TransnetBW, a German electricity transmission operator, recently ordered a power transformer from Siemens. The specification called for the transformer to be filled with natural ester dielectric fluid instead of mineral transformer oil. This natural ester fluid to be made from European-grown crops. The specification also called for robust cold-start capability.
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 use of Midel’s eN1204 rapeseed ester dielectric fluid delivered clear benefits in this project: The fluid has a high fire point (K class fluid >300°C) and is readily/fully biodegradable. Its superior performance over soya natural ester fluid at lower temperatures was a critical factor for the customer, enabling the transformer to withstand a cold start after any period of outage.
In addition to this performance advantage, the use of Midel’s eN1204 rapeseed ester dielectric fluid satisfied the local authority’s mandate for the transformer materials to be locally sourced because the company’s sources its rapeseed from central Europe. Using this particular brand of rapeseed ester fluid also supports sustainable land use, as the yield per hectare for rapeseed is greater than that for soya. The transformer Siemens built for TransnetBW used over 100 t of rapeseed ester fluid.
The use of Midel’s eN1204 rapeseed ester dielectric fluid is growing in EHV transformers. Other major power utilities are also producing “greener” transformers by using Midel’s ester transformer fluids.
Dr Beatrix Natter, the CEO of Siemens Energy Transmission, says that the innovative cold start technology in this transformer demonstrates Siemens’ expertise in combining industry leading innovations with eco-friendly solutions for the benefits of its customers and society.
Contact Vin Staniforth, Midel, email@example.com