Partial Discharge Pulse Shape Analysis for Progression of Insulation Degradation in Medium Voltage Cable

Measurement of partial discharge (PD) pulses is a method used in quantifying PD activity within defective insulation. PD pulses propagate away from the defect along the cable and can be measured by sensors such as high frequency current transformers (HFCT). These PD pulses contain information that describes the behavior of PD activity in the degrading insulation. Pulse shape analysis (PSA) is an efficient method to analyze the degradation behavior of insulation. In this study, the PSA is performed on a medium voltage cable sample with surface discharges emerging from a damaged cable termination. PSA is performed based on rise time, fall time, and pulse width of individual PD pulses that are extracted from the PD data measured in the form of phase resolved PD pattern under increasing electrical stress conditions. The Gaussian model is implemented to find best-fit lines which describe the correlation of PSA quantities and electrical stress. The presented study results can be useful in improving the diagnostics of aging power cables.