Experimental investigation of different cavity arrangements in the high voltage solid insulation systems

Abstract

The partial discharge (PD) test is a widely used technique for evaluating the performance of the insulations in the high voltage (HV) plant. Electrical sparks, or PD, can deteriorate the insulation of HV equipment. Once present, however, they become the primary mechanism of deterioration and can lead to system failure, resulting in capital costs and economic consequences. The effects of PD defects in a cavity of various sizes will be investigated in this paper. Experiments were carried out using polyethylene terephthalate (PET) samples, with various cavity arrangements, and PD data was captured over a long stressing period. Cavities of interest include single, serial, parallel and electrode bounded cavities. The result shows that the discharge patterns of serial and single cavities are similar but distinct from those of parallel cavities. Further studies using single cavities with diameters of 0.6mm and 1mm show that there is no discernible difference in their PD patterns, though smaller discharges with higher amplitude are observed in the 1mm cavity. There is a high asymmetry between the negative and positive half power cycle discharges for the electrode bounded cavity, which can be explained better by the PD mechanism.