Mechanical Properties Analysis of Domestic Large Tonnage Porcelain Insulators Based on Operating Load Conditions

Porcelain insulators are basic and important insulation components in UHV transmission lines, in which mechanical property deterioration poses serious threat to the operational stability of the power grid. In this paper, the mechanical characteristics of large-tonnage porcelain insulators under running load conditions are investigated. The coupling model of porcelain insulator string and transmission conductor is also established. The mechanical properties of stress and deformation of large tonnage insulator are calculated based on strong wind operation conditions. The results reveal that the steel cap and steel foot possess large stress level and plastic deformation, and the plastic deformation of steel cap is larger than steel foot. Hence, the steel cap is the component which is more easily to be damaged. Maximum tensile stress and stress gradient in porcelain piece can be found at the head region. High stress gradient induces local crack and expansion of the porcelain which cause potential damage of porcelain piece. An existing defect in proximity to the head region also accelerates the deterioration process. In this research, a theoretical basis for the design and manufacture of large tonnage porcelain insulator strings is provided.