High-temperature superconducting transformers can perform the necessary change in voltage in a transmission system without the 23,000 liters of oil in conventional transformers. This reduces the weight of a power transformer from about 75 tons to about 45 tons for a 30 megavolt-ampere (MVA) unit, the size typical of a substation in a medium-sized city. What's more, eliminating the oil permits the electrical insulation system to continue to function during certain overload, or high-stress conditions, without any loss of transformer service life. Oak Ridge National Laboratory and industrial partners Waukesha Electric Systems in Wisconsin and SuperPower in New York are testing the world's first 5 MVA prototype at the Waukesha factory. According to Waukesha, low-cost, second-generation high-temperature superconducting wires like ORNL's RABiTS (rolling assisted, biaxially textured substrates), a patented technology and winner of an R&D 100 Award, will be required if high-temperature superconducting transformers are to be a big player in the upgraded electric grid of tomorrow.
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