Find the most up-to-date version of JIS A at Engineering Japan’s largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies. JIS A Protection of structures against lightning (FOREIGN STANDARD). Available for Subscriptions. Content Provider Japanese Industrial Standards.
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You need Adobe Reader 7. If Adobe Reader is not installed on your computer, click the button below and go to the download site. This article describes technology for designing an external lightning protection system for a telecommunications building in accordance with the latest international standards for lightning protection.
The design method for an air-termination system that applies lightning-strike risk assessment and an a421 of a design a201 are also described. High-speed and dependable access networks using optical fibers are becoming ji now, and progress on an information and communications technology ICT society has accelerated. As the dependence on information and telecommunications increases, companies and society will face a high risk of damage from system failures, and the damage itself could be extremely severe.
Therefore, a2401 importance of high reliability for the IP Internet protocol network infrastructure, which supports the progress of our information s4201, is growing steadily. Diversification, advanced features, and complexity are being pursued to enable the IP network infrastructure to provide us with greater benefits. However, jos resistance, which protects against problems such as lightning surges, is declining in today’s information technology IT equipment, which focuses on high-speed, power-saving, and low-voltage operation.
Moreover, the break-in path of lightning surges is being complicated by the diversification of networks and equipment connection configurations Fig. Therefore, the IP network infrastructure is now more vulnerable to lightning damage, and the problems caused by lightning damage have increased . Consequently, the importance js lightning protection Fig. Break-in path of lightning surges. Importance of lightning protection. Although the theory of lightning is being elucidated, complete protection against lightning damage is still difficult to achieve with present technology.
Because of the importance and value of the facilities that we are dealing with and the impact on society of damage to them, we need to apply lightning protection based on risk management to reduce the potential for damage effectively and economically. International Electrotechnical Commissionwhich is a new international standard that includes risk management technology for lightning damage, was published in January The Jjs comprehensively defined lightning protection and risk management for structures and infrastructure services Table 1 —.
These regulations are more effective and economical than previous ones. Thus, more iis and uis lightning protection that applies risk assessment on a case-by-case basis, rather than uniform lightning protection, needs to be implemented.
This in turn requires appropriate lightning protection standards and risk assessment design methods. Lightning protection requires a synthetic measure against the various break-in paths of lightning surges, which are shown in Fig. However, the scope of this article focuses on the protection of structures against lightning. We present design technology that takes into consideration an assessment of the risk to an air-termination system, which is one element of an external lightning protection system that consists of a down-conductor system and an earth-termination system.
These technical requirements have become JIS A The version, JIS A Points of JIS A revision.
JIS A – Wikidata
In JIS A However, JIS A For these levels, there are three different design methods for achieving protection protection angle method, mesh method, and rolling sphere method. It is possible to achieve protection by selecting either one of these methods or a combination of two or all three.
Moreover, each method is regulated according to the protection level. For example, when the rolling sphere method is selected, the sphere radius is specified as 20, 30, 45, or 60 m, according to the protection level. It was also recognized that designs conforming to JIS A Thus, both versions of JIS A are currently still in legal use, though in practice they cannot be combined.
When JIS A Although all of the sidewalls of structures taller than the rolling sphere radius are protected at each of the four protection levels, their lightning-strike risk, i.
Therefore, for an air-termination system, we need a design method that takes into account lightning-strike risk assessment. However, the standard has a serious drawback in that it does not take into consideration flashes to sidewalls. NTT has developed and applied a design method that incorporates lightning-strike risk assessment as the design method for air-termination systems of the NTT Group.
This method is based on JIS A This method can provide designs that are both economical and effective in terms of lightning protection. This can be achieved after evaluating the occurrence probability of flashes to the sides of structures using the rolling sphere method based on IEC This evaluation is a measure taken in addition to the design of an air-termination system based on the protection angle method of JIS A After the technical requirements of JIS A Design method using lightning-strike risk assessment.
