Engineers at Rockwell Automation, Greenville, S.C., have developed a 1,600-hp synchronous motor that uses high-temperature superconducting (HTS) field windings. It is a precursor of lighter, smaller, and more-efficient motors in the future. Built as a research tool, the motor should have less than half the energy losses as conventional high-efficiency induction motors with the same rating. The low losses are due to the low resistance HTS windings have at temperatures above absolute zero.
The HTS field windings are made of bismuth, strontium, and calcium oxide in a silver alloy matrix, and will be cooled to between 25 and 40K. The new motor uses more than 20 kilometers of this wire and a 4 Tesla dc magnetic field in the motor. The motor also features air-core construction, so that the air-gap field can be increased without core loss and saturation problems common to motors with laminated iron stator and rotor cores.