Classification of groups of environmental parameters and their seventies
IEC 60721-3-4-2019 pdf download.Classification of environmental conditions — Part 3-4: Classification of groups of environmental parameters and their seventies — Stationary use at non-weatherprotected locations
Classification des conditions d’environnement — Partie 3-4: Classification des groupements des agents d’environnement et de leurs sévérités — Utilisation a poste fixe, non protégé contre les intempéries.
A product may be subjected to a range of environmental conditions during its lifetime. These conditions have been separated into classes described in IEC 60721-3 (all parts). The classes given may be used for defining the maximum short-term environmental stresses on a product. However, they do not provide information regarding the long-term or total lifetime environmental stresses a product may experience. This means that no reliability or lifetime assessment is possible based on these classes alone. Refer to IEC 60721-2 (all parts) and
applicable technical reports (IEC TR 62130, IEC TR 62131-2, IEC TR 62131-3,
IEC TR 62131-4 and IEC TR 62131-5) for further information on actual environmental conditions.
A product may be simultaneously exposed to several environmental parameters, for example. solar radiation and temperature, temperature and humidity, as well as vibration and temperature change. Combinations of the environmental parameters given may increase the stress effect on a product. Therefore, combined conditions should be considered in the design and evaluation of a product.
Products should be designed to survive and operate In different environments. Basically, they will be affected by 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 environmental stresses which may slowly degrade the product and finally cause malfunction or destruction of the product.
Short-term extreme environmental conditions may occur at any time in a product’s life. A product may be unaffected by an extreme condition when it is new but fail when it is subjected to the same condition after being used for a long period of time due to the effect of ageing. The order in which the environmental conditions are applied may affect the results of an evaluation.
It is important for the product specification, when referring to a certain class in IEC 60721-3 (all parts), to define whether the product is required to be capable of operating when being exposed to the conditions described by the class.
The environmental classes may be used as a basis for the selection of design and test seventies with respect to the consequence of failure. Information contained in IEC 60721-3 (all parts) may be used to help establish expected requirements for use, storage, transportation. etc., and in the development of relevant specifications, The selected seventies used for testing should attempt to produce the effects of the actual environment.
EXAMPLE 1 A high temperature test on a heat dissipating product is designed to simulate the thermal effect of subjecting a product to conditions of high air temperature, solar radiation and other possible heat sources dependent on the application.
5.2 Climatic conditions (K)
The classes defined in previous versions of this document have been replaced with new classes as a result of recent efforts at collecting information regarding climatic conditions. Those results are contained in technical reports referenced in this document.
At non-weatherprotected locations, the influence of special climatic conditions constitutes a more significant share of the effects bearing upon a product and its functional parts than at weatherprotected locations. Particularly the effects of temperature change, solar radiation, precipitation, air velocity and wind-chill should be considered in this respect.
The severity of these effects may be influenced for instance by constructional details (sort and thickness of material, colour of surface, sealing or breathing of casings or enclosures, product heating, etc.) and by mounting details (selection of mounting site, consideration of degree of exposure to prevailing wind and weather, etc.).
The climatic conditions specified for classes 4K23 to 4K27 refer to the non-weatherprotected conditions where products may be used. These conditions have been experienced world-wide over a long time period. The conditions should cover all normal cases, but not exceptional events. These conditions are specified in Table 1. The interdependence of temperature to relative humidity is shown in Annex A.
Sheltered non-weatherprotected locations
4K23 applies to sheltered non-weatherprotected locations in tropical, arid, temperate, and cold climatic classification with the thermal effects from solar radiation encompassed in the temperature.
4K24 applies to sheltered non-weatherprotected locations in the polar climate type with the thermal effects from solar radiation encompassed in the temperature.
Open-air non-weatherprotected locations
4K25 applies to open-air locations in the tropical climatic classification.
4K26 applies to open-air storage in the arid and temperate climatic classifications.
4K27 applies to open-air storage in the cold and polar climatic classifications.IEC 60721-3-4-2019 pdf download.