【正文】 ? pipe, power and telemunication lines not connected to a structure. NOTE Usually these systems are under special regulations made by various specific authorities. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 623052, Protection against lightning – Part 2: Risk management IEC 623053, Protection against lightning – Part 3: Physical damage to structures and life hazard IEC 623054, Protection against lightning – Part 4: Electrical and electronic systems within structures IEC 623055, Protection against lightning – Part 5: Services 1 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. lightning flash to earth electrical discharge of atmospheric origin between cloud and earth consisting of one or more strokes 1 To be published. – 9 – EN 623051:2020 dow nw ard flash lightning flash initiated by a downward leader from cloud to earth NOTE A downward flash consists of a first short stroke, which can be followed by subsequent short strokes. One or more short strokes may be followed by a long stroke. upw ard flash lightning flash initiated by an upward leader from an earthed structure to cloud NOTE An upward flash consists of a first long stroke with or without multiple superimposed short strokes. One or more short strokes may be followed by a long stroke. lightning stroke single electrical discharge in a lightning flash to earth short stroke part of the lightning flash which corresponds to an impulse current NOTE This current has a time to the half value T2 typically less than 2 ms (see Figure ). long stroke part of the lightning flash which corresponds to a continuing current NOTE The duration time Tl ong (time from the 10 % value on the front to the 10 % value on the tail) of this continuing current is typically more than 2 ms and less than 1 s (see Fi gure ) multiple strokes lightning flash consisting on average of 34 strokes, with typical time interval between them of about 50 ms NOTE Events having up to a few dozen strokes with intervals between them ranging from 10 ms to 250 ms have been reported. point of strike point where a lightning flash strikes the earth, or protruding object (. structure, LPS, service, tree, etc.) NOTE A lightning flash may have more than one point of strike. lightning current i current flowing at the point of strike peak value I maximum value of the lightning current average steepness of the front of short stroke current average rate of change of current within a time interval t2 – t1 NOTE It is expressed by the difference i(t2 ) – i(t1 ) of the values of the current at the start and at the end of this interval, divided by t2 – t1 (see Figure ). EN 623051:2020 – 10 – front time of short stroke current T1 virtual parameter defined as 1,25 times the time interval between the instants when the 10 % and 90 % of the peak value are reached (see Figure ) virtual origin of short stroke current O1 point of intersection with time axis of a straight line drawn through the 10 % and the 90 % reference points on the stroke current front (see Figure )。 – vehicles, ships, aircraft, offshore installations。r Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B 1050 Brussels 169。en de Normalisation Electrotechnique Europ228。tze (IEC 623051:2020) This European Standard was approved by CENELEC on 20200201. CENELEC members are bound to ply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Uptodate lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical mittees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Rumania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit233。n233。ISCHE NORM February 2020 ICS 。 BSI 2020 ISBN 0 580 48846 2 Amendments issued since publication EUROPEAN STANDARD EN 623051 NORME EUROP201。BRITISH STANDARD BS EN 623051:2020 Protection against lightning — Part 1: General principles The European Standard EN 623051:2020 has the status of a British Standard ICS 。 Amd. No. Date Comments BS EN 623051:2020 National foreword This British Standard was published by BSI. It is the UK implementation of EN 623051:2020. It is identical with IEC 623051:2020. Th