1、 3404593 0084885 641 EUROPEAN STANDARD EN 60721-3-0 A NORME EUROPENNE EUROPISCHE NORM July 1993 UDC 62 1.3:620.193 Supersedes EID 478.3.0 S2 : 1989 Descriptors: Environmental parameter English version Classification of environmental conditions Part 3: Classification of groups of environmental parame
2、ters and their severities Introduction (IEC 721-3-0 : 1984 + Al : 1987) Classification des conditions d environnement Troisime partie: classification des groupements des agents denvironnement et de leurs svrits Introduction fr den Anwender Kiassifierung von Umweltbedingungen Teil 3: Klassen von Umwe
3、lteinfluGgrBen und deren Grannverte Einfuhning und Hinweise (CE1 721-3-0 : 1984 + Al : 1987) (IEC 721-3-0 : 1984 + Al : 1987) “his European Standard was approved by CENELEC on 1993-07-06. CENELEC members are bound to comply with the CENICENELEC Internal Regulations which stipulate the conditions for
4、 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 the Central Secretariat or to any CENELEC member. This European Standard exists in three offic
5、ial 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 Centrai Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical commi
6、ttees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnicai Standardization Comit Europen de Normalisation Electrotechnique Eur
7、opisches Komitee fr Elektrotechnische Normung Centrai Secretariat: me de Stassart 35, B-1050, Brussels O 1993 Copyright reserved to CENELEC members Ref. No. EN 60721-3-0 : 1993 E LPage 2 EN 60721-3-0 : 1993 Foreword At the request of the 72nd Technical Board Al : 1987) was submitted to the CENELEC v
8、oting procedure for conversion into a European Standard. The text of the International Standard was approved by CENELEC as EN 60721-3-0 on 6 July 1993. The following dates were fixed - latest date of publication of an identical national standard (dop) 1994-03-01 - latest date of withdrawal of confli
9、cting national standards (dow) - Annexes designated normative are part of the body of the standard. In this standard, annex ZA is normative. HD 478.3.0 S2 : 1989 (IEC 721-3-0 : 1984 + k 3404583 0084886 588 = 3404583 0084887 4/11 721-3-0 0 IEC 1984 CLASSIFICATION OF ENVIRONMENTAL CONDITIONS Pari 3: C
10、lassification of groups of environmental parameters and their severities Introduction Scope I EC Publication 72 1-3: Classification of Environmental Conditions, Part 3: Classification of Groups of Environmental Parameters and Their Severities, establishes classes of environ- mental parameters and th
11、eir severities, covering the extreme (short-term) conditions which may be met by a product when being transported, installed, stored and used. Separate groups of classes are given for different product applications (e.g. weather-protected stationary, mounted in ground vehicles, transportation). The
12、classes also take into account the degree of restriction of the use of the product from very restricted conditions (e.g. in temperature- controlled rooms) to unrestricted conditions. The classification covers natural as well as man-made conditions. 2. Object This Introduction is a guide for the use
13、of all parts of IEC Publication 721-3. It contains background information including information on application and limitation of the classes given in various parts of I EC Publication 721-3. It describes the difference between the envir- onmental conditions the product will meet during its life, des
14、cribed by the classes in IEC Publication 721-3, and conditions of test used to assure that the product will work satisfac- torily under such environmental conditions. The use of IEC Publication 721-3 in the design, limitation of conditions and protection is also included. The differences are explain
15、ed between extreme environmental conditions with a small probability of being exceeded, normally approached only for short periods, and more long-lasting normal environmental conditions. 1 This Introduction also gives guidance for applying factorsof duration and frequency of occurrence Reference to
16、IEC Publication 721-3-0 is strongly recommended in order to avoid misuse of in characterizing the contribution of a significant parameter of a class. the classes defined in the other parts of IEC Publication 721-3. 3. Content and layout Separate groups of classes of environmental conditions are give
17、n for the following product Publications 721-3-1: Storage; applications: 72 1-3-2: Transportation; 72 1-3-3: Stationary Use, Weather-protected; I m 3404583 0084888 350 m 721-3-0 O IEC 1984 721-3-4: Stationary Use, Non-weatherprotected; 721-3-5: Ground Vehicle Installations: 721-3-6: Ship Environment
18、; 721-3-7: Portable and Non-stationary Use. The classes are identified by: - a digit defining the application (1 for storage, 2 for transportation, 3 for stationary use, etc.); - a letter for climatic conditions (K), biological conditions (B), chemically active substances (C), mechanically active su
