1、 IEC 60721-2-2 Edition 2.0 2012-12 INTERNATIONAL STANDARD NORME INTERNATIONALE Classification of environmental conditions Part 2-2: Environmental conditions appearing in nature Precipitation and wind Classification des conditions denvironnement Partie 2-2: Conditions denvironnement prsentes dans la
2、nature Prcipitations et vent IEC60721-2-2:2012 THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2012 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including p
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16、-2-2 Edition 2.0 2012-12 INTERNATIONAL STANDARD NORME INTERNATIONALE Classification of environmental conditions Part 2-2: Environmental conditions appearing in nature Precipitation and wind Classification des conditions denvironnement Partie 2-2: Conditions denvironnement prsentes dans la nature Prc
17、ipitations et vent INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE M ICS 19.040 PRICE CODE CODE PRIX ISBN 978-2-83220-570-9 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale Warning
18、! Make sure that you obtained this publication from an authorized distributor. Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agr. 2 60721-2-2 IEC:2012 CONTENTS FOREWORD . 3 1 Scope . 5 2 Normative references . 5 3 Terms and definitions . 5 4 General 5 4.
19、1 Introductory remark . 5 4.2 Precipitation 5 4.3 Wind 6 5 Characteristics . 6 5.1 Rain 6 5.2 Hail . 7 5.3 Snow . 8 5.4 Wind 8 6 Classification 8 6.1 General . 8 6.2 Normal rain . 8 6.3 Driving rain 9 6.4 Formation of ice 9 6.4.1 General . 9 6.4.2 Air hoar . 9 6.4.3 Rime 9 6.4.4 Clear ice 9 6.4.5 Gl
20、aze ice . 9 6.4.6 Process of ice formation 9 6.5 Hail . 10 6.6 Snow load . 10 6.7 Drifting snow . 10 6.8 Wind force . 10 Bibliography 12 Table 1 Characteristics of rain (average over long periods) 6 Table 2 Characteristics of hailstones . 8 60721-2-2 IEC:2012 3 INTERNATIONAL ELECTROTECHNICAL COMMISS
21、ION _ CLASSIFICATION OF ENVIRONMENTAL CONDITIONS Part 2-2: Environmental conditions appearing in nature Precipitation and wind FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC Nati
22、onal Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publi
23、cly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governm
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30、f any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the
31、referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. I
32、nternational Standard IEC 60721-2-2 has been prepared by IEC technical committee 104: Environmental conditions, classification and methods of test. This second edition cancels and replaces the first edition, published in 1988, and constitutes a technical revision. The main changes with regard to the
33、 previous edition are as follows: subclause Precipitation: simplified; data not possible to validate are removed; subclause Wind: text rewritten; Table 1 simplified and aligned with definition used by 11; subclause Hail: data added; formula changed; formula for impact energy added; 1References in sq
34、uare brackets refer to the Bibliography. 4 60721-2-2 IEC:2012 subclause Snow: text changed and aligned with definitions used by 1; Table 3 removed; subclause Normal rain: text has been modified and numeric values removed; subclause Driving rain: text has been modified and numeric values removed; sub
35、clause Formation of ice: text has been modified and numeric values removed; subclause Drifting snow: text added; subclause Wind force: formula changed; Figure 1 to 5 removed. The text of this standard is based on the following documents: FDIS Report on voting 104/583/FDIS 104/596/RVD Full informatio
36、n on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60068 series, under the general title Classification of environment
37、al conditions, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication wi
38、ll be reconfirmed, withdrawn, replaced by a revised edition, or amended. 60721-2-2 IEC:2012 5 CLASSIFICATION OF ENVIRONMENTAL CONDITIONS Part 2-2: Environmental conditions appearing in nature Precipitation and wind 1 Scope This part of IEC 60721 presents fundamental properties, quantities for charac
39、terization, and a classification of environmental conditions dependent on precipitation and wind relevant for electrotechnical products. It is intended to be used as background material when selecting appropriate severities of parameters related to precipitation and wind for product applications. Wh
40、en selecting severities of parameters related to precipitation and wind for product application, the values given in IEC 60721-1 should be applied. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applicati
41、on. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60721-1, Classification of environmental conditions Part 1: Environmental parameters and their severities. 3 Terms and definitions T
42、erms and definitions are defined, in context, throughout the present standard. 4 General 4.1 Introductory remark The atmosphere of the Earth is in permanent motion. It is locally heated, cooled and moistened. The resulting gradients in density create high and low pressure areas. The equalizing winds
43、 do not blow directly from high to low pressure areas, but are deflected by Coriolis force due to the rotation of the Earth. The continuous horizontal movement may cause slow upward motion over wide areas, or surface heating may give more localized updrafts in thermals. The air cannot maintain its w
44、ater content in vaporous form if the reduction of pressure and temperature is sufficient, and precipitation may form. As an example, an air mass at +20 C temperature is able to contain water in a quantity of 17,3 g/m3in vaporous form. If it cools to 0 C the maximum water content is only 4,8 g/m3. 4.
45、2 Precipitation The specific kind of precipitation (rain, hail or snow) is a result of complicated processes in the clouds. 6 60721-2-2 IEC:2012 Formation of raindrops or ice crystals depends on various conditions, for instance vertical air currents, temperature distribution, and the resulting cours
46、e of droplets or ice crystals within the cloud. 4.3 Wind Wind is defined as lateral movement of the Earths atmosphere from high-pressure areas to low-pressure areas. Winds are often referred to by their strength and the direction from which the wind is blowing. Gusts are short bursts of high speed w
47、ind. Winds of long duration have various names associated with their average strength, such as breeze, gale, storm, hurricane and typhoon. Wind occurs on a scale ranging from thunderstorm flows, lasting tens of minutes, through local breezes generated by heating of land surfaces and lasting a few ho
48、urs, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The two main causes of large scale atmospheric circulation are the differential heating between the equator and the poles and the rotation of the planet. 5 Characteristics 5.1 Rain Ra
49、in is characterized by the following physical parameters: rain intensity measured in millimetres per hour (as the height accumulated on a horizontal surface without drain); drop size distribution; typical 1 mm to 2 mm in diameter, in thunderstorms the size could be up to 5 mm to 8 mm; falling velocity distribution; typical 2 m/s to 12 m/s; raindrop temperature. Other parameters such as d
