Ageing of cellulose in mineral-oil insulated transformers

The guide describes the normal ageing processes in the cellulose of oil impregnated insulation systems for transformers. The various cellulose materials and their properties are described. New knowledge on oxidation and hydrolysis and the influence of the chemical condition of oil and of paper together with thermal stresses are described. Also possibilities for diagnostics and for maintenance of the cellulose are discussed.