Experimental investigation of the dependencies between PD in polyethylene insulation and treeing fractal characteristics

Exploitation of equipment with polyethylene (PE) insulation requires condition monitoring and diagnostics. Traditionally diagnostics of insulation condition is carried out by means of partial discharges (PD) registration. There are a number of works that allow identification of the defect by the PD method. However, such identification of defects, for example, voids, inclusions or treeing, does not show the danger from the point of view of full insulation gap breakdown and insulation construction failure. Information about the form and size of defects formed on high voltage treeing is necessary for prediction of the remained resources of PE insulation. For this purpose we carry out experimental research for determination of the dependencies of PD characteristics in PE upon electrical stress and fractal dimension of corresponding treeing. The investigations were carried out by means of electrical measurement of PD current and simultaneous optical recording of treeing form