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1、BRITISH STANDARD BS 2011-2.1 Kc: 1991 Environmental testing Part 2.1: Tests Test Kc and guidance. Sulphur dioxide test for contacts and connections This Part should be read in conjunction with Part 1.1 General and guidance Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 200
2、6, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 This British Standard, having been prepared under the direction of the General Electrotechnical Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 29 March 1991 BSI 04-1999 First published Aug
3、ust 1977 Second edition March 1991 The following BSI references relate to the work on this standard: Committee reference GEL/15 Draft for comment 90/28737 DC ISBN 0 580 19314 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the General Elec
4、trotechnical Standards Policy Committee (GEL/-) to Technical Committee GEL/15, upon which the following bodies were represented: Association of Manufacturers of Domestic Electrical Appliances British Telecommunications plc Directorate of Telecommunications EEA (The Electronics and Business Equipment
5、 Association) Electronic Components Industry Federation Ministry of Defence National Supervising Inspectorate Society of Environmental Engineers Society of Motor Manufacturers and Traders Limited Telecommunication Engineering and Manufacturing Association The following bodies were also represented i
6、n the drafting of the standard, through subcommittees and panel: Biodeterioration Society Institute of Metals Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 BSI 04-
7、1999i Contents Page Committees responsibleInside front cover Forewordii 1General1 2Object1 3Test chamber1 4Test atmosphere1 5Initial measurements1 6Conditioning2 7Final measurements2 8Information to be given in the relevant specification2 Appendix A Generation of the conditioning atmosphere by direc
8、t mixing of sulphur dioxide with air3 Appendix B Generation of the conditioning atmosphere by combustion5 Appendix C Guidance8 Figure 1 Schematic drawing of apparatus with generation of conditioning atmosphere by direct mixing of sulphur dioxide with air4 Figure 2 Polluted atmosphere cabinet (combus
9、tion method) Schematic flow diagram6 Figure 3 Polluted atmosphere cabinet (combustion method) General arrangement7 Table I5 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 ii BSI
10、 04-1999 Foreword This British Standard has been prepared under the direction of the General Electrotechnical Standards Policy Committee and supersedes BS 2011-2.1Kc:1977 which is withdrawn. It is related to IEC Publication 68-2-42:1976 “Basic environmental testing procedures. Part 2: Tests Test Kc:
11、 Sulphur dioxide test for contacts and connections” and IEC Publication 68-2-49:1983 “Basic environmental testing procedures. Part 2: Tests Guidance to Test Kc: Sulphur dioxide test for contacts and connections” published by the International Electrotechnical Commission (IEC). For ease of reproducti
12、on, the IEC text has been used for the main text of the standard. It should be noted that the 1976 edition of IEC 68-2-42 has been withdrawn on the issue of the 1982 revision of IEC 68-2-42. This British Standard is not identical with IEC 68-2-42:1982 and/or IEC 68-2-49:1983 and should not be regard
13、ed as being other than a related standard, i.e. one whose content is short of identity or technical equivalence. Guidance on the sulphur dioxide test for contacts and connections is given in Appendix C. A British Standard does not purport to include all the necessary provisions of a contract. Users
14、of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 14, an inside back cover and a b
15、ack cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1
16、991 BSI 04-19991 1 General This test: is intended to provide accelerated means to assess the corrosive effects on contacts and connections of atmospheres polluted with sulphur combustion products; is particularly suitable for giving information on a comparative basis; is not suitable as a general co
17、rrosion test, i.e. it may not predict the behaviour of contacts and connections in industrial atmospheres. 2 Object a) To determine the influence of atmospheres containing sulphur dioxide on the contact properties of precious metal or precious-metal-covered contacts excluding contacts consisting of
18、silver and some of its alloys. b) To check wrapped or crimped connections with regard to their tightness or effectiveness. In all tests, the major criteria of performance will be the change in contact resistance caused by exposure to the sulphur dioxide containing atmosphere. 3 Test chamber The test
