RESEARCH-AND-DEVELOPMENT OF SUPERCONDUCTORS FOR 70MW CLASS GENERATORS

Super-GM has been developing 70 MW class superconducting generators (m odel machines) for 500 MW class pilot generator, Three types of NbTi c onductors were developed for each of three model machines, Regarding t o the high stability type conductors, residual resistance value of 6.5 mu Omega/m was achieved by adopting Al stabilizer, Regarding to the h igh current density type, Ic of 13.8 kA at 5T was realized by reducing void fraction in conductors and maintaining high residual resistivity ratio, For the low AC loss type, high Je and low AC loss (8.1 kW/m(3) ) have been succeeded by applying strand insulation and two stage cabl ing. To confirm superconducting characteristics concerning long-term r eliability, Ic and AC loss of each conductors were measured under 10,0 00 times repeated compressive force of 30 MPa that is supposed in dail y start and stop operation of generator for 30 years. In parallel to t he R&D of NbTi conductors, R&D of Nb3Sn conductors were also conducted for enhancement of critical current density and critical magnetic fie ld.