1、CEPT T/L*QZ-LZ*E 88 I 2326414 0005764 7 TL02-12 Page E 1 Recommendation T/L 02-12 dinburgh 1988) ENVIRONMENTAL CONDITiONS AND ENVIRONMENTAL TESTS FOR TELECOMMUNICATIONS EQUIPMENT Recommendation proposed by Working Group T/WG 12 “Transmission and miiltiplexing” (TM) Text of the Recommendation adopted
2、 by the “Telecommunications” Commission: “The European Conference of Posts and Telecommunications Administrations, considering - that the relevant CCITT and CCIR Recommendations do not provide for the necessary standardization, - that it is essential to use the testing philosophy relating to environ
3、mental classes and equipment characteristics, recommends that members of the CEPT adhere to the following specifications.” Edition of January 30, 1989 CEPT T/L*02-l12*E ! 2326434 0005965 O = T/L 02-12 E Page 2 Contents Page 1 . PURPOSE 4 2 . REFERENCE DOCUMENTS 4 3 . ENVIRONMENTAL ENGINEERING 4 3.2.
4、 Economical and technical aspects . 4 3.3, Survey 3.1. Purpose 4 4 4 . 4.1. 4.2. 4.3. 4.4. 4.5. 4.6. 4.6.1. 4.6.2. ENVIRONMENTAL DESCRIPTION General Purpose of classification . Classes Parameters Severities . Limitations and considerations Application Simultaneous occurrence . 6 6 6 6 6 7 11 11 11 5
5、 . EQUIPMENT PROPERTIES 11 5.1. Resistibility and performance . 12 . . 5.2. Failure consequences 12 5.3. Emission 13 5.4. Protection 13 6 . 6.1. 6.2. 6.2.1. 6.2.2. 6.3. 6.4. 6.4.1. 6.4.2. 6.4.3. 6.5 . 6.5.1. 6.5.2. 6.5.3. ENVIRONMENTAL TESTING . 13 Purpose and philosophy . 13 Transformation from cla
6、ss to test 15 Stress-strength 15 Failure consequences and perjormance . 16 Test methods 17 Environmental resistibility test 18 Purpose and limitations . 18 Test sequence . 18 Environmental test programme 18 Testing related to operational life Genecal . . . 19 19 Reliability 20 Endurability 20 . TERM
7、INOLOGY . 7 . 21 7.1. 7.1.1. 7.1.2. 7.1.2.1. 7.1.3. 7,1.3.1. 7.1.4. 7.1.5. 7.1.6. 7.2. 7.2.1. 7.2.1.1. 7.2.1.2. 7,2.1.3, 7.2.2. 7.2.2.1. -7.2.2.2. 7.2.2.3. 7.2.2.4. 7.2.2.5. Environmental description 21 Environment. environmental conditions . 21 Environmental parameters 21 Detail parameters . 21 Cha
8、racteristic severity 21 Environmental class . 21 Requirements on the environment . Environmental protection 22 Application . Portable and non-stationary use . 22 Transport conditions 22 Storage conditions . 22 Weatherprotected location 22 Non-weatherprotected location 22 Severity 21 22 : 22 Inuse.,
9、22 Stationary use 22 Mobile use 22 Notinuse. 22 . . Storage 22 Edition of January 30. 1989 CEPT T/L*02-L2*E 8 I 232611111 0005966 2 W . 7.3. 7.3.1. 7.3.2. 7.3.2.1, 7.3.2.2. 7.3.2.3. 7.3.2.4. 7.3.3. 7.3.3.1. 7.3.3.2. 7.3.4. 7.3.4.1. 7.3.4.2. 7.3.4.3. 7.3.5. 7.4. 7.4.1. 7.4.2. 7.4.3. 7.4.4. 7.4.5. 7.5
10、. O Performance requirements Normalpeiformance Rediicedpeiformance Primary fiinctions . Secondary functions Intermittent function Cessation of function Resistibility requirements Environmental resistibility Performance requirements Failure consequences Minor failure consequences . Moderate failure c
11、onsequences . . Severe failure consequences . . Emission requirements Testing Environmental testing Environmental test programme . . Environmental test specijcafion . . Standard atmospheric conditions for Type test . Environmental specification . testing . T/L 02-12 E Page 3 Page 22 22 23 23 23 23 2
12、3 23 23 23 23 23 23 24 24 24 24 24 24 24 24 24 . /? Edition of January 30. 1989 _i _I T/L 02-12 E Page 4 1. 2. 3. 3.1. 3.2. 3.3. PURPOSE The aim of this document is to give the user the following information: - an explanation of the main concepts and the terminology with examples; - the purpose and
13、use of environmental classes; - the testing philosophy relating to environmental classes and equipment characteristics; - the principles underlying environmental specifications. REFERENCE DOCUMENTS IEC 721 IEC 68-1 Classification of environmental conditions. Basic environmental testing procedures. P
14、art 1 : General and guidance. ENVIRONMENTAL ENGINEERING Purpose The purpose of environmental engineering is to make the equipment and the environment mutually compatible. This means that in some instances the equipment has to be modified and/or protected to resist a given environment, in other insta
15、nces the environment itself must be conditioned to fit to the equipment. The fitting of the equipment to its environment and its effect on the environment need to be carefully evaluated. Finally testing reveals whether the equipment/environmental fitting is successful. Economical and technical aspec
16、ts Environmental requirements have a number of economical and technical consequences. These include: - the equipment specification - the equipment design - the choice of materials - the testing procedure and protection, if any - the operational conditions and application The environmental requiremen
17、ts relating to equipment specification and design must be considered and stated in an early phase of a project. If this is not done, significant economic and technical difficulties may occur during later phases of the project. An “overspecification” resulting in “overdesign” will be costly, complex
