1、BRITISH STANDARD BS 5142:1974 IEC 428:1973 Specification for Standard cells UDC 621.352.122BS5142:1974 This British Standard, having been approved by the Electrical Industry Standards Committee, was published under the authorityof the Executive Boardon 19 July 1974 BSI 10-1999 The following BSI refe
2、rences relate to the work on this standard: Committee reference ELE/13/5 Draft for comment 71/24546 ISBN 0 580 08208 3 Co-operating organizations The Electrical Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Go
3、vernment departments and scientific and industrial organizations: The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British St
4、andard: Associated Offices Technical Committee Department of the Environment Association of Consulting Engineers* Department of Trade and Industry Association of Manufacturers of Domestic Electric Cable Makers Confederation Electrical Appliances Electrical Contractors Association Association of Mini
5、ng, Electrical and Electrical Contractors Association of Scotland Mechanical Engineers Electrical Research Association Association of Supervisory and Executive Electricity Supply Industry in England and Engineers* Wales* British Electrical and Allied Manufacturers Electronic Engineering Association
6、Association Engineering Equipment Users Association* British Electrotechnical Approvals Board for Institution of Electrical and Electronics Household Equipment Technician Engineers British Non-ferrous Metals Federation Institution of Electrical Engineers* British Radio Equipment Manufacturers Lighti
7、ng Industry Federation Limited Association Ministry of Defence* British Railways Board National Inspection Council for Electrical British Steel Corporation Installation Contracting Crown Agents for Oversea Governments and Oil Companies Materials Association Administrations Post Office* Department of
8、 Employment (HM Factory South of Scotland Electricity Board Inspectorate) British Industrial Measurement and Control National Physical Laboratory (Department of Apparatus Manufacturers Association Trade and Industry) Department of Trade and Industry (British Radio Electronic Component Manufacturers
9、Calibration Service) Federation Electrical Power Engineers Association Scientific Instrument Manufacturers Ministry of Defence, Navy Department Federation Ministry of Defence, Procurement Executive Transmission and Distribution Association (B.E.A.M.A.) Amendments issued since publication Amd. No. Da
10、te of issue CommentsBS5142:1974 BSI 10-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Classification 2 4 Operating temperature range of standard cells 3 5 E.m.f. of standard cells 3 6 Permissible deviation of e.m.f. over one year 3 7 Test c
11、onditions for certification 3 8 Requirements for the electrical and mechanical characteristics 4 9 Transport and storage 5 10 Markings and symbols 6 Appendix 7 Table I Class indices for standard cells 2 Table II Permissible e.m.f. deviation over one year 3 Table III Tolerance on stabilization and me
12、asurement temperature 4 Table A.I Limit of permissible change in e.m.f. during temperature cycling 7 Publication referred to Inside back coverBS5142:1974 ii BSI 10-1999 Foreword This British Standard has been prepared under the authority of the Electrical Industry Standards Committee. It is identica
13、l both in technical content and format with Publication428 “Standard cells” of the International Electrotechnical Commission. Because the text of an IEC Publication has been copied, it includes some minor material not appropriate to a British Standard. For the purposes of this British Standard, the
14、text of IEC Publication428, given in this publication, is amended as follows. Terminology. The words “British Standard” replace “Recommendation” wherever it appears. Cross-references. The references to other IEC Recommendations are replaced by references to British Standards as follows: A British St
15、andard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Subclause Reference to IEC Publication Appropriate Br
16、itish Standard 10.1 f) and 10.2 f) Publication 51:1973 “Recommendations for direct acting indicating electrical measuring instruments and theiraccessories”. 10.1 and Table XI BS 89 “Direct acting electrical indicating instruments”, Part1:1970 “Single purpose direct acting electrical indicatinginstru
17、ments and their accessories”. 10.1 and Table 15 Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will b
18、e indicated in the amendment table on the inside front cover.BS5142:1974 BSI 10-1999 1 1 Scope 1.1 This recommendation applies to the following two types of standard cells used as electromotive force (e.m.f.) references, viz.: saturated standard cells; unsaturated standard cells. 1.2 This recommenda