19、bstances (S) or mechanical conditions (M). To be extended if necessary; - a further digit indicating severity, where a higher digit normally indicates more stringent conditions. A class may be further divided into H (High) or L (Low) to allow for condi- tions where, for example, the temperature may
20、be severely low but never high. Example: Class 2K3, where: 2 = transportation; K = climatic conditions; 3 = severity. The parts of I EC Publication 721-3 contain tables giving all classes, including the severity of each environmental parameter for each class. In addition, every publication includes
21、an appendix giving details of conditions which products are assumed to meet and which form a basis for the classes. These appendices are intended to guide the user of the publication in his selection of the class appropriate to his special product application. 4. Background information for the selec
22、tion of environmental parameters and severities for the classes The environmental parameters listed for a class are the conditions covered by the class to which a product will be subjected. They are selected by using the complete set of environ- mental parameters in I EC hblication 721-1: Classifica
23、tion of Environmental Conditions, Part I: Classification of Environmental Parameters and Their Severities, as a “check list”. The severities given for each environmental parameter are those which are exceeded either for an insignificant part of the continuous exposure time (e.g. temperature conditio
24、ns), or for an insignificant fraction of the total number of events (e.g. shocks). Thus the classes given in IEC Publication 721-3 can be used for defining the maximum short-term environmental stresses of a product, but do not give any information on the long-term, or total life duration of the prod
25、uct environmental stresses. This is illustrated in Figure I, page 1 1. 2 3404583 0084889 297 721-3-0 O IEC 1984 P(X xo) Fraction of time of fraction of total number 4 of events when xa is exceeded 10- 05- - x, xo Severity t P(x XI) 15 low 45-5/84 FIG. 1. - Illustration of the fraction of time or fra
26、ction of the total number of events when a certain environmental severity is exceeded. The severities given in the classification are represented by one value XI, whilst the infor- mation needed for defining the totality of environmental stresses during the lifetime of a product includes the total c
27、urve, P(x xg) for all values of 0. Although available data do not make it possible to give an exact figure on the probability level used in the classification, P(x xi) is usually considerably less than 0.01. A product will be simultaneously exposed to a large number of environmental parameters. Some
28、 of the parameters are statistically dependent, for example, low air velocity and low temperature, sun radiation and high temperature. Other parameters are statistically inde- pendent, for example vibration and temperature (normally). The probability of simultaneous exposure to extreme severities of
29、 independent environ- mental parameters x and y is equal to the product of the probabilities of exposure to each of the parameters, i.e.: P(X,YXl,Yi) = P(XXi)- PO,Yi) Example: If the probability of exceeding each of the parameters P(xxl)= PO,yi)=O.Ol,thenP(x,yx,y)=O.OOO1 It shoiild be noted that in
30、many cases the product is exposed for only limited periods to the environment from which the statistical data have been collected. In such cases severities in the classification have been selected which have a probability higher than 0.01 of being exceeded. Consequently, the probability of the combi
31、nation of the product being exposed to the environment and of the class limit severity is reasonable (in the order of magnitude of 0.01). 3 3404583 0084890 TO9 H 721-3-0 0 IEC 1984 5. Guidance for the use of IEC Publication 721-3 5.1 General All products have to be designed to survive and work in mo
32、re or less severe environments. Basically they will be affected by the environmental influences in two ways: - by the effects of short-term extreme environmental conditions, which may directly cause malfunction or destroy the product; - by the effect of long-term subjection to non-extreme environmen
33、tal stresses, which may slowly degrade the product and finally cause malfunction or destruction of the product. The short-term extreme environmental conditions, defined in I EC Publication 721-3, may occur at any time in the products life. A product may be unaffected by an extreme condition when it
34、is new but fail when it is subjected to the same condition after being used for a long period due to the effect of ageing. Extreme conditions may affect the product: - only when the product is non-operating (e.g. during storage and transportation), - only when the product is operating, or both. It i