18、and may not necessarily lead to a more reliable product. To stringent a requirement for the environmental conditions at the equipment locations may also be costly and complex. The introduction of a protection whether in the equipment or on the environment always requires an economical evaluation. In
19、 the test specification this protection must always be taken into account. Thorough testing is costly and time consuming. Hence selecting the most relevant and cheapest test procedures for the equipment is most important. Proper environmental engineering seeks to balance the above costs against the
20、costs of environmentally induced failures. Such costs arise from - elimination of the failure - possible redesign - operational losses - possible compensations The process involves both technical and economic optimization according to the application of the environment. Survey Figure 1 (T/L 02-12) s
21、hows a total, but simplified, procedure for preparing an environmental resistibility test based on environmental data. Some main elements of the procedure will be described in the following clauses with the emphasis on environmental classes, the transformation and the resulting test specification wh
22、ilst taking into account the performance requirements of the equipment. Edition of January 30, 1 TIL 02-12 E Page 6 NATURE -t PROTECTION EXTERNAL CONDITIONS DESCRIPTION (Section 4.1.) ENVIRONMENTAL DATA 1 ENVIRONMENTAL GROUPING IN . ENVIRONMENTAL CLASSES - DEFINITIONS OF PARAMETERS APPLICATIONS * WI
23、THCHARACTERISTIC - SEVERITIES CLASS TO TESTING (Section 6.2.) MODELS PHILOSOPHY FAILURE CONSEQUENCES EXPERIENCE FORMATION SPECIFICATION (Sections 6.1. and 6.3.) - TEST METHODS - V RESISTIBILITY REQUIREMENTS ACCORDING TO ENVIRONMENTAL CLASSES I II SPECIFICATION AND TESTING (Section 6.4.) i .II ENVIRO
24、NMENTAL PERFORMANCE- REQUIREMENTS TEST SEQUENCES SPECIFICATION Figure 1 (T/L 02-12). Outline for the preparation of the test specification. Edition of January 30, 1989 P - - - CEPT T/L*02-L2*E 88 I 232b4L4 00059b9 I T/L 02-12 E Page 6 4. ENVIRONMENTAL DESCRIPTION 4.1. General In this context environ
25、mental conditions are limited to the physical and chemical conditions to which an equipment is subjected at a certain time for (more or less) well-defined locations and applications. Physical and chemical conditions should be considered in a very broad sense. They cover not only the two main areas -
26、climatic and mechanical conditions-, but also borderline and transitional areas, e.g. biological and chemical conditions as well. The environmental conditions comprise those conditions appearing in nature as well as “artificial” con- ditions. The “artificial” conditions may be of a favourable nature
27、, e.g. a house being heated during the cold season, but may also be of an unfavourable nature, e.g. thermal influence from the equipment itself or from other equipment. Typical environmental conditions usually have simple names, such as “outdoors”, “in a car”. However, such “typical” conditions invo
28、lve numerous environmental factors (parameters) varying apparently at random in strength (severity) and having complex interactions. These factors determine the actual influence of the environment on the relevant equipment. Because of this only parameters having a singificant effect on the equipment
29、 are considered. 4.2. Purpose of classification The main purpose of environmental classes is to establish a number of “standardized” and operational frames of reference for a wide range of applications of (telecommunications) equipment. These classes cover use, transportation, etc. in typical enviro
30、nmental conditions. The classification is derived from the fact that it is generally very difficult to describe environmental conditions in detail and even more difficult to apply the results in practice. Until recently the only tool was some specific tests covering few environmental effects. The in
31、troduction of the concept of environmental classes is a more powerful tool. The environmental classes apply to: - Requirements on the environment prescribed by the Administration or the manufacturer. - Resistibility requirements on the equipment. (Important for the designer and forming a basis for t
32、esting.) - Emission re uirements on the equipment which, in certain situations, may need restricting, e.g. dissipated heat, such t 9, at the interference on the original environment is “negligible”. (Where negligible in this context means that conditions defined by the environmental class are stili
33、valid.) 4.3. Classes An environmental class is a systematic representation of the environment for a family of locations with “similar properties”. This means that the detailed description of the class is like an envelope around a group of related environmental conditions. The class itself may not be
