National Grid completes first phase of £130m refurbishment of overhead power lines
The first phase of National Grid’s £130million project to refurbish 170km of overhead power lines between Lincoln and Stevenage has been completed.
The renewal of the transmission line began in March at Cottam Power Station and reached Peterborough, passing through Newark and Stamford en route. He saw workers from National Grid and Morrison Energy Services operating crews working at heights of up to 50m. They installed approximately 1440 km of new overhead lines, replacing the original cables from the 1960s which were nearing the end of their lifespan.
The second phase of the works will take place in 2023 and will see the installation of an additional 1,670 km of new cables.
The renovation of the overhead lines is carried out in two distinct work periods. Overhead lines have two circuits, one on each side of the tower, so work is done on one side only, so the other side can be kept live. Once all work is complete on one side of the catenary, the circuit is re-energized and the opposite side is cut off so that work can be done on that side.
The line is divided into cable sections of 10 to 15 pylons (between 3.5 km and 5 km). The old overhead lines are laid in temporary bearing blocks, which are suspended from the crosspieces of the pylons, then winches are installed at each end of the wiring section.
The old overhead line is attached to the traction winch and the new line is attached to the old one at the other end of the section via a tension winch. The new line is pulled through the pylons using the old line. The tension winch acts as a brake, maintaining sufficient tension in the new lines while they are being installed, preventing it from falling to the ground. Once pulled into position, the new line is secured with new insulators and spacers, the process being repeated on each section.
At the same time as the catenary replacement work, specialized teams climbed and observed 248 pylons along the route. They installed 52 t of steel to reinforce the pylons and support the new line system.
National Grid overhead line engineer Martin Bage said: “This project is just one example of how our engineers work every day to maintain the electricity grid in England and Wales. The excellent progress we are making on this renovation is a testament to the skill and great teamwork of everyone involved.
“We look forward to completing the second half of the project and continuing our work ensuring our grid can play its part in delivering safe and secure electricity.”
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