National Grid has constructed working versions of the new electrical transmission pylons it has adopted following a competition in 2011 to find a new design suitable for the future UK grid. (See MPS January 2012).
Six of the new pylons have been erected at the National Grid's training academy in Eakring, Nottinghamshire, each demonstrating a different function in the network - including the so-called 'F10 flying angle suspension' pylon which can allow a turn of up to 10 degrees along the route. and taller versions to be used as 'tension towers' - where a change of direction of 30 degrees is required. National Grid says it will respond to the need to harvest energy from an increasing number of lower-carbon energy sources.
Designed by the Danish architecture and engineering firm Bystrup, the new pylon is a monopole T-shaped mast with two suspended diamond shaped elements that hold three cables each side of the central pole. Its creators say it is designed to have a reduced visual impact on the landscape: it has a smaller footprint than the traditional steel pylon and is about a third lower in height than its lattice forebears standing at about 120 ft (36 m). National Grid's existing 88 000 pylons are typically 165ft high and will not be replaced by the new design - they are destined to be used principally in the construction of new power lines in England and Wales. The new tower is still capable of operating at 400 k volts because of the way the cables are arranged on their carries.
Each arm has to carry 60 tonnes, but with only eight main structural components plus bolts, it is easier to erect and install - prefabricated in bolt-together sections, it can be assembled by a team of five people in a day, compared with the nine people working for five days required for the original design.
"Our aim was to minimise visual impact and create a design that could adapt well to the English landscape," said Brian Endahl, project manager at Bystrup, which won the project in a competition in 2011. "We have built similar pylons in Denmark and found that the monopole structure works well in hilly areas as it requires less space and can follow the contours of the land."
David Wright, director of electricity transmission asset management at the National Grid, said the new design was not intended as a replacement for the lattice pylon. "But it's a new option and in some landscapes its shorter height and sleeker appearance can offer advantages," he said.
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