An objective approach for selecting ice or wet-snow design loads on transmission lines

摘要

Ice and wet-snow design loads affect the investment costs and the potential maintenance costs for overhead lines more than any other single loading case in most countries exposed to snow and freezing temperatures during winter. The dependence of ice loads on investment costs for both steel towers and wood poles as well as the climatic variations of icing are shown. The paper summarizes the need for such data and refers to IEC recommendations for procedures and measurements of loads: especially as probabilistic methods for design require more comprehensive information on ice accretions on overhead lines, including variations due to conductor configurations. Icing information from icing models based on general meteorological data is summarized, including the potential for future application of atmospheric boundary-layer models as used by weather forecasting centres. A methodology for handling some topographic influences is introduced. The paper concludes with two case studies, one for glaze ice and one for wet-snow loadings. [References: 29]