Characterization of space charge and DC field distribution in XLPE and EPR during voltage polarity reversal with thermal gradient

A comparative study of the space charge behavior under voltage polarity reversal in cross-linked polyethylene (XLPE) and ethylene propylene rubber (EPR) in the presence of thermal gradient was conducted. For power cable under load conditions, a temperature gradient is established across the cable insulation. Due to the resistive grading under high voltage direct current, such thermal gradient will result in the accumulation of space charge. A modified pulsed-electroacoustic system was developed so that the space charge behavior in thin films under thermal gradient can be investigated. Moreover, the role of degassing process on both XLPE and EPR was investigated. The study indicates a large amount of space charge accumulation in XLPE results in field enhancement during polarity reversal, while it is not observed in EPR.