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industrial drives MCQs

Practise focused industrial drives questions with marked answers for exam preparation and subject revision.

industrial drives Mcqs
1. The diameter of the rotor shaft for an electric motor depends on which of the following ?
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A. Horse power only

B. Horse power and r.p.m.

C. Horse power, r.p.m. and power factor

D. r.p.m. only

2. While selecting motor for an air conditioner which of the following characteristics is of great importance ?
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A. None of the above

B. Type of bearings

C. Type of enclosure

D. Arrangement for power transmission

E. Noise
3. The starting torque of a D.C. motor is independent of which of the following?
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A. Flux

B. Armature current

C. Speed

D. Flux and armature current

4. A reluctance motor_________________?
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A. requires starting gear

B. is provided with slip rings

C. is compact

D. has high cost

5. ___________________has least range of speed control?
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A. D.C. shunt motor

B. Schrage motor

C. Slip ring induction motor

D. Synchronous motor
6. Battery operated scooter for braking uses________________?
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A. plugging

B. mechanical braking

C. regenerative braking

D. rheostatic braking

7. The cost of an induction motor will increase as________________?
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A. horsepower rating decreases but r.p.m. increases

B. horsepower rating and operating speed increases

C. horsepower rating increases but r.p.m. decreases

D. horsepower rating and operating speed decreases

8. For a D.C. shunt motor which of the following is incorrect ?
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A. Torque varies as armature current

B. Unsuitable for heavy duty starting

C. Torque is zero for zero armature current

D. Torque-armature current is a straight line

9. Belted slip ring induction motor is almost invariably used for_________________?
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A. jaw crushers

B. centrifugal blowers

C. water pumps

D. none of the above

10. In case of _______________ speed control by injecting e.m.f. in the rotor circuit is possible?
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A. d.c. shunt motor

B. slip ring induction motor

C. schrage motor

D. synchronous motor

11. The starting torque in case of centrifugal pumps is generally_________________?
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A. less than running torque

B. slightly more than running torque

C. same as running torque

D. double the running torque

12. Which of the following motors has series characteristics ?
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A. Capacitor start motor

B. None of the above

C. Repulsion motor

D. Shaded pole motor

13. Which of the following motors is used for elevators ?
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A. Synchronous motor

B. Any of the above

C. Induction motor

D. Capacitor start single phase motor

14. The characteristics of drive for crane hoisting and lowering are which of the following ?
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A. Precise control

B. All of the above

C. Fast speed control

D. Smooth movement

15. The capacity of a crane is expressed in terms of_______________?
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A. any of the above

B. type of drive

C. span

D. tonnes
16. Heat control switches are used in__________________?
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A. three phase induction motors

B. cooling ranges

C. single phase

D. transformers

17. ________________ motor is a constant speed motor?
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A. Schrage motor

B. Universal motor

C. Induction motor

D. Synchronous motor
18. In squirrel cage induction motors which of the following methods of starting cannot be used ?
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A. Resistance in rotor circuit

B. Star-delta starting

C. Resistance in stator circuit

D. Auto-transformer starting

19. In series motor which of the following methods can be used for changing the flux per pole ?
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A. Series-parallel control

B. Diverter field control

C. Tapped field control

D. Any of the above
20. In ______________ the speed can be varied by changing the position of brushes?
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A. induction motor

B. slip ring motor

C. repulsion motor

D. schrage motor
21. A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is____________________?
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A. low windage losses

B. slop speed operation

C. high starting torque

D. all of the above

22. For crane travel which of the following motors is normally used ?
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A. D.C. differentially compound motor

B. Synchronous motor

C. AC. slip ring motor

D. Ward-Leonard controlled D.C. shunt motor

23. For a motor-generator set which of the following motors will be preferred ?
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A. Slip ring induction motor

B. Synchronous motor

C. Squirrel cage induction motor

D. Pole changing induction motor

24. For which of the following applications D.C. motors are still preferred ?
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A. Reversibility

B. Variable speed drive

C. High efficiency operation

D. High starting torque

25. need frequent starting and stopping of electric motors ?
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A. Paper mills

