Bienvenido > Prensa y publicaciones > A present day evaluation of the potential of the traditional and active lightning rods
Prof. Dr.Sc.Techn. Eng. Stefan Iliev, ROSTI Ltd. Bulgaria
Eng. Peter Respondek, Dehn+Söhne GmbH+Co.KG, Germany
Specialists in Bulgaria have shown a great interest in obtaining objective present day evaluation on the real potential of lightning protection of the traditional lightning protection systems and the active (Early Streamer Emission, ESE) lightning rods (LR). The topicality of the problem is defined by the enormous responsibility for material, people and live creatures, which need to be protected against lightning.
Fundamental laboratory studies and observations in natural conditions, for evaluation of the potential of the traditional lightning protection systems and ESE active lightning rods (LR) over the latest 15-20 years, ran parallel to a erudite international discussion. Participating were leading specialized research institutes, laboratories and researchers, together with powerful producers. The subject of debate was whether the active lightning rods (LR) have better protective potential in comparison with the traditional lightning protection systems, and if so, to reflect it on and regulate it in the international and national legislation.
The main argument with the active lightning rods (LR) is the claim that here the break-down occurs earlier at a time T = 10 ÷ 60 µs in comparison with the traditional LR. This is how we arrive at a 4÷6 times 'virtual' increase of the height of the active LR. This leads to an increase of the protective action and the protected area, and possibility of reducing the number of LR in comparison with the traditional ones.
The claim for a stronger protective action with an active (with advanced action) LR faces the strongest contention from a scientific point of view. This is chiefly due to insufficient knowledge of the process of a break-down and the difficulty of the replication.
The numerous studies of samples (at the Institute for Science and Technology, University of Manchester, the Technical University, Darmstadt, Germany etc.) with traditional and active LR, placed in identical conditions, a mutual change of their positions, in stimulation of a break-down do not confirm the presence of advantages of LR in comparison with others. In this chance character of the break-down process, even the break-downs at the traditional LRs exceeds the break-downs at the active LRs.
At the study of the All-Russian Electro-engineering Institute, on the efficiency of the criterion T, determined by the difference between the moments of lightning-break-down by traditional and active LRs, the conclusion is drawn that T does not allow the determination of real advantages of the active LR before the traditional LR.
The comparative testing under real conditions at Kuala Lumpur - the capital of Malaysia, have not shown the advantages in the protective potential of the active LR. The results have led to their being banned in the country.
The summarized practical results of international laboratory studies and studies in real conditions shows, that the active LR function like traditional LR.
The International Electrotechnical Commission, which evaluates and summarizes the world studies and experience, adopted in 2006 a clearly arranged structure of a standard for Lightning Protection IEC 62305, section 1-4:2006. It does not envisage the use of active LRs. Proposed are traditional LR, network LR and attached conductor. In the separate parts of the standard include the following information and requirements in accordance with:
The European norms have been adopted by the European Committee for Electrotechnical Norms CENELEC *, appearing as EN 62305 sections 1-4:2006 at 01.02.2006 in three official languages: german (Europäische Norm), english (European standard) and french (Norme europeenne), with no changes what so ever in IEC 62305, section 1-4:2006.
NFPA, the American norms for lightning protection system, show a similar attitude to the active LRs.
Bulgaria adopted the European norms in 2006 as BDS EN 62305, 1-4:2006, for the present without a Bulgarian translation. A translation is forthcoming.
The fact of the principle contradiction between EN and Ordinance Nº8 dated 28.12.2004 for lightning protection of buildings, outdoor facilities and open space, still not changed to this day is causing confusion for designers, investors and contractors. Ordinance Nº8 offers a provision for active LR - namely Chapter 4 of the Ordinance.
It is beyond the point to introduce a difference in the interpretation of the internationally accepted understanding of the synonymous meaning of 'norms' and 'standards'. Harmonization of our national norms (standards) should be done, as Bulgaria is a member of the European Union. The Bulgarian Institute for Standardization should clearly pronounce itself on this matter, in order to avoid a transition period. The responsibility for the choice of LR should not be left to teams of the designers and construction companies. Normally whoever insists on any other solution should assume the responsibility and the consequences.
The great interest towards the problem of the external and internal protection against atmospheric and switching overloads shall be discussed in the several issues of the paper by articles of the authors. Presented shall be detailed information on fundamental laboratory studies of LR, studies in real conditions, data on damages from lightnings on targets with active LR, protection of electrical units and electronic devices in buildings etc.
* CENELEC - Comité Européen de Normalisation Electrotechnique
Members of CENELEC are the national electrotechnical committees of all European Union countries.