19 .Transformer cores are built up from laminations rather than from solid metal so that A. Oil penetrates the core more easily B. Eddy current loss is reduced C. Less lamination is required for the windings D. Turn ratio is higher than voltage ratio

19 Transformer cores are built up from laminations rather than from solid metal so that
A. Oil penetrates the core more easily
B. Eddy current loss is reduced
C. Less lamination is required for the windings
D. Turn ratio is higher than voltage ratio
by

1 Answer

Answer :

B. Eddy current loss is reduced
by

Related questions

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Last Answer : C. Decrease the reluctance of the magnetic path

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Last Answer : B. Leakage path do not saturate

7 The main advantage of auto transformer over a two winding transformer is A. Hysteresis losses are reduced B. Saving in winding material C. Copper losses are negligible D. Eddy losses are totally eliminated

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Last Answer : A) hysteresis losses is reduced

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Description : What is Eddy current loss in transformer?

Last Answer : In transformer, we supply alternating current in the primary, this alternating current produces alternating magnetizing flux in the core and as this flux links with secondary winding, there will be induced ... dissipated as heat. This type of energy loss is called eddy current loss of transformer.

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Last Answer : A. Eddy current loss

17. Which type of loss is not common to transformer and rotating machines? A. Eddy current loss B. Copper loss C. Hysteresis loss D. Windage loss

Description : 17. Which type of loss is not common to transformer and rotating machines? A. Eddy current loss B. Copper loss C. Hysteresis loss D. Windage loss

Last Answer : D. Windage loss

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Description : 13) In an ideal transformer A. windings have no resistance B. core has no losses C. core has infinite permeability D. all of the above

Last Answer : D. All of the above

29. In transformer terminology, the ratio 20:1 indicates that A. there are 20 turns on primary one turn on secondary B. secondary voltage is 1/20th of the primary C. primary current is 20 times greater than the secondary current D. for every 0 turns on primary, there is one turn on secondary

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Last Answer : A. there are 20 turns on primary one turn on secondary

Brush sparking during commutation may be caused by ________. A. eddy currents in the armature core B. laminations in the generator field pieces C. induced current opposite to coil inductance D. coil inductance discharge occurring at commutation

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Last Answer : Answer: D

77 The transformer laminations are insulated from each other by A. Mica strip B. Thin coat of varnish C. Paper D. Any of the above

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Last Answer : B. Thin coat of varnish

The thickness of laminations used in a transformer is usually?

Last Answer : The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.

The transformer laminations are insulated from each other by?

Last Answer : The transformer laminations are insulated from each other by thin coat of varnish.

42 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

Description : 42 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

Last Answer : D. Copper losses = iron losses

How can eddy current loss be minimized?

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Last Answer : By laminating the core.

How do we minimize eddy current loss?

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Last Answer : A. By laminating the core we can minimize eddy current loss.

How to minimize Eddy current loss?

Description : How to minimize Eddy current loss?

Last Answer : By using less thickness of laminations By using less value of Magnetic flux density

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Last Answer : D. To take care of the expansion and contraction of transformer oil due to variation of temperature of surroundings

54] In operating a 400hz transformer at 50Hz A. Only voltage is reduced in the same proportion as the frequency B. Only KVA rating is reduced in the same proportion as the frequency C. Both voltage and KVA rating are reduced in the same proportion as frequency d. None of the above

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Last Answer : B. Only KVA rating is reduced in the same proportion as the frequency

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

Last Answer : When a given transformer is run at its rated voltage but reduced frequency, its core flux density is increased.

[53] The iron loss of the transformer is negligible during short circuit test because A. The entire input is just sufficient to meet Cu losses only B. Flux produced is a small fraction of the normal flux C. Iron core becomes fully saturated D. Supply frequency is held constant

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Last Answer : B. Flux produced is a small fraction of the normal flux

49 The open circuit test is carried out in a transformer to find the A. Cu loss B. Core loss C. Total loss D. Insulation resistance

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Which of the following properties is not necessarily desirable in the material for transformer core? A. Mechanical strength B. Low hysteresis loss C. High thermal conductivity D. High permeability

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Last Answer : C) high thermal conductivity

A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The

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Last Answer : A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is 0.707

Transformer cores are laminated to reduce _____________. A. eddy currents B. secondary flux C. leakage flux D. all of the above

Description : Transformer cores are laminated to reduce _____________. A. eddy currents B. secondary flux C. leakage flux D. all of the above

Last Answer : Answer: A

A saturable-core reactor operates on the principle of controlling a load winding's inductance by varying the core's _____________. A. dielectric B. permeability C. reactance D. inductance

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

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Last Answer : When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.

