PNNL

Abstract

Planar capacitor sensors have been proposed to measure the aging related dielectric constant variation of the jacket or insulation materials of cables. Although capacitor sensors have been used to monitor the aging of cable insulation by removing the jacket, through the jacket measurement of cable insulation dielectric constant variation is difficult because once the sensor is placed on the jacket it would either measure the aging of the jacket or that of the jacket and insulation together. A reconfigurable sensor along with innovative cable specific models could be used to determine the jacket and insulation aging using the same sensor. For the proposed novel reconfigurable sensor, the electric field penetration depth is changed by activating and deactivating PIN diode switches. In one instance, the sensor measures the dielectric constant variation of the jacket, while in the next it measures the dielectric constant variation of both the jacket and the insulation. By leveraging previously developed capacitance estimation models from large scale finite element simulations for a specific cable these two sets of measurement data are used to evaluate the aging related dielectric constant variation of the insulation.