Alternators

#1. Alternators are rated in….?

KW

KVA

KVAR

HP

incorrect

#2. What is the number of poles if the speed is 3000 rpm and frequency is 50Hz of an alternator?

4

2

6

8

incorrect

N = 120f/P

P= (120 x 50)/3000 = 2

#3. 2

self induction

mutual induction

electromagnetic induction

none of the above

#4. 2

low speed applications

high speed applications

high power applications

low power applications

#5. Alternator is also called…..?

synchronous motor

synchronous generator

asynchronous motor

asynchronous generator

#6. A 4 pole 1500 rpm alternator will generate emf at the frequency of……?

40 Hz

50 Hz

60 Hz

20 Hz

N = 120f/p

f = (1500 x 4) /120= 50

#7. The Stator core is laminated, this is to reduce….?

hysteresis loss

eddy current loss

copper loss

frictional loss

#8. In modern alternators, the rotating part is….?

field system

armature

armature as well as field

none of the above

#9. In synchronous machine stator frame is made up of…?

CRGO Steel

silicon steel

cast steel

cast iron or welded steel plates

#10. In synchronous machine stator core is made up of…?

cast iron

silicon steel

cast steel

copper

#11. Which type of alternator used in hydroelectric power station?

salient pole type

non salient pole type

turbo alternator

any of the above

#12. In high speed application which type alternator is used?

salient pole

non salient pole

turbo alternator

none of the above

#13. Which type of alternator used in Steam power station?

turbo alternator

salient pole

non salient pole

any of the above

#14. A 6 pole 60 Hz alternator runs at speed of ….. rpm?

1000

1200

1500

3000

(120 x 60) / 6 =1200

#15. Field system of alternator is excited at use of…?

ac supply

dc supply

ac or dc supply

any of the above

#16. In salient pole structure the pole shoes covers about…?

cast iron

cast steel

forged steel

silicon steel

#17. In salient pole structure the pole shoes covers about…?

one half

one third

one fourth

two third

#18. A large diameter and short axial length alternator running at …..?

slow speed

slow and medium speed

high speed

any of the above

#19. Zero power factor method for an alternator is generally used to determine….?

efficiency of alternator

voltage regulation of alternator

synchronous impedence of alternator

any of the above

#20. Damper windings in alternator is to…..?

reduce harmonics

reduce hunting

help in starting

reduce hunting and help in starting

#21. For parallel operation, alternators must have the same?

same voltage ratings

same phase sequence

same frequency

all the above

#22. Most commonly used alternator is……?

revolving armature

revolving field

induction type

none of the above

#23. Cylindrical rotor alternators use ……. ducts for efficient cooling?

only radial

only axial

both radial and axial

none of the above

#24. Skew of rotor bar is to eliminate….?

vibrations

effect of space harmonics

effect of crawling

noise

#25. The stator of modern alternators are wound for ….. phase groups?

60°

180°

120°

240°

#26. The stator poles of an alternator is ……as rotor poles?

less than

greater than

equal to

none of above

#27. Turbo alternators generally used….type rotor?

salient pole

cylindrical pole

any of the above

none of the above

#28. A 3 phase delta connected alternator having a rotating armature will have…?

2 sliprings

3 sliprings

4 sliprings

6 sliprings

#29. The speed of a 6 pole, 60Hz alternator is….?

600 rpm

1200 rpm

1800 rpm

3000 rpm

#30. At no loaded condition, the terminal voltage per phase of alternator is …… to the generated voltage per phase?

less than

greater than

equal to

any of the above

#31. Calculate the pitch factor for a winding having 36 slots 4 poles with a coil span of 1 to 8?

0.6

0.8

0.94

0.84

#32. The effect of armature reaction in an alternator depends on the….?

resistance of armature

reactance of armature

power factor of the load

impedene

#33. Terminal voltage of an alternator increases with the load when the power factor is…..?

zero

lagging

leading

unity

#34. Alternator said to be over excited when it is operating at…..?

unity power factor

lagging power factor

leading power factor

all the load

#35. The power factor of an alternator is determined by…..?

speed

excitation

current

load

#36. In cylindrical rotor….. portion of rotor is wound?

one third

two third

one half

whole

#37. The angle between induced emf and terminal voltage on no load for a single phase alternator is….?

180°

90°

260°

0°

#38. The effect of leading powerfactor on the voltage regulation of an alternator is…..?

increasing in nature

decreasing in nature

oscillating

constant value

#39. Which method gives more accurate voltage regulation of an alternator?

