Evolution of Cable Termination Interface Pressure Considering Low Temperature

In recent years, there have been many accidents in GIS cable terminations and the fault are related to low- temperature extreme weather (as low to -40°C). For this kind of accident, surface breakdown is the main fault phenomenon. In this paper, the thermal-stress coupling model of110 kV GIS termination was developed to study the thermal stress coupling characteristics of the interface bonding state between pre- molded rubber stress cone and epoxy insulator. The result shows that under low temperature, the uneven constriction of the silicone rubber resulted in an interface pressure decrease. Under -40°C, the lowest interface pressure will drop below to 0.1MPa, which is much lower than that of the requirement and easy to initiate interface discharge; In addition, nearby the stress cone end and the metal insert, the interfacial pressure drops obviously, which as low as 0MPa, it is easily introduce air gaps and cause partial discharges. Therefore, under extremely cold environment, the bonding state of the termination interface should be considered.