With the ever increasing demand on high voltage transmission systems minimizing outages has become an even higher priority. For transmission lines located in regions of the country that experience conductor galloping, this phenomenon can significantly contribute to the flashover rate if not properly accounted for in the design of the line.Recent experience in some areas has shown that traditional methods of calculating the magnitude of galloping ellipses do not provide adequate phase separation. An alternative method being evaluated is the design approach proposed by CIGRE. The CIGRE methodology is derived from actual galloping observations and incorporates conservative empirical approximations. While this conservatism minimizes the probability of flashover or conductor impact during galloping, it also leads to larger vertical and horizontal phase spacing which directly affects structure configuration and cost. The impact can be even more significant for rebuild or reconductor projects where the original design criteria did not consider the larger CIGRE galloping ellipses.This paper provides a comparison of galloping ellipses calculated by CIGRE with traditional methods and includes several examples of the impact on structure configuration, structure weight, and foundation size.
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