The increasing rating requirements of modern transformers and electrical apparatus results in greater electrical stress in insulating material and fluids. In order to handle these greater stresses, oils are required to have better dielectric strength, and lower residual water content must be maintained. The timely and proper treatment of these insulating fluids will result in the improvement of the properties of the entire insulating system of power transformers. The principal functions of the insulating fluid are to serve as a dielectric material and an effective coolant. To perform these functions, the insulating fluid must have specific necessary qualities at the time of initial impregnation and filling at the factory which must be maintained at the same quality level in field operation if optimum performance is to be assured.

Almost 75 percent of the transformer failures happen due to contaminated and deteriorated oil. It is important to filter the transformer oil. Regular maintenance is of utmost significance as it is a great financial burden to replace or repair the transformer. Ignoring transformer oil filtration can lead to:
Arcing
Overheating, which reduces electrical efficiency as well as the life of the transformer
Corona Discharges
Decrease in insulating strength of the transformer oil, and more.