Detail of GB/T 2424.5-2021

Introduction of GB/T 2424.5-2021

This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents. This document is Part 5 of GB/T 2424. The components of standard GB/T 2424 are given in Annex NA. This document partially replaces GB/T 2424.5-2006 Environmental tests for electric and electronic products - Confirmation of the performance of temperature chambers. In addition to structural adjustment and editorial changes, the following main technical changes have been made with respect to GB/T 2424.5-2006: a) The term and definition of "temperature extremes" is deleted (see 3.10 in Edition 2006); b) The content of "test area environment" is simplified (see 4.1, 4.1 of Edition 2006); c) "Determination of temperature performance" is deleted (see 4.5 of Edition 2006); d) "Measurement method is added" (see 4.5); e) The content of Chapter 5 of the 2006 edition is adjusted to 4.6. This part, by means of translation, is identical to IEC 60068-3-5:2018 Environmental testing - Part 3-5: Supporting documentation and guidance - Confirmation of the performance of temperature chambers. The Chinese document consistent and corresponding with the normative international document in this Documentation is as follows: ——GB/T 2424.7-2006, Environmental tests for electric and electronic products - Measurements in temperature chambers for tests A and tests B (with load) (IEC 60068-3-7:2001, IDT); ——GB/T 2424.27-2013, Environmental testing - Supporting documentation and guidance - Calculation of uncertainty of conditions in climatic test chambers (IEC 60068-3-11:2007, IDT). The following editorial changes have been made in this document: ——The name of this document is changed to Environmental testing - Part 3: Supporting documentation and guidance - Confirmation of the performance of temperature chambers; ——An annex "Components of the standard GB/T 2424" is added (see Annex NA). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights. This document was proposed and is under the jurisdiction of SAC/TC 8 National Technical Committee on Environmental Conditions and Testing for Electric and Electronic Products and of Standardization Administration of China. The previous editions of this standard are as follows: ——This standard was issued in 2006 as first edition (GB/T 2424.5-2006). ——This edition is the first revision. Introduction IEC 60068 (all parts) contains fundamental information on environmental testing procedures and severities. The expression "environmental conditioning" or "environmental testing" covers the natural and artificial environments to which components or equipment may be exposed so that an assessment can be made of their performance under conditions of use, transport and storage to which they may be exposed in practice. Temperature chambers used for "environmental conditioning" or "environmental testing" are not described in any publication, although the method of maintaining and measuring temperature and/or humidity has a great influence on test results. The physical characteristics of temperature chambers can also influence test results. In this series of standards, each document of GB/T 2424 Environmental testing - Part 3: Supporting documentation and guidance - Confirmation of the performance of temperature chambers gives a set of background information for environmental testing. Since 1981, GB/T 2424 has successively issued more than 20 documents (13 current national standards, 12 of which use IEC 60068 Environmental Test). The current components of GB/T 2424 are detailed in Appendix NA. This revision of GB/T 2424.5 uses the translation method to be equivalent to the use of IEC 60068-3-5: 2018 Environmental testing - Part 3-5: Supporting documentation and guidance - Confirmation of the performance of temperature chambers. The revised version is consistent with international standards. Maintaining the same level will help eliminate technical trade barriers and better promote trade, exchanges and technical cooperation. Environmental testing - Part 3: Supporting documentation and guidance - Confirmation of the performance of temperature chambers 1 Scope This document provides a uniform and reproducible method of confirming that temperature test chambers, without specimens, conform to the requirements specified in climatic test procedures of IEC 60068-2 (all parts) and other standards. This document is intended for users when conducting regular chamber performance monitoring. 