Localized PRPD pattern for defect recognition on MV and HV cables

Abstract

Partial discharge (PD) diagnostic is a well proven method for detecting weak spots in medium and high voltage cables. Beside the key parameters, like partial discharge inception / extinction voltage and partial discharge level in Pico-coulomb, one of the most important parameter is the point of localization along the cable. Without exact localization even the interpretation of the key parameters could lead to wrong conclusions. However even when the PD is localized additional information about the type of defect would be very helpful in addressing the severity of the detected defect. Does the PD weak spot need to be replaced directly, or can the cable be safely energized and the replacement of the defective component can be scheduled on a later time period. This paper goes into detail to PD localization, PRPD patterns and finally localized PRPD patterns. With help from “localized” PRPD patterns new ways of identifying the type of defect are possible and more reliable conclusions can, with regards to the severity of the defect, be drawn.