Nexans detailed how its new technology, currently being unveiled in Brazil, can assist utilities in making better use of overhead lines for power distribution at a roundtable event in London on Friday.

Francis Debladis, Overhead Lines Corporate Technical Manager and Jean-Maxime Saugrain, Corporate Vice President- Technical emphasised the advantage of using the new resilient cable compared to the expensive and complication of building new lines
Overhead power lines
The French international cable manufacturer introduced its new Lo-Sag technology, their latest innovation, which serves to carry around twice the power of conventional steel reinforced conductors with almost no sag on overhead lines.

Nexans pioneered the lines in a project in Rio De Janeiro, working in conjunction with Brazilian utility, Light, to develop the technology in large urban areas.

Complementing the composite core conductor is the company’s Direct Line Rating system, which enable utilities to access Nexans CAT-1 Transmission Line Monitoring System to manage their operations according to real-time information and predictive analytics.

Francis Debladis told the gathering that the need for reliability in transmission had been highlighted by recent events.

In the New York/US East Coast area 55 million people had been affected by outages caused by Hurricane Sandy, while 600 million people in India were affected by a massive outage there.

The overhead cable Nexans have come up with enables more capacity and voltage to be carried without the traditional restraints of weather dependency for example.

The composite core in the new cable has very low sag, a high ratio of strength to mass and crucially a highly effective thermal co-efficiency, making for a safer and more reliable line.

The technology was developed to meet the particular needs of Brazil’s transmission networks, especially in upgrading projects. Brazil’s situation is particularly acute as it undergoes a period of ongoing economic growth. It is also hosting a number of major international sporting events, including the World Cup and the Olympics over the next few years.

The creation of new power routes in areas with a high population density is posing a real problem both in land and equipment costs, along with the extended timescales required to obtain the necessary permits and rights of way.

Nexans therefore focused on an alternative approach which is enabling power transmission routes to be uprated to carry the extra power required. In essence the company is using the same power structures that exist but which have been upgraded to enable handling of much more power.

Price is between three and six times that of a traditional conductor but compared to the scenario of increasing power by building new line is relatively inexpensive, with Debladis pointing out that the new product is “less capital intensive than building a new line and of course right of way is more difficult to achieve.”

Developed at the company’s technology centres in France and Belgium  the Lo-Sag line consists of a thermal resistant aluminium conductor wrapped around a composite carbon core. Compared with the traditional ACSR core, a steel variety, the composite core is much lighter as well as being 50 per cent stronger, characteristics that have made existing infrastructure upgrading a reality, instead of the setting down of new lines and pylons.

Significantly the carbon core’s co-efficient of thermal expansion is roughly one tenth of that of steel, so it expands much less and sags much less when heated by the current flowing through the conductor, enabling the vital safety clearances to be maintained between the conductor and the ground, even at high operating temperatures.

The first such line is operating in the field for six months connecting SE Cascadura to SE Sao Jose in Pavuna, Rio De Janeiro.

From a utility point of view, another important element to Nexans new cable is it has an 80 year longetivity, significantly longer than the 50 year average lifespan.

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