Europe | January 4, 2014

Green transformers: using biodegradable vegetable oil

Green transformers are starting to change the environmental footprint of substations, as well as many other applications where transformers are used.

 

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Green transformers are starting to change the environmental footprint of substations, as well as many other applications where transformers are used.

The high voltage transformer parts need to be well insulated and this is usually done by filling the transformer with a non-conducting oil that prevents electrical arcs from the transformer to the ground, as well as coronal discharges – where the area around the transformer becomes electrically charged and glows blue. The same insulation approach is also used with certain other types of electrical equipment, including some high-voltage capacitors, switches and circuit breakers.

One of the best types of fluid for doing this is polychlorinated biphenyls (PCBs) as they are not flammable but these compounds do not break down when they are released into the environment. They build up in plant and animal tissues and can cause cancer and serious deformities, and release other highly toxic compounds when they are burned – including dioxins.

As a result, PCBs were banned and substitutes, such as mineral oils, started to be used. They still had a negative effect on the environment as they dissolve PCBs  so they often became contaminated.
Mineral oil is now often being replaced in new green transformers by other more eco-friendly compounds.

Back in July, Siemens announced that it had produced the first large scale transformer in the world that uses vegetable oil from sustainable sources which is biodegradable and is actually less flammable than mineral oil. The vegetable oil also acts as an efficient coolant for the transformer. The Siemens transformer is due to be installed at a Karlsruhe substation, Germany.

Source: Greener Ideas