基础防雷外文资料翻译

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1、 毕业设计(论文)外文资料翻译系 （院）：电子与电气工程学院专 业：电气工程及其自动化姓 名： 学 号： 外文出处： (用外文写)Baidu library附 件：1.外文资料翻译译文；2.外文原文。指导教师评语： 年月日签名： （手写签名） 注：请将该封面与附件装订成册。附件1：外文资料翻译译文基础防雷简介 闪电是一个反复无常，随机和不可预测的事件。它的物理特征包括：电流超过400 kA；温度超过50000华氏度，速度接近或超过三分之一的光速。自2000年以来持续雷击地球约100次每秒。美国保险公司的资料显示每57索赔有一次是因为雷击损坏。这些数据还不包括商业，政府和工业雷电造成的损失。在美

2、国每年因雷电造成的火灾超过26000起，财产损失在5-6亿美元。 地球上的雷击现象，按目前的技术角度来看，遵循一个近似的规律：1。从顶层雷云朝地球的向下脉冲，寻求电气地面目标。2。地基对象（围栏，树木，草叶，建筑，避雷针，等等）对此事件发出不同程度的电力活动。从这些地基对象向上发送电力波动，在离地面几十米的位置，会出现一个“聚集区”加剧当地的电场。3。当带有异种电荷的雷云相遇，相当于电路“开关”被关闭，于是有电流流过。我们就会看到闪电。闪电效果可以直接也可能是间接的。直接影响是有电阻发热，出现电弧并可能燃烧起来。间接影响是，多数时候对电容，电感出现电磁影响。在绝对意义上实现闪电的防护是不可能的

3、，只能使其产生的影响减少，可以由一个整体性，系统性的风险缓解办法来实现保护。下面对通用条款进行描述。避雷针 从富兰克林研究雷电开始，就使用避雷针进行建筑物防雷并引流接地。避雷针，是现在最常用的防雷装置，根据建筑物不同的地点，高度和形状，使用合适类型的避雷针来达到设计要求。一些公共事业如架空线、变电所喜欢屏蔽电线。在某些情况下，没有任何避雷装置的使用是最适当的。 高空避雷装置的使用可能会改变闪电的动作。在等效电力场所，钝尖杆被看作是一种有效的避雷针类型。高空防雷装置的设计和性能是一个有争议的并尚未解决的问题。因为“消除”闪电是一个值得怀疑的办法。进一步的研究和试验仍在进行中，以便更充分地了解各种

4、高空防雷装置的可行性。引下线连接 引下线应通过一个安全的方式安装，在已知电路外面敷设。引下线不可以涂漆，因为这样会增加阻抗。渐进弯曲半径最小为八英寸，应采取避免闪络的方式。建筑钢材可用于与大地连接的引下线，要保证所有的金属建材有效的连接成网。所有金属导体应进入连接，如燃气及水管道，信号线，空调管道，铁路轨道，桥式起重机等应被接地系统。各金属导体的连接应该是热连接，而不应是机械连接。机械连接时容易受到腐蚀和物理伤害。接地 接地系统必须面对地球的低阻抗和阻力。一个闪电的脉冲光谱研究揭示闪电既有高频率也有低频率的内容。高频率性能是频谱变化速度非常迅速的，达到10微秒的峰值电流。低频率分量延续时间长，

5、是一种高能量后续的冲击电流。接地系统是将雷电脉冲传入大地来减少危害的。 单点接地系统是将所有内部设备连接到一根主母线在连接到外部接地系统。接地系统的设计应以减少交流阻抗和直流电阻为前提。地球的零电位是防雷接地最重要的原因。采用径向技术可以降低阻抗，能让雷电能量发散，因为每个接地导体的都有一个电压梯度，他们应该被连接到地面设施。瞬变和浪涌 普通熔断器和断路器并没有与闪电感应瞬变的能力。避雷设备可以是电流分散，滤波器的特定频率，钳位组合等都是可以实现这个功能的组合。电压钳位器件可以处理极高峰值的浪涌，以及具有减少极快的上升沿瞬态的能力。采用壁垒防御是一种需要谨慎的行为：其可以保护主面板，保护所有相

