EDF Energy Networks, UK, has switched on what is believed to be the world’s first purpose-built 132-kV transformer filled with vegetable oil. The new green transformer, based in a substation in north Luton, will play an essential role in the transmission of electricity to homes and businesses in the town. Its role is to reduce the voltage from 132 kV from overhead lines for the next stage of its journey, at 33 kV, towards homes and businesses.

The Envirotemp FR3 liquid, made from edible soy beans, is being used to replace mineral oil in the transformer. About 30,000 liters of oil are needed to act as a coolant and insulator between the metal tank and the electrical equipment inside. This is the first time that vegetable oil has been used at such a high voltage in the UK and it is the first purpose-built 132-kV transformer in the world to be energized – although there have been some mineral oil transformers which have been retrospectively filled with vegetable oil. The liquid is an environmentally-friendly alternative to depleting mineral oils. It is made from a natural, renewable resource, is biodegradable and more fire resistant. It is also expected to extend the life of the transformer.

The new transformer is an integral part of EDF Energy Networks’ wider project to improve the electricity network in Luton and the transformer is capable of supplying electricity to at least 30,000 customers in the area. Paul Dyer, an EDF Energy Networks transformer specialist, said: “This new technology complements the commitment to the environment which runs throughout our company -- it brings many advantages and is one of the cleanest types of transformer available today. “We have installed it in Luton on a trial basis and will be monitoring its performance in association with the company that built it. If successful, we hope to roll out the technology to other suitable sites across our electricity distribution areas in the East of England, London and the South East.”

The transformer has been purpose-built for EDF Energy Networks by AREVA T&D with the oil supplied by Cooper Power Systems. The fluid was shipped to Felixstowe Docks from New York in one-ton cubes and delivered to Luton by road tanker. Demand for vegetable oil transformer coolant is only growing slowly in the UK but, as the benefits to the environment are extensive, Cooper Power Systems plans to introduce European production and the refining of locally-grown seeds -- rapeseed and sunflower being the most promising candidates.

EDF Energy Networks is working with the School of Electrical and Electronic Engineering at the University of Manchester and AREVA T&D to compare the performance of the new transformer with a second transformer traditionally filled with mineral oil. Equipment has been fitted to the transformer so that staff can remotely monitor the live performance data.