Precise partial discharge localization in axisymmetric geometries

A predictive diagnosis of the health of insulating electrical components subjected to partial discharges seems still hard to achieve. Especially the determination of the residual life is, in many cases, very uncertain. In highly valuable components, such as cables and joints, the precise localization of partial discharge events may provide a valuable tool to estimate the progression of degeneration phenomena such as the electrical treeing. In this work we introduce a novel technique used to locate the position of moving charges that exploits the induced current on a set of properly placed electrodes. This technique has been previously developed in the framework of radiation detectors. In particular, we develop and analyze the performances of a localization method based on the measurement and analysis of induced currents and especially tailored to locate the internal discharges in axis symmetric components. The method is also capable to determine the real dipole moment produced by a discharge. This provides a measurement of the discharge strength that is more physically relevant than the commonly used apparent charge mentioned by international standards. The evaluation of the performances of the method is performed by building a proper test bed with a known defect.