Parts of a Power Transformer

Updated on July 22, 2019
goodnews11 profile image

Electrical and Automation Engineer . Specialized in LV Switchgear Design and process automation

What Is a Transformer?

A transformer is an electrical device that transfers electrical energy from one circuit to another by electromagnetic induction (also called transformer action). It is used to step up or step down AC voltage.

Components of a Transformer

Basic Parts of a Transformer

These are the basic components of a transformer.

  1. Laminated core
  2. Windings
  3. Insulating materials
  4. Transformer oil
  5. Tap changer
  6. Oil Conservator
  7. Breather
  8. Cooling tubes
  9. Buchholz Relay
  10. Explosion vent

Of the above, laminated soft iron core, windings and insulating material are the primary parts and are present in all transformers, whereas the rest can be seen only in transformers having a capacity of more than 100KVA.

Don't have the patience to read? Watch the video.

Core

Core

The core acts as support to the winding in the transformer. It also provides a low reluctance path to the flow of magnetic flux. It is made of laminated soft iron core in order to reduce eddy current loss and Hysteresis loss. The composition of a transformer core depends on such as factors voltage, current, and frequency. The diameter of the transformer core is directly proportional to copper loss and is inversely proportional to iron loss. If the diameter of the core is decreased, the weight of the steel in the core is reduced, which leads to less core loss of the transformer and the copper loss increase. When the diameter of the core is increased, the vise versa occurs.

Why Are Windings Made of Copper?

  • Copper has high conductivity. This minimizes losses as well as the amount of copper needed for the winding (volume & weight of winding).
  • Copper has high ductility. This means it is easy to bend conductors into tight windings around the transformer's core, thus minimizing the amount of copper needed as well as the overall volume of the winding.

Winding

Two sets of winding are made over the transformer core and are insulated from each other. Winding consists of several turns of copper conductors bundled together, and connected connected in series.

Winding can be classified in two different ways:

  1. Based on the input and output supply
  2. Based on the voltage range

Within the input/output supply classification, winding are further categorized:

  1. Primary winding - These are the winding to which the input voltage is applied.
  2. Secondary winding - These are the winding to which the output voltage is applied.

Within the voltage range classification, winding are further categorized:

  1. High voltage winding - It is made of copper conductor. The number of turns made shall be the multiple of the number of turns in the low voltage winding. The conductor used will be thinner than that of the low voltage winding.
  2. Low voltage winding - It consists of fewer number of turns than the high voltage winding. It is made of thick copper conductors. This is because the current in the low voltage winding is higher than that of high voltage winding.

Input supply to the transformers can be applied from either low voltage (LV) or high voltage (HV) winding based on the requirement.

Insulating Materials

Insulating paper and cardboard are used in transformers to isolate primary and secondary winding from each other and from the transformer core.

Transformer oil is another insulating material. Transformer oil performs two important functions: in addition to insulating function, it can also cool the core and coil assembly. The transformer's core and winding must be completely immersed in the oil. Normally, hydrocarbon mineral oils are used as transformer oil. Oil contamination is a serious problem because contamination robs the oil of its dielectric properties and renders it useless as an insulating medium.

Parts of the Transformer

Conservator

The conservator conserves the transformer oil. It is an airtight, metallic, cylindrical drum that is fitted above the transformer. The conservator tank is vented to the atmosphere at the top, and the normal oil level is approximately in the middle of the conservator to allow the oil to expand and contract as the temperature varies. The conservator is connected to the main tank inside the transformer, which is completely filled with transformer oil through a pipeline.

Breather

Breather

The breather controls the moisture level in the transformer. Moisture can arise when temperature variations cause expansion and contraction of the insulating oil, which then causes the pressure to change inside the conservator. Pressure changes are balanced by a flow of atmospheric air in and out of the conservator, which is how moisture can enter the system.

If the insulating oil encounters moisture, it can affect the paper insulation or may even lead to internal faults. Therefore, it is necessary that the air entering the tank is moisture-free.

The transformer's breather is a cylindrical container that is filled with silica gel. When the atmospheric air passes through the silica gel of the breather, the air's moisture is absorbed by the silica crystals. The breather acts like an air filter for the transformer and controls the moisture level inside a transformer. It is connected to the end of breather pipe.

