EFFECT OF SEMICONUCTING SCREEN ON THE SPACE CHARGE DYNAMIC IN XLPE AND POLYOLEFIN INSULATION UNDER DC AND 50HZ AC ELECTRIC STRESSES CONDITIONS

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Description/Abstract

In the past two decades, significant advances in space charge measurements in polymers have resulted in a better understanding of charge dynamics and their effect on material selection and processing. However, little attention has been given to the effect of semiconducting screens on space charge formation in the bulk insulation. This paper reports on space charge measurements on ~1.5 mm thick XLPE and polyolefinic plaques with different treatments and semicon electrodes, using the modified laser induced pressure propagation (LIPP) system. Samples were subjected to dc or 50 Hz ac electric stresses in the region of 25 kV/mm at ambient temperature. Emphasis has been placed on comparing the space charge characteristics of the two insulation systems with the different semicon electrodes using an established method termed “X-plots” for analysing data. The effects of sample treatment (i.e. degassing) on the space charge dynamics are also presented.