Overhead lines are indispensible in the transmission grid

Swissgrid is aware that overhead power lines represent an encroachment on the countryside, but they remain essential for the Swiss transmission system.

The backbone of the Swiss transmission system consists of around 6,700 km of overhead lines at voltage levels of 380 and 220 kV. The transmission of electrical power via alternating current overhead lines continues to be one of the most important components of power transmission systems around the world. Overhead lines are tried and tested, safe, economical and always use state-of-the-art technology.

After many years of operating experience we now have extensive practical knowledge about how overhead lines behave in a complex system, to what degree they can be loaded and how lines can be constructed and maintained as efficiently as possible. This valuable expertise is the result of decades of experience.

Technological developments

There have been many developments in overhead line technology. New construction techniques allow magnetic fields to be optimised, noise to be reduced and transmission capacity to be increased.

A comprehensive system for monitoring line conductors enables additional capacity to be transferred to existing lines. Measuring instruments attached directly to the line conductors transmit readings to the control system. This combined with local weather forecasts enables more or less electricity to be transported based on the ambient temperature.

By replacing conventional conductors with high-temperature conductors, lines are able to withstand higher temperatures, which in turn allows greater transmission capacities to be achieved.

Fibre-optic cables have long been embedded alongside the ground wires to enable the existing infrastructure to also be used for telecommunication purposes. The latest developments go even further, with line conductors now being produced to achieve the same goal.