Tap Changer

Tap Changer

The output voltage of transformers vary according to its input voltage and the load. During loaded conditions, the voltage on the output terminal decreases, whereas during off-load conditions the output voltage increases. In order to balance the voltage variations, tap changers are used. Tap changers can be either on-load tap changers or off-load tap changers. In an on-load tap changer, the tapping can be changed without isolating the transformer from the supply. In an off-load tap changer, it is done after disconnecting the transformer. Automatic tap changers are also available.

Cooling Tubes

Cooling tubes are used to cool the transformer oil. The transformer oil is circulated through the cooling tubes. The circulation of the oil may either be natural or forced. In natural circulation, when the temperature of the oil rises the hot oil naturally rises to the top and the cold oil sinks downward. Thus the oil naturally circulates through the tubes. In forced circulation, an external pump is used to circulate the oil.

Buchholz Relay

The Buchholz Relay is a protective device container housed over the connecting pipe from the main tank to the conservator tank. It is used to sense the faults occurring inside the transformer. It is a simple relay that is operated by the gases emitted during the decomposition of transformer oil during internal faults. It helps in sensing and protecting the transformer from internal faults.

Explosion Vent

The explosion vent is used to expel boiling oil in the transformer during heavy internal faults in order to avoid the explosion of the transformer. During heavy faults, the oil rushes out of the vent. The level of the explosion vent is normally maintained above the level of the conservatory tank.

More About Transformers

I have written a series of articles to help the reader understand power transformers. I've listed two here, and if you are interested in finding more, you can find them by clicking on my author profile at the top of this article.

How Does a Transformer Work - Basic working principles of the transformer.

Comments

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    • profile image

      Amitabha Manna 

      7 days ago

      Very Vital Part Of Electrical Enginearing.

      I Am Now study Of Junior Enginearing

    • profile image

      ANKUR YADAV 

      2 weeks ago

      VERY HELPFULL ,,

      GREAT JOB SIR

    • profile image

      Eric Oduwah 

      6 weeks ago

      Please for transformers are they base on the principles of mutual inductance OR faraday's law.

    • profile image

      SK myni 

      2 months ago

      Sir pls tell me which transformer is best current transformer or potential transformer

    • profile image

      Akhilesh Kumar 

      2 months ago

      sir, your notes is more well

    • profile image

      Rajat Rajendra Thorve 

      2 months ago

      Nice

    • profile image

      babu lal jatiya 

      2 months ago

      good

    • profile image

      Anil Patel 

      2 months ago

      Which material use when LV busbar joint time some luddi type put on LV Busbar and jonit and bresing. I forgot that material name.some one say asbestos shit .anybody help the find name.

    • profile image

      Phel 

      2 months ago

      Thanks sir

    • profile image

      dhilleswara rao 

      3 months ago

      good

    • profile image

      Mukesh Poddar 

      4 months ago

      Good

    • profile image

      Khan abutaha 

      4 months ago

      Thanks sir

    • profile image

      CK.Lakshminarayana 

      4 months ago

      Exclent topic for Engineering students ,

    • profile image

      santhakumar 

      5 months ago

      such a nice article thank you so much

    • profile image

      Narendra Singh rathore 

      6 months ago

      Electricity is very important dont work do work depend all people

    • profile image

      Amzad 

      6 months ago

      please explain about the drain coke.

    • profile image

      Philip Tsetsekple 

      7 months ago

      thanks for helping me understand my reseach

    • profile image

      ZAKIR HUSSAIN 

      7 months ago

      VERY EXCELLENT TOPICS AND BRIEF DESCRIPTIONS

    • profile image

      Shrimant 

      8 months ago

      What is the core tansformer

    • profile image

      Sowmya 

      9 months ago

      Hello..! It is nice to learn n helpful.. But i would like to know much more in deep regarding the transformer action & briefly about the conversion process which differs from theoretical to practical.. So i wanted to learn little more for my practice.. Thankyou..

    • profile image

      Nanaji 

      9 months ago

      Hi sir good evening parts of transformer nice sir

    • profile image

      Ajjaih 

      9 months ago

      Thank u sir

    • profile image

      endyboy 

      9 months ago

      it was an awesome experience in this website. i pray for further upgrading, thanks

    • profile image

      Jwala nayak 

      10 months ago

      Very well explanation

    • profile image

      Saumya 

      10 months ago

      Very nicely explained but there should be some diagrams also for our convinence

    • profile image

      Saumya 

      10 months ago

      Very well explained

    • profile image

      Dinesh Kumar 

      12 months ago

      Dg and transformer rating from low to high explain and DG rating depends upon what factor in company and industries,home , residential complex etc ..

