Nonflammable Liquid Transformers in Paper Mill Applications

Prior to the complete ban on PCB use in electrical equipment in 1979, transformers filled with askarels (PCB's) were available from several knanufacturers. These units gave the user advantages such as low losses, nonflammability, and the reliability of liquid-filled units. Silicone-filled transformers were introduced into the market- place in early 1974. These units proved to be environmentally acceptable but were classified as high fire point-not nonflammable- units. Other transformers filled with a high-temperature hydrocarbon oil are available, but these also were classified as high-fire point units. In the period 1979-1980 two types of nonflammable fluid-filled transformers were introduced. One type used a Freon R-113™fluid and a vapor-cooling concept to dissipate the heat generated within the unit. The second type used a tetrachloroethylene (C
₂
CL
₄
) fluid as the insulating medium with the same conventional cooling concept of heat dissipation utilized in other fluid filled transformers. The installation, maintenance, and operating concerns in installing tetrachloroethylene filled transformers are discussed. Data on units installed in three separate types of paper and forest product mills in three areas of the Southeast will be presented.