1、BRITISH STANDARDBS EN 50476:2008Product standard to demonstrate the compliance of broadcast station transmitters with the reference levels and the basic restrictions related to public exposure to radio frequency electromagnetic fields (3 MHz 30 MHz)ICS 13.280; 17.220.20; 33.170g49g50g3g38g50g51g60g4
2、4g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 50476:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on
3、30 September 2008 BSI 2008ISBN 978 0 580 56859 6National forewordThis British Standard is the UK implementation of EN 50476:2008. The UK participation in its preparation was entrusted to Technical Committee GEL/106, Human exposure to low frequency and high frequency electromagnetic radiation.A list
4、of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal o
5、bligations.Amendments/corrigenda issued since publicationDate CommentsEUROPEAN STANDARD EN 50476 NORME EUROPENNE EUROPISCHE NORM June 2008 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung
6、Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 50476:2008 E ICS 13.280 English version Product standard to demonstrate the compliance of broadcast station transmitte
7、rs with the reference levels and the basic restrictions related to public exposure to radio frequency electromagnetic fields (3 MHz - 30 MHz) Norme produit pour dmontrer la conformit des metteurs de service de radiodiffusion, aux niveaux de rfrence et aux restrictions de base pour lexposition du pub
8、lic, dans les bandes HF (3 MHz 30 MHz) Produktnorm zum Nachweis der bereinstimmung von Rundfunksendern mit den Referenzwerten und den Basisgrenzwerten bezglich der Exposition der Allgemeinbevlkerung gegenber hochfrequenten elektromagnetischen Feldern (3 MHz bis 30 MHz) This European Standard was app
9、roved by CENELEC on 2008-04-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nat
10、ional 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 langua
11、ge and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvi
12、a, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 50476:2008 2 Foreword This European Standard was prepared by the Technical Committee CENELEC TC 106X, Electromagnetic fields in the human env
13、ironment. The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50476 on 2008-04-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2009-04
14、-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2011-04-01 _ BS EN 50476:2008 3 EN 50476:2008 Contents 1 Scope . 4 2 Normative references . 4 3 Terms and definitions 4 4 Conditions for calculation and measurement . 6 5 Limits . 6 6 Evaluation of res
15、ults and determination of compliance . 7 7 Documentation provided by the equipment manufacturer 7 Annex A (informative) Declaration of conformity with EN 50476 . 8 Annex B (informative) A-deviations 10 Bibliography 11 BS EN 50476:2008EN 50476:2008 4 1 Scope This standard applies to short wave broadc
16、ast transmitters operating in the frequency range 3 MHz to 30 MHz. The object of this standard is to demonstrate the compliance of such equipment with the basic restrictions (directly or indirectly via compliance with reference levels) related to public human exposure to radio frequency electromagne
17、tic fields. 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. EN 50475 , Bas
18、ic standard for the calculation and the measurement of human exposure to electromagnetic fields from broadcasting service transmitters in the HF bands (3 MHz - 30 MHz) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 antenna device that serves
19、 as a transducer between a guided wave (e.g. coaxial cable) and a free space wave, or vice versa 3.2 basic restriction restrictions of 1999/519/EC 1 on exposure to time-varying electric, magnetic, and electromagnetic fields that are based directly on established health effects 3.3 broadcasting servi
20、ce radio communication service in which the transmissions are intended for direct reception by the general public. This service may include sound transmissions, television transmissions or other types of transmission 3.4 compliance distance minimum distance from the antenna to a point of investigati
21、on where field level is deemed to be compliant to the limits 3.5 compliance boundary surface around the antenna outside of which all field levels are deemed to be compliant to the limits 3.6 contact current (IC) contact current between a person and an object exposed to the field, is expressed in amp
22、eres (A). A conductive object in an electric field can be charged by the field BS EN 50476:2008 5 EN 50476:2008 3.7 current density (J) current density is defined as the current flowing through a unit cross section perpendicular to its direction in a volume conductor such as the human body or part o
23、f it, expressed in amperes per square meter (A/m) 3.8 induced current current induced inside the body as a result of direct exposure to electromagnetic fields, expressed in the unit ampere (A) 3.9 electric field strength (E) magnitude of a field vector at a point that represents the force (F) on a p
24、ositive small charge (q) divided by the charge qFE = electric field strength is expressed in units of volt per meter (V/m) 3.10 magnetic field strength (H) vector quantity obtained at a given point by subtracting the magnetization M from the magnetic flux density B divided by the permeability of fre
25、e space 0: BH M=0Magnetic field strength is expressed in the unit ampere per metre (A/m) NOTE In vacuum, the magnetic field strength is at all points equal to the magnetic flux density divided by the permeability of free space: H = B / 03.11 modulation process by which a quantity that characterises
26、an oscillation or wave is constrained to follow the values of a characteristic quantity of a signal NOTE Two modulation, in particular, are used for this standard: AM (Amplitude Modulation) and COFDM (Coded Orthogonal Frequency Division Multiplex); it must also be taken into consideration when carry
