What are Transformers Made of?

August 3, 2023

Electrical transformers are essential components of power systems. They convert electrical energy from one voltage level to another, allowing for efficient power transmission and distribution.Understanding the components of a transformer is crucial to understanding how it works and how to maintain it. In this blog post, we will discuss the various components of an electrical transformer and its functions.


The core is the central part of a transformer and is made of laminations of high-grade silicon steel. The core's main function is to provide a low reluctance path for the magnetic flux generated by the transformer's windings. The core's quality directly affects the transformer's efficiency and performance.


The windings are the coils of wire wrapped around the core. There are two types of windings: primary and secondary. The primary winding is connected to the power source, while the secondary winding is connected to the load. The number of turns in the primary and secondary windings determines the transformer's voltage ratio.


Insulation is essential to prevent electrical breakdown between the windings and the core. Insulation materials used in transformers include paper, pressboard, and oil-impregnated cellulose. The insulation's quality affects the transformer's lifespan and performance.

Tap Changer

The tap changer is a device used to adjust the transformer's output voltage. It is usually located on the high-voltage winding and allows for small adjustments to be made in the voltage ratio. Tap changers can be either manual or automatic.

Tank (When LiquidFilled)

The tank is the outer shell of the transformer and is usually made of steel. Its main function is to protect the transformer's components from environmental factors such as moisture and dirt. The tank also contains the transformer's oil, which is used for insulation and cooling.


Bushings are insulating devices used to connect the transformer to the power system. They are usually made of porcelain or polymer and are located on the tank's sides. Bushings provide a safe and reliable means of transferring power to and from the transformer.

Cooling System

Transformers generate heat during operation, and a cooling system is necessary to prevent overheating. The most common cooling systems are oil-immersed and air-cooled. Oil-immersed transformers use oil as a coolant and insulator, while air-cooled transformers use natural air cooling as well as fans (forced air) to dissipate heat.

Electrical transformers are complex devices that require careful design, construction, and maintenance. Understanding the various components of a transformer is crucial to ensuring its efficient operation and longevity. By familiarizing yourself with the core, windings, insulation, tap changer, tank, bushings, and cooling system, you can gain abetter understanding of how transformers work and how to keep them running smoothly.

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