Present and future transformer ratings require high quality and high purity insulating oils at the point of use. The increasing voltage and rating of the modern transformer and electrical apparatus results in greater electrical stress in insulating material and fluids. To handle these greater stresses, oils with better dielectric qualities are required. Also lower residual water content in insulating fluids and material must be maintained. The proper treatment and upgrading of the insulating fluid will result in the improvement of the properties of the entire insulating media of power transformers. The principal functions of the insulating fluid are to serve as a dielectric material and as an effective coolant. To perform these functions, the insulating fluid must have the necessary qualities at the time of initial impregnation and filling at the factory and later maintain the same quality in the field operation. ENERVAC’s High Vacuum Process upgrades the new or used electrical insulating fluids including transformer oils, polybutenes and silicone fluids. These systems and equipment were developed as a result of 50 years of experience in vacuum treatment of electric insulating fluids.