Development of a Measuring Technique to Determine the Acidity of Insulating Paper

Monitoring the ageing of insulation is a crucial aspect of transformer maintenance. It involves monitoring and diagnosing the current condition of the transformer insulation to maximize the transformer's service life. The diagnostic methods should help to predict the future behavior and performance of the insulation. Today, a wide range of indirect diagnostic techniques coexist side by side. As insulation ages, cellulose degrades into distinct compounds that dissolve in the insulating liquid as a result of natural ageing. The nature and composition of these ageing products provide indirect information about the insulation's state. The degradation of cellulose is directly linked to the development of acidic components in insulating paper. However, a significant number of acidic substances remains in the insulating paper and cannot be absorbed by the insulating oil. Currently, there is no method available to directly determine the acidity of the insulating paper. In this research, a new approach to measuring the acidity of insulating paper is introduced, along with a functional model of an infrared-based sensor for ongoing monitoring of acids in paper. The study included the extraction and measurement of acidic components in paper samples using potentiometric titration, followed by establishing a correlation between the results and the sensor readings. The research capitalizes on the characteristic C=O double bonds present in molecular compounds containing acid functionality.