Life Estimation and Investigation of Dielectric Strength and Siloxane Backbone of High Voltage Silicone Rubber Composites Under Accelerated Multistress Conditions

Abstract

Room-temperature-vulcanized silicone rubber (RTV-SiR) is an excellent polymer for the coatings of high voltage outdoor insulators. However, like other polymers it also degrades by environmental stresses and lessens its service life. Silica-based composites may improve this behavior. To investigate the effect of multiple environmental stresses such as acid rain, heat, UV radiations, salt fog, etc., on silica-based composites, we prepared a sample neat SiR, two SiR nano-composites (5% and 2.5% nano-silica loading), an SiR micro-composite (15% micro-silica loading) and a hybrid composites (2% nano $$+$$ 10% micro-silica loading). The prepared samples are subjected to accelerated multistress environment for a long term. Dielectric strength, leakage current and siloxane backbone are analyzed periodically during entire aging period. Composites showed improved characteristics and service life. Silicone rubber nano-composite with 5% nano-silica loading (SNC-5) showed longest estimated service life of 29 lab years in comparison with 19.8 lab years of neat silicone rubber. Similarly, after aging 17 kV/mm of dielectric of SNC-5 was highest among the all samples. Siloxane backbone also showed improved intactness in the case of SNC-5.