Customer: Major UK grid operator

Location: London

Application:  Power transformers

Highest voltage: 400kV

Bringing Together Safety and Reliability

A major UK grid operator needed an innovative solution to the challenge of installing 400kV transformers in a densely-populated area of London. The aim was to combine safety and reliability with a heat exchanging device (directing the captured transformer heat-loss to a nearby school). A world leader in transformer manufacturing provided the operating assets – 400kV transformers – and selected MIDEL 7131 as the best choice of dielectric fluid.

Safety, reliability and environmental impact are crucial considerations for grid operators and transformer manufacturers, especially for installations in large cities. Residential properties, hospitals and business premises where people work must be protected from the risk of fire or explosion from the installed electrical assets. The environment and appropriate corporate social responsibility considerations are also critical factors. Furthermore, space constraints are very often a key issue in cities.

MIDEL 7131 synthetic ester insulation was chosen for the project as it greatly reduced the risk of fire and explosion. The fire point of synthetic ester fluid (316°C) is very high compared to mineral oil (170°C). In order to manufacture the transformers according to the required performance levels (dielectric characteristics, insulation and projected lifetime), specialized constructive changes were calculated and planned in the design phase.

Waste heat from the power transformer was re-used using heat exchange devices. Planning and construction of this additional feature was done in close collaboration between the transformer factory, the customer and the supplier of the heat exchange device.

When installing transformers in urban areas, noise plays a key role, as do reliability and safety. The transformer and cooling devices need to operate silently regardless of transformer load. The transformer filled with MIDEL 7131 was manufactured with a low-noise-design. Bespoke housing, as well as noise-optimized cooling with frequency-regulated fans was added to the low-noise concept.

Download the full technical paper about this project here.

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