Direct Measurement of Accumulated Space Charge Using External Currents

Abstract

In the past few decades, immense contributions have been put in by researchers to measure the accumulation of space charge in dielectric materials. At the same time, the direct measurement of the amount of space charge in materials has been completely neglected, probably due to the difficulties in measuring currents at high-voltage (HV) electrode. Although the amount can be measured indirectly with the available methodologies, the measured results suffer from accuracy issue. Also, indirect measurements involve complex, post measurement mathematical analysis such as deconvolution and filtering to get the amount of accumulated charge. Keeping the lacunas in mind and contrary to the basic approach of the present methodologies, a novel wireless system is developed which separately monitors the ultralow, volumetric, electrode currents flowing into and out of the material at both HV and ground electrodes. The obtained current data are further processed to observe the accurate temporal variation in the accumulated charge using the fundamental concept of charge conservation law. Some more parameters have also been identified which unmistakably determine the presence of the packet-like-charge phenomenon in dielectric materials such as low-density polyethylene. Furthermore, for comparing the results of the proposed electrode system, space charge measurements have been done using pulsed electroacoustic system. Based on the comparison of the results, it is concluded that the newly developed electrode system monitors the charge accumulation closely but with less effort and complexity.