Most Asked Electrical Engineering Objective Question on Industrial Drive

Most Asked Electrical Engineering Objective Question on Industrial Drive
1. 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

2. 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

3. 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

4. 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

5. Which of the following motors are preferred for overhead travelling cranes ?
(a) Slow speed motors
(b) Continuous duty motors
(c) Short time rated motors
(d) None of the above
Ans: c

Also Read - Basic of Electrical Engineering and Basic Electrical Formulas

6. ____ is preferred for synthetic fiber mills.
(a) Synchronous motor
(b) Reluctance motor
(c) Series motor
(d) Shunt motor
Ans: b

7. 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

8. 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

9. Which part of a motor needs maximum attention for maintenance ?
(a) Frame
(b) Rearing
(c) Stator winding
(d) Rotor winding
Ans: b

10. _______ motor is a constant speed motor.
(a) Synchronous motor
(b) Schrage motor
(c) Induction motor
(d) Universal motor
Ans: a

11. 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

12. 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

13. 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

14. A reluctance motor
(a) is provided with slip rings
(b) requires starting gear
(c) has high cost
(d) is compact
Ans: d

15. 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

16. 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: c

17. Which of the following is essentially needed while selecting a motor ?
(a) Pulley
(b) Starter
(c) Foundation pedal
(d) Bearings
Ans: b

18. ____ 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

19. 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

20. In jaw crushers a motor has to often start against ______ load.
(a) heavy
(b) medium
(c) normal
(d) low
Ans: a

21. Heat control switches are used in
(a) transformers
(b) cooling ranges
(c) three phase induction motors
(d) single phase
Ans: b

22. has relatively wider range of speed control.
(a) Synchronous motor
(b) Ship ring induction motor
(c) Squirrel cage induction motor
(d) D.C. shunt motor
Ans: d

23. 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

24. Battery operated scooter for braking uses
(a) plugging
(b) mechanical braking
(c) regenerative braking
(d) rheostatic braking
Ans: b

25. _____ 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
(a) slop speed operation
(b) high starting torque
(c) low windage losses
(d) all of the above
Ans: b

32. Which of the following motors has series characteristics ?
(a) Shaded pole motor
(b) Repulsion motor
(c) Capacitor start motor
(d) None of the above
Ans: b

33. For a D.C. shunt motor which of the following is incorrect ?
(a) Unsuitable for heavy duty starting
(b) Torque varies as armature current
(c) Torque-armature current is a straight line
(d) Torque is zero for zero armature current
Ans: a

34. For which of the following applications motor has to start with high acceleration?
(a) Oil expeller
(b) Floor mill
(c) Lifts and hoists
(d) Centrifugal pump
Ans: c

Also Read - MCQ on Measurement and Instrumentation for Electrical Engineering

35. Which of the following types of motor enclosure is safest ?
(a) Totally enclosed
(b) Totally enclosed fan cooled
(c) Open type
(d) Semi closed
Ans: b

36. The diameter of the rotor shaft for an electric motor depends on which of the following ?
(a) r.p.m. only
(b) Horse power only
(c) Horse power and r.p.m.
(d) Horse power, r.p.m. and power factor
Ans: c

37. The cost of an induction motor will increase as
(a) horsepower rating increases but r.p.m. decreases
(b) horsepower rating decreases but r.p.m. increases
(c) horsepower rating and operating speed increases
(d) horsepower rating and operating speed decreases
Ans: a



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