Power transformers (generally, those rated above 33 kV) are critical assets in energy infrastructure. They are also expensive and difficult to transport. Power transformers are often deployed in areas of high density population or environmental sensitivity, so fire safety and the behaviour of the fluid in case of a leak are also prime considerations.

That’s why the world’s leading utilities and transformer manufacturers turn to Shell MIDEL ester fluids.

Shell MIDEL eN 1204, Shell MIDEL eN 1215 and Shell MIDEL 7131 are all suitable for use in power transformer applications up to 400kV. The ester base oils used in all Shell MIDEL fluids are readily biodegradable according to OECD 301 and biodegrade faster than conventional mineral oil. Shell MIDEL 7131 is perfectly suited for non-breathing and breathing transformers (due to its excellent oxidation stability) located indoors or outside. In 2016, Shell MIDEL 7131 was specified and used in a 400kV urban transformer installation in London.

Our natural ester fluids Shell MIDEL eN 1204 (rapeseed) and Shell MIDEL eN 1215 (soya) are made from bio-based raw materials (100 % bio-based carbon, ASTM D6866-21) and provide an effective solution for non-free-breathing power transformers. Shell MIDEL eN 1204 (rapeseed), with its pour point of -31°C, is better suited to colder installation climates than soy-based natural ester fluids.