6、关二次配电盘，保护一切有价值的插件设备，如过程控制仪表，计算机，打印机，火灾报警，数据记录和SCADA系统设备等。此外，还可以保护传入和传出的数据和信号线。保护那些服务的主要资产，如井口，远程安全报警，闭路电视摄像头，高桅杆照明，空调通风等穿透一个结构从另一个不应被忽略的需要防雷的设施中工作的设备。 安装电涌抑制器的最小的引线长度取决于各自的电气面板。快速上升时间条件下，电缆电感成为重要的高瞬态电压可以使用较长的引线。检测闪电探测仪，在不同的成本和技术条件下，有时是可以起到雷电早期预警的作用的。一个最普通的应用是，被用来作为AC线路电源断开到雷电到来之前的备用电源。用户应提防过度依靠设备，因为

7、这不是每次都可用的。教育所有人都应该接受防雷安全教育。在出现雷暴的时候，在室内或汽车里的时候，应避免接触水和其他一些的金属物件;避免在一些制高点行车，不要在孤立的树木下面躲雨;不要在下雨的时候在室外打电话。如果在户外时附近有闪电击中，应该躲到安全的位置，丢掉手中的金属物体，双脚蜷缩在一起，低着头，双手捂在耳朵上，以避免雷声震坏耳膜。 综述需要申明的重要的一点，上述所有的内容都是通过安全防雷的角度分析的。没有绝对理想的防雷措施。因为闪电可能超出每一个人的想象。系统化的防雷措施是一种有效减少雷电危害的方法。参考文献1。 2003年空气污染指数，对所产生的静电，火灾2008闪电和杂散电流，美国石油研

8、究所，华盛顿特区，1991年12月。2。 Golde，G.H.，闪电，学术出版社，纽约，1977。3。哈瑟，体育，低电压系统，彼得Peregrinus出版社，伦敦，1992年过电压保护。4。 Hovath，蒂博尔，防雷，威利计算，纽约，1991年。5。 IEEE标准1100，供电和敏感的电子设备的接地，符合IEEE，纽约州。 1992。6。肯尼迪航天中心，用于连接和接地，工程开发局，约翰肯尼迪航天中心，美国航天局，1991年标准。7。莫里斯，i，et.al.，火箭引雷研究的重要资产，在行业的应用，卷汇刊保护。 30，第3号，5 / 1994年6月。8。森德，E.D.输电系统接地传导效应，四凡诺

9、斯特兰有限公司，纽约，1949年。9。汤，四，波动现象，多佛出版社，台北。10。乌曼，马丁，闪电，多佛出版社，纽约，1984。11。 Viemeister，彼得，闪电书，麻省理工学院出版社，剑桥大学硕士，1972年附件2： Fundamentals of Lightning ProtectionIntroductionLightning is a capricious, random and unpredictable event. Its physical characteristics include current levels sometimes in excess of 400 kA

10、, temperatures to 50,000 degrees F., and speeds approaching one third the speed of light. Globally, some 2000 on-going thunderstorms cause about 100 lightning strikes to earth each second. USA insurance company information shows one homeowners damage claim for every 57 lightning strikes. Data about

11、commercial, government, and industrial lightning-caused losses is not available. Annually in the USA lightning causes more than 26,000 fires with damage to property (NLSI estimates) in excess of $5-6 billion.The phenomenology of lightning strikes to earth, as presently understood, follows an approxi

12、mate behavior:1. The downward Leaders from a thundercloud pulse towards earth seeking out active electrical ground targets.2. Ground-based objects (fences, trees, blades of grass, corners of buildings, people, lightning rods, etc., etc.) emit varying degrees of electric activity during this event. U

