Real time nondestructive aging sensors for cables

The performance of power cables exhibits a great impact on the transmission capacity. Normal load current will cause resistance loss and generate heat in the cable. Due to the surrounding environment, the heat cannot be dissipated in time, which seriously leads to thermal oxidation aging of cable insulation layer. Therefore, the effective monitoring of cables before aging failure is a problem in power system. In this paper, an aging sensor based on the same insulation materials with the cable filled with conductive fillers is developed. Ethylene-propylene-diene monomer/carbon black composite (EPDM/CB) sensor can quantify the aging degree of EPDM cable by the real-time change of the resistivity of the sensor, and achieve nondestructive and real-time detection of the aging of the cable. At the meantime, the relation between the residual life and resistivity is established by the modified Arrhenius equation. Three samples were fabricated. Thermal aging was carried out at 136°C, 150°C and 170°C, respectively, The resistivity of the sensor at different temperatures and different aging time was tested and fitted to the Arrhenius curve, so as to predict the remaining life under normal operation. By analyzing the curves of mechanical and electrical properties before and after the aging of the conductive material, the accuracy of the sensor in monitoring the aging of the cables with EPDM insulation layer is demonstrated. It is proved that the resistance change of the aging sensor based on EPDM/CB can reflect the degree of aging of the material, and the aging condition of the cable can be monitored by measuring the resistance of the sensor.