61 The degree of mechanical vibrations produced by the laminations of a transformers depends on A. Tightness of clamping B. Gauge of laminations C. Size of laminations D. All of the above

Description : 61 The degree of mechanical vibrations produced by the laminations of a transformers depends on A. Tightness of clamping B. Gauge of laminations C. Size of laminations D. All of the above

Last Answer : D. All of the above

60)The noise resulting from vibrations of laminations set by magnetic force, is termed as A. magnetostriction B. boo C. hum D. zoom

Description : 60)The noise resulting from vibrations of laminations set by magnetic force, is termed as A. magnetostriction B. boo C. hum D. zoom

Last Answer : C. Hum

Silicon steel used in laminations mainly reduces?

Last Answer : Silicon steel used in laminations mainly reduces hysteresis loss.

The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Description : The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Last Answer : Answer: C

Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

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Last Answer : Answer: C

Why stepped cores are used?

Description : Why stepped cores are used?

Last Answer : (i) To reduce the space effectively. (ii) To obtain reduced length of mean turn of the windings. (iii) To reduce I² R loss.

71 High frequency transformers sometimes make use of ferrite cores because it has A. High specific gravity B. High resistance C. High hysteresis D. low permeability

Description : 71 High frequency transformers sometimes make use of ferrite cores because it has A. High specific gravity B. High resistance C. High hysteresis D. low permeability

Last Answer : B. High resistance

The frequency of the secondary voltage of a transformer will be..... A. less than frequency of the primary voltage B. equal to the primary voltage C. greater than the frequency of the primary voltage D. much greater than the frequency of the primary voltage

Description : The frequency of the secondary voltage of a transformer will be..... A. less than frequency of the primary voltage B. equal to the primary voltage C. greater than the frequency of the primary voltage D. much greater than the frequency of the primary voltage

Last Answer : B. Equal to the primary voltage

What is voltage ratio of a transformer?

Description : What is voltage ratio of a transformer?

Last Answer : A. Voltage ratio is the ratio of the voltage between the line terminals of one winding to that between the line terminals of another winding at no load.

What will happen if transformer in parallel connection have different voltage ratio?

Description : What will happen if transformer in parallel connection have different voltage ratio?

Last Answer : Two transformers in Parallel should have the same primary and secondary voltage ratings. Any error in the voltage ratio would cause heavy circulating currents to flow between the transformers. ... in overloading of one transformer. This circulating current will result in increased copper losses.

The voltage transformation ratio of a transformer is equal to the ratio of?

Description : The voltage transformation ratio of a transformer is equal to the ratio of?

Last Answer : The voltage transformation ratio of a transformer is equal to the ratio of secondary induced e.m.f. to primary induced e.m.f.

In a transformer, low voltage winding is placed near the core in case of concentric windings so

Description : In a transformer, low voltage winding is placed near the core in case of concentric windings so as to  1. Reduce the leakage flux 2. Reduce the insulation requirement 3. Reduce the risk of voltage shock in case of insulation breakdown 4. Reduce the ... a) 1, 2, 3 (b) 2, 3, 4 (c) 1, 2, 3, 4 (d) 2, 3

Last Answer : In a transformer, low voltage winding is placed near the core in case of concentric windings so as to  1. Reduce the leakage flux 2. Reduce the insulation requirement 3. Reduce the risk of voltage shock in case of insulation breakdown 4. Reduce ... ) 1, 2, 3 (b) 2, 3, 4 (c) 1, 2, 3, 4 (d) 2, 3

A ferrite core has less eddy current loss than an iron core because ferrites have (A) High resistance. (B) Low resistance. (C) Low permeability. (D) High hysteresis.

Description : A ferrite core has less eddy current loss than an iron core because ferrites have (A) High resistance. (B) Low resistance. (C) Low permeability. (D) High hysteresis.

Last Answer : (A) High resistance.

A ferrite core has less eddy current loss than an iron core because?

Description : A ferrite core has less eddy current loss than an iron core because?

Last Answer : A ferrite core has less eddy current loss than an iron core because ferrites have high hysteresis.