IV Power Station System B. Collection Module Photovoltaic (2) Power Distribution R. C. Kennedy Control Systems Development Division Introduction The collection module distribution system as discussed here includes the power busses and any regulation and control equipment external to the solar cell blankets. Its primary function is to provide the conductive path between the blanket modules and the transmitting antenna gimbal joint. Conceptually, the system will comprise a matrix of large continuous conductor busses with a maximum current level of several hundred thousand amperes at the gimbal. Any switching or power regulation required of the distribution system will be done at the interface where the blanket modules feed to the busses. Amperage levels at this interface will be only a few thousand amperes. No switching or other power control will be attempted on the main busses. The nominal operating voltage for the station was arbitrarily set at 40 KV. Previous studies chose a 20 KV level presumably to match the operating voltage of the Amplitron DC-RF converter. In this study, the Klystron was the preferred converter and is directly compatible with the selected operating voltage. It remains the subject of much research and analysis to determine if 40 KV, or even 20 KV, is a practical operating voltage of the station. The plasma environment, both natural and artificial, surrounding the station will interact with unprotected busses and result in power losses (leakage) and, under adverse conditions, breakdown may occur causing potentially dangerous arcing between conductors. The quantitative assessment of plasma effects is beyond the scope of this study and, except for recognition of the problem, will not be treated further. ■ Conventional metallic conductor material was selected for the bus structure. Cryogenic superconductor systems were not seriously considered because of the complexity and reliability of the refrigeration system. Weight trades were not conducted, but it is thought that the overall cryogenic superconductor system would show only a marginal advantage. The eventual development of room temperature superconductors has been speculated upon, but there is no evidence that technology will produce usable materials for application to this program. The product of electrical resistivity and weight density was used as a figure of merit to select the conductor material. The following table shows this parameter for candidate conventional materials at room temperatures.
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