Compression and temperature effect on RTV-SiR composites for the coating of high voltage ceramic insulators /

Abstract

Water and heat are the most degrading factors for the outdoor insulators. Whenever the insulators are placed in an outdoor field, they are subjected to severe mechanical compression which affects the dielectric properties. The RTV-SiR and its composites are discussed in this study under high temperature and humidity and mechanical compression effects. There were five different sample compositions. There were two micro composites (15 wt% silica) and (15 wt% ATH). A nano-composite (2.5wt% SiO2) and a hybrid composite (10wt% micro ATH with 2wt% nano-silica). After preparing the samples they were subjected to mechanical compression of 0 MPa to 12 MPa with a step of 3 MPa. LCR meter was used to measure the effect of mechanical compression on dielectric properties. Hydrothermal aging setup was used. The temperature was set to 70° C and 80% humidity. Hydrophobicity, structural and chemical analysis as well surface degradation was used to analyze the chemical and physical properties of silicone rubber after hydrothermal-stress is applied. The analyses confirmed the excellent recovery characteristics of silicone rubber towards the applied conditions. SMC 15% ATH outperformed the other samples by showing most resistance and recovery. Hybrid composite showed excellent hydrophobic behavior among other composites. It showed the highest contact angle of 138˚ after 120 hours. High temperature caused rapid recovery of hydrophobicity for all samples. The surface topography of SMC 15% ATH sample showed no cracks and lesser pathways as compared to other samples. In Fourier Transform Infrared (FTIR) Spectroscopy ATH based microcomposites has shown values of 123, 116%, 110, 116%, and 120% in prominent functional groups peaks. Microcomposite with 15% ATH samples outperformed the other samples. ATH filler based composite is used in high temperature and humidity environment. Similarly for mechanical compression it has the ability to bear the most mechanical stress with least change in the dielectric properties. For high voltage insulation purpose the silicone-based composites should be designed with ATH filler.