Full load copper loss in a transformer is 1600 watts. At half load the copper loss will be: A) 6400 watt B) 1600 watt C) 800 watt D) 400 watt
Last Answer : Full load cupper loss in a transformer is 1600 watts. At half load the cupper loss will be: 400 watt
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Jun 4, 2018
by
anonymous

In an actual transformer the iron loss remains practically constant from no load to full load because?
Last Answer : In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.
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Mar 19, 2018
by
anonymous

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
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
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May 8, 2018
by
anonymous

At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is : (A) 7000 W (B) 6000 W (C) 8000 W (D) 4000 W
Last Answer : At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is : 6000 W
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asked
Apr 30, 2018
by
anonymous
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Even at no-load, a transformer draws current from the mains. Why?
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Apr 28, 2020
by
anonymous

Last Answer : No-load current in a transformer lags behind the voltage by about 75°.
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asked
Mar 19, 2018
by
anonymous

Last Answer : The no load current in a transformer lags behind the applied voltage by an angle of about 75°.
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188 views
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asked
Mar 19, 2018
by
anonymous

Last Answer : No-load current of a transformer has small magnitude and low power factor.
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Mar 19, 2018
by
anonymous

Last Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.
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asked
Mar 19, 2018
by
anonymous

In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
Last Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.
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asked
Mar 19, 2018
by
anonymous

For a transformer, operating at constant load current, maximum efficiency will occur at?
Last Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.
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124 views
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asked
Mar 19, 2018
by
anonymous
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The maximum load that a power transformer can carry is limited by its?
Last Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.
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133 views
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asked
Mar 19, 2018
by
anonymous

A no-load test is performed on a transformer to determine?
Last Answer : A no-load test is performed on a transformer to determine magnetizing current and loss.
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1 answer
asked
Mar 19, 2018
by
anonymous

In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?
Last Answer : In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of less than 15A.
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156 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : If the supply frequency to the transformer is increased, the iron loss will increase.
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170 views
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asked
Mar 19, 2018
by
anonymous

Last Answer : Iron loss of a transformer can be measured by low power factor wattmeter.
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Mar 19, 2018
by
anonymous

40 No load test on a transformer is carried out to find A. Copper loss B. magnetising current C. Magnetising current and loss D. Efficiency of the transformer
Last Answer : C. Magnetising current and loss
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22 No load test on a transformer is carried out to find A. copper loss B. magnetising current C. Magnetising current and no load loss D. Efficiency of the transformer
Last Answer : C. Magnetising current and no load loss
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52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250
Last Answer : A. 1600
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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 ... voltage applied on primary side is low D. Full-load current is not supplied to the transformer
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A 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is (A) 50.0% (B) 70.7% (C) 141.4% (D) 200.0%
Last Answer : A 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is 70.7%
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asked
May 17, 2018
by
anonymous

Explain the effect of Harmonics on the Transformer.
Last Answer : Effect of Harmonics on the Transformer: 1. Core loss: Harmonic voltage increases the hysteresis and eddy current losses in the lamination. The amount of the core loss depends on ... small core vibrations. 5. Saturation problem: Sometimes additional harmonic voltage causes core saturation.
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127 views
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May 22, 2020
by
anonymous
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List two special feature of welding transformer.
Last Answer : Special features of welding transformer: i) It is a step down transformer that reduces the source voltage to a voltage desired according to the demands of the welding process. ii) Having large primary turns and less ... V ii) Secondary voltage - 40 to 60 V iii) Secondary current - 200 to 600 A
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May 22, 2020
by
anonymous

State two applications of isolation transformer
Last Answer : Applications of isolation transformer: i) Isolates the load equipment from supply ground: ii) Reduction of voltage spikes iii) It acts as a decoupling device. iv) Protects loads from harmonic distortion.
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54 views
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May 22, 2020
by
anonymous

State why a transformer always have an efficiency of more than 90%.
Last Answer : As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.
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269 views
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May 22, 2020
by
anonymous

Equivalent circuit of transformer
Last Answer : Equivalent Circuit Diagram of Transformer Referred to Primary: V1 -Primary Input voltage I1 - Input Current I0- Exciting current/ No load current Im- Magnetizing component ... equivalent of secondary terminal voltage ZL- Load impedance ZL ′- Primary equivalent of load impedance
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2 answers
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May 17, 2020
by
anonymous

Single phase transformer
Last Answer : Single phase Transformer Transformer
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May 16, 2020
by
anonymous

What is the use of transformer?
Last Answer : The use of transformer is to do lower or raise the voltage or currents in an electrical circuit. That's quite so simple.
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159 views
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asked
May 15, 2020
by
anonymous
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Write about transformer on DC.
Last Answer : Transformer on DC : Transformer cannot work on DC. Transformer works on electromagnetic induction principle. Electromagnetic induction principle means when flux linking with coil changes and EMF induced in it ... winding insulation will burn. https://youtu.be/TVp_0fIfxqY
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248 views
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asked
May 10, 2020
by
anonymous

State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
Last Answer : Transformer A with 4% voltage regulation is better. Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.
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179 views
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asked
Jul 27, 2019
by
anonymous

State any four characteristics of core type transformer.
Last Answer : Characteristics of core type transformer: i) It has one window. ii) It has one magnetic circuit. iii) Core surrounds the winding. iv) Average length of core is more. v) Area of cross ... Better cooling for winding. vii) Mechnical strength is comparatively less. viii) Repair and maintenance is easy.
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132 views
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asked
Jul 27, 2019
by
anonymous

Explain construction and working of single phase Auto transformer.
Last Answer : Construction of single phase auto transformer: (i) It has only one winding wound on a laminated circular magnetic core. (ii) The core is made of silicon steel stampings. (iii) The two terminals of the ... help of handle. 5) The same transformer can be used as step-up or step down auto-transformer
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asked
Jul 26, 2019
by
anonymous

Last Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
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Mar 19, 2018
by
anonymous

Last Answer : In the transformer low voltage winding has got more cross-sectional area.
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256 views
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Mar 19, 2018
by
anonymous
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Last Answer : A transformer cannot raise or lower the voltage of a D.C. supply because Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero.
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344 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : Primary winding of a transformer could either be a low voltage or high voltage winding.
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Mar 19, 2018
by
anonymous

Last Answer : High voltage winding in a transformer has more number of turns.
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1 answer
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Mar 19, 2018
by
anonymous

Last Answer : The efficiency of a power transformer is of the order of 98 percent.
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1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : In a transformer, routine efficiency depends upon load current and power factor of load.
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133 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The maximum efficiency of a distribution transformer is at 50% full load.
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140 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : Transformer breaths in when load on it decreases.
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90 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.
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546 views
1 answer
asked
Mar 19, 2018
by
anonymous
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Last Answer : The power transformer is a constant main flux device.
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63 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : In a transformer, the tappings are generally provided on low voltage side.
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92 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The use of higher flux density in the transformer design reduces weight per kVA.
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126 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The chemical used in breather for transformer should have the quality of cleansing the transformer oil.
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187 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : An ideal transformer has infinite values of primary and secondary inductances. The statement is false.
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324 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : The transformer ratings are usually expressed in terms of kVA.
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318 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : Material used for construction of transformer core is usually silicon steel.
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241 views
1 answer
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Mar 19, 2018
by
anonymous

Last Answer : The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.
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98 views
1 answer
asked
Mar 19, 2018
by
anonymous
