209 + Mcqs in Transformers Page 2 McqOptions

51.	*$_A Buchholz relay can be installed on?
A.	auto-transformers
B.	air-cooled transformers
C.	welding transformers
D.	oil cooled transformers
Answer» E.

Discussion

52.	*$_For the parallel operation of single phase transformers it is necessary that they should have?
A.	same efficiency
B.	same polarity
C.	same kVA rating
D.	same number of turns on the secondary side.
Answer» C. same kVA rating

Discussion

53.	*$_The efficiency of a transformer will be maximum when?
A.	copper losses = hysteresis losses
B.	hysteresis losses = eddy current losses
C.	eddy current losses = copper losses
D.	copper losses = iron losses
Answer» E.

Discussion

54.	/_Which winding in a transformer has more number of turns??
A.	Low voltage winding
B.	High voltage winding
C.	Primary winding
D.	Secondary winding
Answer» C. Primary winding

Discussion

55.	/_The maximum load that a power transformer can carry is limited by its?
A.	temperature rise
B.	dielectric strength of oil
C.	voltage ratio
D.	copper loss
Answer» D. copper loss

Discussion

56.	/_When secondary of a current transformer is open-circuited its iron core will be?
A.	hot because of heavy iron losses taking place in it due to high flux density
B.	hot because primary will carry heavy current
C.	cool as there is no secondary current
D.	none of above will happen
Answer» B. hot because primary will carry heavy current

Discussion

57.	/_Power transformers are generally designed to have maximum efficiency around?
A.	no-load
B.	half-load
C.	near full-load
D.	10% overload
Answer» D. 10% overload

Discussion

58.	/_A transformer can have regulation closer to zero?
A.	on full-load
B.	on overload
C.	on leading power factor
D.	on zero power factor
Answer» D. on zero power factor

Discussion

59.	/_The degree of mechanical vibrations produced by the laminations of a transformer depends on?
A.	tightness of clamping
B.	gauge of laminations
C.	size of laminations
D.	all of the above
Answer» E.

Discussion

60.	/_For a transformer, operating at constant load current, maximum efficiency will occur at?
A.	0.8 leading power factor
B.	0.8 lagging power factor
C.	zero power factor
D.	unity power factor
Answer» E.

Discussion

61.	/_Star/star transformers work satisfactorily when?
A.	load is unbalanced only
B.	load is balanced only
C.	on balanced as well as unbalanced loads
D.	none of the above
Answer» C. on balanced as well as unbalanced loads

Discussion

62.	/_The function of breather in a transformer is?
A.	to provide oxygen inside the tank
B.	to cool the coils during reduced load
C.	to cool the transformer oil
D.	to arrest flow of moisture when outside air enters the transformer
Answer» E.

Discussion

63.	/_Minimum voltage regulation occurs when the power factor of the load is?
A.	unity
B.	lagging
C.	leading
D.	zero
Answer» D. zero

Discussion

64.	/_In an actual transformer the iron loss remains practically constant from noload to fullload because?
A.	value of transformation ratio remains constant
B.	permeability of transformer core remains constant
C.	core flux remains practically constant
D.	primary voltage remains constant
Answer» D. primary voltage remains constant

Discussion

65.	/_Which of the following loss in a transformer is zero even at full load ??
A.	Core loss
B.	Friction loss
C.	Eddy current loss
D.	Hysteresis loss
Answer» C. Eddy current loss

Discussion

66.	/_The transformer laminations are insulated from each other by?
A.	mica strip
B.	thin coat of varnish
C.	paper
D.	any of the above
Answer» C. paper

Discussion

67.	/_When a given transformer is run at its rated voltage but reduced frequency, its?
A.	flux density remains unaffected
B.	iron losses are reduced
C.	core flux density is reduced
D.	core flux density is increased
Answer» E.

