interview questions on transformer and answers pdf

Interview Questions On Transformer And Answers Pdf

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If you are an expert in electrical technology then this is for you. Let us know if you looking for a job change? If you are preparing for Transformer job interview then go through Wisdomjobs interview questions and answers page.

300+ TOP TRANSFORMER Interview Questions and Answers

What is a Transformer? A transformer is a static device which can transfer power from one circuit to another at same frequency. How Does a Transformer Work? Transformer consists of two coils. If one coil is connected with ac voltage source then it will produce alternating flux in the core. What are the various types of Transformers?

Based on supply. What is Auto-transformer? In these transformer only one winding is used as primary and secondary. Also, primary and secondary are conductively coupled. What is Two winding transformer? Two separate windings one as primary and other as secondary are used. Both windings are magnetically coupled. What is Three winding transformer? Three windings are used each work as primary and secondary.

Also primary and secondary windings are conductively couple. They are three phase auto transformer. What is Six winding transformer? Three windings in primary and three windings in secondary are used, They are three phase transformers. They are connected in either star-star, delta-delta, star delta or delta star. What are the advantages of shell type transformer over core type transformers?

In shell type transformers the coils are well supported on the all sides and so they can withstand higher mechanical stresses developed during short circuit conditions. Also the leakage reactance will be less in shell type transformers. Where is core type and shell type construction suitable for a transformer? Core type transformers are popular in High voltage applications like Distribution transformers, Power transformers, and obviously auto transformers.

Where as, Shell type transformers are popular in Low voltage applications like transformers used in electronic circuits and power electronic converters etc.

What are power transformer? It is big in size as compared to distribution transformer, it used in generating station and Transmission substation. It is generally rated above MVA. What are distribution transformer? The distribution transformer is used for the distribution of electrical energy at low voltage as less than 33KV in industrial purpose and vv in domestic purpose.

Its load depends on distribution demand. What are Current transformer? They are protective devices used to measure very high value of current in power system. The Current Transformer C. What are Potential transformer? They are protective devices used to measure very high value of voltage in power system. What are dry type transformer? In this type of transformer, air is used as coolant. The heat is taken to walls of tank and dissipated to the surrounding air. What is oil immersed type transformer?

In this type of transformer, oil is used as coolant. Entire assembly including core and windings is kept immersed in oil. The developed heat is transferred to the walls of tank through oil.

Finally the heat is transferred to the surrounding air from tank wall by radiation. What are step up transformers? They step up voltage from lower value to higher value. What are step down transformers?

They step up voltage from higher value to lower value. What are isolation transformers? In this type of transformer the primary and secondary are same. When it is required to isolate the primary and secondary circuits these type of transformers are used.

It protects the circuits connected in secondary side when major fault occurs in primary side. What is yoke section of transformers? The sections of the core which connect the limbs are called yoke. The yoke is used to provide a closed path for the flux. What is the purpose of laminating the core in a transformer?

In order to minimize eddy current loss. Explain on the material used for core construction? A:The core is constructed by sheet steel laminations assembled to provide a continuous magnetic path with minimum of air gap included.

The steel used is of high silicon content sometimes heat treated to produce a high permeability and a low hysteresis loss at the usual operating flux densities. The eddy current loss is minimized by laminating the core, the laminations being used from each other by light coat of coreplate varnish or by oxide layer on the surface.

The thickness of lamination varies from 0. Why the cross-section of iron is less than total cross section area of core? What is Stack factor? The ratio of total cross section of iron to the total cross section of core is called stack factor. What is voltage transformation ratio or turn ratio? It is expressed as ratio of the primary and secondary voltages of transformer. What is transformation ratio for step up, step down and isolation transformer? What are the properties of ideal transformer?

There should be no losses. The permeability of core should be so high that the negligible current is required to establish the flux in it. Does the transformer draw any current when secondary is open? Yes,it primary will draw the current from the main supply in order to magnetize the core and to supply iron and copper losses on no load.

There will not be any current in the secondary since secondary is open. What are two components of no load current in transformer?

It magnetizes core. How much is the no load current of transformer? Give equivalent resistance, reactance and impedance referred to primary circuit. Give equivalent resistance, reactance and impedance referred to secondary circuit. Why to calculate equivalent impedance referred to primary or secondary side? Equivalent impedance is essential to be calculated because the electrical power transformer is an electric power system equipment, for estimating different parameters of electric power system which may be required to calculate total internal impedance of an electric power transformer, viewing from primary side or secondary side as per requirement.

This calculation requires equivalent circuit of transformer referred to primary or equivalent circuit of transformer referred to secondary sides respectively. What is Meant by Regulation in a Transformer? Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage.

The change in secondary terminal voltage from no load to full load expressed as a percentage of no load or full load voltage istermed as regulation.

