Drying transformer cellulose insulation by means of synthetic ester

The article concerns the drying of power transformer cellulose insulation by means of synthetic ester. The introduction describes the negative influence of cellulose insulation moisture on transformer operation reliability. It presents the operation limitations resulting from high water content in cellulose insulation. The article presents currently applied methods of drying of cellulose insulation and a new proposed method which makes possible effective and safe water reduction in the transformer. This method consists in replacing mineral oil by synthetic ester during the drying time of cellulose. This electro-insulating liquid is being more widely applied as liquid insulation in transformers mainly due to its fire safety properties and biodegradability. Synthetic ester is characterized by high water solubility, which was used by the author of this article to dry cellulose insulation. The article presents the research results which confirmed the possibility of using synthetic ester for effective drying of cellulose insulation. The author compared the effectiveness of cellulose insulation drying by means of synthetic ester and mineral oil.