Development of Superconducting Bearings for Industrial Application

High-temperature superconducting (HTS) magnetic bearings are promising candidates for application in machines with high rotational speed. The interaction between HTS and permanent magnets can be technically exploited to realize bearings with novel properties. In recent years a number of small experimental HTS bearings were manufactured and tested worldwide. Encouraging findings on these bearings gave evidence for several advantages. HTS bearings show self-stabilizing behaviour without any active control. Due to their contactless design they provide wearless suspension with very low friction. They are inherently safe. Because of their oil-free design these bearings can reduce environmental risks and fire hazard. The fire load is minimized. Rapid progress in development of high quality HTS enables and accelerates application of HTS in electrical machines and levitation systems. Single-domain YBCO monoliths fabricated by a top-seeded-melt-growth process at Nexans SuperConductors exhibit self-field critical current densities up to 1.3 x 10 5 A/cm 2 at 77 K. Typical areas of application for passive HTS bearings are rotating machines with high rotational speed like motors and generators, energy storage flywheels and oil-free turbines.