FA5C91C5d01 - IEEE Transactions on Dielectrics and...

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IEEE Transactions on Dielectrics and Electrical Insulation Vol. 8 No. 1, February2001 Material LTV 1 LTV 2 97 Composition LTV silicone rubber + Si0.2 17 wt% LTV silicone rubber + SiO.2 17 wt%; Silicone oil is Accelerated Weatherability of Shed Materials EVA EPDM for Composite Insulators EVA + Al(OH)3 40 wt% + ,%lo t A1(OH)3 25 wt% t zno t carbon Y. Mirano, T. Inohara, M. Toyoda, H. Murase and M. Kosakada Japan Toshiba Co., Kawasaki v bf carbon arc V ABSTRACT Shed materials for hollow composite insulators (low temperature vulcanized (LTV) silicone rubber, high temperature vulcanized (HTV) silicone rubber, ethylene vinyl acetate (EVA) and ethylene propylene diene monomer (EPDM)) were examined through accelerated weathering tests and their weathering resistances were evaluated from changes of surface and bulk prop- erties. For silicone rubber, changes in the content of low molecular weight (LMW) silicone (silicone oil) related to maintaining water repellency were investigated. The results showed that silicone rubbers had excellent weathering resistance and kept high water repellency dur- ing long term weathering tests. Using an equivalent model, an investigation was also carried out on how non-soluble contaminations deposited on the surfaces of sheds in outdoor service could cut off uv rays. I T uv Spray A Tminmin 1 INTRODUCTION OLLOW composite insulators rapidly have come into widespread H use, because of improved explosion-proof property and easier handling than porcelain insulators. Typical shed materials for hollow composite insulators are silicone rubber and EPDM. In contrast to porcelain, however, these materials are affected by electrical, physical, and chemical factors, and they grad- ually lose their properties during service. To use hollow composite insulators outdoors for long periods, such degradation must be taken into account. Recognizing aging characteristics, a weathering test on specimens was carried out, yielding interesting and useful results [l-31. However, there were differences in test conditions and the composition of the materials was not clear; therefore, a comparison of their results is difficult. This report presents the details on both samples and the experimen- tal procedures for assessing weatherability The samples used were base I richer than LTV 1 I HTV silicone rubber t Al(OH).3 50 wt% HTV 48to52 I 58to62 163+311021 18 1 2 MATERIALS AND EVALUATION METHODS polymers, and fillers reported as having some effect on outdoor insu- lation. The items evaluated included most of the important test items discussed in other papers and newly added topics of water repellency and content of LMW silicone. 2.1 MATERIALS The used for evaluation and their compositions are sum- marized in Table 1. The extensive evaluation under the same conditions enabled the weatherability of several materials to be compared at the same line, 2.2 METHOD FOR ASSESSING WEATHERABILITY permitting pdints of note in a clear selection of;naterials.
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FA5C91C5d01 - IEEE Transactions on Dielectrics and...

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