Light and tight

How convenient it would be if only all high-voltage power transmission lines could be buried. This is often impossible because of distance, geography, and high civil engineering costs. So, overhead lines are the only feasible solution. However, overhead lines present challenges, especially sag, which can cause “galloping” in high winds, or cascading power failures and blackouts.

Cascading consists of a series of increasingly dramatic events. HV lines are “meshed,” meaning that during maintenance or when lightning strikes, current is handed over to adjacent lines. Due the Joule effect, they heat up, stretch, and sag over trees or branches (they don’t even have to touch), putting the lines in default. Current then flows through the remaining live lines, and the story repeats itself until the whole network defaults, creating a blackout.

Lo-Sag™ greatly reduces this risk. While standard overhead lines are made with aluminum or steel strength elements which add extra weight and volume to the conductor, Lo-Sag™ incorporates a lightweight carbon fiber inner core to provide maximum strength for minimum weight.

Lo-Sag™ is particularly suited for river or valley crossings. Also, it significantly decreases the number of towers on long-distance transmission lines.

This innovative conductor resolves a number of age-old problems:

• Low weight: the composite core is far lighter than aluminum or steel cores, allowing spans of up to 2.5 km, reducing the number of pylons in the landscape and significantly lowering the height (and cost) of towers when spanning broad rivers.
• Reduced sag: even at high temperatures, the thermal expansion coefficient of composite cores is at least 10 times lower than the ones of steel and aluminum.
• High mechanical strength: composite cores are two times stronger than steel.
• Available design improvements: Nexans compact Aero-Z® design further reduces drag, and the probability of galloping.
•  Reduced power generation and transmission costs: due to the use of annealed aluminum.
• Wide range of available diameters: to meet specific load specifications, network needs, weather conditions, etc.
• Accessories: specified, developed and tested right down the line. 

New dawn for overhead lines