Areva Supplies Vegetable Oil-Filled Transformers to EDF Energy Systems

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Researched by Industrial Info Resources (Sugar Land, Texas)--Areva SA (EPA:CEI) (Paris), through its power transmission and distribution subsidiary Areva T&D (Philadelphia, Pennsylvania), will supply power transmission transformers filled with vegetable oil to EDF Energy Networks (London) for installations in the East of England region if a current pilot test installation is successful. EDF Energy is a subsidiary of Electricite de France SA (EPA:EDF) (Paris).

Traditionally, transformers used in high-voltage power transmission systems have used mineral-based oil, which has high electrical insulating properties and is stable at high temperatures, to insulate and cool the electrical windings inside the transformer. The oil is also used to prevent a condition known as corona, which refers to electrical arcing within the transformer. The oil is known to be a dielectric. During the 1970s, it often consisted of polychlorinated biphenyl (PCB). However, concerns over the toxicity of PCB resulted in bans on their usage in many countries. Currently, fluorinated hydrocarbon or stable silicone oils are used, but these are expensive, particularly if fire-resistant additives are used and add considerably to the manufacturing cost of the transformer.

The new oil used by Areva, known as Envirotemp FR3, is manufactured by Cooper Power Systems (Waukesha, Wisconsin), a division of Cooper Industries (NYSE:CBE) (Houston, Texas). The fluid is fire-resistant and manufactured from edible seed oils such as soya beans, with food grade additives, enabling it to meet the highest standards of the U.S. Environmental Protection Agency (EPA). According to the EPA, Envirotemp FR3 is classified as having "ultimate biodegradability."

In addition to its environment-friendly properties, the oil has other advantages in power transformers. It has an exceptional ability to draw out moisture from the paper used internally in transformers, increasing the life cycle of the paper and preventing it from degradation. With lower viscosity than silicon- or hydrocarbon-based oils, the fluid offers superior cooling performance. It has the added advantage of being fully compatible with conventional mineral oils, so that it can be used to retro-fill transformers for prolonged life and reliability.

The transformer supplied by Areva T&D to EDF Energy is a 132-kilovolt (kV), 90-megavolt-ampere model. It has been installed in a substation in north Luton, Bedfordshire, and will be used to reduce the voltage level from 132 kV as supplied by the National Grid to 33 kV for onward transmission to homes and businesses in the town. The transformer requires about 30,000 liters of fluid. Under the terms of the supply contract, Areva produced two identical transformers, one filled with mineral oil and the other filled with the new Envirotemp FR3 fluid. The firm also used its proprietary MS 2000 comprehensive online monitoring system to ensure that the transformer filled with the new fluid meets the exacting requirements of EDF Energy.

The transformer, the first of its kind to be designed from scratch to use the new fluid, has been installed on a trial basis at Luton. If successful, EDF will use further transformers with the new fluid in substations in the East of England, London and South East England. Cooper Power Systems is also following the test closely and plans to introduce production of environment-friendly transformer oils in Europe, using locally grown source crops such as rape and sunflower seeds.

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