by Neil Hitchcock
Project Director, SSEN Distribution's Large Capital Delivery division
When you conjure up an image in your mind of our electricity distribution network, you’ll likely think of the wooden poles which carry wires over longer distances in more rural areas. But these lines wouldn’t be able to deliver the power they do, to your home or business, if it wasn’t for other vital equipment you don’t see.
Chief among these are Scottish and Southern Electricity Networks’ transformers. These are large, specialist pieces of equipment whose role is to convert electricity from higher voltages necessary for the long journey power must make from where it’s generated, to where it’s used at the lower voltages homes, businesses and workplaces need.
We also try to shield them from view, as we know they’re not the prettiest things to look at. But for us, their beauty comes from the essential role they play for all of us.
ABOVE: The newly-installed transformers are surrounded by trees to help minimise their visual impact, but the power they carry is vital for homes and businesses nearby.
Our transformers are regularly inspected and maintained, like all the assets on our network. But even the best-maintained equipment has a shelf life. That’s why we have a rolling replacement programme underway across our network areas.
Take our recently-completed £2m project to replace two transformers at our substation in Chertsey, just beyond the M25 in Surrey. The equipment there was more than 40 years old, and was beginning to approach the end of its useful life. So, we’ve been swapping them out for state-of-the-art models before they reach that stage, as part of our ongoing investment in renewing the existing network.
There are two transformers for a very important reason; it guarantees a high level of redundancy in the network. This means that if one transformer needs to be repaired or serviced, the network can operate as normal, meaning no adverse impact for our customers who depend on the power the substation seamlessly helps deliver.
We give a lot of thought as to the placement of these two transformers within the substation compound. They both need to be connected to other equipment, which affects their position to a degree. But we always ensure a safe distance between them. This means - in the unlikely event a serious issue develops in one transformer – it’s less likely to affect the other unit.
And in addition to the placement of the transformers, a lot of other detailed work goes into the installation process. Once the new transformer arrives on site, it’s ‘skidded’ into position, and precisely manoeuvred into its final place using hydraulic jacks and beams.
Once that’s done, all the ancillaries which were removed to ease transportation from the factory to our site can be re-installed. This part of the process sees the fans, radiators and the conservator reattached. This final bit of kit ensures the transformer itself always contains the correct amount of oil; specially-formulated mineral oil is vital for the safe and efficient operation of the transformer.
ABOVE: After arriving on site, the transformers are carefully moved into their final position by hydraulic jacks.
Now the installation is complete, these new transformers are performing their discreet but vital role in keeping power flowing to homes and businesses in the Chertsey area.
This brand-new equipment also provides additional headroom so that when homes and businesses want to adopt new low-carbon tech – things like heat pumps, EV chargers, and solar panels, the capacity on the network will be available, provided any necessary network upgrades have also been completed.
Now the Chertsey project’s completed, we’re moving on to the next sites; projects like this one are under way, or being planned in locations across our network areas in central southern England and the north of Scotland.
So, the next time you walk past one of our substations, we hope this gives you a better idea of the vital work that’s going on, behind that secure perimeter fence.