The basic design requirements for the compression frame tension web concept are as follows: o 1-km diameter surface (or equivalent) o Web angular misalignment: ±0.08° under environmentally and operationally induced loads and temperatures o Optimize for light weight o Compatible with on-orbit fabrication and assembly o Compatible with operational equipment o Service life: >30 years The tri-beam girder material thickness is 4.36 x lO^-4 m (0.17 in.) and its side dimension and bay length dimension are 30.57 m. The catenary cables and tension web cables are woven graphite, 0.0396 m (1.56 in.) and 0.0064 m (0.25 in.) in diameter, respectively. Power Distribution - Figure R-l5 illustrates the basic power distribution concept considered for the satellite antenna network. Sixteen independent power risers (one per siip-ring/brush are routed to sixteen dedicated high voltage, high-power dc-dc converters. The output of the dc-dc converters are summed on two independent summing power bus sets (each set consists of five different voltage levels from 8-40 kV). A network of secondary feeders then routes the power to the individual dc-RF converters distributed on the antenna surface. A backup power system is located on the antenna structure with an emergency bus routed along side the regular network for operation during powered down periods such as may occur during solar eclipse periods. It must be emphasized that the emergency bus is separate from and cannot be used to supplement, in any configuration, the transmission of power. Conditioning - The power conversion equipment converts the nominally 40 kV DC main bus voltage to the subsystem voltages required for the various subsystem loads. The major requirement is to supply the five basic voltages, (40 kV, 32 kV, 24 Kv, 16 kV and 8 kV) to the klystron DC-RF power converters. A secondary requirement is the need to supply low voltages (<100 V) to the various operating electronics.
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