An investigation into gas pressure generation in new and aged aluminum conductor cable and the internal pressure withstand capabilities of joints

Cable samples were divided into three groups and tested with different conductor treatments. Cables were aged for four months, filled with water, and heated with induced current to achieve 70°C conductor temperature to determine if the gas reaction occurs after previous heating. After 24 h of continuous heating, the samples all registered some increase in internal pressure. There was considerable variation in the pressure values. Samples were allowed to cool to ambient and then were reheated with induced current to 90°C for 24 h. The sample population showed both increases and decreases in internal pressure after 90°C heating compared to 70°C heating. The tests indicate that gas generation can occur in aged cable. The distribution of the data indicates that the reaction mechanism has other variables whose impact is not fully understood. Three joint technologies were tested for internal-pressure withstand capabilities under load with applied voltage. This was done to determine if the accessories were capable of withstanding possible service conditions. Heat-shrink exhibited the highest withstand capability. The pressures measured on new and aged cable exceeded the withstand of some joints. Those joints with lower pressure withstand levels may fail in service from pressure venting and interfacial breakdown