19、tion does not apply to: cells used as international or national standards of e.m.f.; assemblies consisting of a temperature-controlled enclosure containing one or more standard cells; sources of e.m.f. intended to supply a current. 2 Definitions For the purposes of this recommendation, the following
20、 definitions apply. 2.1 saturated standard cell a cell used as an e.m.f. reference, having the negative electrode of cadmium amalgam and the positive one of mercury covered with a paste of Hg 2 SO 4and a saturated aqueous solution of cadmium sulphate, the electrolyte remaining saturated throughout t
21、he operating temperature range of the cell by the presence of crystals of3 CdSO 4 .8 H 2 O NOTEA small amount of sulphuric acid may be present in the electrolyte to improve the electrical stability of the cell. 2.2 unsaturated standard cell a cell used as an e.m.f. reference, having the negative ele
22、ctrode of cadmium amalgam and the positive one of mercury covered with a paste of Hg 2 SO 4and an unsaturated aqueous solution of cadmium sulphate, the electrolyte remaining unsaturated throughout the operating temperature range of the cell NOTE 1A small amount of sulphuric acid may be present in th
23、e electrolyte to improve the electrical stability of the cell. NOTE 2At the lower limit of this range, the electrolyte may become saturated. 2.3 Reference temperature range 2.3.1 for saturated standard cells that temperature range stated by the manufacturer within which the difference between the me
24、asured e.m.f. and the e.m.f. predicted by the formula given in Sub-clause5.3 does not exceed50% of the value corresponding to the class index 2.3.2 for unsaturated standard cells that temperature range stated by the manufacturer within which the difference between the measured e.m.f. and the e.m.f.
25、at the certification temperature does not exceed50% of the value corresponding to the class index 2.4 certification value of e.m.f. a value of e.m.f. given on a calibration certificate 2.5 certification temperature a temperature given on the calibration certificate as applying to a certification val
26、ue of the e.m.f. 2.6 temperature-hysteresis effect the residual difference between two or more values of the e.m.f. of the same cell measured at the same temperature before and after a specified temperature cycle of specified duration (SeeAppendix.)BS5142:1974 2 BSI 10-1999 2.7 deviation of the e.m.
27、f. (with respect to the certified value) the difference between the e.m.f. measured at the certification temperature and the certification value 2.8 accuracy class a classification of standard cells all having the same stability with respect to time. The stability of a standard cell is defined by th
28、e maximum permissible deviation of the e.m.f. during a period of one year from the date of initial certification provided that the cell is used and maintained under specified conditions 2.9 class index the number which designates the accuracy class 2.10 operating temperature range the temperature ra
29、nge to which the cell may be subjected while still complying with the requirements of this recommendation 2.11 permissible discharge the quantity of electricity, expressed in coulombs, which a cell can discharge (or absorb) without the difference in e.m.f. measured immediately before and a specified
30、 time after the discharge (absorption) exceeding a specified amount NOTEThe discharge can be: either of a small value which can occur in normal use of the standard cell due to deterioration (see Sub-clause8.1.1); or of a more considerable value which can occur accidentally (see Sub-clause8.1.2). 2.1
31、2 permissible cumulative discharge the sum of the absolute values of all the quantities of electricity (including the accidental ones), expressed in coulombs, which the cell can discharge or absorb whilst still fulfilling the requirements related to its accuracy class (See Sub-clause8.1.3.) 3 Classi
32、fication Standard cells satisfying this recommendation are classified as follows: 3.1 According to their types: saturated cells; unsaturated cells. 3.2 According to their accuracy class (as defined in Sub-clause 2.8) in one of the classes designated by the class indices given inTable I. There are tw
33、o permissible methods of expressing the class index of a standard cell. They are both related to the deviation of the e.m.f., one being expressed as a percentage, for example0.0002, the other being expressed in parts per million, for example2p.p.M. The class index of a standard cell can be given usi
34、ng either method or both methods. Table I Class indices for standard cells Type of cell Class index Saturated Expressed in % 0.000 2 0.000 5 0.001 0.002 0.005 0.01 Expressed in p.p.M. 2 5 10 20 50 100 Unsaturated Expressed in % 0.002 0.005 0.01 Expressed in p.p.M. 20 50 100BS5142:1974 BSI 10-1999 3
