The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of ...The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of a mixture of epoxy resin,curing agent,and alumina fillers.In recent years,frequent incidents of mechanical cracking and breakdown of tri-post insulators have been reported,which are attributed to residual stress concentration.However,the formation mechanism and distribution characteristics of the residual stress remain unclear.This study focuses on the curing kinetics and re-sidual stress modelling of GIL tri-post insulators.It is verified that the epoxy resin/alumina reaction system follows the autocatalytic curing kinetic model by differential scanning calorimetry tests,and the model fitted by Malek's method corresponds well with the experimental results.Based on the Cure Hardening Instantaneously Linear Elastic model and the density inhomogeneity,it is found that a tensile stress concentration with a maximum value of 58.9 MPa at the edge of the insulator/sleeve interface,due to the mismatch of chemical and thermal shrinkage effects.Besides,the filler sedimentation can decrease the coefficient of thermal expansion and suppress the residual stress concen-tration.The investigation would help with the visualisation of the residual stress distri-bution in GIL tri-post insulators and provide some guidance for their processing treatments.展开更多
基金National Science and Technology Major Project,Grant/Award Number:2024ZD0802403National Natural Science Foundation of China,Grant/Award Number:52377153Measurement and Technology Key Project of Tianjin City,Grant/Award Number:2024TJMT011。
文摘The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of a mixture of epoxy resin,curing agent,and alumina fillers.In recent years,frequent incidents of mechanical cracking and breakdown of tri-post insulators have been reported,which are attributed to residual stress concentration.However,the formation mechanism and distribution characteristics of the residual stress remain unclear.This study focuses on the curing kinetics and re-sidual stress modelling of GIL tri-post insulators.It is verified that the epoxy resin/alumina reaction system follows the autocatalytic curing kinetic model by differential scanning calorimetry tests,and the model fitted by Malek's method corresponds well with the experimental results.Based on the Cure Hardening Instantaneously Linear Elastic model and the density inhomogeneity,it is found that a tensile stress concentration with a maximum value of 58.9 MPa at the edge of the insulator/sleeve interface,due to the mismatch of chemical and thermal shrinkage effects.Besides,the filler sedimentation can decrease the coefficient of thermal expansion and suppress the residual stress concen-tration.The investigation would help with the visualisation of the residual stress distri-bution in GIL tri-post insulators and provide some guidance for their processing treatments.
