Online oil drying in transformer 1

[ravindranathan]

Why do we need online oil drying system in transformers? With aircell in use,ingress of moisture is anyway likely to be low.So why do we still need additional online oil drying system?

 

[prc]

Nothing is 100 % impermeable. Through air cells also moisture can get into oil. In case of any oil leaks in the transformer moisture from outside can get into. In addition when paper insulation ages some quantity of water is generated. Online drying systems will remove only a very small quantity of water from the transformer.

 

[bacon4life]

PRC answered the question as to how water appears inside the transformer tank. Some transformer owners find that online oil drying avoids taking a multiday outage for the traditional offline transformer drying process.

A common question is why not just swap out the the wet oil. Unfortunately, most of the moisture stored in the transformer is in the paper. The online drying process allows time for the moisture in the paper to slowing move into the oil where the moisture can be removed.