The scenario resulting from the introduction of the free energy market and the increasing need to reduce energy dependency on fossil fuels, thus reducing the emission of climate-changing gases into the atmosphere, poses the need to increase the electrical power transmitted by transmission lines. This is done by optimizing the use of existing lines as much as possible due to the difficulties caused by the construction of new power lines.

The most easily viable solution to this problem appears to be the progressive replacement of the conductors of existing lines with conductors that can be exercised at high temperatures (HTLS – High Temperature Low Sag).

The design characteristics and materials used to make these conductors make it possible to increase the capacity of existing power lines without incurring the limitations of a traditional conductor operating at high temperatures. These limitations include premature aging of the materials, resulting in a reduction of the mechanical seal and an excessive increase in elongation. This would result in a significant reduction in ground clearance and thus the risk of dielectric breakdown and consequent line disruption.

Indeed, it should be remembered that the electric field to which conductors are normally subjected is close to the ionization value in air, which is assumed to be 30 kV/cm. In order to further investigate the mechanical behavior of the conductors at high temperature, particularly in creep tests, analyses were carried out preparatory to the realization of this test.

The evaluations focused, in particular, on the material constituting the reference bar of the displacement detection system by carrying out a characterization of the new material identified, a modeling of its thermal behavior during a creep test and a comparison test between the current measurement system and the one to be adopted.

The results provided an understanding of the behavior of the carbon fiber reference bar subjected to temperature change and an evaluation of its application in creep tests. Also included in the report is an additional analysis, again aimed at HTLS conductors, to test for possible current migration to the composite core to evaluate its possible effects on conductor behavior. These preliminary analyses did not reveal any particular critical issues.