Industrial Drives -- MCQs with Answers
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1. The selection of an electric motor for any application depends on which of the following factors ?
(a) Electrical characteristics
(b) Mechanical characteristics
(c) Size and rating of motors
(d) Cost
(e) All of the above
Ans: e
2. For a particular application the type of electric-and control gear are determined by which of the following considerations ?
(a) Starting torque
(b) Conditions of environment
(c) Limitation on starting current
(d) Speed control range and its nature
(e) All of the above
Ans: e
3. Which ofthefollowingmotors is preferred for traction work ?
(a) Universal motor
(b) D.C. series motor
(c) Synchronous motor
(d) Three-phase induction motor
Ans:
4 Which of the following motors always starts on load ?
(a) Conveyor motor
(b) Floor mill motor
(c) Fan motor
(d) All of the above
Ans: d
5 is preferred for automatic drives.
(a) Squirrel cage induction motor
(b) Synchronous motors
(c) Ward-Leonard controlled D.C. motors
(d) Any of the above
Ans: c
6. When the load is above _____ a synchronous motor is found to be more economical.
(a) 2 kW
(b) 20 kW
(c) 50 kW
(d) 100 kW
Ans: d
7. The load cycle for a motor driving a power press will be
(a) variable load
(b) continuous
(c) continuous but periodical
(d) intermittent and variable load
Ans: d
8. Light duty cranes are used in which of the following ?
(a) Power houses
(b) Pumping stations
(c) Automobile workshops
(d) All of the above
Ans: d
9. While selecting an electric motor for a floor mill, which electrical characteristics will be of least significance ?
(a) Running characteristics
(b) Starting characteristics
(c) Efficiency
(d) Braking
Ans: d
10. Which of the following motors are pre-ferred for overhead travelling cranes ?
(a) Slow speed motors
(b) Continuous duty motors
(c) Short time rated motors
(d) None of the above
Ans: c
11 is preferred for synthetic fibre mills.
(a) Synchronous motor
(b) Reluctance motor
(c) Series motor
(d) Shunt motor
Ans: b
12. Ward-Leonard controlled D.C. drives are generally used for ______ excavators.
(a) Light duty
(b) Medium duty
(c) Heavy duty
(d) All of the above
Ans: c
13. Which of the following motors is used for elevators ?
(a) Induction motor
(b) Synchronous motor
(c) Capacitor start single phase motor
(d) Any of the above
Ans: a
14. Which part of a motor needs maximum attention for maintenance ?
(a) Frame
(b) Rearing
(c) Stator winding
(d) Rotor winding
Ans: b
15 need frequent starting and stopping of electric motors,
(a) Paper mills
(b) Grinding mills
(c) Air-conditioners
(d) Lifts and hoists
Ans: d
16. Which feature, while selecting a.motor for centrifugal pump, will be of least significance ?
(a) Starting characteristics
(b) Operating speed
(c) Horse power
(d) Speed control
Ans: d
17. _______ motor is a constant speed motor.
(a) Synchronous motor
(b) Schrage motor
(c) Induction motor
(d) Universal motor
Ans: a
18. The starting torque in case of centrifugal pumps is generally
(a) less than running torque
(b) same as running torque
(c) slightly more than running torque
(d) double the running torque
Ans: a
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19. Which of the following motors are best for the rolling mills ?
(a) Single phase motors
(b) Squirrel cage induction motors
(c) Slip ring induction motors
(d) D.C. motors
Ans: d
20 is not a part of ball bearing ?
(a) Inner race
(b) Outer race
(c) Cage
(d) Bush
Ans: d
21. The starting torque of a D.C. motor is independent of which of the following?
(a) Flux
(b) Armature current
(c) Flux and armature current
(d) Speed
Ans: d
22. Rotor of a motor is usually supported on _______ bearings.
(a) ball or roller
(b) needle
(c) bush
(d) thrust
Ans: a
23. For which of the following applications D.C. motors are still preferred ?
(a) High efficiency operation
(b) Reversibility
(c) Variable speed drive
(d) High starting torque
Ans: c
24. In a paper mill where constant speed is required
(a) synchronous motors are preferred
(b) A.C. motors are preferred
(c) individual drive is preferred
(d) group drive is preferred
Ans: c
25. A reluctance motor
(a) is provided with slip rings
(b) requires starting gear
(c) has high cost
(d) is compact
Ans: d
26. The size of an excavator is usually expressed in terms of
(a) 'crowd' motion
(b) angle of swing
(c) cubic metres
(d) travel in metres
Ans: c
27. For blowers which of the following motor is preferred ?
(a) D.C. series motor
(b) D.C. shunt motor
(c) Squirrel cage induction motor
(d) Wound rotor induction motor
Ans: b
28. Belted slip ring induction motor is almost invariably used for
(a) water pumps
(b) jaw crushers
(c) centrifugal blowers
(d) none of the above
Ans: b
29. Which of the following is essentially needed while selecting a motor ?
(a) Pulley
(b) Starter
(c) Foundation pedal
(d) Bearings
Ans: b
30. Reluctance motor is a
(a) variable torque motor
(b) low torque variable speed motor
(c) self starting type synchronous motor
(d) low noise, slow speed motor
Ans: c
31 method of starting a three phase induction motor needs six terminals.
