Parts Of A Transformer

Parts Of A Transformer: Transformer Parts Study

Transformers look like a round, rectangular, or usable shape. It tends to be much heavier. Barricades are placed on top of it or around the transformer, safe from human and animal hands. Special measures are taken to protect against various natural calamities. A complete transformer is made by joining different parts together. The main part of the transformer is discussed in this blog.


Main Parts of a Transformer

The main parts of the transformer are different from one to others. And it works for several purposes. A complete transformer is made by combining all the parts. The names of the main parts of the transformer:


A metal tank holds the internal and external components of a transformer. It varies according to the size of the transformer. It protects the main part of the transformer from various injuries and unintentional accidents.

It is usually white, which reflects the sun’s heat and helps keep the transformer cool. Aluminum tanks are currently used to reduce the weight of transformers, which are more expensive than steel plates.


The transformer’s laminated core is made of high-grade grain-oriented steel. Thin insulating materials isolate these steels. The carbon content of the core is maintained below 0.1%, so that hysteresis and eddy currents are kept to a minimum.

Silicon is mixed with the core to reduce the hysteresis furtherment of the transformer further. The primary and secondary ends of the core are twisted with windings. Magnetic forces are flow from one coil to another coil through the core, which is generated by the primary windings.


Windings are considered the main parts of a transformer. A transformer has two phage and three phages windings. Windings are twisted with thin insulating wires on the core. The primary windings are connected with the AC source, and the secondary windings are connected with the load.

In a shell transformer, the secondary windings are rolled over the primary windings. Insulating materials are placed between the two windings so that they do not connect physically.


Bushing works like a circuit breaker. It makes from high-quality glazed porcelain. It ensures the safety passes of current from the joint between the two wires. The bushing isolates the AC and LT connections from the transformer’s heat and reduces flashover. It works on 12 to 33kV volts. The upper shape of the bushes is designed plain for disposal of rainwater.

Conservatory Tank

It is usually like a round drum made of metal which is placed on top of the transformer. We know transformers are full of oil. Due to the heat, the expanded oil enters the conservatory tank from the inside of the transformer and maintains equilibrium.

Pressure Release Device

If, for any reason, the pressure in the main tank of the transformer increases or decreases, then it opens up and maintains the balance of air pressure inside and outside to protect it from accidents.

Oil Level Indicator

The oil level indicator is an important device for a transformer. It connects with the conservatory tank and measures the oil level. If the oil goes down or increases, then the meter of the oil indicator shows it.

Temperature Gauge

A temperature gauge is a meter that shows the temperature of the transformer. There are three types of temperature gauges. They are Oil temperature indicators (OTI), Winding temperature indicators (WTI), and Remote temperature indicators (RTI). The temperature gauge can measure -40° to 400° temperature of a transformer.

Oil Inlet Valve

We know the transformers are filled with insulating oil by the oil inlet valve. The oil inlet valve is located at the top of the transformer. After filling the transformer, it is tight with the cork; therefore, the oil can’t pass out from it. When needs to drain the oil, then lose the valve for equilibrium the air pressure.

Oil Outdoor Drain Cock

Transformer oil is getting wasted day by day. So it needs to be changed after a certain period of time. An oil outdoor drain cock is located at the bottom of the transformer, and it helps to remove the wasted oil from the transformer.


Breather is full of silica gel, and it works like a nose of a human body. It helps to cool down the transformer by breathing. When the transformer warm-up, then the density of oil decreases, and it goes to the conservator tank.

Then the conservatory tank releases its pressurized wind by breather and takes natural air-cooled air by the same process. It happens turn by turn and by this method the transformer stays cool. The breather plays an important role in it.

Tap Changer

Tap changer is seen as a high voltage winding transformer. There are two types of tap changers. One is On Load Tap Changer, and another is Off Load Tap Changer. The on-load tap changer can work even if the transformer is active, but the off-load tap changer cabin can only work if the transformer is off.

It is a complex process, and in some transformers, it works automatically. By increasing or decreasing the number of primary windings through the tap changer, the obtained voltage of the secondary winding is maintained.

Explosion Valve

It stays on top of the transformer. When the internal pressure in the transformer increases or decreases for any reason, it automatically opens and balances the internal and external pressure of the transformer. As a result, the device is protected from accidents.

Buchholz Relay

Internal defects in the transformer and its insulating oil produce various hydrocarbon gases which need to be removed. Due to the expansion of the oil, it accumulates in the Buchholz relay when it enters the container.

Insulating Transformer Oil

Insulator transformer oil works a lot. It helps keep the transformer cool. Protects the device from major accidents by controlling the sparks from winding. Reduces current loss of the transformer. It needs to be replaced when the oil is lost as a result of regular use. The transformer has to maintain certain values in this oil.

Cooling Tubes

On both sides of the transformer, many pipes can be seen on the four sides of the transformer. Inside of which insulating hot oil flows. In the radiation method, heat from these pipes escapes into the air and keeps the transformer cool.

Insulating Materials

Insulators are used to increase the efficiency of transformer work. It is also used to avoid the connection between two wires. It protects the transformer from various accidents—a heated element of a transformer such as heated crepe paper, transformer oil, etc.

Earth connector

When an electric current is complete, electrons flow from negative to positive. And the electric current flows from positive to negative. If for some reason suddenly the amount of positive charge in the transformer increases, it has to be reduced, otherwise there is a possibility of an accident.

So, the ground connection is given to the transformer to eliminate this positive charge because this extra charge will go to the ground and protect the transformer from accidents.


The transformer is a very heavy device, so it cannot be transferred very easily. But sometimes, it needs to be relocated. Therefore, the wheel is provided as required with its lower structure for easy transfer.

The transformer uses to change the voltage or current to the secondary terminal. All of the parts of the transformer helps to increase its workability. It’s is improving day by day. More advanced transformers will be seen in the future.


About the Author: Mehedi Hasan

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