In D.C. generators the polarity of the interpoles_____________?

is the same as that of the immediately preceding pole

is the same as that of the main pole ahead

is the same as that of the immediately preceding pole

is opposite to that of the main pole ahead

is neutral as these poles do not play part in generating e.m.f.

In case of a flat compounded generator:

speed varies in proportion to the load on the generator

voltage generated is less than the rated voltage

generated voltage is proportional to the load on the generator

voltage remains constant irrespective of the load

speed varies in proportion to the load on the generator

In a level compounded D.C. generator, full load terminal voltage is______________?

more than no-load terminal voltage

equal to no-load terminal voltage

more than no-load terminal voltage

less than no-load terminal voltage

In a four-pole D.C. machine____________?

all the four poles are south poles

all the four poles are north poles

alternate poles are north and south

all the four poles are south poles

two north poles follow two south poles

In a D.C. machine stray loss is the sum of_____________?

total copper loss and mechanical loss

armature copper loss and iron loss

shunt field copper loss and mechanical loss

In a D.C. generator:___________________?

magnetisation characteristic = external characteristic

external resistance = internal char-acteristic – armature reaction

internal characteristic = magnetisation characteristic – ohmic drop

external characteristic = magnetisation characteristic – ohmic drop – armature reaction

magnetisation characteristic = external characteristic

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by_____________?

using conductor of annealed copper

using commutator with large number of segments

using carbon brushes of superior quality

In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when_______________?

the generator runs on full load

there is no load on|he generator

the generator runs on full load

the generator runs on designed speed

In a D.C. generator the critical resistance can be increased by_____________?

increasing its field resistance

decreasing its field resistance

In a commutator_____________?

mica and copper are equally hard

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be________________?

cross magnetisation as well as mag¬netisation

crossmagnetisation as well as demagnetising

If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to______________?

increase the speed of primemover

check armature insulation resistance

If a D.C. generator fails to build up the probable cause could not be_____________?

no residual magnetism in the generator

field resistance less than the critical resistance

no residual magnetism in the generator

faulty shunt connections tending to reduce the residual magnetism

For the parallel operation of two or more D.C. compound generators, we should ensure that_______________?

all conditions mentioned above should be satisfied

voltage of the incoming generator should be same as that of bus bar

polarity of incoming generator should be same as that of bus bar

all the series fields should be run in parallel by means of equilizer connection

series fields of all generators should be either on positive side or negative side of the armature

all conditions mentioned above should be satisfied

For a D.C. machines laboratory following type of D.C. supply will be suitable___________?

synchronous motor D.C. generator set

induction motor D.C. generator set

synchronous motor D.C. generator set

For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f___________ ?

Depends on other features of design

Fleming’s right-hand rule regarding direction of induced e.m.f., correlates__________?

magnetic field strength, induced voltage and current

magnetic flux, direction of current flow and resultant force

magnetic flux, direction of motion and the direction of e.m.f. induced

magnetic field strength, induced voltage and current

magnetic flux, direction of force and direction of motion of conductor

Flashing the field of D.C. generator means:______________?

making the magnetic losses of forces parallel

neutralising residual magnetism

creating residual magnetism by a D.C. source

making the magnetic losses of forces parallel

increasing flux density by adding extra turns of windings on poles

Eddy currents are induced in the pole shoes of a D.C. machine due to______________?

relative rotation between field and armature

D.C. generators are connected to the busbars or disconnected from them only under the floating condition________________?

to avoid sudden loading of the primemover

to avoid mechanicaljerk to the shaft

to avoid burning of switch contacts

D.C. series generator is used_________________?

to supply industrial load at constant voltage

voltage at the toad end of the feeder

Copper brushes in D.C. machine are used_____________?

where high voltage and small cur-rents are involved

where low voltage and high currents are involved

where high voltage and small cur-rents are involved

Compensating windings are used in D.C. generators______________?

mainly to reduce the eddy currents by providing local short-circuits

to provide path for the circulation of cooling air

to neutralise the cross-magnetising effect of the armature reaction

Armature reaction in a generator results in_____________?

demagnetisation of trailing pole tip and magnetisation of leading pole tip

demagnetisation of leading pole tip and magnetisation of trailing pole tip

demagnetisation of trailing pole tip and magnetisation of leading pole tip

damagnetising the center of all poles

magnetising the center of all poles

109 + Mcqs in DC Generators in Electrical Engineering Questions Page 2 McqOptions

51.	In D.C. generators the polarity of the interpoles_____________?
A.	is the same as that of the main pole ahead
B.	is the same as that of the immediately preceding pole
C.	is opposite to that of the main pole ahead
D.	is neutral as these poles do not play part in generating e.m.f.
Answer» B. is the same as that of the immediately preceding pole

Discussion

52.	In D.C. generators, the cause of rapid brush wear may be___________?
A.	severe sparking
B.	rough commutator surface
C.	imperfect contact
D.	any of the above
Answer» E.

