Research on Temperature Characteristics of Space Charge Distribution in Epoxy Composites for HVDC GIL

To study the effect of temperature on the space charge characteristics of epoxy composites for HVDC GIL, epoxy/alumina micro-composites (EP-AL) and epoxy/silica micro-composites (EP-SI) were selected for comparative study, and their space charge behavior and trap characteristics were analyzed at different temperatures. The results indicate that the space charge distribution of the epoxy composite exhibits significant temperature characteristics. Higher temperature will increase the charge injection at both electrodes and the trapping rate inside the material, thereby increasing the overall number of charge carriers. Through horizontal comparison, it is found that EP-AL is more likely to accumulate homopolar charges compared to EP-SI. At 80 ℃, the dissociation effect of impurities inside the EP-AL is greatly enhanced, and the phenomenon of heteropolar charge accumulation is more obvious, reducing the charge accumulation of the sample. The insulation performance of EP-AL at high temperature is better than that of EP-SI. Due to the fewer deep traps in EP-SI, the mobility of charge carriers significantly increases, and at the same capture rate, the migration depth of charge carriers is deeper, resulting in more severe distortion of internal electric field.