Classification of environmental conditions—Classification of groups of environmental parameters and their severities—Part 4: Stationary use at non-weatherprotected locations
Classification of environmental conditions - Classification of groups of environmental parameters and their severities - Part 4: Stationary use at non-weatherprotected locations
1 Scope
This document classifies groups of environmental parameters and their severities to which products are subjected when installed for stationary use at non-weatherprotected locations. Weatherprotected locations where products can be mounted for stationary use permanently or temporarily are addressed in GB/T 4798.3-2023.
The environmental conditions specified in this document are limited to those which can directly affect the performance of products. Only environmental conditions as such are considered. No special description of the effects of these conditions on the products is provided.
Environmental conditions directly related to fire or explosion hazards, microclimate within a product, and conditions related to effects from ionizing radiation are excluded. Any other unforeseen incidents are also excluded.
A limited number of classes of environmental conditions is given, covering a broad field of application.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
IEC Electropedia: available at http://www.electropedia.org/
ISO Online browsing platform: available at http://www.iso.org/obp
3.1
stationary use
use of a product mounted firmly on a structure, or permanently placed at a certain site
3.2
non-weatherprotected location
location at which a product is not protected from meteorological conditions
3.3
sheltered location
location at which a product is covered by a structure to protect it from direct meteorological conditions, i.e. direct sunlight, heavy rain
4 General
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 severities 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 severities 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.
Example 2: In a mechanical shock test, the product can be subjected to mechanical shocks of simple pulse shapes (e.g., half-sine), while the actual conditions cannot be described by such simple pulses.
It is recognized that extreme or special environmental conditions may exist which require consideration of severities that are not addressed in this document. The user of this document should select the lowest classification necessary for covering the conditions of the intended use.
