I. Introduction
October 14, 1998 is the 29th World Standards Day, the International Organization for Standardization ISO President, IEC President and ITU Secretary General issued a message entitled "standards in everyday life". The message pointed out: standards are a kind of "benchmark", which provides people with a criterion for judging things, a basis for quality measurement and a guarantee of compatibility and interconnection. The purpose of the standard is to help and serve the society, help people to enjoy and utilize the environment without destroying the environment; help people to shape their lives without making them clueless; help people to live safely without encountering dangers; help people to master advanced scientific methods without lagging behind the society; and help people to learn to protect their legitimate rights and interests with the law without being easily harmed.
The world's three major standardization organizations are committed to international standardization. the IEC (International Electrotechnical Commission) in the preamble to the standards they promulgate are declared: in order to promote international unity, the IEC national committees should, to the greatest extent possible, the IEC standard as their standard, the national standards and the IEC corresponding standards of any divergence in the national standards, should be clearly indicated in the national standards. The Standardization Law of the People's Republic of China*** and the State of China provides. "The State encourages the adoption of international standards and advanced foreign standards." The State Economic Commission, the Planning Commission, the Science and Technology Commission and the Bureau of Technical Supervision have jointly issued the "Several Provisions on Promoting the Adoption of International Standards and Foreign Advanced Standards" (No. 532 of 1993), which states even more explicitly that "the adoption of international standards and foreign advanced standards is a major technological and economic policy in China, and is an important means to promote technological progress, to improve the quality of products, to expand the opening up to the outside world, to accelerate the convergence with the International practice, the development of socialist market economy is an important measure."
Standards from practice and scientific research, is the crystallization of the wisdom of millions of scientific and technological workers, with the progress of technology, standards are constantly revised and updated. In the IEC standards have the following instructions: the version of this standard is valid at the time of publication, encourage the use of the latest version of the standard document. China's national standards are also commonly used to issue a "revision order" in the form of standard modifications, or in the new standard issued by the notice of the original standard is invalidated. Adoption and promotion of international standards is an important and inexpensive technology transfer in the world. At present, most of the countries in the world, including our country, are adopting the principle of equivalent use, a large number of international standards, to promote the progress of national technology.
Two, the international lightning protection technology standards framework
Lightning protection technology standards are mainly prepared by the IEC and ITU (International Telecommunication Union, used to be known as CCITT), according to the agreement of the IEC and ISO close collaboration. National Electrotechnical Commissions (IEC National Committees) participate in IEC international cooperation on standardization in the electrical and electronic fields and fulfill the obligation to adopt the IEC standard equivalent (eqv) or equivalent (idt) as the national standard of the country.
The earliest international work on technical standards for lightning protection was begun in 1980 by IEC/TC81 (Technical Committee 81 - Lightning Protection), with the initial goal of developing standards and guidelines for lightning protection of buildings. China is one of the 25 P members (Participating members), which is a country that actively participates in the work, assumes the obligation to vote on the draft standards, and participates in the meetings as much as possible. Mr. Lin Weiyong participated in the 1992 meeting as a representative of China, and is currently participating in the revision of IEC1024-l.
With electronic equipment subjected to lightning overvoltage (often referred to as atmospheric overvoltage in the standard) and overvoltage (input or removal of the grid, also known as operational overvoltage) losses are becoming increasingly serious, through the coordination of the central office of the IEC, some of the TCSI experts to join the work of other relevant committees of the IEC, and other committees of the experts were invited to join the work of the TCSI Committee, so that the various disciplines of technology to interpenetrate, due to the workload of the focus on the workload, and the work of the TCSI Committee. Mutual penetration of various disciplines and technologies, due to the focus of different workloads, in addition to TC81 on the celebration of technical standards for lightning protection, by the TC64, TC37, TC77 related to the promulgation of the building of electrical installations, over-voltage protection devices, electromagnetic compatibility (EMC) and other relevant standards. ITU and CIGRE (International Conference on Large Electricity Grids), respectively, from the telecommunications industry, the power supply system industry characteristics, the enactment of lightning protection technology standards related to the industry, the principle is that in the case of IEC standards do not contradict the development of more specific and feasible technical standards.
In the International Organization for Standardization under the fruitful organization of experts in various countries to give full play to, since 1990 IECI 0241 promulgated a large number of lightning protection technology standards, and there are many drafts in the discussion for the solution to the rapid development of electronic technology and relatively lagging behind the protection of the technology of this prominent contradiction in the reality of China to provide a cheap technology transfer.