    • profile image

      JSV 

      12 months ago

      Thanks for your article, Sir.

    • profile image

      MAAN Shahzada 

      12 months ago

      Thanks sir for me help

    • profile image

      ishrat gull 

      12 months ago

      thanks, sir

    • profile image

      Nahabwe Bruno 

      12 months ago

      Thanks for that helpful information

    • profile image

      Shweta Pandit 

      13 months ago

      Nice explanation...

      My question is what are the various insulating materials used in trasformer and for what purpose?

    • profile image

      Prakash.b 

      13 months ago

      Super notes

    • profile image

      Mahendra Patil 

      13 months ago

      Send to HT to LT voltage and current formula.

    • profile image

      salman 

      14 months ago

      nice explanation

      thnxxxxxx

    • profile image

      Ashish mundele 

      15 months ago

      Very nice explen sr.

    • profile image

      Dibya 

      15 months ago

      Please send electrical book

    • profile image

      Sundaraperumal 

      15 months ago

      Transformer

    • profile image

      Sai 

      15 months ago

      Give more information about the how the instrument in transformers are made up and some other things which are not in books

    • profile image

      Emmanuel Mba Santumah 

      15 months ago

      Thanks a lot, you are really ready to help. Great work.

    • profile image

      eldhose k shaju 

      16 months ago

      very much helpful information..thank you for your help...

    • profile image

      Parag 

      16 months ago

      Very Nice, simply understood about transformer operation

    • profile image

      Solomon 

      16 months ago

      Now i understand better,well done.

    • profile image

      pury 

      16 months ago

      well done

    • profile image

      Shaik Ali shabbeer 

      16 months ago

      Superb and nice

    • profile image

      Visi 

      16 months ago

      Nice

    • profile image

      prashanth kuamr 

      17 months ago

      Short answer and very nice

    • profile image

      Rakesh Kumar 

      17 months ago

      Very useful article and perfectly explained details of transformer. Which is easy to understand.

    • profile image

      RUTH AMANKWAH 

      17 months ago

      Well done,

      The arrangement and the simplification of the concept is understandable and meaningful for a certain standard.

    • profile image

      Nisha 

      18 months ago

      Easy to understand..

      U have any u tube channel..

    • profile image

      abidoye smuel 

      18 months ago

      this is a very good lecture

    • profile image

      Bharamana gouda 

      18 months ago

      Nice

    • profile image

      Kiran kumar 

      18 months ago

      Very a simple answer in transformer parts

    • profile image

      Dinesh 

      18 months ago

      Very use full to get the knowledge about transformer.thanks a lot.

    • profile image

      Anthony Opara 

      19 months ago

      Good lecture, I have learnt lot today

    • profile image

      Umesh Singh 

      19 months ago

      If we measure voltage between neutral and a phase, we'll get 220V.

      But if we measure the voltage between two phases say phase R and phase Y, we'll get nearly 400

      (√3 x 220), due to three phase.

    • profile image

      tej 

      19 months ago

      three phases are R,Y and B

      voltage between R and Y is 220

      voltage between Y and B is 220

      voltage between R and B is sum of ry and by is 440.

      it is ideally practically 220 to 240 volts in single phase

    • profile image

      Shaikh F.A 

      19 months ago

      Sir, I want to work in the field of transformer designing

      How can I?

    • profile image

      sareem deshmukh 

      20 months ago

      In the transformer each phase have 230V a transformer have three phase 230+230+230=690

      how does become 440V

      Why not come to 690?

    • profile image

      NAGARAJ 

      20 months ago

      Thanks u for sharing this post.

    • profile image

      nitin 

      21 months ago

      nice...

    • goodnews11 profile imageAUTHOR

      OSBERT JOEL C 

      22 months ago from CHENNAI

      The primary function of the transformer is insulation. Apart from that it also acts as a coolant and arc suppressor also. When the temperature of the oil rises the hot oil naturally rises to the top and the cold oil at the top moves downward. (Natural Cooling) Evaporating point of transformer oil is above 200 deg. celsius. So it is a rare phenomenon.

