Relationship Between Electrical Treeing Degradation and DCIC-Q(t) Characteristics of XLPE Insulation

This paper focuses on the relationship between the electrical treeing degradation and the direct current integrated charge (DCIC-Q (t)) characteristics of cross-linked polyethylene (XLPE) insulation for high-voltage cables. The XLPE insulation samples are prepared, whose electrical trees are initiated under AC voltage, and the DCIC characteristics are investigated to study the relationship between initial charge, absorption charge, conduction charge and electrical treeing morphology. It is indicated that the higher AC voltage results in more severe electrical treeing degradation, while the absorption charge and conduction current enhance significantly since the enlargement of defects and conductance in XLPE insulation. Besides, the relationship between electrical tree morphology and DCIC characteristic parameters is examined using the Pearson correlation coefficient. It is revealed a significant correlation between absorption charge, time constant, conduction current and electrical tree degradation. Among them, a correlation coefficient of 0.93 is found between the conduction current and the width of electrical tree. It is concluded that some DCIC-Q(t) characteristic parameters, specifically absorption charge, time constant and conduction current, reveal a strong correlation with the electrical tree morphology and have a great potential to characterize the level of insulation electrical tree degradation.