IV-C-6-2 ROTARY JOINT TO SWITCH GEAR DISTRIBUTION Power from the solar array is brought across the rotary joint interface where it is conducted by cables which run through the structure trusswork to switch gears located on the axis of the antenna. Figure IV-C-6-3 shows the relative locations of the switch gears and rotary joint along with the dimensions involved. IV-C-6-3 SWITCH GEAR TO SUBARRAY DISTRIBUTION Figure IV-C-6-4 shows one quadrant of the antenna with the switch gears located along one axis. The 10 areas determined by the 10-step 10 db taper are outlined. Power is conducted from each switch gear to a distribution point within a subarray or group of subarrays. The total amount of current required by all the klystrons in one quadrant of the antenna was calculated to be 42,000 amperes. It was felt that four switch gear per quadrant was reasonable from both a complexity and a distributive point of view. This implies a current level of approximately 11,000 amperes per switch gear, which also seemed reasonable. In addition to being a distribution point, it is felt that each switch gear will be a protective device and should be capable of being remotely controlled so that during initial power-up, or reinitialization following an eclipse, power could be brought up in a programmed sequence. The implementation of a control system for the switch gear is an area which must be investigated further. IV-C-6-4 SUBARRAY DISTRIBUTION Tiie technique for distributing power throughout a subarray is shown in Figure IV-C-6-5a. Power is input at a distribution point from where it is distributed by feeders to each row of klystrons. Wire size for each feeder is determined by the number of klystrons it services since this determines the total current per row. The 10 db, 10-step truncated Gaussian taper determines the number of klystrons per subarray. Those subarrays close to the center of the antenna have a greater klystron density than those close to the edge. In order to reduce the number of wires from each switch gear to the subarrays, the subarrays having the lowest klystron density (6-13) and therefore requiring the lowest current (8-16 amps) would be arranged in groups of fours and would be serviced by one distribution point. Those subarrays having a somewhat greater klystron density (17-25) would be paired and each pair would be serviced by one distribution point. Figures IV-C-6-5b and IV-C-6-5c depict this method.
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