The effect of degassing on morphology and space charge

It is believed that space charge buildup in cross-linked polyethylene (XLPE) insulation is one of the main cause for premature failure of underground power cables. The space charge activities in XLPE depend on many factors such as additives, material treatment, ambient temperature, insulator/electrode interface, etc. Degassing is one of the material treatment processes commonly employed in cable manufacturing to improve insulation performance. In this paper, investigation on the effect of degassing period on the morphology and space charge was carried out. Planar XLPE samples of the same composite were subjected to different degassing time. It is discovered that apart from removing volatile by-products, degassing also anneals XLPE material; changing the morphology as a result.