What is the condition for zero voltage regulation? Negative sign indicates zero voltage regulation. It occurs when load is capacitive and power factor is leading.

What is the condition for maximum voltage regulation? It occurs when load is inductive and power factor is lagging. What is Eddy current loss in transformer? 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 voltage in secondary, resulting current to flow through the load connected with it. Some of the alternating fluxes of transformer; may also link with other conducting parts like steel core or iron body of transformer etc.

As alternating flux links with these parts of transformer, there would be a locally induced emf. Due to these emfs, there would be currents which will circulate locally at that parts of the transformer. These circulating current will not contribute in output of the transformer and dissipated as heat.

This type of energy loss is called eddy current loss of transformer.

Transformers Interview Questions & Answers

Different between megger and contact resistance meter? Answers: Megger used to measure cable resistance, conductor continuity, phase identification where as contact resistance meter used to measure low resistance like relays ,contactors. When we connect the capacitor bank in series? Answers: we connect capacitor bank in series to improve the voltage profile at the load end in transmission line there is considerable voltage drop along the transmission line due to impedance of the line. Answers: Diversity factor is the ratio of the sum of the individual maximum demands of the various subdivisions of a system, or part of a system, to the maximum demand of the whole system, or part of the system, under consideration. Diversity factor is usually more than one. Answers: In motors at the time of starting the armature resistance is introduced to reduce the high starting current and the field resistance is kept minimum to have high starting torque.

Power Transformer: 100 Interview Questions !

A Not b Because short circuit test means full load test means find out the copper loss in high voltage side. Thanks Dear You can also learn and prepare answer for your exams from EG website. For engineering students from various departments, require more information about final year projects.

Solved examples with detailed answer description, explanation are given and it would be easy to understand. Here you can find objective type Electrical Engineering Transformers questions and answers for interview and entrance examination. Multiple choice and true or false type questions are also provided. You can easily solve all kind of Electrical Engineering questions based on Transformers by practicing the objective type exercises given below, also get shortcut methods to solve Electrical Engineering Transformers problems.

Transformer Interview Questions & Answers

Why is transformer flux constant?

Basic Electrical Engineering Interview Questions and Answers

What will be the effect of open circuiting the secondary of a C. Ans : If the secondary of a C. For these reasons open circuiting of a C. Ans : The standard secondary rating of P.

In today post, we will be sharing the frequently asked electrical engineering interview questions and answers related to electrical engineering. Electrical engineering deals with high voltage especially AC above the range of or V. When manufacturers design a transformer, they have no idea which kind of load will be connected to the transformer. The output of real power may vary depending on the power factor. A real transformer has the following losses;. The losses occur due to the current flow through the windings that causes resistive heating of the conductors. There are two types of core or iron losses.

If you are preparing for Transformer job interview then go through Wisdomjobs interview questions and answers page. Transformer is an electrical device.

Electrical Engineering - Transformers

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In this page , we have dicussed about lots of transformer interview question. All transformer interview question have been collected from exprience Electrical Engineers. There are 13 nos. Hope transformer interview question should be help you for preparing your interview. Ans : A transformer is a static piece of apparatus which transforms electrical energy from one Circuit to another circuit without changing the frequency either stepping up or stepping down the voltage. Ans : The principle of operation of a transformer is based upon the theory of mutual induction Between two electrical linked by a common magnetic flux. Ans: The rating of a transformer is the maximum power which can be drawn from it without the temperature rise in the winding exceeding the safe limits for the particular class of insulation employed.

What is a Transformer? A transformer is a static device which can transfer power from one circuit to another at same frequency. How Does a Transformer Work? Transformer consists of two coils. If one coil is connected with ac voltage source then it will produce alternating flux in the core. What are the various types of Transformers? Based on supply.

ГЛАВА 116 - Читайте, мистер Беккер! - скомандовал Фонтейн. Джабба сидел весь потный, положив руки на клавиатуру. - Да, да, - сказал он, - читайте эту благословенную надпись. Сьюзан стояла рядом, у нее подгибались колени и пылали щеки. Все в комнате оставили свои занятия и смотрели на огромный экран и на Дэвида Беккера. Профессор вертел кольцо в пальцах и изучал надпись. - Читайте медленно и точно! - приказал Джабба.

На ней стояли пустая бутылка из-под шампанского, два бокала… и лежала записка. Протерев глаза, она натянула на плечи одеяло и прочла: Моя драгоценная Сьюзан. Я люблю. Без воска, Дэвид. Она просияла и прижала записку к груди.

Он объяснил, что кандзи - это система японского письма, основанная на видоизмененных китайских иероглифах. Он же давал им китайские значения, потому что такую задачу они перед ним поставили.


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How is magnetic leakage reduced to a minimum in commerical transformers?



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