Siemens recently became the first manufacturer in Europe to start up a high-temperature superconductor (HTS) motor at its research center in Erlangen, Germany. Sponsored by the Federal German Ministry for Education and Research, this project involves testing high-temperature superconduction technology with a trial motor. The rotor (with superconducting coils) is mounted in a motor housing with an air-gap stator winding. Then, it is cooled in a closed-circuit system. During experimental operation in motor and generator modes, the trial motor reached a continuous power output of 400kW, which is equivalent to about 550 hp.

According to American Superconductor, Westborough, Mass., high-temperature superconductors can carry high-density current with virtually no loss. Power output is more than double that of conventional motors of similar size with copper windings, while losses are halved. Suitable applications for the compact motor include those calling for space- and energy-saving machines. The technology is also suitable for gas turbines, making it possible to build extremely high-speed generators, which can be coupled directly to a turbine without the need for a gear box.

Below the transition temperature, the electrical resistance of superconducting materials disappears. Until now, it was necessary to reduce temperatures to -273°C to obtain the superconducting effect. With high-temperature superconductors, electrical resistance disappears around -190°C. This enables virtually loss-free current conduction with a considerably lower line diameter, greater efficiency, and higher magnetic field strength.