Quiz  /  Industrial Drives Electrical Engineering MCQ Interview Questions and Answers PDF

  • 1. 
    The selection of an electric motor for any application depends on which of the following factors ?

  • Electrical characteristics
  • Mechanical characteristics
  • Size and rating of motors
  • Cost
  • All of the above

  • 2. 
    For a particular application the type of electric-and control gear are determined by which of the following considerations ?

  • Starting torque
  • Conditions of environment
  • Limitation on starting current
  • Speed control range and its nature
  • All of the above

  • 3. 
    Which of the following motors is preferred for traction work ?

  • Universal motor
  • D.C. series motor
  • Synchronous motor
  • Three-phase induction motor

  • 4. 
    Which of the following motors always starts on load ?

  • Conveyor motor
  • Floor mill motor
  • Fan motor
  • All of the above

  • 5. 
    is preferred for automatic drives.

  • Squirrel cage induction motor
  • Synchronous motors
  • Ward-Leonard controlled D.C. motors
  • Any of the above

  • 6. 
    When the load is above _____ a synchronous motor is found to be more economical.

  • 2 kW
  • 20 kW
  • 50 kW
  • 100 kW

  • 7. 
    The load cycle for a motor driving a power press will be

  • variable load
  • continuous
  • continuous but periodical
  • intermittent and variable load

  • 8. 
    Light duty cranes are used in which of the following ?

  • Power houses
  • Pumping stations
  • Automobile workshops
  • All of the above

  • 9. 
    While selecting an electric motor for a floor mill, which electrical characteristics will be of least significance ?

  • Running characteristics
  • Starting characteristics
  • Efficiency
  • Braking

  • 10. 
    Which of the following motors are pre-ferred for overhead travelling cranes ?

  • Slow speed motors
  • Continuous duty motors
  • Short time rated motors
  • None of the above

  • 11. 
    is preferred for synthetic fibre mills.

  • Synchronous motor
  • Reluctance motor
  • Series motor
  • Shunt motor

  • 12. 
    Ward-Leonard controlled D.C. drives are generally used for ______ excavators.

  • Light duty
  • Medium duty
  • Heavy duty
  • All of the above

  • 13. 
    Which of the following motors is used for elevators ?

  • Induction motor
  • Synchronous motor
  • Capacitor start single phase motor
  • Any of the above

  • 14. 
    Which part of a motor needs maximum attention for maintenance ?

  • Frame
  • Rearing
  • Stator winding
  • Rotor winding

  • 15. 
    need frequent starting and stopping of electric motors,

  • Paper mills
  • Grinding mills
  • Air-conditioners
  • Lifts and hoists

  • 16. 
    Which feature, while selecting a.motor for centrifugal pump, will be of least significance ?

  • Starting characteristics
  • Operating speed
  • Horse power
  • Speed control

  • 17. 
    _______ motor is a constant speed motor.

  • Synchronous motor
  • Schrage motor
  • Induction motor
  • Universal motor

  • 18. 
    The starting torque in case of centrifugal pumps is generally

  • less than running torque
  • same as running torque
  • slightly more than running torque
  • double the running torque

  • 19. 
    Which of the following motors are best for the rolling mills ?

  • Single phase motors
  • Squirrel cage induction motors
  • Slip ring induction motors
  • D.C. motors

  • 20. 
    is not a part of ball bearing ?

  • Inner race
  • Outer race
  • Cage
  • Bush

  • 21. 
    The starting torque of a D.C. motor is independent of which of the following?

  • Flux
  • Armature current
  • Flux and armature current
  • Speed

  • 22. 
    Rotor of a motor is usually supported on _______ bearings.

  • ball or roller
  • needle
  • bush
  • thrust

  • 23. 
    For which of the following applications D.C. motors are still preferred ?

