| 1. | In electric motors carbon brushes are used to ? | |
|
provide a path for flow of current
|
||
|
prevent sparking during commutation
|
||
|
prevent overheating of armature windings
|
||
|
brush off carbon deposits on the commutator
|
||
View Answer
Discuss in Forum
Report Question| 2. | The series parallel system of speed control of D.C. series motors widely used in traction work gives a speed range of about ? | |
|
1:10
|
||
|
1:8
|
||
|
1: 6
|
||
|
1: 4
|
||
| 3. | Which of the following loss in a D.C. generator varies significantly with the load current ? | |
|
Field copper loss
|
||
|
Windage loss
|
||
|
Armature copper loss
|
||
|
None of the above
|
||
| 4. | Which of the following motor is used in the locomotives motor drives ? | |
|
D.C. series motor
|
||
|
A.C. series motor
|
||
|
Synchronous motor
|
||
|
Induction motor
|
||
| 5. | D.C. shunt motors are used for driving ? | |
|
trains
|
||
|
cranes
|
||
|
hoists
|
||
|
machine tools
|
||
| 6. | Regenerative method of braking is based on that ? | |
|
back e.m.f. is less than the applied voltage
|
||
|
back e.m.f. is equal to the applied voltage
|
||
|
back e.m.f. of rotor is more than the applied voltage
|
||
|
none of the above
|
||
| 7. | Which motor should be used for centrifugal pumps ? | |
|
Series motor
|
||
|
Shunt motor
|
||
|
Either of the above
|
||
|
None of the above
|
||
| 8. | Which of the following motor is preferred for operation in highly explosive atmosphere ? | |
|
Series motor
|
||
|
Shunt motor
|
||
|
Air motor
|
||
|
Battery operated motor
|
||
| 9. | D.C. series machine bas field consisting of ? | |
|
many number of turns of thick wire
|
||
|
many number of turns of thin wire
|
||
|
few number of turns of thick wire
|
||
|
few number of turns of thin wire
|
||
| 10. | The armature voltage control of D.C. motor provides ? | |
|
constant voltage drive
|
||
|
constant current drive
|
||
|
constant torque drive
|
||
|
none of the above
|
||