Question 1

The noise produced by a transformer is termed as

Accepted Answer

A) zoom 
B) hum 
C) ringing 
D) buzz 
A) zoom 
B) hum 
C) ringing 
D) buzz B

Question 2

The efficiency of a transformer, under heavy loads, is comparatively low because

Accepted Answer

A) copper loss becomes high in proportion to the output 
B) iron loss is increased considerably 
C) voltage drop both in primary and secondary becomes large 
D) secondary output is much less as compared to primary input 
A) copper loss becomes high in proportion to the output 
B) iron loss is increased considerably 
C) voltage drop both in primary and secondary becomes large 
D) secondary output is much less as compared to primary input A

Question 3

Losses which occur in rotating electric machines and do not occur in transformers are

Accepted Answer

A) friction and windage losses 
B) magnetic losses 
C) hysteresis and eddy current losses 
D) copper losses 
A) friction and windage losses 
B) magnetic losses 
C) hysteresis and eddy current losses 
D) copper losses A

Question 4

In a given transformer for a given applied voltage, losses which remainconstant irrespective of load changes are

Accepted Answer

A) hysteresis and eddy current losses 
B) friction and windage losses 
C) copper losses 
D) none of the above 
A) hysteresis and eddy current losses 
B) friction and windage losses 
C) copper losses 
D) none of the above

Question 5

Which of the following parts of a transformer is visible from outside ?

Accepted Answer

A) Bushings 
B) Core 
C) Primary winding 
D) Secondary winding 
A) Bushings 
B) Core 
C) Primary winding 
D) Secondary winding

Question 6

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

Accepted Answer

A) zero 
B) 10 Q 
C) 1000 Q 
D) infinity 
A) zero 
B) 10 Q 
C) 1000 Q 
D) infinity

Question 7

Reduction in core losses and increase in permeability are obtained with transformer employing

Accepted Answer

A) core built-up of laminations of cold rolled grain oriented steel 
B) core built-up of laminations of hot rolled sheet 
C) either of the above 
D) none of the above 
A) core built-up of laminations of cold rolled grain oriented steel 
B) core built-up of laminations of hot rolled sheet 
C) either of the above 
D) none of the above

Question 8

Which of the following protection is normally not provided on smalldistribution transformers ?

Accepted Answer

A) Overfluxing protection 
B) Buchholz relay 
C) Overcurrent protection 
D) All of the above 
A) Overfluxing protection 
B) Buchholz relay 
C) Overcurrent protection 
D) All of the above

Question 9

The hum in a transformer is mainly attributed to

Accepted Answer

A) load changes 
B) oil in the transformer 
C) magnetostriction 
D) mechanical vibrations 
A) load changes 
B) oil in the transformer 
C) magnetostriction 
D) mechanical vibrations

Question 10

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

Accepted Answer

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 
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

Question 11

A good voltage regulation of a transformer means

Accepted Answer

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 ismaximum 
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 ismaximum

Question 12

The maximum load that a power transformer can carry is limited by its

Accepted Answer

A) temperature rise 
B) dielectric strength of oil 
C) voltage ratio 
D) copper loss 
A) temperature rise 
B) dielectric strength of oil 
C) voltage ratio 
D) copper loss

Question 13

A transformer transforms

Accepted Answer

A) voltage 
B) current 
C) current and voltage 
D) power 
A) voltage 
B) current 
C) current and voltage 
D) power

Question 14

For a transformer, operating at constant load current, maximum efficiency will occur at

Accepted Answer

A) 0.8 leading power factor 
B) 0.8 lagging power factor 
C) zero power factor 
D) unity power factor 
A) 0.8 leading power factor 
B) 0.8 lagging power factor 
C) zero power factor 
D) unity power factor

Question 15

In a power or distribution transformer about 10 per cent end turns are heavily insulated

Accepted Answer

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 fromdamage 
C) to reflect the line surge and save the winding of a transformer from damage 
D) none of the above 
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 fromdamage 
C) to reflect the line surge and save the winding of a transformer from damage 
D) none of the above

Question 16

Which of the following acts as a protection against high voltage surges due to lightning and switching ?

