The Distribution of Thermal Expansion Stresses in Dry-Type Bushings Under Various Fixed Angles

Dry-type bushings, as crucial components of transformers, are susceptible to varying degrees of fatigue damage and cracking under complex and changing load conditions, posing threats to the safe and reliable operation of electrical systems. This paper establishes a three-dimensional finite element simulation model for 110 kV dry-type bushings. By altering the applied load conditions and the installation angle between the bushing and the tank, different distributions of the first principal stress in the bushing are obtained, investigating the influence of thermal expansion effects on the distribution of the first principal stress. Simulation results indicate that the first principal stress experienced by the bushing mainly concentrates at the joint ring between the core and the flange. The first principal stress in the bushing increases linearly with the increase of load conditions and installation angles. Under the influence of thermal expansion, the maximum first principal stress experienced by the bushing exceeds 100 MPa, surpassing the tensile strength of the epoxy-impregnated paper core material. Epoxy-impregnated paper is a brittle material, and its failure theory conforms to the first strength theory, specifically the first principal stress; material failure occurs when the first principal stress exceeds its tensile strength.