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

Exploitation of equipment with polyethylene (PE) insulation requires its condition monitoring and diagnostic. Traditionally diagnostics of insulation condition is carried out by means of partial discharges (PD) registration. There are a number of works directed on data base creation that permits to identify the defect by the PD form. However such identification of a defect, for example, void, inclusion or treeing, does not say about its danger from a point of view of full insulation gap breakdown and insulation construction failure. The information about the form and size of formed upon high voltage treeing is necessary for prediction of the remained resource of PE insulation. For this purpose we carry out experimental research for determination of the dependencies between 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.