My topic today is the Transformers parts. The transformers you see on the sidewalk, in the market, or in the village. Seeing that transformer may raise various questions in your mind. Many parts of it can be seen, what is the function of this distribution transformer parts?

Distribution transformer parts

The most important role in our current daily life is electricity. Without which the wheel of lifestyle progress becomes much slower.

Because we work in different factories, shopping malls, or any shop to earn money. Again, if there is no electricity in that workplace, the workplace becomes unusable, as a result of which our income also stops.

This electricity is generated in one place and reaches far and wide. However, it does not reach your house directly from the power source, because its voltage is much higher. Your home needs low voltage, so you have to convert that high voltage to low voltage.

And the transformer works for this conversion. That converted electricity is distributed to everyone’s house. The transformer that is converted by this is called a distribution transformer. I will take away all your curiosity related to this transformer.

Parts of Distribution Transformer

A distribution transformer has many parts that work differently. And we will first know the names of all the parts of the transformer we see, then we will discuss the work of those parts.

  1. Core and Type
  2. Windings and type
  3. Tank and type
  4. Transformer Oil
  5. Buchholz Relay
  6. Breather
  7. Cooling tube & Radiator
  8. Terminal & bushing
  9. Explosion Vent

Main Tank

First I will talk about Tank. It is completely empty and all the parts of the transformer are kept inside. This tank has three parts, they are core, winding around the core, and coil.


The core is the center of the tank and it is made of soft iron. It is thick but not made of one piece of iron. The core is made of many thin iron plates. Take a look at the photo below, for example, you will understand that you played a lot with them as a child.

Now the question may come to your mind, why the core is made of plates in this way? There is a reason for this, to avoid ED current. Now talking about what is ED current?

ED current is excess current. Where current flows, if there is space, the extra current is generated, which is called ED current. It is well varnished at the core for relief. As a result of applying varnish, if there are gaps, they are filled.


Copper wire is winding on this core. This copper is wrapped around its two parts. These are divided by insulator paper. That is, insulator paper is used to prevent the second part from being attached to the primary part.

Nephtha oil

The core is then lifted and inserted into the tank. There is a lot of space around the core and as I said before, space cannot be kept. Because if there is a gap, ED current will be generated, which prevents the original current. This gap must be filled so that ED current is not generated. To fill this gap, a type of thick oil called naphtha oil is used.

Conservator Tank

Above the main tank is a small sub-tank with which the main tank is linked. This is called a conservator tank. Suppose you are heating milk. When overheated, the milk boils. In exactly the same way when the naphtha oil gets overheated, the oil boils.

The tank is completely welded and sealed. In such a situation, the oil may overflow and the tank may burst and an accident may occur. But that doesn’t happen because the surged oil goes into the conservator tank.

There is a way to put oil on the top of this tank. One thing to keep in mind is that up to half of this tank is filled with oil. Now speaking, why is the conservator tank kept half?

Why is the conservator tank kept half?

Conservator tanks are not filled mainly for two reasons. Those two reasons are —-

  1. First, the conservator tank is used to keep the oil from overflowing and preventing the transformer from exploding. If the oil rises too much, the excess oil goes to the upper part of the hollow. This protects the transformer from blasting.
  2. Second, the oil level goes down when the transformer is old. Then the empty space is left and Bebong ED current is created. Excess oil in the conservator tank fills that gap.


To solve this problem, a blue breather is attached to the conservator tank. The breather is mounted on the top of the conservator tank but tilted downwards. Silica jelly is inserted into it which absorbs the water in the air.

The transformer is usually on the side of the road or in an open space. This will allow dust and sand to enter naturally. For this, a little oil is placed on the bottom part of the breeder. When air enters through the breather, this oil separates dust and sand from that air. So the advantage of a breather is to purify the air.

How is the transformer oil inserted and removed?

If you are wondering if the tank is completely sealed, then how is the main tank filled with oil and how is it barred? A hole is drilled in the top of the conservator tank to fill the main tank with oil. And there are holes in the bottom of the transformer to drain the oil from the tank.

Buchholz Relay

Suppose the transformer overheats, then any interruption can occur. In this case, the transfer needs to be stopped. But shutting down like this, not manually possible, requires an automatic process. And for him And for that Buchholz relay is fitted, it acts as a circuit breaker.

The Buchholz Relay is a type of machine that has nothing to do with electricity. It has a switch that does not have to be pressed, it is automatic. How? It contains mercury which expands when heated. It is mounted in a place that expands and controls the switch.

This switch is also called a mercury switch. This machine is mounted between the main tank and the conservator tank. The machine is used for the safety of the transformer.

Explosion Vent

Suppose the Buchholz relay is damaged and the transformer gets very hot. Then the transformer explodes and a big accident can happen. To avoid this danger, an explosion vent is mounted on the main tank. It is made with a long pipe and its endpoints are closed with a soft valve.

When the oil boils so much that the conservator tank also fills up. Then that extra oil goes out through this explosion pipe. You are wondering if the pipe is closed, how will the oil come out? The oil will leak out, as the valve softens under pressure. Nowadays in new transformers, it is not so big, it is small.

Cooling Tube or Radiator

The oil got hot and the transformer went off This is fine in emergencies, but if it happens often, it’s a problem. To get rid of this problem, the oil must always be kept cool. Cooling tubes or radiators are used to keep the oil cool.

We know that when a liquid is heated, the hot liquid at the bottom goes up and the cold liquid at the top goes down. The same thing happens with transformers. In this way, the oil continues to rise and fall inside the transformer.

The oil also travels through the cooling tube. When the hot oil goes through the tube, the oil cools. Because the tube shots take in outside air. This is possible in the case of low-power transformers but in the case of high-power transformers, the fan is fitted.

Terminal or Bushes

Terminal, simple to say connector. The terminal usually consists of seven, four high voltage input terminals, and three low voltage output terminals. The high voltage current enters the transformer through the input terminal. And low voltage current is distributed from the transformer through the output terminal.

Hindi Video on Distribution Transformer


I hope I have been able to overcome all the curiosity you had about the transformer. There are many more things besides these that I could not discuss. Watch the full video to learn more about them. If you need any post related to Electronics, please comment.

A transformer is a high voltage converter through which a high voltage current flows. So the more you stay away from it, the better for you. One small mistake of yours can lead to a big accident in your life.

P. Mahata (West Bengal)

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