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

Primary winding of a transformer$?

is always a low voltage winding

is always a high voltage winding

could either be a low voltage or high voltage winding

The secondary of a current transformer is always short-circuited under operating conditions because it$?

avoids core saturation and high voltage induction

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

Primary winding of a transformer?

is always a low voltage winding

is always a high voltage winding

could either be a low voltage or high voltage winding

The secondary of a current transformer is always short-circuited under operating conditions because it?

avoids core saturation and high voltage induction

A good voltage regulation of a transformer means?

output voltage fluctuation with power factor is least

output voltage fluctuation from no load to full load is least

output voltage fluctuation with power factor is least

difference between primary and secondary voltage is least

difference between primary and secondary voltage is maximum

In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are?

hysteresis and eddy current losses

The size of a transformer core will depend on?

flux density of the core material

If a transformer is switched on to a voltage more than the rated voltage?

its power factor will deteriorate

its power factor will remain unaffected

The starting torque of a squirrel-cage induction motor is

slightly more than full-load torque

If R‚Äö√á√á is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be$

R‚Äö√á√á¬¨‚â§/K¬¨‚â§

R‚Äö√á√á/‚Äö√ √∂K

R‚Äö√á√á/K¬¨‚â§

R‚Äö√á√á¬¨‚â§/K¬¨‚â§

R‚Äö√á√á¬¨‚â§/K

Greater the secondary leakage flux

less will be the primary induced e.m.f.

less will be the secondary induced e.m.f.

less will be the primary induced e.m.f.

less will be the primary terminal voltage

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

Eddy losses are totally eliminated

209 + Mcqs in Transformers in Electrical Engineering Page 4 McqOptions

151.	The path of the magnetic flux in transformer should have$?
A.	high reluctance
B.	low reactance
C.	high resistance
D.	low resistance
Answer» C. high resistance

Discussion

152.	In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?$?
A.	0 W
B.	14.1 W
C.	111.5 W
D.	1,020 W
Answer» D. 1,020 W

Discussion

153.	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
Answer» B. interleaved primary and secondary windings

Discussion

154.	Primary winding of a transformer$?
A.	is always a low voltage winding
B.	is always a high voltage winding
C.	could either be a low voltage or high voltage winding
D.	none of the above
Answer» D. none of the above

Discussion

155.	Efficiency of a power transformer is of the order of$?
A.	100 per cent
B.	98 per cent
C.	50 per cent
D.	25 per cent
Answer» C. 50 per cent

Discussion

156.	A common method of cooling a power transformer is$?
A.	natural air cooling
B.	air blast cooling
C.	oil cooling
D.	any of the above
Answer» D. any of the above

Discussion

157.	The secondary of a current transformer is always short-circuited under operating conditions because it$?
A.	avoids core saturation and high voltage induction
B.	is safe to human beings
C.	protects the primary circuit
D.	none of the above
Answer» B. is safe to human beings

Discussion

158.	A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 ≈í¬©. The load resistance as seen by the source is?
A.	1.3 ≈í¬©
B.	7.8 ≈í¬©
C.	78 ≈í¬©
D.	13 ≈í¬©
Answer» E.

Discussion

159.	While conducting short-circuit test on a transformer the following side is short circuited?
A.	High voltage side
B.	Low voltage side
C.	Primary side
D.	Secondary side
Answer» C. Primary side

Discussion

160.	Two transformers operating in parallel will share the load depending upon their?
A.	leakage reactance
B.	per unit impedance
C.	efficiencies
D.	ratings
Answer» C. efficiencies

Discussion

161.	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

162.	No-load on a transformer is carried out to determine?
A.	copper loss
B.	magnetising current
C.	magnetising current and loss
D.	efficiency of the transformer
Answer» D. efficiency of the transformer

Discussion

163.	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
Answer» B. interleaved primary and secondary windings

Discussion

164.	Primary winding of a transformer?
A.	is always a low voltage winding
B.	is always a high voltage winding
C.	could either be a low voltage or high voltage winding
D.	none of the above
Answer» D. none of the above

Discussion

165.	The path of the magnetic flux in transformer should have?
A.	high reluctance
B.	low reactance
C.	high resistance
D.	low resistance
Answer» C. high resistance