19、 chamber and its auxiliary parts shall be made of materials that do not react with or absorb sulphur dioxide and which do not influence the corrosive effects of the test atmosphere. The atmosphere shall enter and leave the chamber through tubes with sufficiently large diameters such that the total f
20、low through the chamber is at least three, but not more than five, changes of the atmosphere per hour. The exhaust from the chamber should not be allowed to enter the laboratory. The detailed construction of the chamber including the method of producing the test atmosphere is optional provided that:
21、 a) the conditions in that part of the chamber occupied by the specimens are within the specified limits; b) the specimens under test are protected from direct impingement of the incoming gas flow; c) arrangements are made to move the specimens through the test atmosphere at an average rate of 20 to
22、 60 m per h (approx. 6 to 17 mm/s) or alternatively to gently stir the atmosphere, obtaining a similar relative velocity between atmosphere and specimen; d) condensation does not occur on the inside walls of the test chamber. Examples for suitable arrangements of test apparatus are given in Appendix
23、 A and Appendix B. 4 Test atmosphere The composition of the atmosphere within the test chamber shall satisfy the following conditions: sulphur dioxide (Note 1): 25 5 parts per million (vol/vol). carbon dioxide maximum: 4 500 parts per million (vol/vol) permitted. temperature: 25 2 C. relative humidi
24、ty: 75 % (Note 2). NOTE 1This shall be taken as the total oxides of sulphur expressed as SO2. Small concentrations of sulphur oxides other than SO2 (such as SO3) are permitted to be present to a maximum concentration of 1 % of the total sulphur oxides. NOTE 2The relative humidity shall be held as cl
25、ose as possible to 75 %, but shall in no case exceed 80 % nor fall below 70 %. The test atmosphere may be obtained by: a) mixing directly the necessary constituents in such a way as to ensure a homogeneous mixture (more than one stage may be necessary to obtain a homogeneous distribution of the smal
26、l quantity of SO2,). An example for such a process is given in Appendix A; b) generating the SO2, by a burning process and adjusting the resulting gas mixture to the specified composition. An example for such a process is given in Appendix B. The test report shall state which of the two methods for
27、obtaining the test atmosphere has been used. 5 Initial measurements The specimens under test shall not be cleaned in any way unless required by the manufacturers instructions, the relevant specification, or agreed upon between the interested parties. The relevant specification may require that befor
28、e and after the test, resistance measurements shall be carried out in combination with mechanical tests (e.g. shock or vibration tests). The specimens shall be measured, mechanically checked and subjected to mechanical endurance as required by the relevant specification. The contact resistance shall
29、 be measured by the low open-circuit voltage method (e.g. 1.2.4.2 of BS 9520:1983) in order to avoid damage to films formed on contact surfaces. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 2 BSI 04-1999 6 Conditioning
30、Prior to the commencement of the test it shall be established by suitable measurements that stable conditions for the concentration of sulphur dioxide, the temperature and the relative humidity have been achieved. Periodic checks shall be made during the test to ensure that these conditions are main
31、tained. Care shall be taken that the specimens are so placed that they do not come into contact with one another and that they do not shield one another from the test atmosphere. Adequate precautions shall be taken to ensure that the contacts are not disturbed during the exposure period. Specimens s
32、hall be exposed with contacts open and/or closed as prescribed in the relevant specification. The loading or functioning of the specimens should be permitted when prescribed in the relevant specification. The specimens shall be continuously exposed to the conditioning atmosphere for 4, 10 or 21 days
33、 as required by the relevant specification. 7 Final measurements The specimens shall be removed, from the chamber and stored under standard recovery conditions for not less than 1 h and not more than 2 h before contact resistance measurements are made. Adequate precautions shall be taken to ensure t
34、hat the contacts are not disturbed. The method used for measuring the contact resistance should be the same as used for the initial measurement. NOTEIf the necessary measurements cannot be made within the specified time, the period of storage under recovery conditions may be extended to a maximum of
