Effect of electrical erosion on composite insulator core rod under acidic environment

Abstract

Silicone rubber housings crack under the combined internal and external factors and expose the core rod. The exposed core rod deteriorates or breaks under electric fields and electrical current. Based on the main characteristics and mechanism of the core rod corrosion, this paper performs an electrical erosion test in an acid-fog environment and analyzes the core rod's macroscopic results and physicochemical properties. The results indicate the following. First, the discharge on core rod during the electrical erosion process contains four consecutive stages. The electrical current, partial discharge, temperature increase, and macroscopic morphology show regular changes at different stages. The arc usually occurs in the carbonization channel, making the channel have the maximum heat. The area of the core rod heating constantly changes but mainly at the high-voltage side and presents as a regional temperature increase. Second, the fracture of glass fiber and ablation of epoxy resin matrix are related to the continuous action of nitric acid. The generation, expansion, and release of pyrolysis gas form bubbles and pores on the epoxy resin matrix. Erosion and pyrolysis cause the loss of the epoxy resin matrix. Third, the combined effect of electrical current, nitric acid, and heat damage the core rod axially and radially. The study provides support for the subsequent core rod deterioration and fracture mechanism.

Keywords

• Electrical erosion
• Composite insulator
• Core rod
• Acidic environment