The first phase of National Grid’s £130M project to refurbish 170km of overhead power lines between Lincoln and Stevenage has been completed.
The renewal of the transmission line started in March at Cottam Power Station and has reached Peterborough, passing Newark and Stamford along the way. It has seen workers from National Grid’s operations teams and Morrison Energy Services working at heights of up to 50m. They have installed around 1440km of new overhead line, replacing the original 1960s wires which were approaching the ends of their working lifespan.
The second phase of work will take place in 2023 and see a further 1,670km of new wires installed.
Overhead line refurbishment is carried out as two separate periods of work. Overhead lines have two circuits, one on each side of the pylon, so work is carried out on one side only, in order that the other side can be kept live. Once all the work has been completed on one side of the overhead line, the circuit is re-energised and the opposite side is switched off so that the work can be carried out on that side.
The line is divided into wiring sections of typically 10 to 15 pylons (between 3.5km and 5km). The old overhead lines are dropped into temporary running blocks, which are suspended from the cross arms of the pylons and then winches are set up at either end of the wiring section.
The old overhead line is attached to the pulling winch and the new line is attached to the old one at the other end of the section through a tension winch. The new line is pulled through the pylons using the old line. The tension winch acts as a brake, keeping sufficient tension in the new lines while they are installed, preventing it from falling to the ground. Once it’s pulled into position, the new line is secured with new insulators and spacers, with the process repeated on every section.
Alongside the overhead line replacement work, specialist teams have climbed and observed 248 pylons along the route. They have fitted 52t of steel to reinforce the pylons and support the new line system.
National Grid overhead lines engineer Martin Bage said: “This project is just one example of how our engineers work every day to maintain the electricity network in England and Wales. The excellent progress we are making on this refurbishment is testament to the skill and great teamwork of all involved.
“We look forward to completing the second half of the project and continuing our work ensuring our network can play its part in delivering safe and secure electricity.”
Like what you've read? To receive New Civil Engineer's daily and weekly newsletters click here.
Tagged with: Morrison Energy Services National Grid
Sign in or Register a new account to join the discussion.