Impact of Moisture and Remaining Life Estimation

This chapter provides a complete overview of water in transformers and discusses the techniques used to measure the water content of insulation. The effect of water on transformer operation is presented to help the reader understand the problems and case studies are shown using measurement data obtained from normally operating power transformers. Within an oil‐filled transformer, the majority of water exists within its cellulosic insulation. Karl Fischer (KF) Titration is an accurate technique to measure the water content of a material or liquid, in mass of water per mass of dry material. The condition of aged paper was quantified by its degree of polymerization (DP). Two detrimental effects of water are presented. The first is from an operational viewpoint. The second is from an asset management perspective, where the remaining life of the insulation is reduced by chemical reactions occurring with water.