Oil Immersed Transformers With Conservator

Oil Immersed Transformers With Conservator
The free breathing transformers are equipped with air cushion under the cover or with a conservator to allow  the oil to expand, at the temperature variations. As it is not hermetic, the oil is always in contact with the air.  Moisture is kept at bay through the use of dehydrating salts contained in special filters (breather). The tank  can be with fin walls or raditors.This design applies to all powers, but especially from 4000kVA and upper  power rates. For higher power rates, in order to avoid contact between the oil and air, a rubber separator  (rubber bag) or a nitrogen cushion is used.

This type of transformer is equipped with an expansion tank or conservator mounted above the main tank.The expansion of the insulating liquid is compensated inside the conservator by raising of the oil level. In the  conservator, the top of the oil is in contact with the air which must remain dry to avoid any oxidation. This is  achieved by admitting the outside air in the conservator through a desiccating device containing silicagel  crystals.