Ageing of liquid impregnated cellulose for power transformers

Cellulose products – paper and pressboard – are used in transformers as electric insulation and mechanical support for windings and leads. This Brochure mainly addresses the mechanical performance of the cellulose products. Products and standards are presented. Then ageing mechanisms are described, along with influence of ageing drivers as water and oxygen, and the performance in different impregnating liquids. Ageing markers, diagnostics and life management techniques are discussed. Finally, various test methods used for ageing studies are described.