The Energy Blog New 90-ton transformer arrives at La Collette by special delivery
Transformer 2

£5 million project to ensure supply reliability remains one of best in Europe

The biggest parcel to arrive in Jersey this side of Christmas has been delivered to La Collette Power Station. Carefully wrapped and transported by Tironi, from Modena, Italy, the 75MW transformer weighs 90 tons and consists of a 5.5m-high tank and 7m-high cooler bank, making it the joint largest in the Island. The unit is at the heart of Jersey Electricity’s latest £5m project to ensure the Island continues to benefit from one of the most reliable and lowest carbon electricity supplies in Europe.

It reduces the voltage of low-carbon electricity imported from France through the subsea cables from 90 thousand Volts (90kV) to 33kV for connection into the Power Station and ultimate distribution throughout the Island. JE engineers will be connecting the unit over the coming months. It will eventually work alongside the existing transformer to provide extra resilience to supplies and prevent the need for on-Island generation should the existing transformer break down.

JE Director of Operations Mark Preece explained: ‘Electricity in Jersey has quite a journey from France via our three undersea cables to reach Island homes and businesses. Once it arrives at either Archirondel Termination Station or South Hill Switching Station at Mount Bingham, it is transmitted to five Primary Substations where it is transformed down to either 33kV or 11kV, and then via almost 800 smaller substations which reduce it to 415V for use in homes and businesses.

‘If the existing transformer at La Collette were to develop a fault, we would have to generate at the Power Station at peak times, not because we wouldn’t have enough electricity but that we wouldn’t have enough at the correct voltage. We wish to avoid on-Island generation as it is much more costly and considerably higher carbon than imports. This new transformer will eradicate these issues.’

Work on the project continued throughout lockdown in March and April, with ducting for cables laid from South Hill to La Collette. The delivery of the unit was logistically complex as it had to be carried out under the strictest of COVD-19 restrictions as well as the standard and robust Health and Safety measures needed for this unique engineering project. Italian and English engineers worked in a sealed bubble with no contact at all with JE employees.

Latest figures released by JE show the Island had just five Customer Minutes Lost last year. That is the supply interruption time averaged by each customer over the year. It is JE’s lowest on record and compares with 80 CMLs averaged by UK electricity distributors.