Discussion

68.	/_If a transformer is continuously operated the maximum temperature rise will occur in?
A.	core
B.	windings
C.	tank
D.	any of the above
Answer» C. tank

Discussion

69.	/_No-load current in a transformer?
A.	lags behind the voltage by about 75¬¨‚àû
B.	leads the voltage by about 75¬¨‚àû
C.	lags behind the voltage by about 15¬¨‚àû
D.	leads the voltage by about 15¬¨‚àû
Answer» B. leads the voltage by about 75¬¨‚àû

Discussion

70.	/_An ideal transformer will have maximum efficiency at a load such that?
A.	copper loss = iron loss
B.	copper loss < iron loss
C.	copper loss > iron loss
D.	none of the above
Answer» B. copper loss < iron loss

Discussion

71.	/_The main reason for generation of harmonics in a transformer could be?
A.	fluctuating load
B.	poor insulation
C.	mechanical vibrations
D.	saturation of core
Answer» E.

Discussion

72.	/_Distribution transformers are generally designed for maximum efficiency around?
A.	90% load
B.	Zero load
C.	25% load
D.	50% load
Answer» E.

Discussion

73.	/_In a power or distribution transformer about 10 per cent end turns are heavily insulated?
A.	to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
B.	to absorb the line surge voltage and save the winding of transformer from damage
C.	to reflect the line surge and save the winding of a transformer from damage
D.	none of the above
Answer» B. to absorb the line surge voltage and save the winding of transformer from damage

Discussion

74.	/_Natural oil cooling is used for transformers up to a rating of?
A.	3000 kVA
B.	1000 kVA
C.	500 kVA
D.	250 kVA
Answer» B. 1000 kVA

Discussion

75.	/_A transformer oil must be free from?
A.	sludge
B.	odour
C.	gases
D.	moisture
Answer» E.

Discussion

76.	/_No-load current of a transformer has?
A.	has high magnitude and low power factor
B.	has high magnitude and high power factor
C.	has small magnitude and high power factor
D.	has small magnitude and low power factor
Answer» E.

Discussion

77.	/_The power factor of an induction motor under no-load conditions will be closer to?
A.	0.2 lagging
B.	0.2 leading
C.	0.5 leading
D.	unity
Answer» B. 0.2 leading

Discussion

78.	/_The 'crawling' in an induction motor is caused by?
A.	high loads
B.	low voltage supply
C.	improper design of machine
D.	harmonics developed in the motor
Answer» E.

Discussion

79.	/_Which motor is preferred for use in mines where explosive gases exist??
A.	Air motor
B.	Induction motor
C.	Shunt motor
D.	Synchronous motor
Answer» B. Induction motor

Discussion

80.	/_Which of the following properties is not necessarily desirable for the material for transformer core??
A.	Low hysteresis loss
B.	High permeability
C.	High thermal conductivity
D.	Adequate mechanical strength
Answer» D. Adequate mechanical strength

Discussion

81.	/_In a transformer the energy is conveyed from primary to secondary?
A.	through cooling coil
B.	through air
C.	by the flux
D.	none of the above
Answer» D. none of the above

Discussion

82.	/_Which of the following is not a part of transformer installation??
A.	Conservator
B.	Breather
C.	Buchholz relay
D.	Exciter
Answer» E.

Discussion

83.	%_No-load current in a transformer_%
A.	lags behind the voltage by about 75¬¨‚àû
B.	leads the voltage by about 75¬¨‚àû
C.	lags behind the voltage by about 15¬¨‚àû
D.	leads the voltage by about 15¬¨‚àû
Answer» B. leads the voltage by about 75¬¨‚àû

Discussion

84.	%_If a transformer is continuously operated the maximum temperature rise will occur in_%
A.	core
B.	windings
C.	tank
D.	any of the above
Answer» C. tank

Discussion

85.	%_When a given transformer is run at its rated voltage but reduced frequency, its_%
A.	flux density remains unaffected
B.	iron losses are reduced
C.	core flux density is reduced
D.	core flux density is increased
Answer» E.

