Posted: 21 May 2015
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Transformer test is a win-win-win
Transformer test is a win-win-win

National Grid sets a world first by successfully testing a synthetic ester-filled transformer at 400kV.

The first of three Midel 7131 transformers will be shipped to National Grid’s Highbury site in north London this summer.

"During the research we got a lot of data about how the fluid behaves. That’s useful for transformer manufacturers when it comes to designing the equipment in future.”

Paul Jarman, Transformer Technical Manager.

A ground-breaking transformer for National Grid successfully built and tested by Siemens is set to deliver a win-win-win solution for consumers, the environment and a north London school.

The development saw National Grid and its partner trial something called Midel 7131 synthetic ester, a chemical compound that’s been used for years as an insulating medium but which has previously been considered unsuitable for high-voltage 400kV transformers.

Before placing a contract for the transformer, National Grid had first conducted research on a small scale at Manchester University, culminating in a full scale-test on a transformer winding at Alstom UK.

Paul Jarman, Transformer Technical Manager, said: “During the research we got a lot of data about how the fluid behaves. That’s useful for transformer manufacturers when it comes to designing the equipment in future.”

Even though modern transformers are very reliable and less prone to fires than ever, it’s not an impossible occurrence. For this reason, high-voltage transformers have previously been positioned a certain minimum distance from occupied premises.

Now, after the successful test, Midel 7131’s high fire point means it now becomes possible to put high-voltage 400kV transformers in closer confines, something that’s much-needed with available space in cities becoming steadily smaller. In an added bonus, the ester is more biodegradable than mineral oil too.

Siemens will ship the first three Midel 7131 transformers to National Grid’s Highbury site in north London. More than 1MW of waste heat from the transformers will be recovered and used to heat a neighbouring school as well.

Gas innovation in full flow