Star/star transformers work satisfactorily when________________?

on balanced as well as unbalanced loads

Helical coils can be used on___________?

low voltage side of high kVA transformers

high voltage side of small capacity transformers

high voltage side of high kVA rating transformers

The function of conservator in a transformer is___________________?

to project against’internal fault

to reduce copper as well as core losses

to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings

Which of the following is the main advantage of an auto-transformer over a two winding transformer?

Eddy losses are totally eliminated

Buchholz’s relay gives warning and protection against_________________?

electrical fault outside the transformer in outgoing feeder

electrical fault inside the transformer itself

electrical fault outside the transformer in outgoing feeder

for both outside and inside faults

During short circuit test iron losses are negligible because of _____________?

full-load current is not supplied to the transformer

the current on secondary side is negligible

the voltage on secondary side does not vary

the voltage applied on primary side is low

full-load current is not supplied to the transformer

Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in____________?

short-circuiting of the secondaries

power factor of one of the transformers is leading while that of the other lagging

transformers having higher copper losses will have negligible core losses

loading of the transformers not in proportion to their kVA ratings

An ideal transformer is one which has_____________?

interleaved primary and secondary windings

a common core for its primary and secondary windings

core of stainless steel and winding of pure copper metal

133 + Mcqs in Transformers Mcqs in Electrical Engineering Questions Page 3 McqOptions

101.	The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?
A.	Conservator
B.	Breather
C.	Bushings
D.	Buchholz relay
Answer» B. Breather

Discussion

102.	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

103.	Distribution transformers are generally designed for maximum efficiency around________________?
A.	90% load
B.	zero load
C.	25% load
D.	50% load
Answer» E.

Discussion

104.	The thickness of laminations used in a transformer is usually____________?
A.	0.4 mm to 0.5 mm
B.	4 mm to 5 mm
C.	14 mm to 15 mm
D.	25 mm to 40 mm
Answer» B. 4 mm to 5 mm

Discussion

105.	The value of flux involved m the e.m.f. equation of a transformer is____________?
A.	average value
B.	r.m.s. value
C.	maximum value
D.	instantaneous value
Answer» D. instantaneous value

Discussion

106.	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

107.	The core used in high frequency transformer is usually___________?
A.	copper core
B.	cost iron core
C.	air core
D.	mild steel core
Answer» D. mild steel core

Discussion

108.	Helical coils can be used on___________?
A.	low voltage side of high kVA transformers
B.	high frequency transformers
C.	high voltage side of small capacity transformers
D.	high voltage side of high kVA rating transformers
Answer» B. high frequency transformers

Discussion

109.	In a transformer the resistance between its primary and secondary is____________?
A.	zero
B.	1 ohm
C.	1000 ohms
D.	infinite
Answer» E.

Discussion

110.	The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be___________?
A.	6400 W
B.	1600 W
C.	800 W
D.	400 W
Answer» E.

Discussion

111.	The function of conservator in a transformer is___________________?
A.	to project against’internal fault
B.	to reduce copper as well as core losses
C.	to cool the transformer oil
D.	to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings
Answer» E.

Discussion

112.	Material used for construction of transformer core is usually___________________?
A.	wood
B.	copper
C.	aluminium
D.	silicon steel
Answer» E.

Discussion

113.	Hysteresis loss in a transformer varies as CBmax = maximum flux density) ?
A.	Bmax
B.	Bmax1-6
C.	Bmax1-83
D.	B max
Answer» C. Bmax1-83

Discussion

114.	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

115.	The noise resulting from vibrations of laminations set by magnetic forces, is termed as_________________?
A.	magnetostrication
B.	boo
C.	hum
D.	zoom
Answer» D. zoom

Discussion

116.	A Buchholz relay can be installed on______________?
A.	auto-transformers
B.	air-cooled transformers
C.	welding transformers
D.	oil cooled transformers
Answer» E.

Discussion

117.	A transformer oil must be free from________________?
A.	sludge
B.	odour
C.	gases
D.	moisture
Answer» E.

Discussion

118.	Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?
A.	50°C
B.	80°C
C.	100°C
D.	150°C
Answer» E.

