Effect of Morphology on Space Charge Dynamics In Polyethylene Insulation (invited plenary lecture)

Chen, G, Tanaka, Y, Vaughan, A. S. and Chong, Y. L. (2003) Effect of Morphology on Space Charge Dynamics In Polyethylene Insulation (invited plenary lecture). The 9th Chinese National Conference on Engineering Dielectrics, Xian, China. 23 - 25 Oct 2003. pp. 30-36 .

Abstract

Polymeric insulation has been progressively replaced traditional paper impregnated insulation. Electrical performance of polymeric materials is determined by many factors. One of them is morphological feature of polymer. Effects of morphological change on electrical performance of polyethylene insulation have been studied due to its technological importance in high voltage power cable system. The results obtained so far, however, are inconclusive. One of the reasons is the complicated relationship between electrical performance and morphology. It has been suggested that the presence of space charge may play a significant role in determining electrical performance of polyethylene insulation. In this paper space charge formation in low density (LDPE) with different morphological features at various temperatures were investigated. Different morphologies were realized via addition of antioxidant which serves as nucleation centres. The space charge dynamics were observed at room temperature, 50, and 70 °C under high voltage application using the pulsed electro-acoustic (PEA) method. It has been found that the morphology change in LDPE does not result in significant changes in charge accumulation. On the other hand the introduction of antioxidants into LDPE leads to negative charge accumulation at high temperatures, indicating the creation of deep traps. In addition space charge in XLPE samples was also measured using the laser induced pressure pulse technique (LIPP). It has been found that heterocharge accumulation in XLPE is greatly affected by heat treatment. The results are discussed in terms of reduction in crosslinking by-products concentration and morphological change caused by the heat treatment. It seems that the space charge in XLPE is more to do with the by-products rather than morphological change.

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Contributors

Author: A. S. Vaughan

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