In order to ensure the continuous and reliable supply of electrical energy to the power grid, it is necessary to evaluate and monitor the degree of impairment of the insulation of electrical cables, as throughout its service life, insulation around cables suffers degradation due to numerous stress factors, which can arise from both environmental and operational causes. This aspect has aroused deep interest among energy professionals, as well as the industrial sector, with focus mainly placed on the undesirable effect caused by unexpected and sudden process stoppages, as well as their consequent financial and social impacts. That said, this article presents a methodology for evaluating the degree of insulation aging using the partial discharge progression curve. For this purpose, a thermal oven was duly constructed, in accordance with the technical premises presented in the literature, capable of homogeneously heating conductor samples. After thermal cycles, these conductors were aptly handled and tested in a controlled laboratory environment to determine the partial discharge progression curve. Through accurate data processing, a correlation was obtained between the degradation of the insulation and the rate of increase in partial discharge. The results are promising, as they provide support for maintenance agents’ ability to monitor and intervene regarding conductors.

This paper presents the preliminary results of a new methodology for detecting high impedance faults in distribution systems based on interharmonic signatures. The methodology involves incorporation of an interharmonic current analysis system into a conventional protection system, such as automatic reclosers. To check the functionality of the proposed methodology, the authors carried out field tests on different types of soil, involving instantaneous current waveform measurements during the occurrence of faults. The results suggest that the methodology, based on interharmonic currents produced by variations in electric arc length during the occurrence of high-impedance faults, shows great promise when it comes to detection of the disturbance.