B. Lifts and hoists

C. Air-conditioners

D. Grinding mills

26. Which of the following motors are best for the rolling mills ?
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A. Squirrel cage induction motors

B. Single phase motors

C. Slip ring induction motors

D. D.C. motors
27. _________________method of starting a three phase induction motor needs six terminals ?
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A. Star-delta

B. Resistance starting

C. Auto-transformer

D. None of the above

28. Ward-Leonard controlled D.C. drives are generally used for _____________________ excavators?
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A. Light duty

B. Heavy duty

C. All of the above

D. Medium duty

29. Rotor of a motor is usually supported on ___________________ bearings?
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A. ball or roller

B. needle

C. thrust

D. bush

30. Which of the following motors is preferred for boom hoist of a travelling crane ?
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A. Single phase motor

B. Synchronous motor

C. A.C. slip ring motor

D. Ward-Leonard controlled D.C. shunt motor

31. Reluctance motor is a________________?
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A. low noise, slow speed motor

B. low torque variable speed motor

C. variable torque motor

D. self starting type synchronous motor
32. The size of an excavator is usually expressed in terms of_________________?
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A. crowd motion

B. cubic metres

C. travel in metres

D. angle of swing

33. Which of the following motors is preferred when smooth and precise speed control over a wide range is desired ?
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A. Squirrel cage induction motor

B. Synchronous motor

C. D.C. motor

D. Wound rotor induction motor

34. In a paper mill where constant speed is required________________?
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A. group drive is preferred

B. individual drive is preferred

C. synchronous motors are preferred

D. A.C. motors are preferred

35. Which of the following alternatives will be cheaper ?
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A. Five motors of 20 H.P. each

B. Four motors of 25 H.P. each

C. A 100 H.P. AC. three phase motor

D. Ten motors of 10 H.P. each

36. Which of the following motors is preferred when quick speed reversal is the main consideration ?
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A. D.C. motor

B. Squirrel cage induction motor

C. Synchronous motor

D. Wound rotor induction motor

37. Which of the following happens when star-delta starter is used ?
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A. Starting voltage is reduced

B. Starting current is reduced

C. Both A. and B.

D. None of the above

38. __________________ has relatively wider range of speed control?
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A. D.C. shunt motor

B. Squirrel cage induction motor

C. Ship ring induction motor

D. Synchronous motor

39. By the use of which of the following m D.C. can be obtained from AC. ?
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A. Mercury arc rectifier

B. Motor generator set

C. Silicon diodes

D. Any of the above
40. In which of the following applications the load on motor changes in cyclic order ?
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A. Electric shovels

B. All of the above

C. Rolling mills

D. Cranes

41. For blowers which of the following motor is preferred ?
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A. Squirrel cage induction motor

B. D.C. series motor

C. D.C. shunt motor

D. Wound rotor induction motor

42. Which of the following machines has heavy fluctuation of load ?
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A. Lathe

B. Planer

C. g machine

D. Punching machine

43. Besides a constant speed a synchronous rotor possesses which of the following advantages ?
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A. Lower cost

B. Better efficiency

C. High power factor

D. All of the above

44. Which feature, while selecting a.motor for centrifugal pump, will be of least significance ?
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A. Operating speed

B. Horse power

C. Starting characteristics

D. Speed control
45. Which of the following types of motor enclosure is safest ?
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A. Totally enclosed

B. Open type

C. Semi closed

D. Totally enclosed fan cooled
46. A pony motor is used for the starting which of the following motors ?
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A. None of the above

B. Schrage motor

C. Squirel cage induction motor

D. Synchronous motor
47. Which of the following motors is usually preferred for kiln drives ?
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A. Three phase shunt wound com-mutator motor

B. Any of the above

C. Slip ring induction motor

D. Cascade controlled A.C. motor

48. In ________________ method of staging three phase induction motors the starting voltage is not reduced?
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A. any of the above

B. auto-transformer

C. star-delta

D. slip ring
49. For a particular application the type of electric-and control gear are determined by which of the following considerations ?
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A. All of the above

B. Limitation on starting current

C. Speed control range and its nature

D. Conditions of environment

E. Starting torque

50. ___________________is not a part of ball bearing ?
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A. Outer race

B. Inner race

C. Bush

D. Cage