Discussion

119.	Which of the following is the main advantage of an auto-transformer over a two winding transformer?
A.	Hysteresis losses are reduced
B.	Saving in winding material
C.	Copper losses are negligible
D.	Eddy losses are totally eliminated
Answer» C. Copper losses are negligible

Discussion

120.	Buchholz’s relay gives warning and protection against_________________?
A.	electrical fault inside the transformer itself
B.	electrical fault outside the transformer in outgoing feeder
C.	for both outside and inside faults
D.	none of the above
Answer» B. electrical fault outside the transformer in outgoing feeder

Discussion

121.	During short circuit test iron losses are negligible because of _____________?
A.	the current on secondary side is negligible
B.	the voltage on secondary side does not vary
C.	the voltage applied on primary side is low
D.	full-load current is not supplied to the transformer
Answer» D. full-load current is not supplied to the transformer

Discussion

122.	The magnetising current of a transformer is usually small because it has___________?
A.	small air gap
B.	large leakage flux
C.	laminated silicon steel core
D.	fewer rotating parts
Answer» B. large leakage flux

Discussion

123.	Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in____________?
A.	short-circuiting of the secondaries
B.	power factor of one of the transformers is leading while that of the other lagging
C.	transformers having higher copper losses will have negligible core losses
D.	loading of the transformers not in proportion to their kVA ratings
Answer» E.

Discussion

124.	Which winding of the transformer has less cross-sectional area?
A.	Primary winding
B.	Secondary winding
C.	Low voltage winding
D.	High voltage winding
Answer» E.

Discussion

125.	Silicon steel used in lamination’s mainly reduces___________?
A.	hysteresis loss
B.	eddy current losses
C.	copper losses
D.	all of the above
Answer» B. eddy current losses

Discussion

126.	An ideal transformer is one which has_____________?
A.	no losses and magnetic leakage
B.	interleaved primary and secondary windings
C.	a common core for its primary and secondary windings
D.	core of stainless steel and winding of pure copper metal
E.	none of the above
Answer» B. interleaved primary and secondary windings

Discussion

127.	Which of the following does not change in a transformer ?
A.	Current
B.	Voltage
C.	Frequency
D.	All of the above
Answer» D. All of the above

Discussion

128.	A transformer core is laminated to__________?
A.	reduce hysteresis loss
B.	reduce eddy current losses
C.	reduce copper losses
D.	reduce all above losses
Answer» C. reduce copper losses

Discussion

129.	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

130.	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

131.	If the supply frequency to the transformer is increased,”the iron loss will__________?
A.	not change
B.	decrease
C.	increase
D.	any of the above
Answer» D. any of the above

Discussion

132.	The path of a magnetic flux in a transformer should have______________?
A.	high resistance
B.	high reluctance
C.	low resistance
D.	low reluctance
Answer» E.

Discussion

133.	The no-load current drawn by transformer is usually what per cent of the full-load current ?
A.	0.2 to 0.5 per cent
B.	2 to 5 per cent
C.	12 to 15 per cent
D.	20 to 30 per cent
Answer» C. 12 to 15 per cent

Discussion

Explore topic-wise MCQs in Electrical Engineering Questions.

The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer?

Star/star transformers work satisfactorily when________________?

Distribution transformers are generally designed for maximum efficiency around________________?

The thickness of laminations used in a transformer is usually____________?

The value of flux involved m the e.m.f. equation of a transformer is____________?

The main reason for generation of harmonics in a transformer could be_______________?

The core used in high frequency transformer is usually___________?

Helical coils can be used on___________?

In a transformer the resistance between its primary and secondary is____________?

The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be___________?

The function of conservator in a transformer is___________________?

Material used for construction of transformer core is usually___________________?

Hysteresis loss in a transformer varies as CBmax = maximum flux density) ?

Power transformers are generally designed to have maximum efficiency around__________?

The noise resulting from vibrations of laminations set by magnetic forces, is termed as_________________?

A Buchholz relay can be installed on______________?

A transformer oil must be free from________________?

Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?

Which of the following is the main advantage of an auto-transformer over a two winding transformer?

Buchholz’s relay gives warning and protection against_________________?

During short circuit test iron losses are negligible because of _____________?

The magnetising current of a transformer is usually small because it has___________?

Two transformers are connected in parallel. These transformers do not have equal percentage impedance. This is likely to result in____________?

Which winding of the transformer has less cross-sectional area?

Silicon steel used in lamination’s mainly reduces___________?

An ideal transformer is one which has_____________?

Which of the following does not change in a transformer ?

A transformer core is laminated to__________?

In a transformer the energy is conveyed from primary to secondary_________?

The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?

If the supply frequency to the transformer is increased,”the iron loss will__________?

The path of a magnetic flux in a transformer should have______________?

The no-load current drawn by transformer is usually what per cent of the full-load current ?