Improved Determination of Moisture in Oil-Paper-Insulations by Specialised Moisture Equilibrium Charts

摘要

This investigation discusses the influences of temperature, initial moisture content, type of cellulose and ageing state of cellulose and oil on moisture equilibrium in oil-paper-insulations. The equilibrium diagrams were derived by comparison of moisture relative to saturation in cellulose and oil. A special emphasis is given to the reliability of coulometric Karl Fischer titration to measure moisture in cellulose and oil. It was found, that especially the aging state (e.g. reflected by acidity) of insulating oil has a very strong impact on moisture receptivity and therefore on equilibrium state.