基礎(chǔ)防雷外文資料翻譯-文庫(kù)吧
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【正文】 心，美國(guó)航天局， 1991 年標(biāo)準(zhǔn)。 7。莫里斯， i， .，火箭引雷研究的重要資產(chǎn)，在行業(yè)的應(yīng)用，卷匯刊保護(hù)。 30，第 3 號(hào)， 5 / 1994 年 6 月。 8。森德， ，四 凡諾斯特蘭有限公司，紐約， 1949 年。 9。湯，四，波動(dòng)現(xiàn)象，多佛出版社，臺(tái)北。 10。 烏曼，馬丁，閃電，多佛出版社，紐約， 1984。 11。 Viemeister，彼得，閃電書，麻省理工學(xué)院出版社，劍橋大學(xué)碩士， 1972年 附件 2： Fundamentals of Lightning Protection Introduction Lightning is a capricious, random and unpredictable event. Its39。 physical characteristics include current levels sometimes in excess of 400 kA, temperatures to 50,000 degrees F., and speeds approaching one third the speed of light. Globally, some 2020 ongoing thunderstorms cause about 100 lightning strikes to earth each second. USA insurance pany information shows one homeowner39。s damage claim for every 57 lightning strikes. Data about mercial, government, and industrial lightningcaused losses is not available. Annually in the USA lightning causes more than 26,000 fires with damage to property (NLSI estimates) in excess of $56 billion. The phenomenology of lightning strikes to earth, as presently understood, follows an approximate behavior: 1. The downward Leaders from a thundercloud pulse towards earth seeking out active electrical ground targets. 2. Groundbased objects (fences, trees, blades of grass, corners of buildings, people, lightning rods, etc., etc.) emit varying degrees of electric activity during this event. Upward Streamers are launched from some of these objects. A few tens of meters off the ground, a collection zone is established according to the intensified local electrical field. 3. Some Leader(s) likely will connect with some Streamer(s). Then, the switch is closed and the current flows. We see lightning. Lightning effects can be direct and/or indirect. Direct effects are from resistive (ohmic) heating, arcing and burning. Indirect effects are more probable. They include capacitive, inductive and magic behavior. Lightning prevention or protection (in an absolute sense) is impossible. A diminution of its consequences, together with incremental safety improvements, can be obtained by the use of a holistic or systematic hazard mitigation approach, described below in generic terms. Lightning Rods In Franklin39。s day, lightning rods conducted current away from buildings to earth. Lightning rods, now known as air terminals, are believed to send Streamers upward at varying distances and times according to shape, height and other factors. Different designs of air terminals may be employed according to different protection requirements. For example, the utility industry prefers overhead shielding wires for electrical substations. In some cases, no use whatsoever of air terminals is appropriate (example: munitions bunkers). Air terminals do not provide for safety to modern electronics within structures. Air terminal design may alter Streamer behavior. In equivalent efields, a blunt pointed rod is seen to behave differentl
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