Eskom’s Transmission Development Plan (TDP) seeks to meet the long-term requirements of electricity consumers in South Africa. The objectives of this initiative will be achieved by upgrading and maintaining the legislated adequacy and reliability of the country’s transmission grid.
“With a growing population and developing economy, electricity supply has become a key focus for government,” Jason Burke, director of overhead line, ARB Electrical Wholesalers, part of the JSE-listed ARB holdings group, says. “In light of the country’s aging, congested and inadequate electricity infrastructure, there is an urgent need for new and upgraded transmission lines.
“Eskom’s transmission programme encompasses the addition of significant lengths of new line to the grid – 3,700 km of 765 kV lines and over 8,600 km of 400 kV lines have either been approved or proposed over the next 10 years.
“ARB will play a key part in this transmission project, by providing a turnkey solution to Eskom and its specified contractors. The company can supply all components needed to construct a line, including the aluminium conductor, insulators, metal-ware and preformed line products. We have also launched new products that are likely to revolutionise the way transmission lines are built in this country and in Africa as a whole.
“The overhead line division of ARB Electrical Wholesalers has expanded significantly over the last 15 years, contributing a significant portion of the company’s annual turnover. The division supplies Eskom turnkey projects, bulk contract and minor works, as well as schools and clinics.
“ARB’s focus has traditionally been on distribution, but our interests have expanded to transmission and sub-station supply, in line with new power stations which are now being built.”
The overhead line division supplies material to distribution and transmission networks, ranging from 11 kV− 66 kV for distribution and 132 kV − 765 kV on the transmission side.
A new development, which will be beneficial for Eskom’s TDP, has been ARB’s appointment in 2012 by CTC Global, as the exclusive distributor for South Africa and the SADC region, of the ACCC conductor. This product has earned a reputation as the world’s most efficient high capacity transmission conductor. To date, over 14,000 km of this product have been installed at over 200 project sites worldwide, including three City Power projects in Johannesburg.
These aluminium conductor composite core (ACCC) conductors, which are certified to ISO 9001-2008 standards, have a carbon fibre core that replaces conventional steel core conductors. These conductors are designed to double the current carrying capacity over existing high voltage transmission and distribution electrical grids. ACCC conductors can significantly increase system reliability by virtually eliminating high temperature sag, resulting in between 30% and 40% line loss reduction.
ACCC conductors offer higher efficiency and enhanced capacity through extensive operating temperatures compared with any other conductor type of similar design. These conductors, with high strength and low thermal sag features, also improve reliability, without compromising structural integrity or safe ground clearances.
The carbon fibre core is corrosion resistant, with twice the capacity of aluminium conductor steel reinforced cable (ACSR) due to its steel to carbon fibre weight ratio reduction. They operate at lower temperatures than conventional overhead conductors under the same load conditions. This increases power efficiency and financial returns year after year over the life of the asset.
With this system, fewer support structures are required – this reduces support construction costs and installation time.
Fushi Copperweld has appointed ARB sole distributor in Africa for dead soft annealed (DSA) Copperweld wire and strand. These low corrosive earthing conductors, which have a strong steel core and copper cladding, are designed to replace conventional bare copper earth wire with various levels of conductivity, a low impedance path to earth and safe installation with combatable standard accessories to the bare copper earth wire conductor. This system is also designed for theft resistance and extended service life.
Common earthing applications for Copperweld wire and strand include earthing for substations, pole earthing wire for transmission and distribution systems and counterpoise wire for high voltage transmission lines.
This product is available in the size, conductivity and strength required for every installation. The specified size of the DSA Copperweld wire or strand depends on short circuit ampacity needed for the type of application.
Copperweld wire or strand, designed for easy handling, has advantages over solid copper for earthing grids in substation and industrial installations. These include high strength of the steel core, fatigue and corrosion resistance, excellent conductivity and extended service life in adverse conditions. Unlike Copperweld, solid copper conductors often need to be upsized to meet the mechanical demands within a system design.
Copperweld has an almost zero scrap value, which deters thieves who sell copper as a scrap metal. Any type of copper used for the various utilities for earthing is susceptible to theft globally. Once the earth wire has been removed or damaged, a system is at risk of unforeseen fault current and there is a higher probability of power outages, damage to equipment and personnel being injured.