Assessing the impact of natural ester oil on RTV silicone rubber for transformer applications
摘要
With the growing use of biodegradable natural ester oils as green substitutes for mineral oils in transformers, this research is unique in exploring the compatibility with long-term thermal aging performance of room-temperature vulcanized (RTV) insulative silicone rubber soaked solely in natural ester oil. RTV silicone rubber, with its hydrophobicity, pollution flashover resistance, and hydrophobic recovery, is widely applied as a protective coating on transformer bushings. Nevertheless, its aging performance under exposure to natural ester oil over extended periods of time at higher temperatures is a relatively unexplored area. This study subjects RTV silicone rubber aged 320 h at 40 °C, 60 °C, and 100 °C to soybean-based natural ester oil to test. Results show oil absorption with mass gain of 5.45%, 15.82%, and 28.45% and surface roughness (Ra) of 0.11 µm to 0.49 µm. Contact angle decreased from 97.65° to 80.71° with aging, which shows loss of temporary hydrophobicity, with recovery seen within 100 h. BDV decreased from 23 kV (unaged) to 11 kV (100 °C-aged), showing loss of dielectric strength. Oil quality analysis contained up to 648.2 ppm moisture, up to 0.47 mg KOH/g TAN, and oil BDV as low as 36.5 kV. This report hints at an emphasis on research work in future to achieve a greater thermo-electrical stability over the long run in RTV silicone rubber based in natural ester oil to suit transformer applications with increased lifetime and dynamic loads.