An Analytical Model for the High Temperature Low Sag Conductor Knee Point Determination

Abstract

The modern high voltage power overhead lines operate with high temperature low sag (HTLS) conductors due to possibility of the current capacity increase. HTLS conductors are material and technological advanced solutions. The main advantage of HTLS conductors is a special designed operation conditions which cause the transformation of tensile stresses from the external aluminium base layers to the core. The conditions of this transformation are called “knee point” because a rapid change of the conductor sag - temperature relationship is observed. Prediction of conditions of the “knee point” temperature (KPT) is a key problem during overhead line design. The KPT is a function of different factors like conductor materials properties, conductor design, span parameters, sagging procedures and overhead line exploitation conditions. The paper presents an original theoretical model for HTLS conductors KPT calculations and shows some examples and comparisons of the different conductor designs and parameters.