35 of 68

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

Cutting of winding wire

Cleaning of slots

Removing of winding

Removing of wedges

Question 35 of 68

Question 36 of 68

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

Reduce the armature current

Control the armature reaction

Regulate the field voltage

Smooth operation of motors

Question 36 of 68

Question 37 of 68

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

Absence of back emf

Series field winding wound with thick wire

Load current flows through field winding

Armature current and field current are same

Question 37 of 68

Question 38 of 68

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

Question 38 of 68

Question 39 of 68

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

To hold the handle plunger firmly

To run motor at low voltage

To protect the motor from high speed

To limit the load current

Question 39 of 68

Question 40 of 68

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

Field diverter method

Field tapping method

Field parallel method

Armature diverter method

Question 40 of 68

Question 41 of 68

41. 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 41 of 68

Question 42 of 68

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

Decreases the armature current

Increases the armature current

Opposes the applied voltage

Assists the applied voltage

Question 42 of 68

Question 43 of 68

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

By interchanging the supply terminals

By changing the direction of armature current

By changing the direction of both field and armature current

By changing the direction of series field current

Question 43 of 68

Question 44 of 68

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

Earth resistance tester

Internal growler

External growler

Megger

Question 44 of 68

Question 45 of 68

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

D.C differential compound motor

D.C shunt motor

D.C cumulative compound motor

D.C series motor

Question 45 of 68

Question 46 of 68

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

Runs at slow speed

Motor runs normally

Stop running

Runs in very high speed

Question 46 of 68

Question 47 of 68

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

Open coil test

Grounded coil test

Shorted commutator test

Shorted coil test

Question 47 of 68

Question 48 of 68

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

Insulate exposed conductors

Insulate slots

Bind the coils

Wrap the conductor

Question 48 of 68

Question 49 of 68

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

Grounded coil test

Voltage drop test

Shorted coil test

Open coil test

Question 49 of 68

Question 50 of 68

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

Runs in high speed

Runs in slow speed

Runs in the same direction

Runs in the reverse direction

Question 50 of 68

Question 51 of 68

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

Open coil fault

Grounded core fault

Short coil fault

Grounded coil fault

Question 51 of 68

Question 52 of 68

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

Differential long shunt

Cumulative long shunt

Cumulative short shunt

Differential short shunt

Question 52 of 68

Question 53 of 68

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

Series motor

Differential compound motor

Shunt motor

Cumulative compound motor

Question 53 of 68

Question 54 of 68

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

Attached with counter balancing

Static balancing

Plugged with lead weight balancing

Dynamic balancing

Question 54 of 68

Question 55 of 68

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

Right hand grip rule

Fleming's left hand rule

Right hand palm rule

Fleming's right hand rule

Question 55 of 68

Question 56 of 68

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

Change shunt field current direction

Change series field current direction

Change the current in armature and shunt field together

Change armature current direction

Question 56 of 68

Question 57 of 68

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

Series type Ohm meter

Megger

Multimeter

Kelvin bridge

Question 57 of 68

Question 58 of 68

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

Right hand grip rule

Right hand palm rule

Fleming's right hand rule

Fleming's left hand rule

Question 58 of 68

Question 59 of 68

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

Progressive winding

Retrogressive winding

Lap winding

Wave winding

Question 59 of 68

Question 60 of 68

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

Protects armature from over loading

Reduces the spark in the commutator segment

Protects from armature reaction

Increases the starting torque

Question 60 of 68

Question 61 of 68

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

Making current flow in different direction

Varying the number of turns in coil

Making parallel connection of coils

Making series connection of coils

Question 61 of 68

Question 62 of 68

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

Single silk covered copper wire

PVC covered copper winding wire

Double silk covered copper wire

Super enameled copper wire

Question 62 of 68

Question 63 of 68

63. 38. Why commutators are sparking heavily?

Incorrect direction of rotation

Incorrect field connection

Incorrect armature connection

Incorrect brush position

Question 63 of 68

Question 64 of 68

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

To regulate field voltage

To keep maximum inductance

To carry the load current

To reduce the armature reaction

Question 64 of 68

Question 65 of 68

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

Armature diverter method

Voltage control method

Series field tapping method

Field diverter control method

Question 65 of 68

Question 66 of 68

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

Question 66 of 68

Question 67 of 68

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

Tapped field speed control

Armature control method

Ward Leonard speed control

Field control method

Question 67 of 68

Question 68 of 68

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

Question 68 of 68