Sensing Moisture Content in Power Cables From Short-Duration Polarization Current Measurements

Estimation of moisture content is vital for the insulation assessment of power cables. A high value of moisture content signifies the presence of water trees in the cable, posing a risk to the reliability of the entire cable network. Polarization-depolarization current (PDC) measurements can be used as an offline noninvasive diagnostic tool for cable insulation monitoring. However, PDC is a time-consuming offline technique. Power utilities generally prefer to keep the maintenance time of power equipment at a minimum. Moreover, quantitative assessment of moisture content in power cable insulation from PDC measurements is also challenging. Considering these aspects, this article introduces a novel technique to significantly reduce polarization current measurement time for power cables while ensuring reliable sensing of moisture content. Experimental validation was conducted on multiple 11- and 33-kV cross-linked polyethylene (XLPE) cable samples with varying moisture content and thermal aging status. The proposed method provides reliable information about moisture content in XLPE cable insulation condition in significantly reduced time frames, saving 75%–92% compared with traditional PDC tests.