The Temperature Dependence of Insulation Mechanical Properties and its Effect on Interface Pressure in Cable Joints

Contact pressure is a vital factor that controls the interfacial electrical breakdown strength. Loss of interface pressure between cable insulation and joint insulation must be avoided in practice to ensure a long life span of power cable joints. The contact pressure depends on the temperature profile in the bulk material, the thermal characteristics and the mechanical properties of the insulation materials. In this paper, a mathematical model using the thermo-elastic equations was developed to estimate the contact pressure taking into account how the mechanical properties (elastic modulus and thermal expansion) change with temperature, along with a realistic radial temperature profile. Two different approaches are compared, one using finite element analysis and the other using a set of differential equations which may be solved without the need for proprietary software.