Continuous condition monitoring of MV cable connections and PD interpretation

Recently an on-line partial discharge (named PD-OL) for power cables is introduced in mainly Dutch medium voltage grids and first data has become available. This paper discusses the results on statistical analysis, including PD magnitude, PD repetition frequency and PD density distributions, employed to study the degradation of cable connections and their components. The potential of Weibull modelling, as a tool to identify the discharge origin, is investigated. PD fielddata is collected over one year from several connections including suspected weak spots in cables, joints and terminations. Continuous monitoring and trend watching of statistical parameters over time enabled us to detect ongoing aging processes, and several outages were prevented. Two cable circuits are specifically examined in more detail