Comparison between IEEE and CIGRE ampacity standards

Abstract

Both IEEE and CIGRE have published industry standards for calculating the ampacity of overhead conductors. Although these two standards use the same basic heat balance concept, they use different approaches to calculate ampacity ratings. As a result of these differences, the ampacity rating calculated by each method may vary by almost 10% depending on the environmental conditions being considered. This paper looks at the different approaches used to calculate individual heat balance terms, at the overall impact of these terms on the ampacity rating, and at the sensitivity of these approaches to various input parameters. The user of these standards should be aware of these variations in calculated ratings and, if they consider these variations significant, the user needs to select a single approach for rating their lines based on their understanding of these different approaches and of the published experimental research supporting each method.