In power transformers some times I see an oil storage tank above it but not all transformer !!?

Question

In power transformers some times I see an oil storage tank above it but not all transformer !!

Question:

1- What the important of that storage tank?
2- When the transformer needs to use it ? and when never need it?

Answer 1

Its called a conservator. It keeps the main tank filled up if there are small leaks and allows for expansion as the oil heats.

Many modern transformers are hermetically sealed and don't need the conservator although its a choice when you order a new transformer which you want.

Modern manufacturing and materials have made the hermetically sealed type much easier to produce than previously and are preferred because of their lower maintenance.

Answer 2

This is a reservoir for oil in an oil-filled transformer. The oil serves as a heat transfer mechanism, used in larger transformers. Small transformers usually get sufficient cooling from the air.

Answer 3

The tank serves two functions.
* As additional cooling area,
* As an expansion tank to reduce pressure changes
in the oil due to thermal cycling.
Not all designs use the tank.
Not all transformers are even oil filled.

Answer 4

It's not WHEN , it's WHAT. For high VA power transformer, oil is necessary for cooling since most of them are oil-filled. However, there are certain air cool transformers, oil cooling is not required.