Discussion

53.	In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?
A.	lie under south pole
B.	lie under north pole
C.	lie under interpolar region
D.	are farthest from the poles
Answer» D. are farthest from the poles

Discussion

54.	In D.C. generators on no-load, the air gap flux distribution in space is______________?
A.	sinusoidal
B.	triangular
C.	pulsating
D.	flat topped
Answer» E.

Discussion

55.	In D.C. generators, lap winding is used for______________?
A.	high voltage, high current
B.	low voltage, high current
C.	high voltage, low current
D.	low voltage, low current
Answer» C. high voltage, low current

Discussion

56.	In D.C. generators, current to the external circuit from armature is given through_____________?
A.	commutator
B.	solid connection
C.	slip rings
D.	none of above
Answer» B. solid connection

Discussion

57.	In case of D.C. machines, mechanical losses are primary function of____________?
A.	current
B.	voltage
C.	speed
D.	none of above
Answer» D. none of above

Discussion

58.	In case of D.C. machine winding, number of commutator segments is equal to______________?
A.	number of armature coils
B.	number of armature coil sides
C.	number of armature conductors
D.	number of armature turns
Answer» B. number of armature coil sides

Discussion

59.	In case of a flat compounded generator:
A.	voltage generated is less than the rated voltage
B.	generated voltage is proportional to the load on the generator
C.	voltage remains constant irrespective of the load
D.	speed varies in proportion to the load on the generator
Answer» D. speed varies in proportion to the load on the generator

Discussion

60.	In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?
A.	4
B.	8
C.	16
D.	32
Answer» C. 16

Discussion

61.	In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called____________?
A.	rotor
B.	stator
C.	field
D.	armature
Answer» E.

Discussion

62.	In a separately excited generator supplying rated load the armature reaction.
A.	is always present
B.	is always absent
C.	may be sometimes present
D.	none of the above
Answer» B. is always absent

Discussion

63.	In a level compounded D.C. generator, full load terminal voltage is______________?
A.	negligibly low
B.	equal to no-load terminal voltage
C.	more than no-load terminal voltage
D.	less than no-load terminal voltage
Answer» C. more than no-load terminal voltage

Discussion

64.	In a four-pole D.C. machine____________?
A.	all the four poles are north poles
B.	alternate poles are north and south
C.	all the four poles are south poles
D.	two north poles follow two south poles
Answer» C. all the four poles are south poles

Discussion

65.	In a D.C. machine stray loss is the sum of_____________?
A.	total copper loss and mechanical loss
B.	armature copper loss and iron loss
C.	shunt field copper loss and mechanical loss
D.	iron loss and mechanical loss
Answer» E.

Discussion

66.	In a D.C. generator:___________________?
A.	external resistance = internal char-acteristic – armature reaction
B.	internal characteristic = magnetisation characteristic – ohmic drop
C.	external characteristic = magnetisation characteristic – ohmic drop – armature reaction
D.	magnetisation characteristic = external characteristic
Answer» D. magnetisation characteristic = external characteristic

Discussion

67.	In a D.C. generator the ripples in the direct e.m.f. generated are reduced by_____________?
A.	using conductor of annealed copper
B.	using commutator with large number of segments
C.	using carbon brushes of superior quality
D.	using equiliser rings
Answer» D. using equiliser rings

Discussion

68.	In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when____________?
A.	r.p.m. is more than 300
B.	r.p.m. is less than 300
C.	number of poles is 4
D.	number of poles is 2
Answer» E.

Discussion

69.	In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when_______________?
A.	there is no load on\|he generator
B.	the generator runs on full load
C.	the generator runs on overload
D.	the generator runs on designed speed
Answer» B. the generator runs on full load

Discussion

70.	In a D.C. generator the critical resistance refers to the resistance of_____________?
A.	brushes
B.	field
C.	armature
D.	load
Answer» C. armature

Discussion

71.	In a D.C. generator the critical resistance can be increased by_____________?
A.	increasing its field resistance
B.	decreasing its field resistance
C.	increasing its speed
D.	decreasing its speed
Answer» D. decreasing its speed

Discussion

72.	In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except______________?
A.	interpoles
B.	dummy coils
C.	compensating winding
D.	shifting of axis of brushes
Answer» C. compensating winding

