Examining the Importance of Conductor Surface Trait on Ampacity Determination

Abstract

Ampacity indicates the maximum amount of current that could be safely transmitted through overhead conductors during certain environmental conditions. The ampacity depends on the conductor surface trait, which affects the heat exchange rates between the conductor and surroundings. However, the ampacity of the round and trapezoidal conductors is currently determined according to the heat transfer capability of the simple cylinder model; hence, it does not represent the actual conductors' performance. This paper investigates the impact of the simplification on the round and trapezoidal conductors' ampacity by modelling the heat exchange mechanisms experienced by the three conductor models using COMSOL Multi-physics. Consequently, each model's temperatures and ampacity values are extracted to identify the importance of the conductor surface trait. The investigation made on the 28.14 mm Drake conductor indicates that considering conductor surface trait could increase the round conductor's ampacity by 2.6 % and 4 % at temperatures of 150°C and 210 °C, respectively. Meanwhile, the discrepancy in the trapezoidal conductor's ampacity could be up to 2%. Hence, using the cylinder model to represent the overhead conductors' ampacity is not entirely appropriate.