Electric Drives and Motors Part-4

1. For a particular type of motor, the cooling time constant is usually________.

a. Smaller than the heating time constant

b. Greater than the heating time constant

c. Equal to the heating time constant

2. For a particular type of motor, the heating time constant is usually________.

a. Increases with the increase in size

b. Decreases with the increase in size

c. Same for all sizes

3. The heating time constant of a totally enclosed motor is relatively_______.

a. Lower

b. Higher

c. Independent of type of enclosure

4. For a certain industrial application, an overrated ac motor was selected. It will lead to operation with_________.

a. Higher efficiency and poorer pf

b. Lower efficiency and better pf

c. Higher efficiency and better pf

d. Lower efficiency and poorer pf

5. A flywheel is generally used in________.

a. A sugar centrifuge drive

b. A rolling mill drive

c. A paper mill drive

d. A cement mill drive

6. In overhead travelling cranes_________.

a. Short-time rating motors are used

b. Continuous minimum rating motors are used

c. Continuous rating motors are used

d. Any of the above

7. 15 minute rated motors are suitable for________.

a. Light duty cranes

b. Medium duty cranes

c. Heavy duty cranes

d. All of the above

8. For medium duty cranes the short-time rating motor used is________.

a. 10 minutes

b. 15 minutes

c. 30 minutes

d. One hour

9. The phase controlled rectifiers used in speed control of dc motors converts fixed ac supply voltage into_______ output voltage.

a. Variable ac 

b. Variable dc

c. Full rectified ac

d. Variable frequency ac

10. A four quadrant operation requires________.

a. Two full converters in series

b. Two full converters connected back to back

c. Two full converters connected in parallel

d. Two semi converters connected back to back

11. The following converters can fees power in any of the four quadrants________.

a. Semi-converter

b. Full converter

c. Dual converter

d. Combination of a semi and full converters

12. For speed control of dc motors using controlled rectifiers, armature voltage control gives speed_________.

a. Above rated speed

b. Below rated speed

c. Above as well as below rated speed

13. For the speed control of ac drive, the preferred method using thyristors is_________.

a. Chopper control

b. Integral cycle control 

c. Phase control 

d. All are equally good

14. The semiconductor device used for speed control of single phase induction motors in every day domestic use is_________.

a. Power transistor

b. SCR

c. Triac

d. Power MOS

15. Which of the following motor is suitable for driving cranes, hoists, centrifugal pumps, conveyor belt etc. ?

a.  DC series motor 

b. DC shunt motor

c. DC compound wound motor

d. Any of the above

 

16. Heavy-duty steel-works cranes having wide load variations are equipped with___________.

a. Synchronous motors

b. Wound rotor induction motors

c. Plain squirrel cage induction motors

d. DC series motor

 

17. The most suitable motor for a steel mill requiring a motor having high starting torque, wide spread range and precise speed control is_______.

a. DC shunt motor

b. DC series motor

c. Wound rotor induction motor

d. Plain squirrel cage induction motors

18. For automatic drives the preferences is for__________.

a. Synchronous motors

b. Ward-Leonard controlled dc shunt motors

c. Plain squirrel cage induction motors

19. The type of motor that can be used for hoisting machinery is________.

a. DC compound motor

b. Ward-Leonard controlled dc shunt motor

c. Wound rotor induction motor

d. Any of the above

 

20. The motor normally used for crane travel is_________.

a.  Plain squirrel cage induction motor

b. DC differentially compounded motor

c. Synchronous motor

d. Wound rotor induction motor

21. The drive, that can be used for derricks and winches is_________.

a. DC shunt motor with Ward-Leonard control

b. AC slip-ring induction motor with variable resistance

c. Pole-changing squirrel cage induction motor

d. Any of the above

 

22. Ward-Leonard controlled dc drives are generally used for_______ duty excavators.

a. Heavy

b. Medium

c. Light

d. None of these

23. The motor suitable for a reciprocating pump required to start under load is__________.

a. Double-squirrel cage induction motor

b. Plain squirrel cage induction motor

c. Synchronous motor

d. DC shunt motor

24. A pole-changing squirrel cage induction motor employed in derricks has four, eight and twenty four poles. The medium speed is used in__________.

a. Lifting

b. Lowering

c. Hoisting

d. Landing the load

25. A pole-changing squirrel cage induction motor employed in derricks has four, eight and twenty four poles. The lowest speed is used in__________.

a. Lifting

b. Lowering

c. Hoisting

d. Landing the load

 

26. Motor preferred for kiln drive is usually________.

a. Ward-Leonard controlled dc shunt motors

b. Cascaded controlled ac motor

c. Wound rotor induction motor

d. Any of the above

• Electric Drives and Motors MCQ Part-1
• Electric Drives and motors MCQ Part-2
• Electric Drives and Motors MCQ Part-3
• 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