Siemens was contracted by the German transmission system operator TransnetBW to supply a power transformer that was to be filled with natural ester fluid rather than mineral oil, and which had to demonstrate robust cold start capability.
A supplemental requirement was for the natural ester fluid to be made from European-grown crops.
Siemens was already familiar with the characteristics of natural ester transformer fluids, specifically those made from soya and rapeseed crops, having used soya-based ester fluid in a power transformer unit in 2014. However, the manufacturer independently acknowledged the superior cold weather performance of rapeseed ester fluid with its pour point of -31°C. This critical performance factor made it necessary to upgrade to a rapeseed-based ester.
"The innovative cold start technology in this transformer demonstrates Siemens' expertise in combining industry leading innovations with eco-friendly solutions for the benefits of our customers and society," said Dr. Beatrix Natter, CEO Siemens Energy Transmission.
In addition to this performance advantage, the use of rapeseed ester MIDEL eN 1204 satisfied the local authority's mandate for the transformer materials to be locally sourced - MIDEL's aggregated source for the rapeseed being central Europe. Using MIDEL eN 1204 also supports sustainable land use, as the yield per hectare for rapeseed is greater than for soya. The transformer for TransnetBW used over 100 tonnes of MIDEL fluid.
The use of MIDEL eN 1204 in the TransnetBW unit reflects the growing uptake at this level of EHV transformers. Leading utilities such as Con Ed and National Grid are also producing greener transformers by using MIDEL ester transformer fluids.
