What are the main applications of transformer oil in power equipment?

Transformer oil is primarily used for electrical insulation and heat dissipation in power and distribution transformers. It fills the tank to insulate windings and core, removes heat by natural or forced circulation, and suppresses internal arcing. In addition, the oil acts as a diagnostic medium because gases and degradation products dissolve in it, allowing condition monitoring through tests such as DGA, moisture, and acidity. Transformer oil is also used in tap changers, oil filled reactors, and some current and voltage transformers.