35、4 Operating temperature range of standard cells Unless otherwise stated by the manufacturer, the operating temperature range shall be: for saturated standard cells: from10 C to40 C; for unsaturated standard cells: from4 C to40 C. 5 E.m.f. of standard cells 5.1 The certification value of the e.m.f. o
36、f a standard cell, together with the certification temperature, shall be stated by the manufacturer or by the certifying laboratory. The uncertainty of the measurement shall be stated. NOTEStandard cells are usually certified at one of the following temperatures:20 C,25 C or28 C. However, any certif
37、ication temperature within the operating range of the cells may be agreed between user and manufacturer or responsible supplier. 5.2 The certified e.m.f. values of standard cells at20 C shall be within the range: from 1.018 54 V to1.01873V for saturated cells, and from 1.018 8V to1.0196V for unsatur
38、ated cells. 5.3 To determine the e.m.f. of a saturated standard cell within the reference temperature range(s), the following formula shall be used: E t= E t1 +a (t t 1 )+b (t t 1 ) 2 + c (t t 1 ) 3 where: E t =e.m.f., in volts, of the standard cell at temperature t E t1 =e.m.f., in volts, of the st
39、andard cell at temperature t 1 t =temperature, in degrees Celsius, at which the e.m.f. is to be determined t 1 =certification temperature, in degrees Celsius and the values of a, b and c are characteristic of the standard cell and of the temperature t 1and shall be given by the manufacturer. See Sub
40、-clause10.4 k). 5.4 For unsaturated standard cells, the difference of the e.m.f. at any temperature within the operating temperature range, from the e.m.f. at the certification temperature, shall not exceed100% of the value corresponding to the class index. 6 Permissible deviation of the e.m.f. over
41、 one year The limits of permissible deviation of the e.m.f. expressed in percentage (%) and in parts per million (p.p.M.), during the period of one year from the date of initial certification, are given inTable II. Table II Permissible e.m.f. deviation over one year NOTEThis recommendation only spec
42、ifies the permissible deviation for a period of one year from the date of initial certification. However, periodic recertification is recommended throughout the life of a standard cell. 7 Test conditions for certification 7.1 General conditions 7.1.1 No certification shall be carried out until the c
43、ells have been subjected to an ageing process specified by the manufacturer. 7.1.2 Standard cells shall be capable of being tested in any mounting position of use specified by the manufacturer or responsible supplier. In the absence of such a statement, any mounting position of use is permissible. C
44、lass index (%) 0.000 2 0.000 5 0.001 0.002 0.005 0.01 Permissible deviation (%) 0.000 2 0.000 5 0.001 0.002 0.005 0.01 Class index (p.p.M.) 2 5 10 20 50 100 Permissible deviation (p.p.M.) 2 5 10 20 50 100BS5142:1974 4 BSI 10-1999 7.2 Conditions under which the e.m.f. shall be determined 7.2.1 Before
45、 the measurement is made, the cell shall have a stabilization period during which no current shall flow through the cell. The stabilization period shall be specified by the manufacturer. The stabilization temperature and the measurement temperature shall be the same. For convenience, they may differ
46、 from the certification temperature by not more than 0.5 C. The e.m.f. corresponding to the certification temperature is obtained from the measured e.m.f. value by applying the formula given in Sub-clause5.3. The temperature tolerances for stabilization and measurement are given inTable III. NOTEThe
47、 stabilization period is not generally short; it may take several weeks to ensure the cells are in a stable condition. Table III Tolerance on stabilization and measurement temperature 7.2.2 During the stabilization and measuring periods, the cell shall be free from vibration. 8 Requirements for the
48、electrical and mechanical characteristics 8.1 Permissible discharge The following permissible discharge values shall be stated by the manufacturer. 8.1.1 Permissible discharge in normal use The permissible discharge for which the difference in e.m.f. measured immediately before and10s after the disc
49、harge does not exceed20% of the value corresponding to the class index. 8.1.2 Permissible discharge of short duration (accidental) The permissible discharge for which the difference in e.m.f. measured immediately before and1h after the discharge does not exceed50% of the value corresponding to the class index. 8.1.3 Permissible-cumulative discharge NOTEIn order to allow stabilization of the e.m.f. after the last discharge, it is recommended that the measurement should be carried out af