Three, on the Chinese people **** and national (national) standards
National standards are divided into mandatory (GB) and non-mandatory (GB/T), also known as voluntary or recommended, by the design unit voluntarily selected.
In addition to national standards, there are industry standards (electric power standards DL, post and telecommunications standards DY, railway standards TB, etc.). Industry standards also have voluntary standards, such as TB / T. In addition, there are local standards DB, Engineering Standardization Association standards CECS.
China's building lightning protection standards for the earliest GBJ57-83. November 1994 by the drafter of Mr. Lin Weiyong IEC 1024-1 was revised, namely GB50057-94 "building lightning protection design specification". In the "Compilation of norms" in many industries, systems of direct lightning protection technology standards are derived from GBJ57-83 or GB50057-94. from the present point of view GB50057-94 is in line with the principles of IEC1024-l, but some provisions have lagged behind. Mr. Lin Weiyong wrote in a letter: "Separate grounding is not the direction. The next revision of the lightning protection code may delete the content of separate grounding (except for independent lightning rods, overhead lightning lines in Category I lightning protected buildings). Because equipotential connection (including 50Hz personal safety) will be the preferred measure. Its usefulness and significance is gradually being accepted."
On Oct. 29, 1996, a group of experts meeting in Beijing issued an appeal, "As long as all aspects of the lightning protection design code are properly followed, lightning disasters can be greatly reduced. Limit the damage caused by lightning strikes to an acceptable level. IEC/TCSI is preparing lightning electromagnetic pulse (LEMP) of a series of standards, which the protection of sensitive electronic devices occupies a considerable number of articles, in 1995 has been officially published in the first part of the general principles (IECI312- l). Our country should pay enough attention and formulate the corresponding norms or refer to the implementation."
In 1998, the State Planning Commission approved the China Meteorological Administration scientific research project "meteorological stations of modern lightning protection technology research", one of the "lightning protection technology standards" development, this work in October 1999 was fully completed. At the same time, and the Ministry of Public Security jointly prepared the "computer information system lightning protection technical specifications" has been completed, and formally implemented. These standards may be China's early reference to the IEC standard comprehensive development of the system lightning protection standards, has played a positive role.
National standard "building electronic information systems lightning protection technical specifications" (GB50343-2004) in June 1, 2004 onwards, Article 5.1.2, 5.2.5, 5.2.6, 5.4.1 (2), 7.2.3 (paragraph) for mandatory provisions, must be strictly enforced. This specification is formulated to prevent and reduce the harm caused by lightning on the building electronic information system to protect people's lives and property safety.
Specification applies to new buildings, expansion, alteration of the building electronic information system lightning protection design, construction, acceptance, maintenance and management.
This specification does not apply to flammable, explosive hazardous environments and places of electronic information systems lightning protection.
Based on this specification in the building of electronic information systems lightning design, should be based on the characteristics of the building of electronic information systems, external lightning protection measures and internal lightning protection measures to harmonize, according to the overall requirements of the project, to carry out a comprehensive planning, to achieve safe and reliable, technologically advanced, economically rational.
The lightning protection of electronic information systems must adhere to the principle of prevention, safety first. When needed, can be designed before the site lightning electromagnetic environment assessment.
Lightning protection of electronic information systems should be based on environmental factors, lightning activity patterns, equipment in the lightning protection zone and the system's immunity to lightning electromagnetic pulse, the degree of damage caused by lightning accidents, as well as the importance of the system equipment, to take appropriate protective measures.
Electronic information systems should be used for external lightning protection (against direct lightning) and internal lightning protection (lightning electromagnetic pulse) and other measures for comprehensive protection.
Four, the international lightning protection standards
1. direct lightning protection (external lightning)
IEC1024-1: in 1990 this is the first international lightning protection standards, which applies to the height of 60m and the following buildings and the design and installation of lightning protection devices, does not apply to the railroad system, buildings outside the transmission system and transmission of telecommunications systems, as well as the mobile Ships, vehicles and aircraft.
The first sentence of the standard reads; "Lightning protection devices cannot prevent the formation of lightning flashes". Mr. Lin Weiyong recently participated in the IEC/TC81 standard revision to see this sentence was revised as follows: "It should be noted that so far there is no device (or method) that can prevent the generation of lightning, and there is no apparatus or method that can prevent lightning from striking a building. The use of metallic materials to catch lightning, lead it down and conduct it to earth is the only effective method of external lightning protection at present."
