Influence Mechanism and Calculation Methods of High Temperature on Interface Pressure Between Cables and Accessories

The interface pressure between cables and accessories plays a crucial role in the long-term reliable operation of cable systems. However, the change in interface pressure at high temperature and its influencing mechanism are still inconclusive. In this study, the changes of interface pressure at high temperature mainly caused by three influencing factors were investigated through theoretical analysis and experimental measurements. The results revealed that the thermal expansion effect will result in a decrease in interface pressure, while the Gough–Joule effect of rubber materials at high temperature will lead to an increase in interface pressure as the temperature rises. Additionally, the stress relaxation effect of rubber-like materials at high temperature will accelerate the decline in interface pressure. Finally, a calculation method for interface pressure based on the comprehensive effect of these factors is proposed. The results showed that the interface pressure increases as the temperature rises, indicating that the Gough–Joule effect of rubber materials dominates the change in interface pressure. The error between the theoretical calculation and actual measurement of interface pressure was < 5%. Therefore, this method can feasibly be used to evaluate the interface pressure in the medium-voltage (MV) and even high-voltage (HV) integral prefabricated cable accessories as the temperature changes.