1、BRITISH STANDARDBS EN 50475:2008Basic 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)ICS 13.280; 17.220.20; 33.170g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40
2、g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 50476:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2008 BSI 2008ISBN 978 0 580 56859 6N
3、ational 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 of organizations represented on this committee ca
4、n 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 obligations.Amendments/corrigenda issued since pub
5、licationDate 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 Central Secretariat: rue de Stassart 35, B - 1050
6、 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 transmitters with the reference levels and the basic restri
7、ctions 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 public, dans les bandes HF (3 MHz 30 MHz) Produktnor
8、m 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 approved by CENELEC on 2008-04-01. CENELEC members a
9、re 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 national standards may be obtained on application to
10、 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 th
11、e 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, Latvia, Lithuania, Luxembourg, Malta, the Netherlands,
12、 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 environment. The text of the draft was submitted to
13、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) 2009-04-01 latest date by which the national standards c
14、onflicting 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 results and determination of compliance . 7 7 Docume
15、ntation 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 broadcast transmitters operating in the frequency range
16、 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 electromagnetic fields. 2 Normative references The following
17、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 , Basic standard for the calculation and the measureme
18、nt 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 as a transducer between a guided wave (e.g. coax
19、ial 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 service radio communication service in which the trans
20、missions 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 investigation where field level is deemed to be compliant to
21、 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 amperes (A). A conductive object in an electric fiel
22、d 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 of it, expressed in amperes per square meter (A/m)
23、 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 positive small charge (q) divided by the charge qF
24、E = 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 free space 0: BH M=0Magnetic field strength is expre
25、ssed 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 an oscillation or wave is constrained to follow t
26、he 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 carrying out measurements and calculations to determin
27、e 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; compliance with all reference levels will ensure co
28、mpliance 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 restrictions 3.13 root-mean-square (r.m.s.) r.m.s. value
29、 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) absorbed by (dissipated in) an incremental mass (dm
30、) 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 transmission in this frequency range is therefore ca
31、lled 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 measurement The near field of a short wave antenna
32、 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 distances, once the far-field region is entered, the fi
33、eld-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 manufacturer specification. Calculations and/or measureme
34、nts 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 the transmitter equipment manufacturer. 5 Limits
35、 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 basic restriction. If the measured or calculated
36、 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 whether additional protective measures are necessar
37、y. 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 compliance distances. 7 Documentation provided by the e
38、quipment 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 to determine exposure levels and compliance dista
39、nces 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 of compliance to interested parties. Information
40、 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 reference antenna, at the distances of at which the
41、 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, the alteration of which is for the time being ou
42、tside 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 been removed. Clause Deviation General Switzerlan
43、d(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-Ionising Radiation, i.e. stationary transmission install
44、ations 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 concerned. _ BS EN 50476:2008 11 EN 50476:2008 Bibliogr
45、aphy 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 Chiswick High Road,London W4 4AL, UKTel +44 (0)2
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