Electric drives and motors MCQ Part-2

1. The capacity of crane is expressed in terms of__________.

a. Tonnes

b. Type of drive

c. Span

d. Any of the above

2. The travelling speed of a crane varies from_______.

a. 0.2 to 1.0 m/s

b. 1.0 to 2.5 m/s

c. 10 to 20 m/s

d. 20 to 25 m/s

3. Heavy duty cranes are employed in________.

a. Steel plants and ore handling plants

b. Powerhouse and pumping stations

c. Automobile workshops

d. Both (a) and (b)

4. In case of centrifugal pumps the starting torque is usually_______.

a. Double of running torque

b. Slightly higher than running torque

c. Same as running torque

d. Less than running torque

 

5. The size of an excavator is usually expressed in terms of _______.

a. Angle of swing

b. Travel in meters

c. m³

d. Crowd motion

6. The range of rating of electric motor used for rolling mills is of the order of________.

a. 10 to 25 kW

b. 25 to 85 kW

c. 85 to 400 kW

d. 400 to 1,000 kW

7. If the liquid to be pumped has relative density of 1.25, the output power required in comparison to that required for pumping water in case of centrifugal pump will be_________.

a. 0.8 times

b. 1.25 times

c. 15 times

d. Same times 

8. The load torque decreases with the increase in speed in case of______.

a. Blowers, fans, centrifugal pumps

b. Lathes, boring machines, milling machines

c. Hoist winches, machine tool feed mechanism

d. Both (b) and (c)

9. In synthetic fiber mills motors with_______.

a. High starting torque are preferred

b. Low starting torque are required

c. Constant speeds are required

d. Variable speeds are required

10. In case of kiln drives, starting torque is__________.

a. Almost zero 

b. Almost equal to running torque

c. Almost root 2 times  of the running torque

d. More than double of the running torque

 

11. The diameter of the rotor shaft for an electric motor depends upon________.

a. Speed only

b. Power output only

c. Speed and power output

d. Speed, power output and power factor

12. Which one of the following is not necessarily the advantage of dc motors over ac motors ?

a. Low cost

b. Excellent torque and speed operating characteristics

c. Flexible speed control

d. None of the above

13. An electric train employing a dc series motor is running at a fixed speed, when a sudden slight drop in the mains voltage occurs. This would result in________.

a. Drop in speed with current unaltered

b. Rise in speed and rise in current

c. Rise in speed and drop in current

d. Drop in speed and rise in current

 

14. A dc series motor is used for an overhauling load. It can word stably if________.

a. A diverter is put across the field 

b. A resistor is put in series with the machine

c. The field winding is reversed

d. The armature is shunted by a resistor 

 

15. DC series motors are very suitable for heavy duty applications such as electric railways, rolling mills because of_______.

a. Nearly constant speed

b. Possibility of speed control

c. High starting torque

d. Low initial as well as maintenance cost  

16. A flywheel is normally fitted to_________.

a. Differentially compound motor driving pulsed torque load

b. Cumulatively compound motor driving pulsed torque load

c. Separately excited dc motor driving pulsed torque load

d. DC series motor driving a constant torque load 

17. Which motor should not be used for centrifugal pumps ?

a. Differentially compound

b. Cumulatively compound

c. Series

d. Shunt

18. For continuously running rolling mills with intermittent loading, the most suitable dc drive is_________.

a. DC cumulatively compound motor

b. DC differentially compound motor

c. DC shunt motor

d. DC series motor

19. For quick speed reversal the motor preferred is________.

a. Synchronous motor

b. Slip-ring induction motor 

c. Squirrel cage induction motor

d. DC motor

 

20. The motor, owing to its inherent characteristics, best suited for the rolling mills is_________.

a. Synchronous motor 

b. Squirrel cage induction motor

c. DC cumulative compound wound motor

d. DC shunt motor

21. Squirrel cage induction motors with high slip  and slip-ring induction motors develop maximum torque at standstill and are used for_________.

a. Elevators

b. Machine tools

c. Presses and punches

d. All of the above

22. Belted slip-ring induction motor is almost invariably employed for_________.

a. Water pumps

b. Centrifugal blowers

c. Jaw-crushers

d. Conveyors

23. Belted wound induction motors are preferred for________.

a. Water pumps

b. Machine tools

c. Screw pumps

d. Gyratory crushers

 

24. The pair used for frequency converters is_________.

a. Squirrel cage induction motor and synchronous motor

b. Slip-ring induction motor and synchronous motor

c. Slip-ring induction motor and squirrel cage induction motor

d. All of the above 

25. For the same rating, the size of the single-phase induction motor is about_______ that of the corresponding three-phase induction motor.

a. one-third

b. 1.5 times

c. The same as

d. Three times 

26. Ward-Leonard controlled dc drives are usually  used for _______duty excavators.

a. Light

b. Medium

c. Heavy

 

• Electric Drives and Motors MCQ Part-1
• Electric Drives and Motors MCQ Part-3
• Electric Drives and Motors MCQ Part-4
• Electric Drives and Motors MCQ Part-5
• Electric Drives and Motors MCQ Part-6
• Electric Drives and Motors MCQ Part-7
• Electric Drives and Motors MCQ Part-8
• Electric Drives and Motors MCQ Part-9
• Electric Drives and Motors MCQ Part-10