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A transformer can have regulation closer to zero on leading power factor.

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Description : A good voltage regulation of a transformer means?

Answer : A good voltage regulation of a transformer means output voltage fluctuation from no load to full load is least.

Description : A ferro resonant transformer regulation is also known as?

Answer : A ferro resonant transformer regulation is also known as constant current transformer.

Description : A transformer has negative voltage regulation when its load power factor is   (1) Zero (2) Unity (3) Leading (4) Lagging

Answer : Leading

Description : Negative voltage regulation is indicative that the load is?

Answer : Negative voltage regulation is indicative that the load is capacitive.

Description : Minimum voltage regulation occurs when the power factor of the load is?

Answer : Minimum voltage regulation occurs when the power factor of the load is leading.

Description : Can the electric field between two positive charges be zero?

Answer : It  can  only  if  they  have  equal  charges.

Description : State and justify which of the following two transformers is better:  Transformer A = 4% voltage regulation  Transformer B = 6% voltage regulation

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.

Description : The magnetic factor required to reduce the residual magnetization zero is called?

Description : Classify hydro-electric power plants according to water flow regulation and explain in brief.

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.

Description : Which of the following has nearly zero temperature coefficient? A) Constantan B) Manganin C) Both A and B D) None of these

Answer : Which of the following has nearly zero temperature coefficient? A) Constantan B) Manganin C) Both A and B D) None of these

Description : ln HRC fuse the time between cut-off and final current zero is called

Answer : ln HRC fuse the time between cut-off and final current zero is called the arcing time

Description : Is electric potential zero when electric field is zero?

Answer : Yes  .If  electric  field  is  zero  then  electric  potential  is  zero  ,  not  even  one.

Description : Define line regulation and load regulation.

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.

Description : Define load and line regulation.

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%.  

Description : 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

Answer : Identify the increasing order of voltage regulation of the following dc generators a same load : under compound, shunt and differential compound 

Description : The unit of speed regulation of a governor is :  (A) Hz (B) Hz/MW (C) Hz/MVA (D) rpm/MVAR

Answer : The unit of speed regulation of a governor is : Hz/MW

Answer : The voltage regulation in magnetic amplifier type voltage regulator is effected by varying the reactance.

Description : Which motor has the best speed regulation?

Description : State why a transformer always have an efficiency of more than 90%.

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%.

Answer : The chemical used in breather for transformer should have the quality of cleansing the transformer oil.

Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.

Description : The path of magnetic flux in a transformer should have?

Answer : The path of magnetic flux in a transformer should have low reluctance.

Answer : Iron loss of a transformer can be measured by low power factor wattmeter.

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

Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.

Description : In a transformer the voltage regulation will be zero when it operates at (A) unity p.f. (B) leading p.f. (C) lagging p.f. D) zero p.f. leading.

Answer : In a transformer the voltage regulation will be zero when it operates at leading p.f.

Description : In a transformer, zero voltage regulation at full load is   (a)Not possible   (b) Possible at unity power factor load   (c) Possible at leading power factor load   (d) Possible at lagging power factor load

Answer : In a transformer, zero voltage regulation at full load is Possible at leading power factor load 

Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.

Answer : Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds 150°C.

Answer : In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.

Answer : If the supply frequency to the transformer is increased, the iron loss will increase.

Description : The hum in a transformer is mainly attributed to?

Answer : The hum in a transformer is mainly attributed to magnetostriction.

Description : An open-circuit test on a transformer is conducted primarily to measure?

Answer : The open-circuit test in a transformer is used to measure

Description : A no-load test is performed on a transformer to determine?

Answer : A no-load test is performed on a transformer to determine magnetizing current and loss.

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

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.

Description : Part of the transformer which is most subject to damage from overheating is?

Answer : Part of the transformer which is most subject to damage from overheating is winding insulation.

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

Answer : If a transformer is switched on to a voltage more than the rated voltage its power factor will deteriorate.

Description : Sumpner's test is conducted on transformer to determine?

Answer : Sumpner's test is conducted on transformer to determine temprature.

Description : The dielectric strength of transformer oil is expected to be?

Answer : The dielectric strength of transformer oil is expected to be 33 kV.

Description : Explain the effect of Harmonics on the Transformer.

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.

Description : List two special feature of welding transformer.

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

Description : State two applications of isolation transformer

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.

Description : Equivalent circuit of transformer

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

Description : Single phase transformer

Answer : Single phase Transformer Transformer

Description : What is the use of transformer?

Answer : The use of transformer  is to do lower or raise  the voltage or currents in an electrical  circuit.  That's quite so simple. 

Description : Write about transformer on DC.

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

Description : Even at no-load, a transformer draws current from the mains. Why?

Description : State any four characteristics of core type transformer.

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.

Description : Explain construction and working of single phase Auto transformer.

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

Answer : No-load current in a transformer lags behind the voltage by about 75°.

Answer : In the transformer low voltage winding has got more cross-sectional area.

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