Transformers change the voltage using electromagnetic induction, in which current is induced in a secondary coil as magnetic lines of force (flux lines) build up and collapse with changes in current traveling through the primary coil.
The secondary voltage is derived by multiplying the primary voltage by the turns ratio, which is the ratio of the number of secondary coils turns to the number of primary coil turns.
Oils used in transformers :
Mineral (petroleum-based) oil is the most frequent type of oil used in transformers. The oil used is commonly referred to as transformer oil or insulating oil. Some of the most commonly utilized ones are: (1) Transformer oil based on naphtha
(2) Transformer oil with a paraffin base. Also, silicone-based synthetic oils were used at one point in time. Mineral oils have been replaced by a few alternatives in recent years. Natural and manufactured esters, as well as Pentaerythritol tetra fatty acid, are among them.
Hence oil based on naphtha, and oil with a paraffin base are used in transformers.
