Electrical Drives MCQs

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

Answer
Answer. e

2. For a particular application, the type of electric and control gear is determined by which of the following considerations?

(a) Starting torque
(b) Conditions of the environment
(c) Limitation on starting current
(d) Speed control range and its nature
(e) All of the above

Answer
Answer. e

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

(a) Universal motor
(b) D.C. series motor
(c) Synchronous motor
(d) Three-phase induction motor

Answer
Answer. b

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

Answer
Answer. 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

Answer
Answer. 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

Answer
Answer. 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

Answer
Answer. 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

Answer
Answer. 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

Answer
Answer. d

10. Which of the following motors are preferred for overhead traveling cranes?

(a) Slow speed motors
(b) Continuous duty motors
(c) Short time rated motors
(d) none of the above

Answer
Answer. c

11. ……………. is preferred for synthetic fibre mills.

(a) Synchronous motor
(b) Reluctance motor
(c) Series motor
(d) Shunt motor

Answer
Answer. 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

Answer
Answer. c

13. Which of the following motors are used for elevators?

(a) Induction motor
(b) Synchronous motor
(c) Capacitor start single phase motor
(d) Any of the above

Answer
Answer. a

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

(a) Frame
(b) Bearing
(c) Stator winding
(d) Rotor winding

Answer
Answer. b

15.   …………… need frequent starting and stopping of electric motors.

(a) Paper mills
(b) Grinding Mills
(c) Air-conditioners
(d) Lifts and Hoists

Answer
Answer. d