聚乙烯
易燃液体
甲烷
爆炸物
高压
材料科学
电压
扩散
电植树
工艺工程
法律工程学
复合材料
环境科学
废物管理
电气工程
局部放电
工程类
化学
物理
热力学
有机化学
作者
A. Smedberg,A.B. Borealis,Detlef Wald
标识
DOI:10.1109/elinsl.2008.4570400
摘要
Today the preferred insulation material for cables rated from 1 kV to 500 kV is crosslinked polyethylene (XLPE). After crosslinking the peroxide by-products are contained within the XLPE matrix. For all power cables there is a need to remove these by-products or to reduce their concentrations, especially for high voltage (HV) and extra high voltage (EHV) cables. One aspect to ensure a long term performance of the cable when put into operation is to secure a proper degassing. It is commonly known that methane, one of the by-products, should be reduced to a very low level for several reasons. Besides deforming the shielding of the cable during the operation the presence of methane can also create a hazardous event during the jointing process as methane is a flammable gas and can create a highly explosive environment. 200 ppm in the cable is regarded as an acceptable level for a safe operation of the cable but still there is a risk due to a possible accumulation in the joints during operation. Here certain producers recommend degassing down to methane levels of 30 ppm. Studies have been carried out to define the field methods detecting methane at these very low levels, but are until now not too successful. The time to reach a proper degassing, e.g. the time needed for a certain reduction of the by-product level, is a very important time factor during the production of high and extra high voltage cables.
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