Electrical treeing characteristics in XLPE power cable insulation in frequency range between 20 and 500 Hz

Sch. of Electron. & Comput. Sci., Univ. of Southampton, Southampton
IEEE Transactions on Dielectrics and Electrical Insulation (Impact Factor: 1.23). 03/2009; DOI: 10.1109/TDEI.2009.4784566
Source: IEEE Xplore

ABSTRACT Electrical treeing is one of the main reasons for long term degradation of polymeric materials used in high voltage AC applications. In this paper we report on an investigation of electrical tree growth characteristics in XLPE samples from a commercial XLPE power cable. Electrical trees have been grown over a frequency range from 20 Hz to 500 Hz and images of trees were taken using CCD camera without interrupting the application of voltage. The fractal dimension of electric tree is obtained using a simple box-counting technique. Contrary to our expectation it has been found that the fractal dimension prior to the breakdown shows no significant change when frequency of the applied voltage increases. Instead, the frequency accelerates tree growth rate and reduces the time to breakdown. A new approach for investigating the frequency effect on trees has been devised. In addition to looking into the fractal analysis of tree as a whole, regions of growth are being sectioned to reveal differences in terms of growth rate, accumulated damage and fractal dimension.

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    ABSTRACT: Silicone rubber (SiR) has been widely used in XLPE cable accessories because of its excellent electrical and mechanical properties. The electrical tree is a serious threat to SiR insulation and it can even cause the insulation breakdown. Addition of nanoparticles into SiR can improve the insulating properties compared with undoped material. The effect of nanoparticles on tree characteristics at temperatures above 0 °C has been widely researched. However, the effect under low temperature has not been researched. In this paper, electrical treeing process in SiR/SiO2 nanocomposites was investigated over a range of low temperatures. The samples were prepared by mixing nano-SiO2 into room temperature vulcanized (RTV) SiR, with the content of 0, 0.5, 1.0, 1.5 and 2.0 wt% respectively. The experiment temperature ranges from -30 °C to -90 °C. AC voltage with a frequency of 50 Hz was applied between a pair of needle-plate electrodes to initiate the electrical tree at different experiment temperatures. Both the tree structures and the growth characteristics were observed by using a digital microscope system. The experiment results indicated that low temperature is an important factors of the treeing process in SiR/SiO2 nanocomposites.
    2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP 2013); 10/2013
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    ABSTRACT: This paper investigated the electrical tree growth process in SiR/SiO2 nanocomposites under the condition of low temperature. Samples were prepared by mixing nano-SiO2 into room temperature vulcanizing silicone rubber, with the content of 0, 0.5, 1, 1.5 and 2 wt% respectively. The experiment temperature ranged from - 30 °C to -90 °C. AC voltage with a frequency of 50 Hz was applied between a pair of needle-plate electrodes to investigate the electrical tree at different temperatures. The experimental results reveal that both nanoparticles and low temperature environment have a significant impact on the electrical tree growth characteristics of SiR/SiO2 composites. This paper studied electrical tree growth characteristics from the aspects such as the patterns of electrical tree, fractal dimension and the proportion of cumulative damage. It is suggested that there are both branch tree and bush tree when the temperature is -30 °C or -60 °C, but only pine tree when the temperature is -90 °C. It is also found that tree structure is closely related to the crystalline state.
    2014 International Symposium on Electrical Insulating Materials (ISEIM); 06/2014
  • Source
    TELKOMNIKA Indonesian Journal of Electrical Engineering. 08/2014; 12(8).

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