Silica Gel Breather of Transformer
This device has the function of serving to avoid the moisture and particulate matter going through the transformer oil during the oil expansion process.
The natural air always consists of more or less moisture in it and this moisture can be mixed up with oil if it is allowed to enter into the transformer. The air moisture should be resisted during the entering of the air into the transformer because moisture is very harmful to transformer insulation. A silica gel breather is the most commonly used way of filtering air from moisture.
Whenever an electrical power transformer is loaded, the transformer gets hot, it will cause the insulating liquid to expand, the volume of the oil is increased, and the air above the oil level in the conservator will come out. As the transformer cools, the insulating liquid will again contract, and the volume of the oil is decreased, which causes the volume of the oil to be decreased which again causes air to enter into the conservator tank.
The silica gel breather for the transformer is connected to the conservator tank by means of a breathing pipe.
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The transformer's silica gel breather has a very simple design. It is nothing more than a silica gel going through which air passes during the breathing of the transformer. Silica gel is a very good moisture absorber. The newly regenerated gel is very effective, it can dry the air to the dew point below -40oC. A well-maintained silica gel breather will usually operate with a dew point of -35oC as long as a sufficient amount of gel has been used. The image shows a silica gel breather of the transformer.
Silica gel crystals have a great ability to absorb moisture. As air passes through these crystals in the breathing tube; The moisture of the air is absorbed by them. As a result, the air entering the conservator is quite dry, and the dust particles in the air are trapped by the oil in the oil-sealed cup. The oil in the oil seal cup acts as a barrier between the silica gel crystal and the air when there is no airflow through the silica gel breather. The color of silica gel crystals is dark blue but when it absorbs moisture; it becomes pink.
When there is enough difference between the air inside the conservator and the outside air, the oil level in the two oil seal components will change until the lower oil level just reaches the edge of the reverse cup, when the Air will move from high-pressure compartment to the low-pressure compartment of the oil seal. Both of these happen when the oil acts as a core filter and removes dust from the outside air.