Abstract：Research purposes: XLPE cables can be widely used in various places. Early degradation of XLPE cables researches may extend its using life.
Research methods: In this paper an accurate water tree model has been created .We have successfully developed a new hot-line diagnostic method called”high frequency superposition method”.We superpose a voltage with high frequency but low amplitude on the shielding layer of power cables to make the loss current more obvious. Then we use fractal methods to analyze loss current signals collected.
Research results: Degradation of XLPE cable by water trees gives rise to harmonics in the loss current. Harmonic components arise as a result of nonlinear voltage-current characteristic of water trees. The fractal dimension of loss current waveform increases because of the growth of harmonics. We calculate 3 fractal dimensions including capacity， information and correlation. We discuss the interrelationship between fractal dimension and harmonics.
Research Conclusions: The fractal dimension provides an extremely good indication of the state of degradation which can be used as a judgment for hot-line dielectric degradation.
屈洪鑫,孙瑶. 交联聚乙烯电缆在线绝缘诊断新方法研究[J]. 铁道工程学报, 2007, 24(4): 69-72.
QU Hong-xin,SUN Yao. Research on the New Hot-line Monitoring Method of XLPE Power Cable. 铁道工程学报, 2007, 24(4): 69-72.
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