13、pward 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 lig

14、htning.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 magnetic behavior. Lightning prevention or protection (in an absolute sense) is impossible. A dimi

15、nution 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 RodsIn Franklins day, lightning rods conducted current away from buildings to earth. Lightning rods

16、, 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 shiel

17、ding 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 e-fields, a blunt point

18、ed rod is seen to behave differently than a sharp pointed rod. Faraday Cage and overhead shield designs produce yet other effects. Air terminal design and performance is a controversial and unresolved issue. Commercial claims of the elimination of lightning deserve a skeptical reception. Further res

19、earch and testing is on-going in order to understand more fully the behavior of various air terminals.Downconductors, Bonding and ShieldingDownconductors should be installed in a safe manner through a known route, outside of the structure. They should not be painted, since this will increase impedan

20、ce. Gradual bends (min. eight inch radius) should be adopted to avoid flashover problems. Building steel may be used in place of downconductors where practical as a beneficial part of the earth electrode subsystem.Bonding assures that all metal masses are at the same electrical potential. All metall

21、ic conductors entering structures (AC power, gas and water pipes, signal lines, HVAC ducting, conduits, railroad tracks, overhead bridge cranes, etc.) should be integrated electrically to the earth electrode subsystem. Connector bonding should be thermal, not mechanical. Mechanical bonds are subject

22、 to corrosion and physical damage. Frequent inspection and ohmic resistance measuring of compression and mechanical connectors is recommended.Shielding is an additional line of defense against induced effects. It prevents the higher frequency electromagnetic noise from interfering with the desired s

23、ignal. It is accomplished by isolation of the signal wires from the source of noise.GroundingThe grounding system must address low earth impedance as well as low resistance. A spectral study of lightnings typical impulse reveals both a high and a low frequency content. The high frequency is associat

24、ed with an extremely fast rising front on the order of 10 microseconds to peak current. The lower frequency component resides in the long, high energy tail or follow-on current in the impulse. The grounding system appears to the lightning impulse as a transmission line where wave propagation theory

25、applies.A single point grounding system is achieved when all equipment within the structure(s) are connected to a master bus bar which in turn is bonded to the external grounding system at one point only. Earth loops and differential rise times must be avoided. The grounding system should be designe

26、d to reduce ac impedance and dc resistance. The shape and dimension of the earth termination system is more important a specific value of the earth electrode. The use of counterpoise or crows foot radial techniques can lower impedance as they allow lightning energy to diverge as each buried conducto

27、r shares voltage gradients. Ground rings around structures are useful. They should be connected to the facility ground. Exothermic (welded) connectors are recommended in all circumstances.Cathodic reactance should be considered during the site analysis phase. Man-made earth additives and backfills a

28、re useful in difficult soils circumstances: they should be considered on a case-by-case basis where lowering grounding impedances are difficult an/or expensive by traditional means. Regular physical inspections and testing should be a part of an established preventive maintenance program.Transients

29、and SurgesOrdinary fuses and circuit breakers are not capable of dealing with lightning-induced transients. Lightning protection equipment may shunt current, block energy from traveling down the wire, filter certain frequencies, clamp voltage levels, or perform a combination of these tasks. Voltage

30、clamping devices capable of handling extremely high amperages of the surge, as well as reducing the extremely fast rising edge (dv/dt and di/dt) of the transient are recommended. Adopting a fortress defense against surges is prudent: protect the main panel (AC power) entry; protect all relevant seco

31、ndary distribution panels; protect all valuable plug-in devices such as process control instrumentation, computers, printers, fire alarms, data recording & SCADA equipment, etc. Further, protect incoming and outgoing data and signal lines. Protect electric devices which serve the primary asset such

32、as well heads, remote security alarms, CCTV cameras, high mast lighting, etc. HVAC vents which penetrate one structure from another should not be ignored as possible troublesome electrical pathways.Surge suppressors should be installed with minimum lead lengths to their respective panels. Under fast

