Conventional and time-resolved measurements of partial discharges as a tool for diagnosis of insulating materials

This paper aims at determining the stage of degradation of a discharging dielectric by a combination of conventional techniques and time resolved techniques. First, discharges in an artificial cavity in polyethylene is analyzed by both techniques. Secondly, internal discharges in epoxy insulation of a current transformer are analyzed, using conventional detection only. The tests indicate that conventional discharge detection including a statistical analyzer (TEAS 570) is well suited for recognizing the stages of deterioration of dielectrics by discharges. This opens the possibility to store discharge patterns of aging stages in an analyzer and monitor the aging of HV equipment, either in service or in laboratory aging tests.<
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