Discussion

166.	In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues??
A.	0 W
B.	14.1 W
C.	111.5 W
D.	1,020 W
Answer» D. 1,020 W

Discussion

167.	A common method of cooling a power transformer is?
A.	natural air cooling
B.	air blast cooling
C.	oil cooling
D.	any of the above
Answer» D. any of the above

Discussion

168.	The secondary of a current transformer is always short-circuited under operating conditions because it?
A.	avoids core saturation and high voltage induction
B.	is safe to human beings
C.	protects the primary circuit
D.	none of the above
Answer» B. is safe to human beings

Discussion

169.	Efficiency of a power transformer is of the order of?
A.	100 per cent
B.	98 per cent
C.	50 per cent
D.	25 per cent
Answer» C. 50 per cent

Discussion

170.	A good voltage regulation of a transformer means?
A.	output voltage fluctuation from no load to full load is least
B.	output voltage fluctuation with power factor is least
C.	difference between primary and secondary voltage is least
D.	difference between primary and secondary voltage is maximum
Answer» B. output voltage fluctuation with power factor is least

Discussion

171.	The noise resulting from vibrations of laminations set by magnetic forces, is termed as?
A.	Magnetostriction
B.	Boo
C.	Hum
D.	Zoom
Answer» D. Zoom

Discussion

172.	The maximum efficiency of a distribution transformer is?
A.	at no load
B.	at 50% full load
C.	at 80% full load
D.	at full load
Answer» C. at 80% full load

Discussion

173.	In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are?
A.	friction and windage losses
B.	copper losses
C.	hysteresis and eddy current losses
D.	none of the above
Answer» D. none of the above

Discussion

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

Discussion

175.	The size of a transformer core will depend on?
A.	frequency
B.	area of the core
C.	flux density of the core material
D.	(A) and (B) both
Answer» E.

Discussion

176.	The chemical used in breather for transformer should have the quality of?
A.	ionizing air
B.	absorbing moisture
C.	cleansing the transformer oil
D.	cooling the transformer oil
Answer» C. cleansing the transformer oil

Discussion

177.	A transformer transforms?
A.	voltage
B.	current
C.	power
D.	frequency
Answer» D. frequency

Discussion

178.	The no load current in a transformer lags behind the applied voltage by an angle of about?
A.	180¬¨‚àû
B.	120¬¨‚àû
C.	90¬¨‚àû
D.	75¬¨‚àû
Answer» E.

Discussion

179.	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

180.	If a transformer is switched on to a voltage more than the rated voltage?
A.	its power factor will deteriorate
B.	its power factor will increase
C.	its power factor will remain unaffected
D.	its power factor will be zero
Answer» B. its power factor will increase

Discussion

181.	Transformer breaths in when
A.	load on it increases
B.	load on it decreases
C.	load remains constant
D.	none of the above
Answer» C. load remains constant

Discussion

182.	Which of the following insulating materials can withstand the highest temperature safely?
A.	Cellulose
B.	Asbestos
C.	Mica
D.	Glass fibre
Answer» D. Glass fibre

Discussion

183.	A shell-type transformer has
A.	high eddy current losses
B.	reduced magnetic leakage
C.	negligibly hysteresis losses
D.	none of the above
Answer» C. negligibly hysteresis losses

Discussion

184.	The starting torque of a squirrel-cage induction motor is
A.	low
B.	negligible
C.	same as full-load torque
D.	slightly more than full-load torque
Answer» B. negligible

Discussion

185.	If R‚Äö√á√á is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be$
A.	R‚Äö√á√á/‚Äö√ √∂K
B.	R‚Äö√á√á/K¬¨‚â§
C.	R‚Äö√á√á¬¨‚â§/K¬¨‚â§
D.	R‚Äö√á√á¬¨‚â§/K
Answer» C. R‚Äö√á√á¬¨‚â§/K¬¨‚â§

Discussion

186.	Greater the secondary leakage flux
A.	less will be the secondary induced e.m.f.
B.	less will be the primary induced e.m.f.
C.	less will be the primary terminal voltage
D.	none of the above
Answer» B. less will be the primary induced e.m.f.

