Siemens delivers world's first vegetable oil transformer in the 420 kV capacity range

The world's first power transformer insulated and cooled using vegetable oil links the 380 kV extra-high voltage level with the 110 kV grid of the subordinate distribution grid operator in the Bruchsal substation.

This ensures that the power transported via the extra-high voltage lines to Bruchsal is fed into the 110 kV grids of the distribution system operator and that this power arrives safely and reliably at households and industry throughout the region.

The special feature of this transformer is the material that it is filled with. For this marks the first time that vegetable oil is used with this voltage category instead of mineral oil for insulation and cooling. This vegetable oil is not only more environmentally friendly, but is also much less flammable than mineral oil.

“The use of this groundwater-neutral and bio-degradable insulating oil, with its high level of environmental compatibility was the decisive factor for us choosing this transformer”, stresses Michael Schäfer, head of systems technology at TransnetBW. The insulating oil for this new transformer is produced solely from renewable, plant resources and is completely bio-degradable.

This is but one of Siemens' decisive contributions to environmental sustainability. The new power transformer for the Bruchsal-Kändelweg substation is the world's first transformer at the 420 kV extra-high voltage level for which no water hazard classification must be issued. As a result, this transformer can be installed and operated in water conservation areas or in zones subject to stringent environmental protection restrictions.

“The properties of this vegetable oil are not only beneficial to the environment, but also offer the customer cost advantages over transformers cooled with conventional mineral oil”, explained Beatrix Natter, CEO of the Transformers business unit at Siemens Energy. “The bio-degradability of the insulating oil means that additional collecting vessels and separation systems are no longer required at the installation location, resulting in cost savings for these items.”

Other important aspects are the substantially higher flashpoint and combustion point of the vegetable oil as compared to that of the mineral oil used up to now. The lower flammability of this insulating oil also provides the transformer with a higher fire protection classification. This means that the fire protection system can be optimized accordingly and that the transformer can also be operated favorably in densely populated residential areas.

Vegetable-oil-based transformers and the associated service are part of Siemens' Environmental Portfolio. Around 43 percent of its total revenue stems from green products and solutions. That makes Siemens one of the world's leading providers of eco-friendly technology.

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