      More: https://owlcation.com/stem/Cooling-of-transformers

    • profile image

      GAURAV KUMAR JHA 

      22 months ago

      OIL IS JUST US AS A COOLANT ,HEAT PRODUCED IN TRANSFORMER IS ABSORBED BY THE OIL THEN OIL GET EVAPORATE AND COMES OUT FROM CONSERVATOR.

    • goodnews11 profile imageAUTHOR

      OSBERT JOEL C 

      22 months ago from CHENNAI

    • profile image

      Sunny 

      22 months ago

      Plz tell me something about oil function

    • profile image

      mahee 

      22 months ago

      Thank you very much for sharing your knowledge like this. it is very helpful to me to enhance my knowledge.

    • profile image

      Tirupati Transformers 

      22 months ago

      Thanks for sharing this post and make us the part of this epic post.

    • profile image

      Saddam hossain 

      23 months ago

      Can we say explosion vent another name PRD=Pressure Relief Device.

    • profile image

      Kishor chandegara 

      2 years ago

      Dear sir

      I don't no English language so please all information in Hindi language

    • profile image

      arun kumar verma 

      2 years ago

      sir , how can i make my career in transformer field

    • profile image

      kuldeep kumar 

      2 years ago

      who many temperature of winding and oil in transformer

    • profile image

      PURUSHOTTAM KUMAR 

      2 years ago

      Its topic my favourite topic so I'm very very thankyou

    • profile image

      Joginder pal 

      2 years ago

      Please taken to knowledge for transformer

    • profile image

      Srinu 

      2 years ago

      Thangs

    • profile image

      sadiq suhail abubakar 

      2 years ago

      Thank you very much sir,my que. Hare is that, what brought the change of windings of tranformer.

    • profile image

      vairachelvam 

      2 years ago

      Difference between kVA AND KW

      KVA

      transfprmer losses depents on voltage ang current (not in pf).so that we are mention in KVA

      KW

      motor losses depnts on load(pf) so that we are mention Kw

    • profile image

      SK 

      2 years ago

      It's awesome....

    • profile image

      Rj H.S.Meena 

      2 years ago

      Is there were 22 parts in the transformer?????????

    • profile image

      Nikunj 

      2 years ago

      Plz u tell me about motor concept

    • profile image

      manoranjan 

      2 years ago

      Deiffrsnce between kva and kw

    • profile image

      Frank mkony 

      2 years ago

      In like it

    • profile image

      SUMAN DEKA 

      2 years ago

      It is nice

    • profile image

      Nnamdi Onwuania 

      2 years ago

      A very useful information on transformer. Now is with me on it components and function. Assembly of it is very important. In de sense of avoiding likely problem that can erupt in de transformer when not properly installed.

    • profile image

      Firoz khan 

      2 years ago

      it is so helpfull web. thnx sir

    • profile image

      tamil 

      2 years ago

      Very usefull sir

    • profile image

      fs 

      2 years ago

      Sir,what's the process during transfer power one circuit to another circuit.....????

    • profile image

      saisaran 

      2 years ago

      what is the current value

    • profile image

      sonam (BHUTAN) 

      2 years ago

      Can u give more information about tabchanging

    • profile image

      Gorakh 

      2 years ago

      Thanks

    • profile image

      dileep 

      2 years ago

      thanks ur informaction

    • profile image

      Ashutosh Dubey 

      2 years ago

      Thank you.....Sir.

    • profile image

      Hassan Iqbal 

      2 years ago

      Information about tap changers is not enough, Can U explain it more precisely? please

    • profile image

      Hassan Iqbal 

      2 years ago

      It was helpful. Thanks

    • profile image

      NILONG 

      2 years ago

      Thank You and God bless!

    • profile image

      Prashant Kotkar 

      2 years ago

      thanks

    • profile image

      Habtamu kasaye 

      2 years ago

      It is really useful. thank you sir!

    • profile image

      shakeel 

      2 years ago

      why dont we make the core simply from 1 sinlge metal...is there any reason to use the cut to length parts like yoke, centre limb or side limb?

      kindly explain

    • goodnews11 profile imageAUTHOR

      OSBERT JOEL C 

      3 years ago from CHENNAI

      Transformer can stepup voltage alone not power. Input power will be equal to the output power ( neglecting losses).

    • goodnews11 profile imageAUTHOR

      OSBERT JOEL C 

      3 years ago from CHENNAI

      You are Welcome.

    • profile image

      jitendra gondaliya 

      3 years ago

      Thanks sir

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