Composite insulators are widely utilized in transmission lines due to their advantages. This paper investigated the effect of the uniform electric field on core rod deterioration. Core rods were performed under a uniform electric field for various test times and electric field strengths to obtain the dielectric properties, microscopic morphology, and elemental content. As increasing test time and electric field strength, the relative permittivity, dielectric loss tangent, and conductivity of the samples increase; the main chain of epoxy resin degrades; the C=O content of the curing agent and coupling agent decreases; the changes in elemental content and chemical groups are close to the fractured core rod, which was consistent with previous research. The dielectric properties of the material change under the long-term electric field, and corona discharge occurs. N₂, O_2, and water in the air produce nitric acid under the action of corona discharge. The particle impact and thermal effect produced by discharge cause the epoxy resin matrix to degrade and the glass fiber to be exposed, and the interface between the two are separated, causing the core rod to deteriorate. The results can provide a reference for fracture characteristics and preventive measures.

composite insulator,Electric Field,discharge,core rod