(a) Star-delta
(b) Resistance starting
(c) Auto-transformer
(d) None of the above
Ans: a
32. In ______ method of staging three phase induction motors the starting voltage is not reduced.
(a) auto-transformer
(b) star-delta
(c) slip ring
(d) any of the above
Ans: c
33. In jaw crushers a motor has to often start against ______ load.
(a) heavy
(b) medium
(c) normal
(d) low
Ans: a
34. For a motor-generator set which of the following motors will be preferred ?
(a) Synchronous motor
(b) Slip ring induction motor
(c) Pole changing induction motor
(d) Squirrel cage induction motor
Ans: a
35. Which of the following motors is usually preferred for kiln drives ?
(a) Cascade controlled A.C. motor
(b) Slip ring induction motor
(c) Three phase shunt wound com-mutator motor
(d) Any of the above
Ans: d
36. Heat control switches are used in
(a) transformers
(b) cooling ranges
(c) three phase induction motors
(d) single phase
Ans: b
37 has relatively wider range of speed control.
(a) Synchronous motor
(6) Ship ring induction motor
(c) Squirrel cage induction motor
(d) D.C. shunt motor
Ans: d
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38. In squirrel cage induction motors which of the following methods of starting cannot be used ?
(a) Resistance in rotor circuit
(b) Resistance in stator circuit
(c) Auto-transformer starting
(d) Star-delta starting
Ans: a
39. In which of the following applications the load on motor changes in cyclic order ?
(a) Electric shovels
(b) Cranes
(c) Rolling mills
(d) All of the above
Ans: d
40. Flame proof motors are used in
(a) paper mills
(b) steel mills
(c) moist atmospheres
(d) explosive atmospheres
Ans: d
41. Which of the following machines has heavy fluctuation of load ?
(a) Printing machine
(b) Punching machine
(c) Planer
(d) Lathe
Ans: b
42. For derries and winches which of the following drives can be used ?
(a) Pole changing squirrel cage motors
(b) D.C. motors with Ward-leonard con-trol
(c) A.C. slip ring motors with variable resistance
(d) Any of the above
Ans: d
43. Battery operated scooter for braking uses
(a) plugging
(b) mechanical braking
(c) regenerative braking
(d) rheostatic braking
Ans: b
44 has least range of speed control.
(a) Slip ring induction motor
(b) Synchronous motor
(c) D.C. shunt motor
(d) Schrage motor
Ans: b
45 has the least value of starting torque to full load torque ratio.
(a) D.C. shunt motor
(b) D.C. series motor
(c) Squirrel cage induction motor
(d) Slip ring induction motor
Ans: c
46. In case of _______ speed control by injecting e.m.f. in the rotor circuit is possible,
(a) d.c. shunt motor
(b) schrage motor
(c) synchronous motor
(d) slip ring induction motor
Ans: d
47. A pony motor is used for the starting which of the following motors ?
(a) Squirel cage induction motor
(b) Schrage motor
(c) Synchronous motor
(d) None of the above
Ans: c
48. In ________ the speed can be varied by changing the position of brushes.
(a) slip ring motor
(b) schrage motor
(c) induction motor
(d) repulsion motor
Ans: b
49. In which of the following applications variable speed operation is preferred ?
(a) Exhaust fan
(b) Ceiling fan
(c) Refrigerator
(d) Water pump
Ans: b
50. Heavy duty cranes are used in
(a) ore handling plants
(b) steel plants
(c) heavy engineering workshops
(d) all of the above
Ans: d
51. The travelling speed of cranes varies from
(a) 20 to 30 m/s
(b) 10 to 15 m/s
(c) 5 to 10 m/s
(d) 1 to 2.5 m/s
Ans: d
52. Besides a constant speed a synchronous rotor possesses which of the following advantages ?
(a) Lower cost
(b) Better efficiency
(c) High power factor
(d) All of the above
Ans: c
53. By the use of which of the followingm D.C. can be obtained from AC. ?
(a) Silicon diodes
(b) Mercury arc rectifier
(c) Motor generator set
(d) Any of the above
Ans: d
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Admin:- Bellapuri saikumar
( Sai Saikumar Jn)
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