Crude Transformer Oil, Form : Liquid

Insulating oil in an electrical power transformer is commonly
known as transformer oil. It is normally obtained by fractional
distillation and subsequent treatment of crude petroleum.
That is why this oil is also known as mineral insulating oil.
Transformer oil serves mainly two purposes one it is liquid
insulation in electrical power transformer and two it dissipates
heat of the transformer e.i. acts as coolant. In addition to
these, this oil serves other two purposes, it helps to preserve
the core and winding as these are fully immersed inside oil
and another important purpose of this oil is, it prevents direct
contact of atmospheric oxygen with cellulose made paper
insulation of windings, which is susceptible to oxidation.