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GB/T 2423 Environmental testing - Part 2: Test methods is divided into several parts according to test methods.
This is Part 7 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 2423.7-1995 Environmental testing for electric and electronic products Part 2: Test methods Test Ec and guidance: Drop and topple Primarily for equipment-type specimens and GB/T 2423.8-1995 Environmental testing for electric and electronic products Part 2: Test methods Test Ed: Free fall
In addition to editorial changes, the following main technical changes have been made with respect to GB/T 2423.7-1995 and GB/T 2423.8-1995:
--the title "Conditional test" is changed to be "Description" (see 5.1.1, and 3.2 of GB/T 2423.7-1995);
--"Test facility” is added (see 5.1.2 and 5.2.2);
--“Information to be given in the test report” is added (see Clause 8);
--"Selection of test severity" is deleted (see A3 of GB/T 2423.7-1995);
--the title "Severity" is changed to be "Test severity" and related contents are changed, "Note: heavy equipment should not be subjected to higher severity "(see 5.2.3, Clause 3 of GB/T 2423.8-1995).
--"Conditional test" is changed to be "Description" and "Testing procedures", (see 5.2.1 and 5.2.4, and Clause 5 of GB/T 2423.8-1995);
--“Information to be included in the relevant specification” is deleted (see Clause 15 of GB/T 2423.8-1995).
This standard, by means of translation, is identical to IEC 60068-2-31: 2008 Environmental testing – Part 2-31: Tests – Test Ec: Rough handling shocks, primarily for equipment-type specimens.
The following editorial changes have been made in this part:
--the standard name is modified;
--in the note of Figure A1 in IEC 60068-2-31, the word barrek is misspelled and should be barrel. Meanwhile, the word steel is omitted. Refer to the French version and revert to steel plate.
This part is under the jurisdiction of the National Technical Committee on Electric and Electronic Product Environment Technology of Standardization Administration of China (SAC/TC 8).
This part replaces GB/T2423.7-1995 and GB/T 2423.8-1995.
The previous editions of GB/T 2423.7-1995 are:
--GB/T 2423.7-1981;
-- GB/T 2424.5-1981.
The previous editions of GB/T 2423.8-1995 are:
--GB/T 2423.8-1981;
-- GB/T 2424.6-1981.
Environmental testing-Part 2: Test methods-
Test Ec: Rough handling shocks, primarily for equipment-type specimens
1 Scope
This part of GB/T 2423 deals with a test procedure for simulating the effects of rough handling shocks, primarily in equipment-type specimens, the effects of knocks, jolts and falls which may be received during repair work or rough handling in operational use.
Where the effects of loose cargo transportation are to be assessed, test Ee: Bounce shall be used. Also, where this effect is to be assessed refer to test Ea: Shock.
Generally, this test is only applicable to small to medium size equipment likely to receive such rough handling, and only be applied to those faces and corners where there is a risk of such treatment being encountered.
In general, equipment which is frequently handled and serviced (for example field equipment and unit spares) can be considered at such risk. Whereas equipment forming an integral part of a permanent installation would not normally be considered at such risk and need not be tested.
Testing may not be applicable to fragile unprotected equipment of irregular shape (for example aircraft nose radar) which, when removed from the installation would be contained in a handling frame or jig. It may however be applicable to these items of equipment when they are in their transit case or in their handling frame or jig.
For equipment which stands only on one face (for example the normal base) the test is generally only applied to that face.
Shock tests are performed on the specimen when fixed to the test machine. Drop and topple, free fall, repeated free fall and bounce tests are performed with the specimen free.
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.
GB/T 2423.39-2008 Environmental testing for electric and electronic products-Part 2: Test methods-Test Ee: Bounce (IEC 60068-2-55: 1987, IDT)
IEC 60068-2-27 Environmental testing-Part 2-27: Tests-Test Ea and guidance: Shock
IEC Guide 104 The preparation of safety publications and the use of basic safety publications and group safety publications
ISO 48:2007 Rubber, vulcanized or thermoplastic-Determination of hardness (hardness between 10 IRHD and 100 IRHD)
ISO 4180-2: 1980 Complete, filled transport packages-General rules for the compilation of performance test schedules-Part 2: Quantitative data
3 General description of test
Rough handling shocks can be simulated by one or more of the following tests:
a) Drop and topple: A simple test intended to assess the effects of knocks or jolts likely to be received primarily by equipment-type specimens during repair work or rough handling on a table or bench.
b) Free fall – Procedure 1: A simple test to assess the effects of falls likely to be experienced due to rough handling. It is also suitable to demonstrate a degree of robustness.
c) Free fall – Procedure 2: A test that simulates repetitive shocks likely to be received by certain component-type specimens, for example connectors in service.
The topple test need not be applied to specimens which have dimensions which make them stable whilst being handled. Reference to points 1) and 2) below should be made for information on the “C – g ratio” and “height ratio” to establish if the test is necessary.
