Study on the influence of thermal aging on the discharge characteristics of the composite interlayer interface between the SCT and EPDM of the vehicle high voltage cable terminal
The interface between the stress control tube (SCT) and ethylene propylene rubber (EPDM) is a common part of the cable terminal insulation breakdown fault caused by frequent discharge, and those changes of thermal aging characteristics of SCT is one of the key factors affecting the development of its discharge. For exploring the influences of thermal aging characteristics of SCT on the discharge characteristics of composite interlayer interface, according to the special insulation structure and actual operation conditions of vehicle high voltage cable terminal, the artificial accelerated thermal aging tests of SCT are designed under three aging environments such as 100 ℃, 125 ℃ and 140 ℃, and the composite interlayer interface model and strong-polar pin-plate electrode model of aging SCT/EPDM are also made, and the composite interface flashover test platform is built. Those influences of the SCT specimen on the initial discharge voltage and flashover voltage of the interface between the composite interlayer under different aging conditions are studied. The surface charge transport model of the stress tube is established, and also the carrier conductivity and migration rate of the SCT surface under different aging conditions are revealed. The influence mechanism of the change on the discharge characteristics of the composite interface model is also explored and revealed from the microscopic level. Through the above research, the development process and evolution law of the composite interlayer interface of the actual cable terminal are revealed indirectly.