  • High efficiency operation
  • Reversibility
  • Variable speed drive
  • High starting torque

  • 24. 
    In a paper mill where constant speed is required

  • synchronous motors are preferred
  • A.C. motors are preferred
  • individual drive is preferred
  • group drive is preferred

  • 25. 
    A reluctance motor

  • is provided with slip rings
  • requires starting gear
  • has high cost
  • is compact

  • 26. 
    The size of an excavator is usually expressed in terms of

  • ‘crowd’ motion
  • angle of swing
  • cubic metres
  • travel in metres

  • 27. 
    For blowers which of the following motor is preferred ?

  • D.C. series motor
  • D.C. shunt motor
  • Squirrel cage induction motor
  • Wound rotor induction motor

  • 28. 
    Belted slip ring induction motor is almost invariably used for

  • water pumps
  • jaw crushers
  • centrifugal blowers
  • none of the above

  • 29. 
    Which of the following is essentially needed while selecting a motor ?

  • Pulley
  • Starter
  • Foundation pedal
  • Bearings

  • 30. 
    Reluctance motor is a

  • variable torque motor
  • low torque variable speed motor
  • self starting type synchronous motor
  • low noise, slow speed motor

  • 31. 
    method of starting a three phase induction motor needs six terminals.

  • Star-delta
  • Resistance starting
  • Auto-transformer
  • None of the above

  • 32. 
    In ______ method of staging three phase induction motors the starting voltage is not reduced.

  • auto-transformer
  • star-delta
  • slip ring
  • any of the above

  • 33. 
    In jaw crushers a motor has to often start against ______ load.

  • heavy
  • medium
  • normal
  • low

  • 34. 
    For a motor-generator set which of the following motors will be preferred ?

  • Synchronous motor
  • Slip ring induction motor
  • Pole changing induction motor
  • Squirrel cage induction motor

  • 35. 
    Which of the following motors is usually preferred for kiln drives ?

  • Cascade controlled A.C. motor
  • Slip ring induction motor
  • Three  phase  shunt  wound  com-mutator motor
  • Any of the above

  • 36. 
    Heat control switches are used in

  • transformers
  • cooling ranges
  • three phase induction motors
  • single phase

  • 37. 
    In squirrel cage induction motors which of the following methods of starting cannot be used ?

  • Resistance in rotor circuit
  • Resistance in stator circuit
  • Auto-transformer starting
  • Star-delta starting

  • 38. 
    In which of the following applications the load on motor changes in cyclic order ?

  • Electric shovels
  • Cranes
  • Rolling mills
  • All of the above

  • 39. 
    Flame proof motors are used in

  • paper mills
  • steel mills
  • moist atmospheres
  • explosive atmospheres

  • 40. 
    Which of the following machines has heavy fluctuation of load ?

  • Printing machine
  • Punching machine
  • Planer
  • Lathe

  • 41. 
    For derries and winches which of the following drives can be used ?

  • Pole changing squirrel cage motors
  • D.C. motors with Ward-leonard con-trol
  • A.C. slip ring motors with variable resistance
  • Any of the above

  • 42. 
    Battery operated scooter for braking uses

  • plugging
  • mechanical braking
  • regenerative braking
  • rheostatic braking

  • 43. 
    has least range of speed control.

  • Slip ring induction motor
  • Synchronous motor
  • D.C. shunt motor
  • Schrage motor

  • 44. 
    has the least value of starting torque to full load torque ratio.

  • D.C. shunt motor
  • D.C. series motor
  • Squirrel cage induction motor
  • Slip ring induction motor

  • 45. 
    In case of _______ speed control by injecting e.m.f. in the rotor circuit is possible,

  • d.c. shunt motor
  • schrage motor
  • synchronous motor
  • slip ring induction motor

  • 46. 
    A pony motor is used for the starting which of the following motors ?

  • Squirel cage induction motor
  • Schrage motor
  • Synchronous motor
  • None of the above

  • 47. 
    In ________  the  speed can be varied by changing the position of brushes.

  • slip ring motor
  • schrage motor
  • induction motor
  • repulsion motor

  • 48. 
    In which of the following applications variable speed operation is preferred ?

