Function of breather in Transformer

• Breather salica gel 

The function of breather in transformer is to filter out the moisture from air. Breather consist of silica gel which absorbs the moisture from air.

When there is overloading on transformer, the winding of transformer gets heated so the oil in main tank of transformer also get heated. The hot oil started expanding. There is conservator tank at the top of transformer which allows adequate space for expansion of oil. Therefore during overloading condition the oil move to the conservator tank.

In normal operating condition, the oil come back to main tank from conservator tank. Now, there is vacant space in the conservator tank which is filled with the air. Conservator tank is never completely filled as it has to allow space for expanding oil from main tank.

The air which is there in conservator tank is coming from atmosphere through the breather and breather contains silica gel in it. This silica gel absorbs the moisture from air. The main reason to remove moisture from air is because the moisture degrades the dielectric strength of the transformer oil.