Deterioration Diagnosis for Silicone Rubber Housing of Polymer Insulators by Infrared Ray Spectrometry

This paper describes pretreatment surface cleaning and analytical methods for evaluating deterioration of silicone rubber housing for out door high voltage insulators. Various solvents and washing methods were studied for effectiveness in removing different contamination types deposited on the surfaces of the silicone housing prior to analytical investigation. An effective method and combination of solvents were found. The analytical methods of SEM, EDX, XPS, FT-IR, and FT-IR-ATR were evaluated for effectiveness in measuring surface deterioration on aged insulators. The presence of aluminum nitride, which was generated by corona discharge and moisture, could easily be analyzed with FT-IR-ATR. Silicone insulator test specimens used in the tests were naturally aged in service and artificially aged by corona discharges and UV. Indexes of deterioration, derived from selected analytical techniques found suitable, were created which were correlated with exposure duration. The purpose of the test program was to determine the feasibility of predicting intrinsic longevity of polymer insulators by studying and quantifying deterioration modes and processes.