Our design procedure was as follows. First, the required level of lightning protection was established, and the occurrence probability of side flashes was calculated for all lightning currents having a probability of a lightning-strike exceeding the lightning current based on each of the lightning protection levels the details are based on IEC Then, based on the results, the lightning-strike probability and the economic efficiency were weighed for designs with the following bases: Next, after taking into consideration the requests of the building owners, the surrounding environments, and the importance of the structures, we checked the validity of our design method.
Our findings showed it to be superior to the other methods. Therefore, we designed the air-termination system using our method. Design case using lightning-strike risk assessment. In one design case, we designed improvements to an existing external lightning protection system using our design method for a structure nearly m high.
Design Technology for an External Lightning Protection System for a Telecommunications Building
Based on the design decision data shown in Fig. We were able to reduce the renovation costs by about one third compared with a design based on JIS A Various laws and specifications such as those of JIS A Therefore, we have developed and used diagnostic tools for the external lightning protection systems of NTT Facilities. Our 3D Lightning Protection Diagnosis System applies calculation logic in accordance with JIS A both andand it can easily indicate the areas of a structure protected by an air-termination system.
Thus, to jos the protected area of a structure, we need a design that provides a more complex calculation and intricate operation than that provided by only the protection angle method of JIS A Using this 3D model, our diagnosis system can create a 3D ji of a building to be protected and analyze the protected and unprotected areas according to the protection level required by JIS A It can then present the analysis results in a 3D visualization.
As a result, it is easy to determine the protected and unprotected areas of the structure Fig. Furthermore, we are also developing an External Lightning Protection Design Support System that includes a function for outputting a 2D engineering drawing for the external lightning protection system to the 3D Lightning Protection Diagnosis System. The number of different structures is as large as the number of structures itself because each structure is a unique combination of its internal electrical jiz, the function of the structure, and the building’s appearance.
Therefore, we need to implement lightning protection that applies lightning-strike risk assessment, not according to a uniform means of lightning protection, but on a case-by-case basis.
This requires advanced research on risk management technology for lightning protection. Hopefully, relevant laws and regulations and various codes and standards will be enacted. We would like z4201 emphasize the importance of implementing comprehensive lightning protection that provides not only external but also js lightning protection. We are conducting research and development of surge protective devices, which are indispensable for internal lightning protection systems, as well as research and development of the external lightning protection system introduced in this article.
Furthermore, we are also actively involved in standardization activities related to lightning protection in groups 4a201 as the IEC international standardization committee and the JIS draft-deliberation committee. NTT Facilities will continue kis develop technology for comprehensive lightning protection that will take into consideration the latest technology trends.
Toshima-ku,Japan Email: Introduction High-speed and dependable access networks using optical fibers are becoming common now, and progress on an information and communications technology ICT society has accelerated. Need for risk assessment Although the theory of lightning is being elucidated, complete protection against lightning damage is still difficult to achieve with present technology.
Design technology for external lightning protection systems Lightning protection requires a synthetic measure against the various break-in paths of lightning surges, which are shown in Fig.
Design example In one design case, we designed improvements to an existing external lightning protection system using our design method for a structure nearly m high. Diagnostic tools w4201 external lightning protection Various laws and specifications such as those of JIS A Conclusion The number of different structures is as a420 as the number of structures itself because each structure is a unique combination of its internal electrical systems, the function of the structure, and the building’s appearance.
He received the B.
He joined NTT Facilities in He is currently studying lightning protection technology. He is a member of the Institute of Electrical Engineers of Japan. He is a42011 member of AIJ.
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He was a visiting professor at the University of Technology in Malaysia in and helped to establish the Malaysian standard for lightning protection for IT systems. He has been in his present post since He moved to NTT Facilities in 4a201 is currently engaged in electrical system design and management. Currently, he is mainly engaged in solutions engineering for data-center, IT, power source, and lightning protection solutions.
He joined NTT in and worked on the maintenance, design, and construction of power equipment. He moved to NTT A421 in and worked on a PHS base station construction promotion project and on a data-center construction task-force. He is currently engaged in lightning protection solutions.