MMF method

EMF methof

portier triangle method

ZPF method

#40. Which method gives higher than actual value of regulation of an alternator?

ZPF

EMF

ZPF

ASA

#41. In alternator, the leading powerfactor of terminal voltage …… with load?

decreases

increases

vary

#42. When the load is removed from an AC generator, its terminal voltage rises from 480V at full load to 660 V at noload. calculate the voltage regulation?

25%

35%

37.5%

43.6%

(660-480)/480 = 37.5

#43. The regulation of an alternator is positive when the power factor is….?

zero

lagging

leading

unity

#44. Regulation of an alternator supplying resistive or inductive load is…..?

always positive

always negative

either of the above

none of above

#45. At leading power factor, an alternator…..?

is over excited

is under excited

has no residual magnetism

no effect

#46. What is the cause for hunting effect in alternators?

over load

Due to continuous fluctuation in load

under load

no load

#47. What is the purpose of using damper winding in AC generator?

remove noise

reduce losses

Prevents the hunting effect

increase speed

#48. What is the use of synchroscope?

Adjust the phase sequence

Indicate the correct instant for paralleling

Adjust the voltage

Adjust the frequency

#49. The number of slip rings in a rotating field system type alternator is…..?

2

3

4

1

#50. The rpm of turbo alternator has…?

Low

Medium

High

Any of these

#1. Alternators are rated in….?

#2. What is the number of poles if the speed is 3000 rpm and frequency is 50Hz of an alternator?

#3. 2

#4. 2

#5. Alternator is also called…..?

#6. A 4 pole 1500 rpm alternator will generate emf at the frequency of……?

#7. The Stator core is laminated, this is to reduce….?

#8. In modern alternators, the rotating part is….?

#9. In synchronous machine stator frame is made up of…?

#10. In synchronous machine stator core is made up of…?

#11. Which type of alternator used in hydroelectric power station?

#12. In high speed application which type alternator is used?

#13. Which type of alternator used in Steam power station?

#14. A 6 pole 60 Hz alternator runs at speed of ….. rpm?

#15. Field system of alternator is excited at use of…?

#16. In salient pole structure the pole shoes covers about…?

#17. In salient pole structure the pole shoes covers about…?

#18. A large diameter and short axial length alternator running at …..?

#19. Zero power factor method for an alternator is generally used to determine….?

#20. Damper windings in alternator is to…..?

#21. For parallel operation, alternators must have the same?

#22. Most commonly used alternator is……?

#23. Cylindrical rotor alternators use ……. ducts for efficient cooling?

#24. Skew of rotor bar is to eliminate….?

#25. The stator of modern alternators are wound for ….. phase groups?

#26. The stator poles of an alternator is ……as rotor poles?

#27. Turbo alternators generally used….type rotor?

#28. A 3 phase delta connected alternator having a rotating armature will have…?

#29. The speed of a 6 pole, 60Hz alternator is….?

#30. At no loaded condition, the terminal voltage per phase of alternator is …… to the generated voltage per phase?

#31. Calculate the pitch factor for a winding having 36 slots 4 poles with a coil span of 1 to 8?

#32. The effect of armature reaction in an alternator depends on the….?

#33. Terminal voltage of an alternator increases with the load when the power factor is…..?

#34. Alternator said to be over excited when it is operating at…..?

#35. The power factor of an alternator is determined by…..?

#36. In cylindrical rotor….. portion of rotor is wound?

#37. The angle between induced emf and terminal voltage on no load for a single phase alternator is….?

#38. The effect of leading powerfactor on the voltage regulation of an alternator is…..?

#39. Which method gives more accurate voltage regulation of an alternator?

#40. Which method gives higher than actual value of regulation of an alternator?

#41. In alternator, the leading powerfactor of terminal voltage …… with load?

#42. When the load is removed from an AC generator, its terminal voltage rises from 480V at full load to 660 V at noload. calculate the voltage regulation?

#43. The regulation of an alternator is positive when the power factor is….?

#44. Regulation of an alternator supplying resistive or inductive load is…..?

#45. At leading power factor, an alternator…..?

#46. What is the cause for hunting effect in alternators?

#47. What is the purpose of using damper winding in AC generator?

#48. What is the use of synchroscope?

#49. The number of slip rings in a rotating field system type alternator is…..?

#50. The rpm of turbo alternator has…?

Results

Recent Posts

Recent Comments

Advertisement

Daily Quiz