How Does a Transformer Work? – Essential Knowledge You Shouldn’t Miss

A transformer is an indispensable electrical device in power transmission and distribution systems. You can find transformers everywhere – from industrial substations to household electrical equipment. In this article, let’s explore the working principle of a transformer, its basic components, and why it plays such a critical role in the modern power grid.

1. What is a Transformer?

A transformer is a passive electrical device used to convert voltage levels from one circuit to another using the principle of electromagnetic induction.

Depending on usage needs, transformers can:

• Increase voltage (called a Step-Up Transformer)

• Decrease voltage (called a Step-Down Transformer)

2. Basic Structure of a Transformer

Core

The core is the central part of the transformer, often referred to as its “heart“. It is made of iron or silicon steel, in the form of thin laminated sheets insulated with varnish or paper.
In a three-phase transformer, the core has three limbs, each of which contains:

• Low voltage winding (LV winding)

• High voltage winding (HV winding)

The core provides a pathway for magnetic flux, which is essential for energy transfer between windings.

Windings

Windings are conductive coils wrapped around the core. There are two main types:

• Primary winding: receives electrical energy from the power source

• Secondary winding: delivers the desired output voltage

3. Working Principle of a Transformer

A transformer operates based on Faraday’s Law of Electromagnetic Induction. When alternating current flows through the primary winding, it generates a changing magnetic flux. This flux links with the secondary winding, inducing an electromotive force (EMF).

If the secondary circuit is closed, current will flow through it – this is how energy is transferred without direct electrical contact between the two circuits.

Voltage Step-Up or Step-Down

• If the number of turns in the secondary coil > primary coil, the transformer increases voltage (Step-Up Transformer)

• If the number of turns in the secondary coil < primary coil, the transformer decreases voltage (Step-Down Transformer)

4. Insulation and Cooling of the Transformer

To ensure safety, insulating materials are used between the windings to prevent short circuits. Additionally, insulated bushings help safely deliver power from the transformer to external systems.

During operation, the transformer experiences various energy losses, such as:

• Eddy current loss

• Hysteresis loss

• Copper loss

These losses generate heat. Therefore, transformers are filled with transformer oil, which serves two main purposes:

• Cooling the copper windings

• Providing internal insulation

Moreover, external cooling tubes or radiators help speed up heat dissipation, thus improving the transformer’s load handling capacity.

5. Protection Devices

To detect and respond to internal faults, transformers are equipped with a Buchholz relay – a critical safety device that helps disconnect the transformer during faults to prevent damage.

6. Conclusion

Transformers play a central role in modern electrical systems. Thanks to the principle of electromagnetic induction, transformers make power transmission and distribution more efficient and safe. Understanding how transformers work is not only valuable for electrical engineers but also essential for anyone involved in industrial and energy sectors.