Discussion

73.	In a D.C. generator in case the resistance of the field winding is increased, then output voltage will____________?
A.	increase
B.	decrease
C.	remain unaffected
D.	fluctuate heavily
Answer» C. remain unaffected

Discussion

74.	In a commutator_____________?
A.	copper is harder than mica
B.	mica and copper are equally hard
C.	mica is harder than copper
D.	none of the above
Answer» D. none of the above

Discussion

75.	If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?
A.	zero
B.	small
C.	the same as rated voltage
D.	high
Answer» B. small

Discussion

76.	If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be________________?
A.	demagnetisation only
B.	cross magnetisation as well as mag¬netisation
C.	crossmagnetisation as well as demagnetising
D.	cross magnetisation only
Answer» D. cross magnetisation only

Discussion

77.	If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by______________?
A.	Blv
B.	Blv2
C.	Bl2v
D.	Bl2v2
Answer» B. Blv2

Discussion

78.	If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to______________?
A.	reverse the field connections
B.	increase the field resistance
C.	increase the speed of primemover
D.	check armature insulation resistance
Answer» B. increase the field resistance

Discussion

79.	If a D.C. generator fails to build up the probable cause could not be_____________?
A.	imperfect brush contact
B.	field resistance less than the critical resistance
C.	no residual magnetism in the generator
D.	faulty shunt connections tending to reduce the residual magnetism
Answer» C. no residual magnetism in the generator

Discussion

80.	For the parallel operation of two or more D.C. compound generators, we should ensure that_______________?
A.	voltage of the incoming generator should be same as that of bus bar
B.	polarity of incoming generator should be same as that of bus bar
C.	all the series fields should be run in parallel by means of equilizer connection
D.	series fields of all generators should be either on positive side or negative side of the armature
E.	all conditions mentioned above should be satisfied
Answer» E. all conditions mentioned above should be satisfied

Discussion

81.	For both lap and wave windings, there are as many commutator bars as the number of_____________?
A.	slots
B.	armature conductors
C.	winding elements
D.	poles
Answer» D. poles

Discussion

82.	For a D.C. machines laboratory following type of D.C. supply will be suitable___________?
A.	rotary converter
B.	mercury are rectifier
C.	induction motor D.C. generator set
D.	synchronous motor D.C. generator set
Answer» D. synchronous motor D.C. generator set

Discussion

83.	For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f___________ ?
A.	Lap winding
B.	Wave winding
C.	Either of A. and B. above
D.	Depends on other features of design
Answer» C. Either of A. and B. above

Discussion

84.	Following D.C. generator will be in a position to build up without any residual magnetism in the poles______________?
A.	series generator
B.	shunt generator
C.	compound generator
D.	self-excited generator
Answer» E.

Discussion

85.	Fleming’s right-hand rule regarding direction of induced e.m.f., correlates__________?
A.	magnetic flux, direction of current flow and resultant force
B.	magnetic flux, direction of motion and the direction of e.m.f. induced
C.	magnetic field strength, induced voltage and current
D.	magnetic flux, direction of force and direction of motion of conductor
Answer» C. magnetic field strength, induced voltage and current

Discussion

86.	Flashing the field of D.C. generator means:______________?
A.	neutralising residual magnetism
B.	creating residual magnetism by a D.C. source
C.	making the magnetic losses of forces parallel
D.	increasing flux density by adding extra turns of windings on poles
Answer» C. making the magnetic losses of forces parallel

Discussion

87.	Equilizer rings are required in case armature is_______________?
A.	wave wound
B.	lap wound
C.	delta wound
D.	duplex wound
Answer» C. delta wound

Discussion

88.	Eddy currents are induced in the pole shoes of a D.C. machine due to______________?
A.	oscillating magnetic field
B.	pulsating magnetic flux
C.	relative rotation between field and armature
D.	all above
Answer» D. all above

Discussion

89.	D.C. generators are connected to the busbars or disconnected from them only under the floating condition________________?
A.	to avoid sudden loading of the primemover
B.	to avoid mechanicaljerk to the shaft
C.	to avoid burning of switch contacts
D.	all above
Answer» E.

