The components of standard GB/T 2423 are given in Annex NA (Informative).
This is Part 3 of GB/T 2423.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 2423.3-2006 Environmental testing for electric and electronic products - Part 2: Testing method - Test Cab: Damp heat, steady state, and the following main technical changes have been made with respect to GB/T 2423.3-2006:
——The structure of this part is rearranged;
——The "Introduction" and Clause 7 "Information to be given in the test report" are added;
——In the seventh line of 4.1, the original "water utilized to maintain humidity levels has electrical conductivity of not more than 500Ω·m" is changed to "water utilized to maintain humidity levels has electrical conductivity of not more than 20μS/cm";
——The specific requirements for recovery conditions in GB/T 2423.3-2006, Clause 9 "Recovery" are deleted.
This part, by means of translation, is identical to IEC 60068-2-78:2012 Environmental testing - Part 2-78: Tests - Test Cab: Damp heat, steady state.
The Chinese documents identical to the normative international documents given in this part are as follows:
——GB/T 2421.1-2008 Environmental testing for electric and electronic products - General and guidance (IEC 60068-1:1988, IDT);
——GB/T 2424.6-2006 Environmental testing for electric and electronic products - Confirmation of the performance of temperature/humidity chambers (IEC 60068-3-6:2001, IDT);
——GB/T 16499-2008 The Preparation of safety publication and the use of basic safety publications and group safety publications (IEC 104 Guide:1997, NEQ).
The following main editorial changes have been made with respect to IEC 60068-2-78:2012:
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——The name of this part is changed to "Environmental testing - Part 2: Testing method - Test Cab: Damp heat, steady state";
——Annex NA (Informative) "Components of the standard GB/T 2423" is added.
This part 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 part are as follows:
——GB/T 2423.3-1981, GB/T 2423.3-1993, GB/T 2423.3-2006;
——GB/T 2423.9-1989, GB/T 2423.9-2001.
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Introduction
This part of GB/T 2423 provides a test method of high humidity at constant temperature without condensation on the specimen over a prescribed period. This test is performed to evaluate the specimen as it is influenced by the absorption and diffusion of moisture and moisture vapour.
Environmental testing - Part 2: Testing method - Test Cab: Damp heat, steady state
1 Scope
This part of GB/T 2423 establishes a test method for determining the ability of components or equipment to withstand transportation, storage and use under conditions of high humidity.
The object of this part is to investigate the effect of high humidity at constant temperature without condensation on a specimen over a prescribed period.
It is applicable to small equipment or components as well as large equipment, and can be applied to both heat-dissipating and non-heat-dissipating specimens.
2 Normative references
The following referenced documents are indispensable for the application 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 60068-1 Environmental testing - Part 1: General and guidance
IEC 60068-3-6 Environmental testing - Part 3-6: Supporting documentation and guidance - Confirmation of the performance of temperature and humidity chambers
IEC Guide 104 The preparation of safety publications and the use of basic safety publications and group safety publications
3 Terms and definitions
None.
4 General test procedure
4.1 Test chamber and measuring system
The temperature and humidity chamber shall be constructed and verified in accordance with specifications IEC 60068-3-6.
The chamber and measuring system shall be such that:
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——sensing devices can be located in the working space to monitor the temperature and humidity;
Note: For heat-dissipating specimens, the temperature and humidity near the specimen may be influenced by the effect of heat dissipation from the specimen.
——condensed water is drained from the chamber and not re-used unless purified;
——no condensed water from the walls and roof of the test chamber can fall on the specimen(s);
——water utilized to maintain humidity levels has electrical conductivity of not more than 20μS/cm;
——the specimen under test shall not be subjected to radiant heat from the chamber conditioning devices;
——injected moisture, when applicable, is injected remotely from the specimen and without being directly on it;
——the volume of the test chamber is at least five times the total volume of the specimen under test;
——a mounting device, when used, has minimum influence on the heat and humidity exchanges between specimen and surrounding conditions, unless otherwise specified in the relevant specification.
4.2 Severity
The test severity is defined by a combination of temperature, relative humidity (RH) and total test duration. Unless otherwise specified in the relevant specification, temperature and RH severities may be selected from the following:
Table 1 Temperature and relative humidity
Temperature
℃ Relative humidity
% RH
30±2 93±3
30±2 85±3
40±2 93±3
40±2 85±3
Preferred test durations are: 12h, 16h, 24h; 2d, 4d, 10d, 21d or 56d.
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The total temperature tolerance of ±2K is intended to take account of absolute errors in the measurement, slow changes of temperature and temperature variations of the working space. However, in order to maintain the RH within the required tolerances, it is necessary to keep the temperature difference between any two points in the working space at any moment within narrower limits. The required humidity conditions will not be achieved if such temperature differences exceed 1K. It may also be necessary to keep short-term fluctuations within ±0.5K to maintain the required humidity.
4.3 Pre-conditioning
The relevant specification may call for pre-conditioning.
4.4 Testing procedure
The specimen shall be introduced into the chamber as required by the relevant specification. The specimen shall be introduced in the unpacked, switched-off, ready-for-use state, or as otherwise specified in the relevant specification.
In certain cases the relevant specification may allow the introduction of the specimen in the chamber when this is already in the condition prescribed for the test; however, condensation on the specimen shall always be avoided. This can be obtained for small specimens by pre-heating them to the chamber temperature.
Adjust the temperature in the chamber to the prescribed severity. In order to avoid condensation on the specimen, control the specimen temperature or allow the specimen to reach the temperature first and then adjust the humidity in the chamber to the prescribed severity.
Adjust the humidity to the prescribed severity within a period of time of not more than 2h.
Expose the specimen to the test conditions and duration as specified in the relevant specification. The duration is measured from the time the specified conditions are achieved.
The relevant specification shall define the operating conditions and the period (or periods) in which they shall be carried out.
After conditioning at the prescribed severity and before the final measurement, the recovery procedure shall be followed.
4.5 Recovery procedure
The relevant specification shall prescribe the recovery method and duration. Recovery conditions are described in IEC 60068-1.
5 Measurements
5.1 Initial measurements
The specimen shall be visually inspected and electrically and mechanically checked, as required by the relevant specification.
5.2 Intermediate measurements
The relevant specification may call for measurements during the test procedure while the specimen is still in the chamber. If such measurements are required, the relevant specification shall define the measurements and the period (periods) at which they shall be carried out. For these measurements, the specimen shall not be removed from the chamber.
5.3 Final measurements
The specimen shall be visually inspected and electrically and mechanically checked, as required by the relevant specification.
Foreword I
Introduction III
1 Scope
2 Normative references
3 Terms and definitions
4 General test procedure
4.1 Test chamber and measuring system
4.2 Severity
4.3 Pre-conditioning
4.4 Testing procedure
4.5 Recovery procedure
5 Measurements
5.1 Initial measurements
5.2 Intermediate measurements
5.3 Final measurements
6 Information to be given in the relevant specification
7 Information to be given in the test report
Annex NA (Informative) Components of the standard GB/T
