Thursday, 28 January 2021

Transformer | All in One | Definition , Types And Working Principles Of Electrical Transformer

Transformer |All in One | Definition , Types And Working Principles Of Electrical Transformer


A Transformer is a Static Electromagnetic Device consisting of two or more Windings which link with a common Magnetic Field.

In Other Words , A Transformer a device that Transfers Electric Power from one circuit to another without a change of Frequency.

It Can Raise or lower the voltage in a Circuit but with a Corresponding Decrease or increase current .

Electrical Transformer
Electrical Transformer


In brief , a Transformer in is a Machine that 

  • Transfers Electrical Energy from one circuit to another 
  • does so without a Change Of Frequency
  • does so by the principle of Electro-magnetic Induction
  • has Electric Circuits that are linked by a Common Magnetic Circuit.

The Basic Construction Of Transformer requires no Moving Part, requires Minimum Amount of Repair and Maintenance

The Transformer usually takes place with a Change of Voltage, although this not always necessary.

Basically , When the transformer Raises the Voltage in Example when the output voltage of a transformer is higher than its input voltage, it is called the Step- Up and when it lowers the voltage, it is called the Step-Down transformer .

A Simple Transformer consists of a Ferromagnetic Core or Silicon Steel Core and two windings placed on it.

The windings are Electrically Separated but magnetically linked through a path of Low Reluctance as shown in Picture 

Electrical Transformer
The Windings are insulated from both the core and each other.

The core is made of thin silicon steel Laminations to provide to the magnetic flux. 

The winding connect to the supply mains is called the primary and the winding connected To the load circuit is called the secondary.

In other words, the winding In to the load from which drawn out is called Secondary Winding.

Example :

A Transformer Have 500 turns Of Primary Winding  And 10 Turns Of Secondary Winding Than Determine The Current In Primary And Secondary Winding?? 
Given there the secondary winding connected with 15ohm resistance Load!! 

Hint : I2=V2/R

Types Of Transformers 

According To Construction, there are two main Types of Transformers namely
  1. Core type and 
  2. Shell type

Core type transformers

In this Type of Transformer, 
The windings surround the iron core

Both windings are divided and half of each winding is placed on each so that the two windings can be closely coupled together to keep the leakage flux and hence leakage reactance low.

Electrical Transformer, Core Type Transformer
Core Type Transformer

The Low Voltage (l.v.) winding is wound on the inside nearer to the core while the High voltage (h.v.) winding is wound over the l.v. winding away from the core in order to reduce the amount of Insulating Materials required and also the insulation of low voltage winding is easy.

With this Arrangement Of Windings, only one layer of high voltage insulation is required and removal or repair of the high voltage winding, 

Which is more liable to faults than the low Voltage Winding, is easy and convenient.

Small transformers have core of square or Rectangular Cross-Section but for large size transformers stepped or cruciform core is used as shown in figer. 

Electrical Transformer, Core Type Transformer

The core section for core type of transformers may be square, rectangular or stepped. 

Shall Type Transformers use cores with rectangular cross-section.

Shell type transformers 

In Shell Type Transformers, the windings are put around the central limb and the flux path is completed through two side limbs as shown in figer .

Electrical Transformer, Shell Type Transformer
Shell Type Transformer

The Central Limb Carries total Mutual Flux while the side limbs forming a part of a parallel magnetic circuit carry half the total Flux.

Consequently, The Cross-Sectional Area and hence width of the central limb is twice that of each of the side limbs. 

The sandwich type of winding is used in which the sections of the Primary Winding are sandwiched in between the sections of the secondary winding.

Therefore, the Leakage Flux is reduced and hence leakage reactance will be Low

To minimize the amount of high voltage insulation, low voltage coils are placed adjacent to the Iron Core.

Electrical Transformer, Shell Type Transformer

In this Type Of Transformer, the coils are better braced mechanically that they are Less easily displaced by the high electro-mechanical forces that frequently develop during short circuits.

For More Detail Check Article Of Types Of Transformers

Ideal Transformers And Auto Transformers

An Ideal Transformer is one which has no losses and magnetic leakage.

An Ideal Transformer has no ohmic resistance in the windings and no leakage flux. 

An auto-transformer is special Type Of Transformer having a single winding of insulated copper wire such that the part of the winding is common to the Primary And Secondary. 
i e. that serves as both primary and secondary

For More Information Of Ideal Transformer Auto Transformer : Click Here

Advantage Of 3 Phase Transformer

A 3-phase AC system is used to generate and transmit Large Amount Of Power.

  • It occupies less floor space for equal ratings
  • It is lighter in weight.
  • Smaller size for the same rating. 1phase
  • A 3- phase transformer is cheaper than a bank of three transformers.
  • It requires few bushings.
  • Less transformer oil is used.
Check Here For Extra information on Advantages of 3 Phase Transformer

Essential Consist In Three Phase Transformers

  1. Magnetic Circuit
  2. Electric Circuit
  3. Dielectric Circuit
  4. Tank and Accessories
  5. More... 

What Is A Advantage Of Scott Connection Of 3- Phase Transformer? 

Scott Connection requires a 3-phase power input and provide two equal single phase outputs.

Check More for Scott Connection Here

What is The Application Of Current Transformer ??

A CT is a device for the transformation of current from a Higher  Values to a lower values that are suitable for measurement of the relay operation.

The VA rating of CTs is very small as compared with Power and Distribution Transformers.
Click Here For More 

What Is The Application Of Potential Transformers ???

Potential Transformers are used for the information of voltage from higher values to a lower values that are suitable for Measurement And Protection.

Potential Transformers are used for measurement and protection. 

The VA rating of PT is very small compared with Power Transformers.

What Is The Tap Changing In The Electrical Transformers ? 

The Tap Changing may be done when the transformers are disconnected from the circuit or when Operating On Load.

Tap Changer is fitted with the transformer for adjusting the Secondary voltage.

The modern practice is to install the tap-changer with the Transformer Tank.

For More information on Tap Changing of Transformer. 

Video Of Transformer