Superconducting linear synchronous motor for urban transport system

The authors describe a superconducting linear synchronous motor (SLSM) for a high capacity urban transport system (10/sup 6/ passengers/day/line) able to climb a hill grade of 12%. The motor is composed of 26 poles installed below one wagon and is sufficient for traction of six wagons of 330 passengers each. The pole coil is a segmented race-track type 23 cm long, 140 cm wide, and 11.2 cm high. The conductor is composed of 14 transposed NbTi wires /spl phi/ 0.7 mm each, 5.04 mm/spl times/1.20 mm cross-section and Cu/SC ratio of 1.35. The current leads are made of high-T/sub c/ superconductor (melt textured growth YBa/sub 2/Cu/sub 3/O/sub 7-x/). These leads allow a pool cooling cryostat (2400 and of LHe) without an on-board refrigerator, and with one year holding time. The quench protection is made with cross-quench heater resistance placed within each coil. The limiting factor is the critical field of the NbTi and its substitution by Nb/sub 3/Sn should reduce the cost by a factor of 40%. Final cost of the SLSM is expected to be in the US600,000 range. Due to the low speed (100 km/h), the suspension is made on conventional bus type tyres.< >