34、 considered directly as a typical example. A class is composed of the most significant single factors, named environmental parameters, selected from those which may be assumed to influence equipment performance. Severities and other characteristics are appended to the parameters to specify the class
35、 (cf. 4.4. and 4.5.). 4.4. Parameters Environmental parameters represent those physical or chemical properties of an environment which can be distinguished and specified in relatively simple terms. In many instances it is necessary to state additional detail parameters in order to make the specifica
36、tion unambiguous. Figure 2 (T/L 02-12) shows typical examples of parameters with their related detail parameters covering both climatic and mechanical conditions. Most detail parameters are quantified by their characteristic severity (cf. 4.5.). In some instances, however, the value of the detail pa
37、rameter may not be considered as a severity, e.g. frequency range, although still a characteristic measure. In Figure 2 (T/L 02-12) these parameters are marked with a *. In a few instances the parameter itself may be qualitatively expressed, e.g. “conditions of condensation”, with the “value” “yes o
38、r no” without further details (considered as a characteristic). However, the fact that these conditions may occur should be reflected in both the design phase and the test procedure. Edition of January 30, 1989 , CEPT T/L*02-L2*E 88 232b414 0005970 4 Environmental Parameter Parameter I Detail parame
39、ter T/L 02-12 E Page 7 Characteristics * or characteristic I Unit I severity for a class Climatic conditions Humidity Relative humidity I I 10 % RH Low I I I High I 100 I %RH I Parameter Detail parameter Displacement Condensation * I Yes * 3.5 10 Mechanical conditions Vibration mm m/sz I Environment
40、al parameter 2-9 * 9-150 * Hz I sinusoidal I I Frequency j, Characteristics * or characteristic Unit severity for a class Figure 2 (T/L 02-12). Examples of environmental parameters and related detail parameters with corresponding characteristics marked with a * or characteristic severities for a cla
41、ss. 4.5. Severities The severity of a parameter or detail parameter is generally the quantitative measure of the stress introduced by the parameter involved. It may be stated as magnitude, rate or duration. A practical example will show some fundamental aspects regarding the concept of severity. The
42、 example considers the climatic parameter “outdoor air temperature” for a defined geographical area. The statistical distribution of the observed temperatures is shown as a histogramme in Figure 3 (T/L 02-12), where the dashed curve is an approximation to a continuous distribution. It seems that the
43、 distribution has two peaks and that the extremes are about - 15” C and 30” C. Considering the definition, where the severity is a measure of the stress, it is obvious that the parameter “outdoor air temperature has to be split into two parameters: - low air temperature - high air temperature becaus
44、e either may induce its own stress with its own consequential failure mechanisms on the equipment. The parameters “Low air temperature” and “High air temperature” are shown in Figure 4 (T/L 02-12). Both show increasing stress and correct fractiles to the right. The values to the left are more or les
45、s undefined. The characteristic severity can thereby comply with the dehition that this severity (Le. the stress) is rarely exceeded. Edition of January 30, 1989 X T/L 02-12 E Page 8 15 14 CEPT T/L*OZ-LZ*E 8 23ZhLIL4 0005973 h I 5 i = 10 + 1 - 15 20 25 30 35 “C TEMPERATURE Figure 3 (T/L 02-12). Dist
46、ribution of outdoor temperature. Edition of January 30, 1989 - 7 CEPT T/L*02-L2*E = 232b4LY 0005772 I, RELATIVE 4(a) HIGH TEMPERATURE DURATION PER YEAR (Tu IS THE UPPER CHARACTERISTIC SEVERITY TEMPERATURE) 15 Tu (23.4“C) I- - STRESS 4(b) (Ti IS THE LOWER CHARACTERISTIC PER YEAR SEVERITY TEMPERATURE)
47、 +10 +5 O -5 i-IO -15 -20 -25 -30 “C TI (-9.3“C) I - SEVERITY STRESS Figure 4 (T/L 02-12). Separated distributions of outdoor air temperature showing the boundary value of the upper (Tu) and the lower (Tl) characteristic temperature. Edition of January 30, 1989 - CEPT T/L*OZ-LZ*E I 2326434 0005973 T
48、 I TIL 02-12 E Page 10 Figure 4(a) (T/L 02-12) shows the right-hand side-i.e. high temperature part, of the distribution shown in Figure 3 (T/L 02-12). The shaded portion of Figure 4(a) (T/L 02-12) represents 1 % of the total area under the curve of Figure 3 (T/L 02-12) and has been calculated by nu
49、merical integration. The left-hand vertical edge of the shaded portion intersects the temperature axis at some temperature Tu. The temperature Tu represents the boundary value, for a given distribution, which is acceptable as an upper characteristic severity. (In the example shown in Figure 4(a) (T/L 02-12), Tu = 23.4“C. Depending upon circumstances a higher severity temperature value may be appropriate. See also Figure IO (T/L 02-12). Figure 4(b) (T/L 02-12) is a mirror-image of the left-hand side-i.e. low temperature part-of the distribu- tion shown in F
