Extension of life span of power transformer on-site improvement of insulating materials

A number of researchers have studied the ageing of cellulose and demonstrated the deleterious effect of high temperature, moisture and air on paper life. This is expressed as a reduction in degree of polymerisation (DP). At low DP values the paper would be brittle and unable to withstand a mechanical shock. Important features creating damage are high levels of acidity and sludge. Acids and peroxides are attracted to and absorbed by the cellulose-with damaging effect-thus acid and sludge removal is a necessary part of the `arresting´ of insulation degradation. The authors discuss ways of arresting insulation degradation including reducing the moisture content in transformers