Siemens has produced the world’s first large-scale transformer that uses vegetable oil. In the future, the device will link the 380-kV ultra-high-voltage level with the 110-kV grid in the Bruchsal-Kändelweg substation plant near Karlsruhe, Germany.

Transformers are usually cooled and insulated with mineral or silicone oil. By comparison, vegetable oils are environmentally friendlier and less flammable. Until now, Siemens has used vegetable oil insulation in power transformers with voltages of up to 123 kV. The new transformer is designed for 420 kV.

Siemens’ new transformer weighs just under 340 tons and contains 100 tons of insulating oil. The oil comes exclusively from renewable vegetable resources. As a result, the device is the world’s first power transformer on the 420-kV ultra-high-voltage level that does not require proof of its water hazard classification.

TransnetBW, a grid operator in the German state of Baden-Württemberg, put the  environmentally friendly transformer into operation in late July.

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