Aging Performance of ATH based RTV Insulator Coatings

The paper presents the results of an investigation about the aging performance of three different types of room temperature vulcanized (RTV) silicone rubber coatings for high voltage insulators when subjected to accelerated tests in acid water. Although all coatings have ATH as the main filler, different performance was observed under simulated acid rain conditions. Erosion area, length of erosion and the development of the 3rd harmonic in the leakage current during inclined plane tests are employed to evaluate the tracking and erosion of acid aged samples. Thermo-gravimetric analysis (TGA) and thermal conductivity was employed to investigate the thermal performance of the coatings. Scanning electron microscope photographs are also used to assess surface changes after aging. Factors that have significant influence on the aging performance of RTV coatings include filler bonding to the polymer matrix and the existence of other fillers, which can improve the performance of RTVs in severe ambient conditions.