A transformer has negative voltage regulation when its load power factor is (1) Zero (2) Unity (3) Leading (4) Lagging
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Apr 30, 2018
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anonymous

Negative voltage regulation is indicative that the load is?
Last Answer : Negative voltage regulation is indicative that the load is capacitive.
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Mar 19, 2018
by
anonymous

Minimum voltage regulation occurs when the power factor of the load is?
Last Answer : Minimum voltage regulation occurs when the power factor of the load is leading.
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Mar 19, 2018
by
anonymous

Last Answer : A transformer can have regulation closer to zero on leading power factor.
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Mar 19, 2018
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anonymous
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A ferro resonant transformer regulation is also known as?
Last Answer : A ferro resonant transformer regulation is also known as constant current transformer.
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Mar 19, 2018
by
anonymous

Identify the increasing order of voltage regulation of the following dc generators a same load : (A) differential compound, shunt and under compound (B) shunt, differential compound and ... C) under compound, shunt and differential compound (D) shunt, under compound and differential compound
Last Answer : Identify the increasing order of voltage regulation of the following dc generators a same load : under compound, shunt and differential compound
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Apr 30, 2018
by
anonymous

Last Answer : The voltage regulation in magnetic amplifier type voltage regulator is effected by varying the reactance.
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Mar 20, 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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Mar 19, 2018
by
anonymous

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.
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166 views
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Mar 19, 2018
by
anonymous
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If a transformer is switched on to a voltage more than the rated voltage?
Last Answer : If a transformer is switched on to a voltage more than the rated voltage its power factor will deteriorate.
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Mar 19, 2018
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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Jul 27, 2019
by
anonymous
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Step-down transformer converts high voltage and low current into: (A) How voltage and high current (B) High voltage and low current (C) Low voltage and high current (D) None of the above
Last Answer : Step-down transformer converts high voltage and low current into: Low voltage and high current
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May 8, 2018
by
anonymous

The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above
Last Answer : The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA
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199 views
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May 8, 2018
by
anonymous

What is a capacitor voltage transformer? A) It is a transformer used in power systems to step up low voltage signals and provide extra high voltage B) It is a transformer used in power systems ... in power systems to step down extra high voltage signals and provide low voltage D) None of these
Last Answer : What is a capacitor voltage transformer? A) It is a transformer used in power systems to step up low voltage signals and provide extra high voltage B) It is a transformer used in power systems ... power systems to step down extra high voltage signals and provide low voltage D) None of these
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Apr 29, 2018
by
anonymous

What is impulse voltage of transformer?
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Mar 10, 2018
by
anonymous

Last Answer : yes High Voltage side of Transformer winding have more number of turns. and low voltage side of Transformer winding have less number of turns.
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Sep 30, 2017
by
anonymous
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Define line regulation and load regulation.
Last Answer : Load regulation is the ability of the power supply to maintain its specified output voltage over changes in the load. Line regulation is the ability of the power supply to maintain its specified output voltage over changes in the input line voltage.
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Jul 24, 2019
by
anonymous

Classify hydro-electric power plants according to water flow regulation and explain in brief.
Last Answer : Classification of hydro-electric power plants according to water flow regulation of water flow:- 1. Large reservoir power plant 2. Run-off river (ROR) power plant with poundage 3. Run-off River ... depends upon rate of flow of water Initial cost is less Its purpose is to generate electricity.
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Sep 7, 2018
by
anonymous

Define load and line regulation.
Last Answer : 1. Load regulation : The load regulation indicates how much the load voltage changes when the load current changes. The load regulation is defined as: % Load regulation = (VNL-VFL) / VFL *100 ... the power supply. A well-regulated power supply can have a line regulation of less than 0.1%.
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Sep 5, 2018
by
anonymous

The unit of speed regulation of a governor is : (A) Hz (B) Hz/MW (C) Hz/MVA (D) rpm/MVAR
Last Answer : The unit of speed regulation of a governor is : Hz/MW
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226 views
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Apr 29, 2018
by
anonymous

Which motor has the best speed regulation?
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Mar 15, 2018
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anonymous

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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350 views
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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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1 answer
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Mar 19, 2018
by
anonymous

Last Answer : When a given transformer is run at its rated voltage but reduced frequency, its core flux density is increased.
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110 views
1 answer
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Mar 19, 2018
by
anonymous
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What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?
Last Answer : 1.Direct loading test 2.Open circuit test 3. Short circuit test 4. Sumpner's or back to back test
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51 A transformer has negative voltage regulation when its load power factor is A. Zero B. Unity C. Leading D. Lagging
Last Answer : C. leading
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For given applied voltage, with the increase in frequency of the applied voltage?
Last Answer : For given applied voltage, with the increase in frequency of the applied voltage eddy current loss will remain unchanged.
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Mar 19, 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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May 22, 2020
by
anonymous

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
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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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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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May 15, 2020
by
anonymous

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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May 10, 2020
by
anonymous

Even at no-load, a transformer draws current from the mains. Why?
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Apr 28, 2020
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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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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Jul 26, 2019
by
anonymous

Last Answer : No-load current in a transformer lags behind the voltage by about 75°.
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90 views
1 answer
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Mar 19, 2018
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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1 answer
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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
1 answer
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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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1 answer
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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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363 views
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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100 views
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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
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Mar 19, 2018
by
anonymous

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

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

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

Last Answer : The power transformer is a constant main flux device.
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1 answer
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Mar 19, 2018
by
anonymous