27、ing out measurements and calculations to determine whether or not the limits are being exceeded by adding the modulation factor to the carrier r.m.s. value. 3.12 reference levels reference levels of exposure are provided by 1999/519/EC 1 for comparison with measured values of physical quantities; co
28、mpliance with all reference levels will ensure compliance with basic restrictions. If measured values are higher than reference levels, it does not necessarily follow that the basic restrictions have been exceeded, but a more detailed analysis is necessary to assess compliance with the basic restric
29、tions 3.13 root-mean-square (r.m.s.) r.m.s. value is obtained by taking the square root of the average of the square of the value of the periodic function taken throughout one period BS EN 50476:2008EN 50476:2008 6 3.14 specific absorption rate (SAR) time derivative of the incremental energy (dW) ab
30、sorbed by (dissipated in) an incremental mass (dm) contained in a volume element (dV) of given mass density () =dVdWdtddmdWdtdSAR SAR is expressed in units of watt per kilogram (W/kg) 3.15 shortwave broadcasting the frequency band between 3 MHz and 30 MHz is called the short wave band. Broadcast tra
31、nsmission in this frequency range is therefore called shortwave broadcasting 3.16 transmitter device to generate radio frequency power for the purpose of communication NOTE A transmitter does not radiate the energy by itself, it needs to be connected to an antenna. 4 Conditions for calculation and m
32、easurement The near field of a short wave antenna may extend to a considerable distance. This may result in field-strengths falling below the levels at locations close to the array, then rising again with increasing distance from the antennas (especially for curtain arrays). However, at large distan
33、ces, once the far-field region is entered, the field-strength levels follow the normal pattern of decreasing with increased distance from the antenna. The calculation and/or measurement shall be performed in accordance with EN 50475. The transmitter shall be operating in accordance with the manufact
34、urer specification. Calculations and/or measurements on broadcast transmitters shall be performed on the final installation. The distances from the radiating antenna at which the calculations and/or measurements shall be performed, shall be the compliance distances for general public as specified by
35、 the transmitter equipment manufacturer. 5 Limits The transmitter shall comply with the relevant limits for public specified as basic restrictions in the Council Recommendation for the general public exposure 1999/519/EC 1. Compliance with the reference level will ensure compliance with the relevant
36、 basic restriction. If the measured or calculated value exceeds the reference level, it does not necessarily follow that the basic restriction will be exceeded. However, whenever a reference level is exceeded, it is necessary to test compliance with the relevant basic restriction and to determine wh
37、ether additional protective measures are necessary. BS EN 50476:2008 7 EN 50476:2008 6 Evaluation of results and determination of compliance The equipment is deemed to fulfil the requirements of this standard if the calculated and/or measured values are less than or equal to the limits at the compli
38、ance distances. 7 Documentation provided by the equipment manufacturer The manufacturer shall provide the following information with the equipment: a) output power, type of modulation of the transmitter; b) compliance distances for general public exposure; and, if appropriate, c) information on how
39、to determine exposure levels and compliance distances for any optional system configuration not specified in detail in the basic standard. BS EN 50476:2008EN 50476:2008 8 Annex A (informative) Declaration of conformity with EN 50476 This declaration can be used as a uniform way of giving information
40、 of compliance to interested parties. Information to whom it may concern DECLARATION OF CONFORMITY WITH EN 50476 Manufacturer, or representative, hereby declares that the equipment BS EN 50476:2008 9 EN 50476:2008 is in full compliance with the requirements of this standard, when connected to the re
41、ference antenna, at the distances of at which the calculations and/or measurements have been performed. Special operating conditions: Other relevant information: Date:_ _ Signature BS EN 50476:2008EN 50476:2008 10 Annex B (informative) A-deviations A-deviation: National deviation due to regulations,
42、 the alteration of which is for the time being outside the competence of the CENELEC national member. This European Standard does not fall under any Directive of the EC. In the relevant CENELEC countries these A-deviations are valid instead of the provisions of the European Standard until they have
43、been removed. Clause Deviation General Switzerland(Ordinance relating to Protection from Non-Ionising Radiation, SR 814.710 of 23 December 1999 (as of 1 January 2008) This product standard must not be applied to installations which are covered by the Ordinance relating to Protection from Non-Ionisin
44、g Radiation, i.e. stationary transmission installations for broadcasting and other wireless applications, as well as transmission installations for mobile telecommunication systems and wireless local loops as far as the compliance testing with the installation limit values of the Ordinance is concer
45、ned. _ BS EN 50476:2008 11 EN 50476:2008 Bibliography 1 Council Recommendation 1999/519/EC of 12 July 1999 on the limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz), Official Journal L 199 of 30 July 1999 BS EN 50476:2008BS EN 50476:2008BSI Group Headquarters389
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