35、 24 h. Such an extension shall be mentioned in the report. In general, specimens which are exposed with contacts in the mated condition shall have their contact resistance measured before they are unmated. Specimens exposed with contacts in the unmated condition shall be mated once and the contact r
36、esistance shall then be measured. Treatment of the contacts before final measurements are made and the details of measurements shall be as required by the relevant specification. Visual inspection of the specimens may be called for by the relevant specification. 8 Information to be given in the rele
37、vant specification The relevant specification shall specify the following details: a) measurements, checks and mechanical endurance to be made prior to the test; b) state of the contacts during the test, i.e. mated (closed) or unmated (open); c) loading or functioning of the specimens if applicable;
38、 d) duration of the test; e) measurements, checks and visual inspection to be made at the end of the test. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 BSI 04-19993 Appendix A Generation of the conditioning atmosphere b
39、y direct mixing of sulphur dioxide with air As an example, this appendix schematically describes an apparatus suitable for producing the test atmosphere by directly mixing the necessary components. Other apparatus and methods of mixing and control may be used provided they comply with all the requir
40、ements of this specification. The test apparatus shown in Figure 1 is composed of an air-conditioning unit, a gas supply with dosing pump, a test cabinet, a gas wash bottle for the removal of sulphur dioxide from the exhaust gases, an air flowmeter and a suction pump. The air-conditioning unit and t
41、est cabinet generally resemble commercially available climatic test cabinets. Commercially available pressure bottles of chemically pure gas, possibly diluted, can be used. The corrosive gas is mixed by way of a pressure reducing valve, a dosing pump and an injector with the flow of (temperature con
42、trolled and humidified) air from the air-conditioning unit. In the test cabinet, the gas is distributed uniformly by means of baffle plates. The test gas is removed from the test cabinet by the suction pump and passes through the gas wash bottle in which the corrosive gas component is removed. A fre
43、ezing trap should be interposed between the gas wash bottle and the suction pump. The air flowmeter measures the air flow which is adjusted to the required value. Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 4 BSI 04-19
44、99 Figure 1 Schematic drawing of apparatus with generation of conditioning atmosphere by direct mixing of sulphur dioxide with air Licensed Copy: sheffieldun sheffieldun, na, Tue Nov 28 13:49:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 2011-2.1Kc:1991 BSI 04-19995 Appendix B Generation of the c
45、onditioning atmosphere by combustion As an example, this appendix describes an apparatus of approximately 200 l capacity. Other apparatus and methods of producing the atmosphere may be used provided they comply with all the requirements of this specification. The test atmosphere is generated by burn
46、ing gas enriched with sulphur and diluting the products of combustion with air so as to give the required condition. This mixture is then continuously passed through the test chamber. Suitable gases are: natural gas, butane or propane. Carbon disulphide is used as a means of providing the enrichment
47、 of sulphur and the level of sulphur dioxide is controlled by adjustment of the temperature of the reservoir of carbon disulphide. The relative humidity and temperature arising from combustion of the gas are unlikely to provide the specified conditions in the test chamber. It will therefore be neces
48、sary to provide means of adjusting the humidity and the temperature of the incoming air. The design of the jet and the flow rates of the air and carrier gas must ensure that complete combustion of the carrier gas is attained, as evidenced by a non-luminous flame. The flame size shall be 3 to 4 mm di
49、ameter and 8 to 12 mm high. The carbon dioxide levels given in Table I correspond to complete combustion and provide a guide to the rate of gas consumption. Table I states the level of carbon dioxide and the flow rate, with appropriate control tolerances, for each of the specified gases. Monitoring the flow rate or the carbon dioxide concentration is required in order to check the stability of the test atmosphere. Table I The apparatus is built in two main parts, the exposure cabinet and the atmosphere generator. The cabinet, a 200 l test