| A laser irradiation technique has been explored to quantify visible as well as invisible degradation of housing materials used for nonceramic insulators. Nonceramic insulators that were removed from service and new samples of the housing that were sub jected to accelerated testing in the laboratory have been evaluated. The method uses a constant power laser source for delivering the same energy to the test specimen. The proposed method is fairly quick and could be looked upon as an additional method for characterizing aging of nonceramic insulators. It has been shown that this method provides a better characterization of aging than is obtained from Fourier transform infrared spectroscopy. The housing materials evaluated include silicone rubber, ethylene propylene diene monomer rubber and cycloaliphatic epoxy resin.; A combination of laser irradiation and thermogravimetric analysis has been utilized to understand the degradation dynamics of polymeric materials used for housings of outdoor high voltage line and apparatus insulators, namely, silicone rubber, ethylene pro pylene diene monomer rubber and cycloaliphatic epoxy. The induced temperature rise was calculated using laser photo-thermal models and the results were found to be in good agreement with experimental findings. It has been shown that there are significant differences in the degradation dynamics of silicone rubber when compared with ethylene propylene diene monomer and epoxy. It has also been shown that the laser irradiation technique can be used as an efficient method to rank polymer materials for arc tracking and erosion resistance, especially for present day materials that will easily pass the screening tests prescribed in the ASTM and IEC standards. |