In GB50057-94, a large number of references to the IEC terminology and definitions, such as lightning protection device in the IEC as "for the need to protect the space for lightning protection against lightning effects of the entire device, which consists of an external lightning protection device and the internal lightning protection device". "External lightning protection device consists of flashover, lead wire and grounding device". "Internal lightning protection devices are all additional measures other than external lightning protection devices. They may reduce the electromagnetic effect produced by lightning current in the space to be protected against lightning".The GB50057-94 nomenclature is: "Lightning protection device: flashover, lead wire, earthing device, over-voltage protector and other connected conductors in general." Please note that the IEC here puts forward the concept of external lightning protection and internal lightning protection, external lightning protection is the application of external lightning protection devices (flashover, lead wire, grounding or both Faraday cage) to attract lightning and as soon as possible and unimpeded introduction of lightning current into the ground in the safe discharge. Mr. Ma Hongda analysis that: lightning protection as flood control, the principle is to provide a low impedance channel for lightning impulse current (Note: external lightning protection), while preventing interference with the equipment through magnetic and electric fields (Note: internal lightning protection). The focus of the dispute on the semiconductor lightning protection device is first of all whether it can prevent the formation of lightning flash (the so-called "anti-thunder" function), followed by the use of non-metallic materials to catch the flash (such as carbon fiber external paint, or such as the optimization of lightning rods using glass fiber reinforced plastic tubes built-in saline and other high-resistance liquids) in the flash receiver and the lead line between the string of 35KΩ "Current limiting" material, whether it will have a positive effect, against the principle of the IEC standard description, should be very clear, so far the IEC standard has not given any unconventional flashover affirmation. In foreign countries only France, Spain and Yugoslavia respectively approved the E.S.E (with an early discharge function of the lightning rod) standard, but in 1992 and 1995 IEC/TC81 meeting, have not made a clear decision, neither negative nor affirmative, but only to call on scientists in various countries of this type of lightning device for more in-depth research.
We can learn from the title of the IEC1024 series of standards, has been promulgated and is still a draft of the 1024-l, 2, 3 and 1-1, l-2 are external lightning protection standards, but are associated with internal lightning protection. For example, IEC 1024-1-2 Appendix B issued in May 1998 is entitled: "Protection against the effects of induced currents in internal installations". It deals with line shielding in addition to external lightning protection, suitable internal cable routing and the positioning of internal electrical and communication installations. Examples are also given of methods of estimating the voltage and energy caused by a single lightning strike on a building. IEC1024-2 sets out additional conditions for lightning protection for buildings above 60 m, and IEC1024-3 sets out additional conditions for flammable and explosive atmospheres.
The IEC external lightning protection standard gives a general feeling that it is more detailed, some foreign standards such as the U.S. Fire Protection Association (NFPA780: 1992) of the "Lightning Protection Regulations", the British Standard (BS6651; 1992) of the "Lightning Protection of Structures Practical Regulations ", the Japanese Industrial Standard J15 (JISA4201-1992) "Lightning Protection Equipment for Structures, etc." is also detailed on ships, wind power stations, stadiums, big tents, trees, bridges, parked airplanes, storage tanks, seaside amusement parks, wharves, and even open-air livestock farms. Exterior lightning protection. In particular, some of the standards on the rocky mountain grounding device is difficult to achieve the required low resistance value to make such provisions: in the ground flat ring flat steel, and with the protected object of the lead wire in four directions connected to the ring-type ground radius should not be less than 5m, this equipotential connection can also play a role.
On the external lightning protection of national standards and foreign standards agree: the external lightning protection standard is based on the statistical law of lightning, is the absolute protection and lightning protection device cost between the take the compromise program. It is also GB50057-94 said: "According to the specification design of lightning protection device lightning safety is not 100%". In January this year, Mr. Lin Weiyong wrote me a letter introducing the revision of GBJ57-83 for the GB50057-94 process of a thing: the use of rolling ball method, the scope of protection than in the past a lot of small, and therefore the need to increase the height of lightning rods and overhead lines or the number of units, especially those who are often independent of the lightning rods and overhead lines of the unit has a comment, and finally can only be the rolling ball radius of the IEC regulations, a class of 20% by 20% of the lightning protection devices, and the number of units. Ball radius increased, a class from 20m increased to 30m, the second class from 30m increased to 45m, which is also a compromise or compromise.
2. Lightning electromagnetic pulse protection (internal lightning)
IEC61312 series currently formally promulgated by the 1312-l General Provisions: 1995. This general rule introduces the principle of internal lightning protection, and at the same time confirms and gives lightning waveform diagrams for the lightning current parameters published in the 1992 edition of 1024-1-l. The analysis and study of lightning current parameters is the basis for lightning electromagnetic pulse (LEMP) protection.
