An Optical SPR Sensor for Monitoring Accelerated Ageing of Oil-Paper Insulation of Transformers

Degradation of electrical insulation due to the oil-paper insulating system is one of the main factors that affect power transformer service life. Although the end of life failure is inevitable, the life of the insulating paper can be maximized through careful monitoring and maintenance. In this paper an optical SPR sensor is reported for high sensitive detection of a chemical marker of the transformers’ insulating paper degradation. Temperature tests were carried out on oil–paper specimens representative of the solid insulating system of transformers, subjected to initial different drying processes and successively exposed to aging temperature. A comparative analysis with standard methods (HPLC—High Performance Liquid Chromatography) confirms that the chemical concentrations detected in oil–paper sampling of different specimens with optical SPR sensors are in good agreement with those measured by standard techniques.