Transformer Types

Hello everyone, hope you all are doing great. In the previous articles, I have provided you an elaboration on Introduction to Transformer, Introduction to Three Phase Transformer and Transformer Ratio. Today, I will be giving you detailed discussion on Types of Transformers. The discussion will provide the various types of transformers based on different voltage levels, core medium, winding arrangements, place of use, parts of transformer and the applications. I will also provide the visual display of each of the transformer for your better understanding. This article provide you various applications associated with individual transformer. I will try my level best to make this article more helpful for you. So, let’s get started with today’s tutorial

Types of Transformer

The transformer can be divided into various types depending upon different parameters as given below.

  • Voltage levels
  • Winding arrangement
  • Core as medium
  • Applications
  • Place of use

Transformer Types based on Voltage Levels

Depending upon the voltage levels a transformer can be divided into two categories and they are given below.

  • Step up transformer
  • Step down transformer

Step Up Transformer

As it is clear from its name, step up transformer is a kind of transformer to be used in the electrical circuits where there is a requirement of higher voltages. It produces high voltage at the output terminal in comparison to its input terminal. As we all know there are two different types of windings in each transformer named as primary winding and secondary winding. In case of step up transformer, the number of turns in secondary windings are greater in number as compared to the number of turns in its primary windings. The figurative display of the windings of step up transformer is shown below.

Step up transformer scheme (transformer types)
Step up transformer scheme

From the above figure, it can be easily seen that the number of turns in secondary windings are more as compared to the primary windings. With the help of these larger no of turns, step up transformer produces higher voltages at the output.


Step up transformer can be used in:
— Stabilizers

Step Down Transformer

Just like step up transformer, similar is the case in step down transformer. Step down transformers are used in appliances or circuits where there is a need of low voltage requirements. It consists of secondary windings having less number of turns in comparison to its primary windings. In this way, it is able to produce lower voltages. The step down transformer windings are shown below.

Step Down Transformer Winding

 From the above figure, it can be seen that the number of turns in primary windings are greater in number as compared to the number of turns on its secondary windings. So, it becomes able to produce lower voltages at the output.


The major application of step down transformers is in:
Electrical distribution system where there is a requirement of low voltage
DC power supplies

Isolation Transformer

Isolation transformer doesn’t convert any voltage levels. Its primary and secondary windings are exactly the same which shows it has same number of turns in both the primary as well as in its secondary windings. Turn ratio of isolation transformer is always equals to 1 because the number of turns in both the windings are same. It is used to isolate both the windings from each other. The windings of an isolation transformer are shown below.

one-to-one Transformer (Isolation Transformer basic)
one-to-one Transformer (Isolation Transformer)

It is clear from the above figure that both the primary as well as secondary windings are exactly the same.


Isolated transformer is used:
— As an isolation barrier
— For safety purposes to cancel transfer of noise from primary to secondary windings or vice versa.

Transformers based on Winding Arrangements

Based on winding arrangements, transformers can be classified into a sub-category named as auto winding transformer as explained below.

Auto-Winding Transformer

In case of an auto-winding transformer, both the primary and secondary windings are connected in series with each other. There is a moveable node at the center of the winding known as center tapped node. The variation in the position of the center tapped node, output voltage at the secondary windings, can be varied accordingly. The windings of an auto-winding transformer is shown below.

Auto Transformer construction
Auto Transformer

Applications of Auto Transformer

The most common applications associated with the auto-winding transformers are listed below.

  • Power transmission
  • Power distribution

Transformers based on Core as Medium

On the basis of core medium, transformers can be classified into the various categories as given below.

Ferrite Core Transformer

Due to higher magnetic permeability, this transformer uses ferrite core. In high frequency applications, there are very low loses in ferrite core transformer.

Applications of Ferrite Core Transformer

Ferrite core transformer can be used in:

  • High frequency applications
  • Switch Mode Power Supply (SMPS)

Iron Core Transformer

Iron core transformer uses various soft iron plates as a core material. It has very high flux linkage due to the good magnetic characteristics. This property results in high efficiency of the iron core transformer.
On the basis of shape and core size, various types of core plates are available in market these days. The most commonly known core plates available in the market are E, I, U & L shaped plates. Few core plates are shown below.

Transformer iron core type
Transformer Laminated Core plates

Air Core Transformer

Such transformers don’t use any type of physical magnetic core as a core material. Air is used for the flux linkage of air core transformer. The alternating current is supplied to the primary windings and electromagnetic field is produced around it as a result. If a secondary coil is placed in a magnetic field, magnetic field will be induced in it. In comparison to iron core transformer and ferrite core transformer, air core transformer generates low mutual inductance. Air core transformer is shown below.

Air Core Transformer

Applications of Air Core Transformer

Iron core transformer can be used in:
Portable electronics
Radio frequency based applications

Toroidal Core Transformer

This transformer consists of toroid shaped core material. Toroid is basically a donut or ring shaped core material. Toroid is used for the purpose of superior electrical performances. The leakage inductance is very low due to the donut or ring shape and it provide higher levels of inductance. Toroidal core transformer windings are shown below.

toroidal core based transformer
Toroid core transformer

Transformer Types based on Applications

On the basis of various applications, transformers can be divided into multiple categories as shown below.

Electronic Domain

  • Audio output transformer
  • Pulse transformer

Power Domain

  • Distribution transformer
  • Power transformer
  • Measurement transformer

Audio Output Transformer Type

It is one of the most commonly known transformer used in electronic devices or equipment. Its most common application is in audio related appliances. It balances an amplifier circuit and load. The load is loudspeaker most of the times. It may have more than one primary as well as secondary coils. The audio transformer is shown below.

Audio Output Transformer

Pulse Transformer

This transformer produces electrical pulses of same amplitude. It is mostly used PCB mounted transformer. It can be used in different circuit where there is a need of generating various desired pulses. Pulse transformer is shown below.

Pulse Transformer

Distribution Transformer

The distribution transformers are used in the very last stage of the power distribution systems. They are basically the step down transformers used for the conversion of high voltage coming from the grid to any desired value of voltage e.g. 110V, 230, 440V etc. It may be either be a single phase or 3-phase. The distribution transformer is shown below.

Basic introduction to Distribution Transformer
Distribution Transformer

Power Transformer

The power transformers are larger in size. They are used to transfer energy towards the electricity supply. Power transformer basically acts as a bridge between a generator and a primary distribution grid. On the basis of power ratings, power transformers can be further divided into three categories as given below.

  • Small power transformers (300-700kVA)
  • Medium power transformers (50-100MVA)
  • Large power transformers (over 100MVA)4

The power transformer is shown below.

Power Transformer basic introduction and types
Power Transformer

These were all the basic types of transformers we need to know for electrical equipment. I hope this tutorial will be quite helpful for you to better understand the basics of transformers. I have tried my level best to cover all the important parameters. If you guys find anything missing, please let me know as soon as possible in order to avoid any future inconvenience. I’ll update it soon accordingly. Shortly, I’ll publish another interesting tutorial on some informative topic. Till then take care 🙂

Here is the list of different full projects based articles that use transformers as main component.

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