WEIGHT AND LOSSES OF ALUMINUM CONDUCTOR SYSTEMS Line Voltage (kV) 4 40 100 Weight of Conductors (kg) 2.8 x 107 2.8 x 10“ 1.1X 10s Conductor Loss (MW) 2,200 220 88 CONCLUSION It is concluded that the SC cable system provides much better efficiency and lighter weight than systems with ordinary conductors, by the comparison of the values described above with the results of the calculations shown in Table 2, wherein it is supposed that SC cable system is replaced by systems of aluminum conductors, with the line voltage of 4 kV, 40 kV and 100 kV and the current density of 3 A/mm2. At this density, a radiator system installed along the conductors is necessary, with a width of 1 m (3.3 ft) for every 20 kA to keep their temperature below 500 K (440° F). It is obvious from the comparison that the SC cable system is superior in both weight and the loss. Only systems of 100 kV or higher line voltage can be competitive, however, they are considered to involve difficulties in electric insulation in the space environment. Therefore, SC cable system is one of the best candidates for power distribution systems on SPSs. REFERENCES 1. P.E. Glaser, Power from the Sun: Its Future, Science 162, Nov. 1968. 2. G.M. Hanley, SPS Concept Definition Study, 5 Syst. Eng./Integration. Res. Technol., NASA CR- 3396, 1981. 3. I. Kudo, I. Ishii, Y. Kimura and N. Higuchi. Cryogenic Power Distribution on a SPS, Proc. 2nd. ISAS Space Energy Symp. II-6, 1983. 4. CRIEPI, Cryogenic Power Transmission (Research and Development of New Transmission System- II), 1973. 5. N. Ito, Electrical Characteristics of Superconducting Cable, Bui. Electrotech. Lab. 35, 161, 1971.
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