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A study of water trees in polymers under different conditions

XLPE cables have been used in power grid in China for many years for its excellent performance. But with the water tree degradation occurring in the XLPE cables which were put into use early, more and more cable insulation breakdown accidents happened. Consequently, study on the water treeing phenomenon and the factors influencing it are of great significance, either to understand the mechanism of polymer aging or to safely operate the power cable. The IEC recommended experimental method and equipment were adopted in this research. In this paper, the factors influencing the initiation and growth of water trees were researched, like aging time, electrical field, frequency, dielectric constant of saline solution and etc. Water trees were developed three polymers, silicon rubber, polyethylene and PMMA. The study emphasis was put on the influence of hydrophilic character and Young's modulus to the water tree growth. The comparison of LDPE sample before and after water treeing shows that the dielectric parameters have great change. This experiment provides a reliable basis to study the water trees growth and development of new types of resist water trees materials.