The falling or topple actions produced by the test procedures given in 5.1.3.1, 5.1.3.2 and 5.1.3.3 are illustrated by Figures 1, 2 and 3. The drop and topple test includes three distinct procedures:
a) Dropping on to a face (5.1.3.1);
b) Dropping on to an edge or a corner (5.1.3.2);
c) Toppling (or pushover) (5.1.3.3).
The purpose of each of these procedures is basically the same, but they represent different kinds of handling.
The test is not intended to be a precise test and a tolerance of ±10 % is allowed on the heights and angles prescribed in 5.1.2.
For a more precise shock test, IEC 60068-2-27 shall be used.
The topple test need not be applied to specimens which have dimensions which make them stable while being handled. When considering the applicability of the topple test, two dimensional ratios are important:
1) The ratio of the height of the centre of gravity from the base, to the smaller dimension of the base, hereinafter referred to as the C – g ratio;
2) The ratio of the height of the specimen to the smaller dimension of the base, hereinafter referred to as the height ratio.
If the C – g ratio is small, for example less than 0.25, the specimen is unlikely to fall over due to sudden sideways displacements. If the height ratio is small, for example less than 0.5, the specimen is unlikely to topple over due to a sudden sideways force or blow at the top. In such cases the writer of the relevant specification shall consider whether the topple test is applicable.
Keys:
h - distance between edge of specimen and test surface;
a - angle between bottom face of specimen and test surface.
Figure 1 – Dropping on to a face
Dimensions in millimetres
Keys:
h - distance between edge of specimen and test surface
a - angle between bottom face of specimen and test surface
Figure 2 – Dropping on to a corner
Figure 3 – Topple (or push over)
4 Initial measurements
Before commencement of the test, the specimen shall be visually examined and electrically and mechanically checked as required by the relevant specification.
5 Testing
5.1 Drop and topple
5.1.1 Description
Having taken into account the manner in which the specimen will be handled in use and during repair, the relevant specification shall state the test procedure to be used and whether covers, cables, etc., are to be in position or not. The relevant specification shall also state whether the specimen is, or is not, operational during the test.
In the test procedure where the specimen is dropped on to a face or corner, it is possible for the specimen to topple onto a different face instead of falling back onto the test face as intended. This shall be avoided by a suitable method.
In any of the test procedures, the specimen shall not be allowed to continue rolling about the next edge.
Where the number of bottom edges exceeds four, the number of drops or topples shall be limited to four and the relevant specification shall prescribe the edges to be used for the test.
5.1.2 Test facility
The test facility surface shall be smooth, hard, rigid, unyielding, horizontal and, for example, made of concrete or steel. The steel plate shall be wet floated, that is, installed while the concrete is still wet in order to remove voids, or bonded to the concrete. For light facility, the surface mass of the facility shall be at least 20 times the mass of the specimen under test. The thickness of the steel plate shall be a minimum of 25 mm. With a specimen in excess of 500 kg, the steel plate shall be at least 40 mm thick, level within two degrees to the horizontal and with a Brinell hardness of 90 – 300.
5.1.3 Testing procedures
5.1.3.1 Dropping onto a face
The specimen, standing in its normal position of use, is tilted along one bottom edge so that the distance between the opposite edge and the test surface is 25 mm, 50 mm or 100 mm, as prescribed by the relevant specification, or so that the angle made by the bottom and the test surface is 30°, whichever condition is less severe. It is then allowed to fall freely onto the test surface.
The specimen shall be subjected to one drop along each of four bottom edges (see Figure 1).
5.1.3.2 Dropping onto an edge or a corner
The specimen, standing in its normal position of use, is raised above the test surface by placing a wooden stud 10 mm high under one corner, and a 20 mm wooden stud under the other adjacent corner of one of the bottom edges. The specimen is then lifted above the test surface by rotating it about the edge on the two studs, until the other corner adjacent to the 10 mm stud is raised 25 mm, 50 mm or 100 mm, as prescribed in the relevant specification, or so that the angle made by the specimen and the test surface is 30°, whichever condition is less severe.
It is then allowed to fall freely on the test surface.
The specimen shall be subjected to one drop on each of the four bottom corners by applying the test along the four bottom edges in turn (see Figure 2).
5.1.3.3 Topple or push-over
The specimen, standing in its normal position of use, is tilted about one bottom edge until it reaches a position of instability. It is then allowed to fall over freely from this position on to an adjacent face.
The specimen shall be subjected to one topple about each of four bottom edges (see Figure 3).
Foreword I
1 Scope
2 Normative references
3 General description of test
4 Initial measurements
5 Testing
6 Final measurements
7 Information to be included in the relevant specification
8 Information to be given in the test report
Annex A (Normative) Test apparatus for repeated free fall test – Procedure
Annex B (Informative) Facility for free fall tests – Guidance