2 Normative references The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60068-2 (all parts) Environmental testing - Part 2: Tests IEC 60068-3-7 Environmental testing - Part 3-7: Supporting documentation and guidance - Measurements in temperature chambers for tests A and B (with load) IEC 60068-3-11 Environmental testing - Part 3-11: Supporting documentation and guidance - Calculation of uncertainty of conditions in climatic test chambers 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 temperature test chamber enclosure or space in some parts of which the temperature conditions, specified in IEC 60068-2 (all parts), can be achieved 3.2 temperature setpoint desired temperature as set by the test chamber control system 3.3 achieved temperature stabilized temperature which desired temperature at the centre of the working space achieves within specified tolerance 3.4 temperature stabilization state of maintaining temperature within specified tolerance during specified time at specified points in the working space 3.5 temperature fluctuation difference, after stabilization, between the maximum and minimum temperatures at specified point in the working space during a specified interval of time Note: For calibration, the centre point of working space may be used. 3.6 working space part of the chamber in which the specified conditions can be maintained within the specified tolerances Note: See Figure 1 and Table 1. Figure 1 Working space Table 1 Practical dimensions Size Volume (L) Distance X mm X (min.)/mm Small <1000 L/10 50 Middle 1000~2000 L/10 100 Large >2000 L/10 150 Note: Not all chambers are cubic in construction. 3.7 temperature gradient maximum difference in mean value, after stabilization, at any moment in time between two separate points in the working space 3.8 temperature variation in space difference in mean value, after stabilization, at any moment in time between the temperature at the centre of the working space and at any other point in the working space 3.9 temperature rate of change rate, in kelvin per minute, for the transition between two specified temperatures measured at the centre of the working space Note: see Figure 2. Figure 2 Example of temperature differences 4 Measuring test chamber performances 4.1 Test area environment The environment around a temperature test chamber may influence the conditions inside the test chamber. The confirmation of performance of temperature chambers should be carried out under standard atmospheric conditions specified in IEC 60068-1. 4.2 Temperature measurement system The uncertainty of measurement of the output of the measurement system should be determined by calibration of the system, traceable to international standards (see ISO 10012). The temperature sensors may be either calibrated platinum resistors or a thermocouple. The thermal response time of the sensors shall be within a minimum of 10 s and a maximum of 40 s for 50 % of response. It is preferred that the thermal response time of the entire measurement system to be less than 40 s. The use of sensors that are compliant to IEC 60584-1 tolerance class 1 (for thermocouples) or IEC 60751 tolerance class A (for resistors) is recommended. 4.3 Test load All measurements described in 4.5 are performed with an empty working space. For measuring with test specimens (with or without heat dissipation), see IEC 60068-3-7. 4.4 Specified location of temperature sensors in working space Temperature measuring sensors are located in each corner and in the centre of the working space (see Figure 3, minimum 9 sensors). For temperature chambers over 2000 L, additional sensors should be located in front of the centre of each wall (see Figure 4, minimum 15 sensors). The measuring system is to be arranged in such a way that the temperature distribution of the empty test chamber will not be affected. For a large capacity chamber, there may be a significant difference between the temperature control sensor(s) and the temperature at the centre of the working space. It may be necessary to adjust the temperature setting to achieve the necessary tolerance. For confirmation monitoring, data shall be recorded at least once a minute. The device used for recording data from the test chamber monitoring sensors shall be independent of the test chamber control system.

Contents of GB/T 2424.5-2021

Foreword I Introduction III 1 Scope 2 Normative references 3 Terms and definitions 4 Measuring test chamber performances 5 Information to be given in the performance test report Annex NA (Informative) Components of the standard GB/T Bibliography Figure 1 Working space Figure 2 Example of temperature differences Figure 3 Location of sensors for temperature chambers up to 2000 L Figure 4 Location of minimal additional sensors for temperature chambers over 2000 L Figure 5 Example of achieved temperature Figure 6 Example of temperature stabilization for chambers up to 2000 L Figure 7 Example of temperature fluctuation Figure 8 Example of temperature gradient for chambers up to 2000 L Figure 9 Example of temperature gradient for chambers <2000 L Figure 10 Example of temperature rate of change Table 1 Practical dimensions