A Holistic Method for Conductor Ampacity and Sag Computation on an OHL Structure

The rating current (ampacity) of a conductor erected on a particular overhead line (OHL) structure installed at a specified location is influenced by the conductor, the OHL structure, as well as weather and operational parameters. Many studies have been carried out regarding calculating an aerial bare conductor´s ampacity at a steady-state conductor temperature, but without considering the OHL structure as part of the system. In this paper, a holistic methodology for calculating the conductor´s ampacity and sag at any temperature and power frequency, erected onto a prespecified OHL structure is developed, considering together the mechanical and electrical parameters of the overall system. This methodology incorporates the conductor´s basic material properties allowing the calculations to be applied to newly developed high-temperature low-sag composite conductors. In this way, it becomes possible to identify, at the system level, the potential benefits that may result from the improved performance of these conductors as well as to indicate new sizes that may better fit a prespecified system, optimizing its performance. The methodology is also validated with a real system application, resulting in correct predictions of the performance of a four-span double-line system.