Six 184-tonne transformers for Harker substation
Over 90 km of upgraded overhead lines and six supergrid transformers strengthen the England–Scotland link.
Harker substation project / Image credit: National Grid
UK: National Grid has completed a major upgrade of overhead electricity transmission lines between its Harker substation near Carlisle and the Scottish border, installing six 184-tonne supergrid transformers as part of the work to reinforce a key cross-border link.
Delivered with principal contractor Morgan Sindall Infrastructure, the project forms part of National Grid’s wider Harker upgrade programme, including new 400 kV and 132 kV indoor substations to support new connections and future-proof the regional network.
The transmission line works replaced existing circuits on two routes with higher-capacity conductors. An additional 12 km circuit was added on existing pylons to improve power flows and reduce congestion. In total, more than 90 km of lines have been installed or upgraded.
Existing pylons were refurbished and strengthened, three new towers installed, and two older towers removed. The six supergrid transformers will enhance resilience and support electricity distribution to homes and businesses, with five already delivered and the final unit scheduled for March.
The new substations will use SF6-free gas-insulated switchgear, helping National Grid meet its target to cut network emissions by 50 % by 2030.
The upgrades, combined with other regional projects, will increase transfer capacity between England and Scotland and support the integration of renewable generation.
Mark Brindley, Construction Director at National Grid Electricity Transmission, said: “This upgrade improves reliability today and creates capacity for cleaner energy in the future. By working closely with our supply chain and local communities, we’ve delivered a complex project safely and efficiently.”
Source: National Grid
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