33、 rise time conditions, cable inductance becomes important and high transient voltages can be developed across long leads.In all instances, use high quality, high speed, self-diagnosing protective components. Transient limiting devices may use a combination of arc gap diverters-metal oxide varistor-s

34、ilicon avalanche diode technologies. Hybrid devices, using a combination of these technologies, are preferred. Know your clamping voltage requirements. Confirm that your vendors products have been tested to rigid ANSI/IEEE/ISO9000 test standards. Avoid low-priced, bargain products which proliferate

35、the market (caveat emptor).DetectionLightning detectors, available at differing costs and technologies, sometimes are useful to provide early warning. An interesting application is when they are used to disconnect from AC line power and to engage standby power, before the arrival of lightning. Users

36、 should beware of over-confidence in such equipment which is not perfect and does not always acquire all lightning data.EducationLightning safety should be practiced by all people during thunderstorms. Preparedness includes: get indoors or in a car; avoid water and all metal objects; get off the hig

37、h ground; avoid solitary trees; stay off the telephone. If caught outdoors during nearby lightning, adopt the Lightning Safety Position (LSP). LSP means staying away from other people, taking off all metal objects, crouching with feet together, head bowed, and placing hands on ears to reduce acousti

38、c shock.Measuring lightnings distance is easy. Use the Flash/Bang (F/B) technique. For every count of five from the time of seeing the lightning stroke to hearing the associated thunder, lightning is one mile away. A F/B of 10 = 2 miles; a F/B of 20 = 4 miles, etc. Since the distance from Strike A t

39、o Strike B to Strike C can be as much as 5-8 miles. Be conservative and suspend activities when you first hear thunder, if possible. Do not resume outdoor activities until 20 minutes has past from the last observable thunder or lightning.Organizations should adopt a Lightning Safety Policy and integ

40、rate it into their overall safety plan.TestingModern diagnostic testing is available to mimic the performance of lightning conducting devices as well as to indicate the general route of lightning through structures. This testing typically is low power, 50 watt or less. It is traceable, but will not

41、trip MOVs, gas tube arrestors, or other transient protection devices. Knowing the behavior of an event prior to occurrence is every businessmans earnest hope. With such techniques, lightning paths can be forecast reliably.Codes & StandardsThe marketplace abounds with exaggerated claims of product pe

42、rfection. Frequently referenced codes and installation standards are incomplete, out dated and promulgated by commercial interests. On the other hand IEC, IEEE, MIL-STD, FAA, NASA and similar documents are supported by background engineering, the peer-review process, and are technical in nature.Summ

43、aryIt is important that all of the above subjects be considered in a lightning safety analysis. There is no Utopia in lightning protection. Lightning may ignore every defense man can conceive. A systematic hazard mitigation approach to lightning safety is a prudent course of action.References1. API

44、2003, Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents, American Petroleum Institute, Washington DC, December 1991. 2. Golde, G.H., Lightning, Academic Press, NY, 1977. 3. Hasse, P., Overvoltage Protection of Low Voltage Systems, Peter Peregrinus Press, London, 1992.

45、 4. Hovath, Tibor, Computation of Lightning Protection, John Wiley, NY, 1991. 5. IEEE Std 1100, Powering and Grounding of Sensitive Electronic Equipment, IEEE, NY, NY. 1992. 6. KSC-STD-E-0012B, Standard for Bonding and Grounding, Engineering Development Directorate, John F. Kennedy Space Center, NAS

46、A, 1991. 7. Morris, M.E., et.al., Rocket-Triggered Lightning Studies for the Protection of Critical Assets, IEEE Transactions on Industry Applications, Vol. 30, No. 3, May/June 1994. 8. Sunde, E.D. Earth Conduction Effects in Transmission Systems, D. Van Nostrand Co., NY, 1949. 9. Towne, D., Wave Phenomena, Dover Publications, NY. 10. Uman, Martin, Lightning, Dover Publications, NY, 1984.