Can you tell distinct types of transformer oil used in systems for purification?

You will find two types of transformer oils in the market, i.e. paraffin based transformer oil and naphtha based transformer oil. There are plants intended by engineers that perform transformer oil purification in efficient way. When we compare both the transformer oils, we discover that paraffin oil is less oxidized. However, oxidation product like sludge in naphtha oil is highly soluble than paraffin oil.

This is why sludge present in naphtha oil is never precipitated at the bottom of the transformer. So, it enables oil circulation, and also let transformer to perform normally. Paraffin oil has lower oxidation rate as compared to Naphtha oil.

Quality transformer oil offers ideal insulation in an electrical power transformer and absorbs heat (works like coolant). Moreover, it helps preserve the core and windings of the system.

Other than these oils, mineral oil is also used for transformer since 18th century. Let’s overview the purification process of petroleum-

  • Crude petroleum

Crude oil is being extracted from crude petroleum. It has long chains of carbon compounds and smaller content of nitrogen and sulphur, accumulated over millions of years under high pressure inside earth’s crust. Hydrocarbon molecules classification is-

  • Paraffin
  • Cycloalkanes
  • Aromatics


Refining petroleum – This crude petroleum needs to be refined to classify petroleum products like gasoline, LPG, lubricating oils, kerosene oil, etc. Refining is done inside the vacuum distillation tower known as fractionating tower where multiple catalysts and distinct temperatures are used to classify the range of products.

Transformer oil or insulating oil is extremely refined mineral oil that is obtained from fractional distillation process with crude petroleum processing. You can classify transformer oil parameters in following categories-

  • Electrical parameters - dielectric strength, specific resistance, acidity, water content.
  • Physical parameters - Viscosity, flash point, inter facial tension, etc.

Moisture and dissolved gases- enemies of transformer oil : 

Moisture or water content is a serious contaminant that put adverse effect on insulation of the transformer and may be you have to call engineerings for repairing the transformers. Moisture makes the transformer oil less thick and the content is directly proportional to transformer oil aging.

Dissolved gases are other contaminants that degrade transformer oil quality.

This story is shared by experts performing transformer oil purification everyday inside their service center using latest tools and technologies. The purpose of this post is to let the readers know about transformer oil filtration range used by industries for their installed transformers.

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