Thermo-mechanical analysis of solid interfaces in HVAC cable joints

Mechanical stresses affect the electrical performance of solid-solid interfaces in high-voltage cable joints. This paper assesses the influence of insulation material mechanical properties and temperature on interface pressure. Based on a hyper-elastic model, the mechanical stresses inside silicone rubber joint tube were determined. Circumferential stresses can reach 50% of the silicone rubber tensile strength at normal pre-operation expansion ratios. An analytical method to determine the thermally induced mechanical stress during operation is presented and its accuracy is confirmed using finite element method. This method is modified to account for the variation of the mechanical properties with temperature. This paper shows that circumferential stresses at the interface increase as temperature drops, which may have a significant impact on the electrical performance of the interface during operation.