In March 1998, IEC61312-2 ballot draft "building shielding, internal equipotential connection and grounding" to the national IEC committee vote, its deadline for August 31, 1998, will soon be promulgated. This standard makes detailed provisions for the calculation of shielding, equipotential connection network and grounding of buildings. Recently, Xi'an Jiaotong University Professor Ye Peisheng edited the "computer room environment technology" book published in the sixth and seventh chapters of a large number of references to the IEC standard, while the eighth chapter of the "computer room shielding technology" as a result of finalization has not yet been obtained by us (Guangdong Provincial Lightning Protection Center and Huayun Kelai company) on the new version of the translation of the IEC61312-2, the content is somewhat thin, please study. The content is a little thin, please pay attention to the study.
IEC61312-3 1996 is the main content of the surge protector (SPD);
IEC61312-4 is the main introduction to the building has been constructed how to improve the provisions of the internal lightning protection;
IEC61312-5 is the application of internal lightning protection guide.
For lightning protection of communication lines, IEC has prepared the 61663 series of standards.
In summary, the main elements of internal lightning protection are: lightning current parameters and lightning waveforms, the division of lightning protection zones, shielding, equipotential connection and grounding, reasonable wiring locations and surge protectors (SPDs), which together with external lightning protection form a comprehensive lightning protection system.
3. Surge Protector (SPD)
Surge Protector (Surge Proteltive Device), also known as surge protector or overvoltage protector. Some manufacturers call it a lightning arrester is inappropriate, called lightning security device is also wrong. IEC standards on SPD: IEC61312-3, 61644-1, 61647-l, 2, 3, 4, 61643-l, 2, 3, 60364-5-534, 60364-4-443 and so on. The field of electromagnetic compatibility (EMC) also involves methods of performing simulation tests on SPDs. This aspect of the problem is quite complex, can only introduce the standard here, interested in Tsinghua University, "Engineering Physics" magazine "modern lightning protection album" (I), (II).
4. Low-voltage system equipment insulation with
Aeronautical Design Institute Mr. Wang Houyu participated in the work of IEC/TC64, is the domestic authority on insulation technology. Mr. Wang drafted the "low-voltage power distribution design code" GB50054-95 and in recent years to publicize the IEC standard to solve the problem of damage to low-voltage electrical devices and personal injury and death of many papers, it is worthwhile to seriously study. Among the standards of TC64, I will only list the section of IEC 60364-5-534:1997 "Overvoltage protective devices". This section sets out the requirements for the selection and installation of SPDs for electrical installations in buildings. These requirements and IEC/TC81 standard principles are consistent, such as in order to prevent the exposed area by 10/350μs waveform surge impact of large energy, in the multi-stage protection of the first level of SPD are used in switching-type SPD, both the use of the discharge gap, the second level of zinc oxide varistor (MOV) as the main component of the SPD. in order to solve the MOV due to aging and the end of the life of the short-circuit faults caused by
5. Electromagnetic compatibility, ITU and other standards and information on the situation
Electromagnetic compatibility (EMC) is defined as the ability of a device or system to function properly in its electromagnetic environment without producing impermissible electromagnetic nuisance to anything in that environment. iec/tc77 published a large number of EMC documents. Since lightning and cast overvoltage are both common sources of external disturbances, there are many EMC documents with standards and test criteria for LEMP protection of equipment or systems.
The International Telecommunication Union (ITU), formerly known as CCITT, publishes a large number of related standards in conjunction with the protection of telecommunication systems, generally referred to as the Blue Book or K Recommendation series. As you can see through Annex 1 (V), the ITU.K series is not only directly effective for telecommunication systems, but its principles and methods can also be used for reference in other systems.
Some of the above standards have been formally published and some are for internal communication. There are also a number of standards are being compiled, will soon be printed, please pay attention to.
Engaged in the work of lightning protection and mitigation not only to understand the technical standards of lightning protection, but also should understand the relevant standards of the service object. Such as "building and complex integrated wiring system engineering design specification", "building and complex integrated wiring system engineering construction and acceptance specification". Another example is the Post and Telecommunications Publishing House published a large number of YD series of standards: related to the design of integrated telecommunications business halls, urban residential areas and office buildings, telephone communications facilities acceptance, satellite communications earth station engineering design, local network communications line engineering acceptance, **** with the computer Internet engineering design, synchronization of digital series (SDH) microwave relay communications system engineering design and so on the postal and telecommunications engineering design and acceptance specifications.