Saturday, August 22, 2015

Silica gel breather in transformers; Silica gel breather functions

Every electrical engineer have seen silica gel in Transformer. This article is wholly based on Silica gel.
Why Silica gel required in Transformer?
What are functions of Silica gel in Transformer?
When to change the silica gel?

In transformers Silica gel portion is referred as Silica gel breather. It is usually connected to conservator tank through a breathing pipe.

Silica gel breather mounting in Transformer

Whenever transformer is loaded i.e. near to full load, temperature of the Transformer oil get increased which leads to expansion of transformer oil means volume of oil get increased. Now when Volume of oil get increased air trapped above oil  level in conservator tank comes out.

Now when transformer is lightly loaded transformer oil cools down which will leads to decrease in transformer oil volume. Which will leads to air from surroundings get enter above conservator oil level, now this air contains moisture which must be needed to removed otherwise it will leads to moisture getting mixed with oil. If this moisture get mixed with oil than that will be very harmful for transformer Insulation. To remove this moisture silica gel is used. Silica gel absorbs this moisture and doesn’t allow moisture gets enter into transformer.
As during this process air leaves and enters the transformer that is why this is knows as silica gel breather. Which means transformer is breathing.

Silica gel breather in Transformers

Silica Gel color and changing silica gel period

Silica gel is blue in color but when it starts absorbing moisture it starts get pink in color. There is not defined life of silica gel , When 50% of silica gel turned into pink means there is need to change the silica gel.

Functions of Silica gel breather
Silica gel breather construction is very simple it just contains a pot filled with blue silica.
1.     Silica gel absorbs moisture form air entering the Transformer
2.     It also contains an oil pot below the silica gel pot. Oil is used to trap the dust particles in air. The oil in the oil sealing cup acts as barrier between silica gel crystal and air when there is no flow of air through silica gel breather.