Network October 2016

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NETWORK / 18 / OCTOBER 2016 WHAT STORAGE DEVELOPERS WANT: To meet the changing demands of a low- carbon future, electricity transmission owners expect to build new transmission circuits and provide additional capacity on existing circuits. Transmission struc- tures are the most visible element of a network and are o en considered to visu- ally detract from the landscapes they are built in by the general public, leading to delays in obtaining planning consent. This research and development project set out to design a suite of new 275kV trans- mission structures that would incorporate a range of innovations, would be smaller, cheaper, quicker to build and easier to maintain. The environmental impacts were also considered. The project whittled down 36 over- head line (OHL) support forms to just two – a monopole with six horizontal vee insulated crossarms (model 510), and a monopole with two tubular crossarms supporting two phase conductors on the lower arm and one on the upper arm (540). The assessment of each design against seven main design aspects was made by a purpose-made spreadsheet – the Support Assessment Matrix – and benchmarked against the L8RD speci' cation lattice steel tower series of supports. The winning designs o" er improved aesthetics, reduced footprints, reduced maintenance and painting requirements, and less impact on birds. A reduced number of components and complexity should sim- plify construction and design. Global cost- ing studies indicate the two winning designs could cut costs by 13% (510) and 3%–(540). The conclusions from this study have now been taken forward in a six-year network innovation competition project (NeSTS) being undertaken by SSEN. The project will prototype and test the new structures before detailing the designs for deployment on a planned overhead line project. If suc- cessful SSEN indicates the new structures could save up to £174 million for customers before 2050. 1 2 Scottish Power has identi' ed a "very large" asset base of concrete structures which are approaching the end of their service life. Traditional practice dictates these will be demolished and replaced with new steel structures, but there are alternative methods that could extend their life span by as much as 20 years. It is estimated that 40-60% of existing concrete structures can be reused and either repaired or reused to increase ser- vice life. Scottish Power aims to create an assess- ment process and speci' cation to determine suitability for reuse, and then a methodol- ogy for a strengthening and repair process during refurbishment. This is anticipated to allow SP to achieve cost savings of £300,000 per bay over the traditional approach, which will help reduce system charges and increase network resilience. New suite of transmission structures SSEN – complete Reuse of existing concrete assets SPT – launched 510 Weight: 9,300kg Approx height: 29m Span: 200m R E U S E A N D R E D E S I G N 540 Weight: 11,900kg Approx height: 25m Span: 200m

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