Accepted Answer

A) Horn gaps 
B) Thermal overload relays 
C) Breather 
D) Conservator 
A) Horn gaps 
B) Thermal overload relays 
C) Breather 
D) Conservator

Question 17

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

Accepted Answer

A) Cellulose 
B) Asbestos 
C) Mica 
D) Glass fibre 
A) Cellulose 
B) Asbestos 
C) Mica 
D) Glass fibre

Question 18

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

Accepted Answer

A) Core loss 
B) Friction loss 
C) Eddy current loss 
D) Hysteresis loss 
A) Core loss 
B) Friction loss 
C) Eddy current loss 
D) Hysteresis loss

Question 19

If a transformer is continuously operated the maximum temperature rise will occur in

Accepted Answer

A) core 
B) windings 
C) tank 
D) All of the above 
A) core 
B) windings 
C) tank 
D) All of the above

Question 20

Which of the following is the most likely source of harmonics in a transformer ?

Accepted Answer

A) poor insulation 
B) Overload 
C) loose connections 
D) Core saturation 
A) poor insulation 
B) Overload 
C) loose connections 
D) Core saturation

The noise produced by a transformer is termed as

The efficiency of a transformer, under heavy loads, is comparatively low because

Losses which occur in rotating electric machines and do not occur in transformers are

In a given transformer for a given applied voltage, losses which remainconstant irrespective of load changes are

Which of the following parts of a transformer is visible from outside ?

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

Reduction in core losses and increase in permeability are obtained with transformer employing

Which of the following protection is normally not provided on smalldistribution transformers ?

The hum in a transformer is mainly attributed to

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

A good voltage regulation of a transformer means

The maximum load that a power transformer can carry is limited by its

A transformer transforms

For a transformer, operating at constant load current, maximum efficiency will occur at

In a power or distribution transformer about 10 per cent end turns are heavily insulated

Which of the following acts as a protection against high voltage surges due to lightning and switching ?

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

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

If a transformer is continuously operated the maximum temperature rise will occur in

Which of the following is the most likely source of harmonics in a transformer ?

Transformer Fundamentals and Operation

Transformer Technology and Design

Transformer: Resistance, Oil, Relays, Harmonics, and Core Properties

Transformers: Efficiency, Design, and Testing

Transformer and D.C Motor

D.C Motors and Starters

D.C Motors and Speed Control

D.C Motors and Controls

D.C Motors and Generators

D.C Machine and Generator Laminations, Commutation, and Components

D.C Generators and Commutators

D.C Generator Operation and Construction

D.C Generators

Direct Current Generators and Parallel Operation

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Exam 5: Transformers: Voltage Regulation, Efficiency, and Protection

The noise produced by a transformer is termed as

The efficiency of a transformer, under heavy loads, is comparatively low because

Losses which occur in rotating electric machines and do not occur in transformers are

In a given transformer for a given applied voltage, losses which remainconstant irrespective of load changes are

Which of the following parts of a transformer is visible from outside ?

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

Reduction in core losses and increase in permeability are obtained with transformer employing

Which of the following protection is normally not provided on smalldistribution transformers ?

The hum in a transformer is mainly attributed to

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

A good voltage regulation of a transformer means

The maximum load that a power transformer can carry is limited by its

A transformer transforms

For a transformer, operating at constant load current, maximum efficiency will occur at

In a power or distribution transformer about 10 per cent end turns are heavily insulated

Which of the following acts as a protection against high voltage surges due to lightning and switching ?

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

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

If a transformer is continuously operated the maximum temperature rise will occur in

Which of the following is the most likely source of harmonics in a transformer ?

Transformer Fundamentals and Operation

Transformer Technology and Design

Transformer: Resistance, Oil, Relays, Harmonics, and Core Properties

Transformers: Efficiency, Design, and Testing

Transformer and D.C Motor

D.C Motors and Starters

D.C Motors and Speed Control

D.C Motors and Controls

D.C Motors and Generators

D.C Machine and Generator Laminations, Commutation, and Components

D.C Generators and Commutators

D.C Generator Operation and Construction

D.C Generators

Direct Current Generators and Parallel Operation

Filters