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Two National Grid representatives observing night-time maintenance on a electricity pylon surrounded by trees


Overhead lines (OHL)


Overhead Lines (OHL)

High-temperature, low-sag (HTLS) overhead line (OHL) conductors can operate continuously at temperatures of 150°C or above, with less increase in sag, little or no loss of strength and reduced noise levels from existing overhead line routes. This capability means conventional conductors can be replaced with a conductor of similar size that allows more power to be transported without strengthening or rebuilding the pylons that hold them. This will facilitate low carbon generation in a sustainable way with minimum time delays and cost to the consumer.

Following a successful trial of one type of HTLS conductor [aluminium conductor composite reinforced (ACCR)] on a decommissioned line, we completed a noise assessment of the ACCR conductor on a live installation. We recorded an immediate and noticeable improvement in noise, producing less electrical discharge (conductor crackle). Noisy conductors can cause problems for people living in the vicinity of overhead lines and this particular installation resolved a problem that had been ongoing for several years.

During 2015/16 we trialled another variant of the HTLS family [aluminium composite carbon core (ACCC)] and a trial installation of the ACCC conductor was carried out at our training centre at Eakring, to develop installation techniques for use on the UK transmission network. Conductor fittings and installation tools from several manufacturers were also trialled during the installation.

Project partners:

3M, Nexans