Introduction: In order to increase a line’s thermal rating without rebuilding or replacing its structures and foundations, the original conductor can be replaced with a special high-temperature, low-sag (HTLS) conductor having the a similar dimensions and properties as the original, but which can be operated safely and reliably at much higher temperatures with far greater ampacity.

This project will assess the suitability of the new generation of high temperature low sag OHL conductors currently available on the market, for deployment on the UK transmission network, in terms of mechanical capability & performance, erection methods, maintenance & repair.

At present National grid have installed both GAP and ACCC (CTC) conductors on the bottom & middle phase on the de-commissioned YYO line near Sheffield in order to evaluate the mechanical performance.

Objectives:

The goal of this project is to string ACCR (3M) on the remaining Top phase in order to evaluate and compare the stringing, sagging and termination of these three HTLS conductor types, to monitor their mechanical behaviour during simulated ice loading conditions and to evaluate the practical application of the three.

HTLS conductors and their component materials have been extensively tested both during and after their development by the manufacturers and various research organizations, but to date National Grid have yet to carry out such works. 

Expected Benefits: This project is successful if we improve the knowledge of alternative conductors.