This functional analysis is constrained to startup and nominal operations because of the limited study time and because of the limited subsystem and system data available. The satellite functions identified and evaluated primarily address the major subsystems to generate and transfer the energy obtained during the primary satellite mission. The startup phase will be used to illustrate the basic activities that may occur during any one of the three operational phases. Startup control functions for satellite power production and transmission are sequenced automatically by the spaceborne and ground computers. An example of the antenna startup sequence and related control issues is shown in Figures 2 and 3. This analysis identified concerns regarding activation, stabilization, and control response times. DISTRIBUTE POWER TO KLYSTRONS • CLOSE ANTENNA RING BRUSH SWITCHGEARS • POWER UP CENTRAL CONVERTERS •5 OUTPUT VOLTAGES TO KLYSTRONS •60+KW POWER TO EACH • CLOSE 5-POLE SWITCHGEARS TO PRIMARY/SECONDARY BUSES • PLACE REDUNDANT SWITCHGEARS ON STANDBY • SEQUENTIALLY CLOSE 5-POLE SWITCHGEARS TO: •MECHANICAL MODULES •POWER MODULES (INDIVIDUAL KLYSTRONS) • STABILIZE POWER TRANSMISSION TO EARTH • MAINTAIN BATTERIES 100% CHARGED • ECLIPSES: OPEN MAIN POWER BUSES •SHUT DOWN POWER MODULES/ENERGIZE BATTERY BUS •MAINTAIN KLYSTRON TEMPERATURES •UPDATE ORBIT PREDICTIONS AND SCHEDULES •MAINTAIN RETRO-ELECTRONICS ON STANDBY Figure 2. Satellite Operations — Startup (Antenna) ACTIVATION & STABILIZATION TIMES |* REPETITIVE STATIONKEEPING & BORESIGHT OPERATIONS • STATUS & CONTROL SEQUENCING THROUGH 100,000+ POINTS •THERMAL STABILIZATION OF KLYSTRONS •INITIATION & STABILIZATION OF FINE POINTING STARTUP TIME SEQUENCES COULD BECOME VERY LONG" POSSIBLE IMPACT TO SPS CONTROL RESPONSE REQUIREMENTS • STARTUP/SHUTDOWN DUE TO ECLIPSES •EMERGENCY RESPONSES AND RECOVERY • RESPONSE TO UTILITY POWER LOADINGS Figure 3. Startup Control Issues
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