Discussion

86.	%_The transformer laminations are insulated from each other by_%
A.	mica strip
B.	thin coat of varnish
C.	paper
D.	any of the above
Answer» C. paper

Discussion

87.	%_A transformer oil must be free from_%
A.	sludge
B.	odour
C.	gases
D.	moisture
Answer» E.

Discussion

88.	%_The 'crawling' in an induction motor is caused by_%
A.	high loads
B.	low voltage supply
C.	improper design of machine
D.	harmonics developed in the motor
Answer» E.

Discussion

89.	%_Which motor is preferred for use in mines where explosive gases exist?_%
A.	Air motor
B.	Induction motor
C.	Shunt motor
D.	Synchronous motor
Answer» B. Induction motor

Discussion

90.	%_No-load current of a transformer has_%
A.	has high magnitude and low power factor
B.	has high magnitude and high power factor
C.	has small magnitude and high power factor
D.	has small magnitude and low power factor
Answer» E.

Discussion

91.	%_The power factor of an induction motor under no-load conditions will be closer to_%
A.	0.2 lagging
B.	0.2 leading
C.	0.5 leading
D.	unity
Answer» B. 0.2 leading

Discussion

92.	%_In a transformer the energy is conveyed from primary to secondary_%
A.	through cooling coil
B.	through air
C.	by the flux
D.	none of the above
Answer» D. none of the above

Discussion

93.	%_Which of the following is not a part of transformer installation?_%
A.	Conservator
B.	Breather
C.	Buchholz relay
D.	Exciter
Answer» E.

Discussion

94.	%_Which of the following properties is not necessarily desirable for the material for transformer core?_%
A.	Low hysteresis loss
B.	High permeability
C.	High thermal conductivity
D.	Adequate mechanical strength
Answer» D. Adequate mechanical strength

Discussion

95.	_ An ideal transformer will have maximum efficiency at a load such that$?
A.	copper loss = iron loss
B.	copper loss < iron loss
C.	copper loss > iron loss
D.	none of the above
Answer» B. copper loss < iron loss

Discussion

96.	_ Sumpner's test is conducted on transformers to determine$?
A.	temperature
B.	stray losses
C.	all-day efficiency
D.	none of the above
Answer» B. stray losses

Discussion

97.	_ Insertion of resistance in the rotcir of an induction motor to develop a given torque$?
A.	decreases the rotor current
B.	increases the rotor current
C.	rotor current becomes zero
D.	rotor current rernains same
Answer» E.

Discussion

98.	_ Star/star transformers work satisfactorily when$?
A.	load is unbalanced only
B.	load is balanced only
C.	on balanced as well as unbalanced loads
D.	none of the above
Answer» C. on balanced as well as unbalanced loads

Discussion

99.	_ In an actual transformer the iron loss remains practically constant from noload to fullload because$?
A.	value of transformation ratio remains constant
B.	permeability of transformer core remains constant
C.	core flux remains practically constant
D.	primary voltage remains constant
Answer» D. primary voltage remains constant

Discussion

100.	_ Which of the following loss in a transformer is zero even at full load ?$?
A.	Core loss
B.	Friction loss
C.	Eddy current loss
D.	Hysteresis loss
Answer» C. Eddy current loss

Discussion

Explore topic-wise MCQs in Electrical Engineering.

*$_A Buchholz relay can be installed on?

*$_For the parallel operation of single phase transformers it is necessary that they should have?

*$_The efficiency of a transformer will be maximum when?

*/*_Which winding in a transformer has more number of turns??

*/*_The maximum load that a power transformer can carry is limited by its?

*/*_When secondary of a current transformer is open-circuited its iron core will be?

*/*_Power transformers are generally designed to have maximum efficiency around?

*/*_A transformer can have regulation closer to zero?

*/*_The degree of mechanical vibrations produced by the laminations of a transformer depends on?

*/*_For a transformer, operating at constant load current, maximum efficiency will occur at?

*/*_Star/star transformers work satisfactorily when?

*/*_The function of breather in a transformer is?

*/*_Minimum voltage regulation occurs when the power factor of the load is?