Discussion

90.	D.C. series generator is used_________________?
A.	to supply traction load
B.	to supply industrial load at constant voltage
C.	voltage at the toad end of the feeder
D.	for none of the above purpose
Answer» D. for none of the above purpose

Discussion

91.	D.C. generator generally preferred for charging automobile batteries is______________?
A.	series generator
B.	shunt generator
C.	long shunt compound generator
D.	any of’the above
Answer» D. any of’the above

Discussion

92.	Copper brushes in D.C. machine are used_____________?
A.	where low voltage and high currents are involved
B.	where high voltage and small cur-rents are involved
C.	in both of the above cases
D.	in none of the above cases
Answer» B. where high voltage and small cur-rents are involved

Discussion

93.	Compensating windings are used in D.C. generators______________?
A.	mainly to reduce the eddy currents by providing local short-circuits
B.	to provide path for the circulation of cooling air
C.	to neutralise the cross-magnetising effect of the armature reaction
D.	none of the above
Answer» D. none of the above

Discussion

94.	Brushes of D.C. machines are made of_________?
A.	carbon
B.	soft copper
C.	hard copper
D.	all of above
Answer» B. soft copper

Discussion

95.	As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?
A.	40 percent
B.	25 percent
C.	10 percent
D.	5 percent
Answer» E.

Discussion

96.	Armature reaction of an unsaturated D.C. machine is_____________?
A.	crossmagnetising
B.	demagnetising
C.	magnetising
D.	none of above
Answer» B. demagnetising

Discussion

97.	Armature reaction in a generator results in_____________?
A.	demagnetisation of leading pole tip and magnetisation of trailing pole tip
B.	demagnetisation of trailing pole tip and magnetisation of leading pole tip
C.	damagnetising the center of all poles
D.	magnetising the center of all poles
Answer» B. demagnetisation of trailing pole tip and magnetisation of leading pole tip

Discussion

98.	Armature coil is short circuited by brushes when it lies_____________?
A.	along neutral axis
B.	along field axis
C.	in any of the above positions
D.	in none of the above positions
Answer» B. along field axis

Discussion

99.	An exciter for a turbo generator is a_____________?
A.	separately excited generator
B.	shunt generator
C.	series generator
D.	compound generator
Answer» C. series generator

Discussion

100.	According to Fleming’s right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of____________?
A.	motion of conductor
B.	lines of force
C.	either of the above
D.	none of the above
Answer» C. either of the above

Discussion

Explore topic-wise MCQs in Electrical Engineering Questions.

In D.C. generators the polarity of the interpoles_____________?

In D.C. generators, the cause of rapid brush wear may be___________?

In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?

In D.C. generators on no-load, the air gap flux distribution in space is______________?

In D.C. generators, lap winding is used for______________?

In D.C. generators, current to the external circuit from armature is given through_____________?

In case of D.C. machines, mechanical losses are primary function of____________?

In case of D.C. machine winding, number of commutator segments is equal to______________?

In case of a flat compounded generator:

In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be__________________?

In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called____________?

In a separately excited generator supplying rated load the armature reaction.

In a level compounded D.C. generator, full load terminal voltage is______________?

In a four-pole D.C. machine____________?

In a D.C. machine stray loss is the sum of_____________?

In a D.C. generator:___________________?

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by_____________?

In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when____________?

In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when_______________?

In a D.C. generator the critical resistance refers to the resistance of_____________?

In a D.C. generator the critical resistance can be increased by_____________?

In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except______________?

In a D.C. generator in case the resistance of the field winding is increased, then output voltage will____________?

In a commutator_____________?

If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be____________?

If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be________________?

If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by______________?

If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to______________?

If a D.C. generator fails to build up the probable cause could not be_____________?

For the parallel operation of two or more D.C. compound generators, we should ensure that_______________?

For both lap and wave windings, there are as many commutator bars as the number of_____________?

For a D.C. machines laboratory following type of D.C. supply will be suitable___________?

For a D.C. generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher e.m.f___________ ?

Following D.C. generator will be in a position to build up without any residual magnetism in the poles______________?

Fleming’s right-hand rule regarding direction of induced e.m.f., correlates__________?

Flashing the field of D.C. generator means:______________?

Equilizer rings are required in case armature is_______________?

Eddy currents are induced in the pole shoes of a D.C. machine due to______________?

D.C. generators are connected to the busbars or disconnected from them only under the floating condition________________?

D.C. series generator is used_________________?

D.C. generator generally preferred for charging automobile batteries is______________?

Copper brushes in D.C. machine are used_____________?

Compensating windings are used in D.C. generators______________?

Brushes of D.C. machines are made of_________?

As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately______________?

Armature reaction of an unsaturated D.C. machine is_____________?

Armature reaction in a generator results in_____________?

Armature coil is short circuited by brushes when it lies_____________?

An exciter for a turbo generator is a_____________?

According to Fleming’s right-hand rule for finding the direction of induced e.m.f., when middle finger points in the direction of induced e.m.f., forefinger will point in the direction of____________?