Investigation of Castor Oil Influence on DC Surface Flashover Voltage Characteristics of Epoxy Resin Insulators

The utilization of epoxy resin insulators for high voltage insulation continues to expand; however, surface flashover remains its significant challenge. Conventional methods for improving surface flashover voltage in epoxy insulators basically focus on physical and chemical changes while neglecting environmental and sustainability concerns involving petroleum epoxy resins. In this study, eco-friendly castor oil is incorporated into the epoxy matrix to enhance surface flashover voltage while promoting reduction of overreliance on finite petroleum resources. The successful integration of castor oil into the epoxy matrix is confirmed by Fourier Transform Infrared Spectroscopy, whereas the Atomic Force Microscopy and Scanning Electron Microscopy reveal smooth surfaces of composites at relatively low concentrations of castor oil, while higher concentrations beyond 30% lead to an increase in roughness. Samples’ relative permittivities are analyzed by using a Novocontrol spectrometer, which reveals the decrease in relative permittivity with the addition of castor oil into epoxy matrix. Notably, the positive and negative flashover voltages are enhanced by 17.47% and 18.49% respectively, at a castor oil concentration of 30 wt% with respect to epoxy resin, which is attributed to moderate trap parameters alongside favorable charge carrier mobility. These findings suggest that epoxy-castor oil biocomposite is a potential high voltage insulation material with reduced petroleum quantity and enhanced flashover voltage.