  • Exhaust fan
  • Ceiling fan
  • Refrigerator
  • Water pump

  • 49. 
    Heavy duty cranes are used in

  • ore handling plants
  • steel plants
  • heavy engineering workshops
  • all of the above

  • 50. 
    The travelling speed of cranes varies from

  • 20 to 30 m/s
  • 10 to 15 m/s
  • 5 to 10 m/s
  • 1 to 2.5 m/s

  • 51. 
    Besides a constant speed a synchronous rotor possesses which of the following advantages ?

  • Lower cost
  • Better efficiency
  • High power factor
  • All of the above

  • 52. 
    By the use of which of the following m D.C. can be obtained from AC. ?

  • Silicon diodes
  • Mercury arc rectifier
  • Motor generator set
  • Any of the above

  • 53. 
    Which of the following motors is preferred when quick speed reversal is the main consideration ?

  • Squirrel cage induction motor
  • Wound rotor induction motor
  • Synchronous motor
  • D.C. motor

  • 54. 
    Which of the following motors is preferred when smooth and precise speed control over a wide range is desired ?

  • D.C. motor
  • Squirrel cage induction motor
  • Wound rotor induction motor
  • Synchronous motor

  • 55. 
    For crane travel which of the following motors is normally used ?

  • Synchronous motor
  • D.C. differentially compound motor
  • Ward-Leonard controlled D.C. shunt motor
  • AC. slip ring motor

  • 56. 
    The capacity of a crane is expressed in terms of

  • type of drive
  • span
  • tonnes
  • any of the above

  • 57. 
    The characteristics of drive for crane hoisting and lowering are which of the following ?

  • Precise control
  • Smooth movement
  • Fast speed control
  • All of the above

  • 58. 
    Which of the following motors is preferred for boom hoist of a travelling crane ?

  • Single phase motor
  • Synchronous motor
  • A.C. slip ring motor
  • Ward-Leonard controlled D.C. shunt motor

  • 59. 
    A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is

  • slop speed operation
  • high starting torque
  • low windage losses
  • all of the above

  • 60. 
    Which of the following motors has series characteristics ?

  • Shaded pole motor
  • Repulsion motor
  • Capacitor start motor
  • None of the above

  • 61. 
    Which of the following happens when star-delta starter is used ?

  • Starting voltage is reduced
  • Starting current is reduced
  • Both (a) and (b)
  • None of the above

  • 62. 
    For a D.C. shunt motor which of the following is incorrect ?

  • Unsuitable for heavy duty starting
  • Torque varies as armature current
  • Torque-armature current is a straight line
  • Torque is zero for zero armature current

  • 63. 
    For which of the following applications motor has to start with high acceleration?

  • Oil expeller
  • Floor mill
  • Lifts and hoists
  • Centrifugal pump

  • 64. 
    Which of the following types of motor enclosure is safest ?

  • Totally enclosed
  • Totally enclosed fan cooled
  • Open type
  • Semi closed

  • 65. 
    While selecting motor for an air conditioner which of the following characteristics is of great importance ?

  • Type of bearings
  • Type of enclosure
  • Noise
  • Arrangement for power transmis¬sion
  • None of the above

  • 66. 
    The diameter of the rotor shaft for an  electric motor depends on which of the following ?

  • r.p.m. only
  • Horse power only
  • Horse power and r.p.m.
  • Horse power, r.p.m. and power factor

  • 67. 
    Which of the following alternatives will be cheaper ?

  • A 100 H.P. AC. three phase motor
  • Four motors of 25 H.P. each
  • Five motors of 20 H.P. each
  • Ten motors of 10 H.P. each

  • 68. 
    The cost of an induction motor will increase as

  • horsepower rating increases but r.p.m. decreases
  • horsepower rating decreases but r.p.m. increases
  • horsepower rating and operating speed increases
  • horsepower rating and operating speed decreases

  • 69. 
    In series motor which of the following methods can be used for changing the flux per pole ?

  • Tapped field control
  • Diverter field control
  • Series-parallel control
  • Any of the above
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