*/*_In an actual transformer the iron loss remains practically constant from noload to fullload because?

*/*_Which of the following loss in a transformer is zero even at full load ??

*/*_The transformer laminations are insulated from each other by?

*/*_When a given transformer is run at its rated voltage but reduced frequency, its?

*/*_If a transformer is continuously operated the maximum temperature rise will occur in?

*/*_No-load current in a transformer?

*/*_An ideal transformer will have maximum efficiency at a load such that?

*/*_The main reason for generation of harmonics in a transformer could be?

*/*_Distribution transformers are generally designed for maximum efficiency around?

*/*_In a power or distribution transformer about 10 per cent end turns are heavily insulated?

*/*_Natural oil cooling is used for transformers up to a rating of?

*/*_A transformer oil must be free from?

*/*_No-load current of a transformer has?

*/*_The power factor of an induction motor under no-load conditions will be closer to?

*/*_The 'crawling' in an induction motor is caused by?

*/*_Which motor is preferred for use in mines where explosive gases exist??

*/*_Which of the following properties is not necessarily desirable for the material for transformer core??

*/*_In a transformer the energy is conveyed from primary to secondary?

*/*_Which of the following is not a part of transformer installation??

%_No-load current in a transformer_%

%_If a transformer is continuously operated the maximum temperature rise will occur in_%

%_When a given transformer is run at its rated voltage but reduced frequency, its_%

%_The transformer laminations are insulated from each other by_%

%_A transformer oil must be free from_%

%_The 'crawling' in an induction motor is caused by_%

%_Which motor is preferred for use in mines where explosive gases exist?_%

%_No-load current of a transformer has_%

%_The power factor of an induction motor under no-load conditions will be closer to_%

%_In a transformer the energy is conveyed from primary to secondary_%

%_Which of the following is not a part of transformer installation?_%

%_Which of the following properties is not necessarily desirable for the material for transformer core?_%

_ An ideal transformer will have maximum efficiency at a load such that$?

_ Sumpner's test is conducted on transformers to determine$?

_ Insertion of resistance in the rotcir of an induction motor to develop a given torque$?

_ Star/star transformers work satisfactorily when$?

_ In an actual transformer the iron loss remains practically constant from noload to fullload because$?

_ Which of the following loss in a transformer is zero even at full load ?$?

/_Which winding in a transformer has more number of turns??

/_The maximum load that a power transformer can carry is limited by its?

/_When secondary of a current transformer is open-circuited its iron core will be?

/_Power transformers are generally designed to have maximum efficiency around?

/_A transformer can have regulation closer to zero?

/_The degree of mechanical vibrations produced by the laminations of a transformer depends on?

/_For a transformer, operating at constant load current, maximum efficiency will occur at?

/_Star/star transformers work satisfactorily when?

/_The function of breather in a transformer is?

/_Minimum voltage regulation occurs when the power factor of the load is?

/_In an actual transformer the iron loss remains practically constant from noload to fullload because?

/_Which of the following loss in a transformer is zero even at full load ??

/_The transformer laminations are insulated from each other by?

/_When a given transformer is run at its rated voltage but reduced frequency, its?

/_If a transformer is continuously operated the maximum temperature rise will occur in?

/_No-load current in a transformer?

/_An ideal transformer will have maximum efficiency at a load such that?

/_The main reason for generation of harmonics in a transformer could be?

/_Distribution transformers are generally designed for maximum efficiency around?

/_In a power or distribution transformer about 10 per cent end turns are heavily insulated?

/_Natural oil cooling is used for transformers up to a rating of?

/_A transformer oil must be free from?

/_No-load current of a transformer has?

/_The power factor of an induction motor under no-load conditions will be closer to?

/_The 'crawling' in an induction motor is caused by?

/_Which motor is preferred for use in mines where explosive gases exist??

/_Which of the following properties is not necessarily desirable for the material for transformer core??

/_In a transformer the energy is conveyed from primary to secondary?

/_Which of the following is not a part of transformer installation??