35、s therefore important for the product specification, when referring to a certain class in IEC Publication 721-3, to define whether the product is required to be capable of operating or only to survive without permanent damage, when being subjected to the condi- tions described by the class. The envi
36、ronmental classes may be used as a basis for the choice of design and test levels. This does not imply that the class limits should be used as design and test levels, nor that zero failure rate should be required at the class limits. Design and test levels must always be chosen from case to case wit
37、h respect to acceptable risk of failure, i.e. with higher or lower severity depending on expected consequences of failure. 5.2 In the design, limitation of conditions andprotection I EC Publication 72 i -3 is basically intended to be used as a basis for defining the actual environmental conditions f
38、or which a product has to be designed. The designer must be aware that the physical influence of environmental conditions may be the result of a certain number of environmental parameters. Example: The highest temperature achieved on the surface of a product may be the result of the combination of t
39、he temperature of the surrounding air, solar radiation, heat radiation from a nearby heating element, open oven, etc. The manufacturer or user of the product may reduce the severity of an environmental parameter by protecting the product, for example, by using an enclosure for transportation and sto
40、rage or by mounting the product on vibration or shock isolators. The environmental severities given by the classes in IEC Publication 721-3 shall then be applied to the product including its protection, not to the product itself. 4 3404583 0084891 945 721-3-0 0 IEC 1984 By means of the information g
41、iven in the appendices to the various parts of IEC Publi- cation 721-3 it is possible for the manufacturer and user to define restrictions in the transpor- tation, storage or use of the product, which will bring the application into compliance with a lower scverity class. It is often economical and
42、technically important to find an optimum between: - the environmental resistance of the unprotected product; - the protection of the product from environmental influences; - restrictions in transportation, storage and use of the product. It should be noted that an overdesign of a product, in order t
43、o withstand environmental conditions more extreme than necessary, does not necessarily result in higher reliability. An overdesign or unnecessary built-in protection may lead to a more complex product with an increased number of failure modes. Furthermore, overdesign of products as well as unne- ces
44、sary requirements on locations in order to ensure environmental conditions less severe than necessary, can become very expensive. 5.3 For defining appropriate levels for qualification testing As mentioned under Sub-clause 5.2 above, the classes in IEC Publication 721-3 can be used as basis for desig
45、n, protection and introduction of restrictions. Demonstration of the capability of the product to meet the environmental condition includes a number of activities, from instructions for selection of basic materials used in the product including material testing, instructions for surface treatments,
46、etc., to testing of samples of the complete product under simulated environmental conditions. The testing is made in a selection of the environmental parameters, or sometimes combina- tions thereof, which may be detrimental to the product. An environmental test requirement is described by: - environ
47、mental parameter; - testing procedure; - testing severities. In addition requirements are given related to the specific product, for example rating, func- tional requirements, acceptable degradation etc. Environmental testing procedures for testing are standardized in I EC Publication 68: Basic Envi
48、ronmental Testing Procedures. The severities used for testing must be related to the testing procedure, which attempts to produce the effects of the actual environment. This reproduction is often different from the actual environmental conditions. Examples: - A high temperature test on a heat dissip
49、ating product is designed to simulate the thermal effect of subjecting it to conditions of high air temperature, solar radiation and other possible heat sources dependent on the application. - In a shock test, the product is subjected to shocks of simple puise shapes (e.g. half-sine), whilst the actual conditions cannot be described by such simple pulses. A transformation by means of comparing the shock spectrum of the actual conditions with the shock spectrum of the test pulse is needed. 5 3404583 0084892 881 W 721-3-0 O IEC 1984 (The transformation of actual
