Interpretation of MV power cables PD diagnostic data using statistical analysis

This document describes application of statistical analysis to several diagnostic parameters obtained during on-site measurements on MV power cables. The goal of this analysis is to estimate statistical borders values for different diagnostic parameters related to PD phenomena for cable insulation as well as different cable accessories like joint and termination. Data input introduced to analysis consist of mass, XLPE and mixed (XLPE +PILC) insulated power cables. Investigated parameters were obtained with application of damped AC (DAC) diagnostic system during on-site non-destructive tests. For the purpose of clear distinction between cable components (joints, termination, insulation parts) categories, of different cable accessories were created). For proper interpretation of collected data related to cable insulation condition as well as different accessories condition, categorization based on such diagnostic parameters e.g. PDIV (Partial Discharge Inception Voltage), PD occurrence, and PD mappings was done. Additionally crated in this way measuring criteria based on calculated statistical norms by fitting data to several statistic distributions were employed for overall condition indexing. Later on condition indexing was used to indicate percentage ration how big population of insulation and components are in very good, good and moderate condition.