2G HTS wires and the implications for motor and generator applications

Over the past few years, first generation (1G) high temperature superconductor (HTS) wires have been used to demonstrate large-scale prototype devices, including a 5 MW U. S. Navy motor and an 8 MW synchronous condenser. In addition, the fabrication and testing of larger devices (a 36.5 MW motor and a 12 MW synchronous condenser) are currently underway. Although 1G HTS wire will continue to be a workhorse for demonstrating this technology over the next few years, the lower cost potential of second-generation (2G) HTS wire is driving its rapid development and scale-up. In addition to reporting on key material properties of this wire for coil applications, this paper presents thermal cycling data on 2G racetrack coils, showing excellent robustness under conditions of significant thermal strain. A 2G solenoid coil with a 5 cm inner diameter has achieved 1.5 T at 64 K. These results are a major step in confirming the viability of 2G HTS wire in coil applications.