Transformer oil, also known as insulating oil, has a crucial role in transferring electrical strains from one power circuit to another. This helps in the efficient functioning of the transformers. This oil is used in the transformers during the change of power from high to low or vice-versa. Acting as both an insulator and coolant, transformer oil is crucial for maintaining the integrity and performance of these transformers. In this article, we will briefly discuss the testing, types, and properties of this essential component…