Evaluation of the Degradation Degree of 20-Year-aged Insulator by Using Surface Discharge

Polymer insulator wherein silicone rubber (SiR) is used as housing material are exposed to various environmental stresses such as ultraviolet (UV) radiation, high temperatures, and pollution, which can lead to degradation over time. Assessing the degree of this degradation is crucial for the long-term maintenance of polymer insulators. This study proposes a novel technique to evaluate the degradation degree of SiR. To effectively expose PDs to specific locations on the SiR surface, we generated surface discharges (SDs). We compared hydrophobicity recovery times between an unused SiR specimen and aged SiR specimens. Our approach involves analyzing the hydrophobicity recovery time after SD treatment. SD treatment temporarily reduces the surface hydrophobicity of SiR, and by measuring the time required for hydrophobicity to recover, we can assess its degradation. Experiments were conducted on SiR specimens extracted from unused, and 20 -year-aged polymer insulators. The SD treatment was applied for 10s. Following each treatment, the contact angle was measured at 5 -minute intervals. Then, we characterized the physical or chemical damage on SiR specimens after the SD treatment using a scanning electron microscope (SEM), and an attenuated reflection-Fourier transform infrared spectroscopy (ATR FTIR). These findings indicate that the contact angle recovery time after SD treatment serves as a valuable parameter for assessing the degradation degree of SiR insulators.