Discussion

187.	In a transformer routine efficiency depends upon
A.	supply frequency
B.	load current
C.	power factor of load
D.	both (B) and (C)
Answer» E.

Discussion

188.	The hum in a transformer is mainly attributed to
A.	load changes
B.	oil in the transformer
C.	magnetostriction
D.	mechanical vibrations
Answer» D. mechanical vibrations

Discussion

189.	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

190.	Short circuit test on transformers is conducted to determine
A.	hysteresis losses
B.	copper losses
C.	core losses
D.	eddy current losses
Answer» C. core losses

Discussion

191.	The complete circle diagram of induetion motor can be drawn with the help of data found from
A.	noload test
B.	blocked rotor test
C.	stator resistance test
D.	all of the above
Answer» E.

Discussion

192.	A transformer can have zero voltage regulation at
A.	leading power factor
B.	lagging power factor
C.	unity power factor
D.	zero power factor
Answer» B. lagging power factor

Discussion

193.	Iron loss of a transformer can be measured by
A.	low power factor wattmeter
B.	unity power factor wattmeter
C.	frequency meter
D.	any type of wattmeter
Answer» B. unity power factor wattmeter

Discussion

194.	The efficiencies of transformers compared with that of electric motors of the same power are
A.	about the same
B.	much smaller
C.	much higher
D.	somewhat smaller
Answer» D. somewhat smaller

Discussion

195.	Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect?
A.	Its secondary current is 5 A
B.	Its secondary voltage is 400 V
C.	Its rating is 2 kVA
D.	Its secondary current is 20 A
Answer» E.

Discussion

196.	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

197.	In a transformer the resistance between its primary and secondary should be
A.	zero
B.	10 Q
C.	1000 Q
D.	infinity
Answer» E.

Discussion

198.	The full-load copper loss of a transformer 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

199.	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

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

Discussion

Explore topic-wise MCQs in Electrical Engineering.

The path of the magnetic flux in transformer should have$?

In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues?$?

An ideal transformer is one which has$?

Primary winding of a transformer$?

Efficiency of a power transformer is of the order of$?

A common method of cooling a power transformer is$?

The secondary of a current transformer is always short-circuited under operating conditions because it$?

A transformer has a 1:6 turns ratio and a secondary coil load resistance of 470 ≈í¬©. The load resistance as seen by the source is?

While conducting short-circuit test on a transformer the following side is short circuited?

Two transformers operating in parallel will share the load depending upon their?

A transformer core is laminated to?

No-load on a transformer is carried out to determine?

An ideal transformer is one which has?

Primary winding of a transformer?

The path of the magnetic flux in transformer should have?

In a certain transformer, the input power to the primary is 120 W. If 8.5 W are lost to the winding resistance, what is the output power to the load, neglecting any other issues??

A common method of cooling a power transformer is?

The secondary of a current transformer is always short-circuited under operating conditions because it?

Efficiency of a power transformer is of the order of?

A good voltage regulation of a transformer means?

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

The maximum efficiency of a distribution transformer is?

In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are?

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

The size of a transformer core will depend on?

The chemical used in breather for transformer should have the quality of?

A transformer transforms?

The no load current in a transformer lags behind the applied voltage by an angle of about?

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

If a transformer is switched on to a voltage more than the rated voltage?

Transformer breaths in when

Which of the following insulating materials can withstand the highest temperature safely?

A shell-type transformer has

The starting torque of a squirrel-cage induction motor is

If R‚Äö√á√á is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be$

Greater the secondary leakage flux

In a transformer routine efficiency depends upon

The hum in a transformer is mainly attributed to

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

Short circuit test on transformers is conducted to determine

The complete circle diagram of induetion motor can be drawn with the help of data found from

A transformer can have zero voltage regulation at

Iron loss of a transformer can be measured by

The efficiencies of transformers compared with that of electric motors of the same power are

Which of the following statements regarding an idel single-phase transformer having a turn ratio of 1 : 2 and drawing a current of 10 A from 200 V A.C. supply is incorrect?

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

In a transformer the resistance between its primary and secondary should be

The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be

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

Hysteresis loss in a transformer varies as (Bmax = maximum flux density)