Transformers With Vegetable Oil

As reported in the current issue of the magazine Pictures of the Future, the “vegetable-oil transformers” are safer and more environmentally friendly than conventional units and also require fewer safety systems for preventing fires and leaks.

Transformer components are normally cooled and insulated with petroleum or silicone oil. Vegetable oil offers the benefit of complete biodegradability, however, and it's also less flammable than mineral oils.

The transformers from Colombia have been installed at North and South American solar and wind power facilities, among other places.

Transformers are utilized at substations to either raise or lower AC voltage, to enable electricity to be transported in high-voltage networks, for example. Their job at wind and solar power facilities is to convert electrical energy to the right voltage for feeding into the grid.

The extremely high currents and voltages the transformers are exposed to cause them to get very hot, which is why thousands of liters of oil are needed to cool them. Mineral and silicone oils have traditionally been used for this, as both are good at channeling off heat and insulating against electrical flashovers. These oils can be highly flammable and bad for the environment, however.

The new insulating oil is made from rapeseed, soy, or sunflowers, which makes it biodegradable. It also has a much higher flashpoint than industrial oils. Moreover, because it poses absolutely no danger to groundwater or rivers, it can be used in areas subject to strict environmental protection regulations. Complex systems for protecting against oil leaks are no longer necessary with the plant-oil transformers, which can therefore be built at a lower cost.

Siemens Energy is currently using its vegetable oil solution in small transformers with a voltage of up to 69 kilovolts and a power rating of 30 megavolt-amperes. Siemens has built more than 30 of the transformers to date. Environment-friendly solutions for power distribution are part of the Siemens Environmental Portfolio, with which the company generated about €30 billion in sales in fiscal year 2011.