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1、BRITISH STANDARD BS 5591:1978 IEC 589:1977 Incorporating Amendment No. 1 Methods of test for Determination of ionic impurities in electrical insulating materials by extraction with liquids UDC 621.315.611.001.4:543.056:543.257.5 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:50:24 GMT+00:
2、00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 This British Standard, having been prepared under the direction of the General Electrotechnical Engineering Standards Committee, was published under the authority of the Executive Board on 30 June 1978 BSI 12-1999 The following BSI references relate t
3、o the work on this standard: Committee reference GEL/16 Draft for comment 77/20330 DC ISBN 0 580 10211 4 Cooperating organizations The General Electrotechnical Engineering Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Go
4、vernment departments and scientific and industrial organizations: Associated Offices Technical Committee British Approvals Service for Electric Cables Ltd. British Electrical and Allied Manufacturers Association (BEAMA) British Radio Equipment Manufacturers Association British Steel Corporation Depa
5、rtment of Energy (Electricity) Electric Cable Makers Confederation Electrical Contractors Association Electrical Contractors Association of Scotland Electrical Research Association* Electricity Supply Industry in England and Wales* Electronic Components Industry Federation Electronic Engineering Ass
6、ociation Engineering Equipment Users Association Health and Safety Executive Home Office Institution of Electrical Engineers Ministry of Defence National Coal Board Oil Companies Materials Association Post Office* Telecommunication Engineering and Manufacturing Association (TEMA) The organizations m
7、arked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: British Industrial Ceramic Manufacturers Association Electrical and Electronic and Insulation Association (BEAMA) Glass Textile A
8、ssociation Rotating Electrical Machines Association (BEAMA) Amendments issued since publication Amd. No.Date of issueComments 2789April 1979Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:50:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 BS
9、I 12-1999i Contents Page Cooperating organizationsInside front cover National forewordii 1Scope and object1 2Definitions and units1 3Apparatus1 4Procedure1 5Calculation2 6Test report2 Appendix A Platinized platinum electrodesInside back cover Appendix B KCl Standard solutionsInside back cover Licens
10、ed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:50:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the General Electrotechnical Engineering Standards Committee. It is identical with IEC Pub
11、lication 589:1977 “Methods of test for the determination of ionic impurities in electrical insulating materials by extraction with liquids”, published by the International Electrotechnical Commission (IEC). The text of the IEC Publication has been accepted as suitable for publication, without deviat
12、ion, as a British Standard. WARNING NOTE. Attention is drawn to the health hazard which may arise when this test is performed (see note 3 to 4.2.1). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct
13、 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 and 2, an inside back cover and a back cover. This standard has been updated (see copyrig
14、ht 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, Fri Dec 01 14:50:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 BSI 12-19991 1 Scope and object The purpose of this stan
15、dard is to determine whether or not ionizable soluble organic and/or inorganic materials are present in electrical insulating materials. Their presence is confirmed by the increase in volume conductivity of the liquid extract and the test is considered to have particular significance when applied to
16、 electrical insulating materials which are to be immersed in coolants or impregnants. 2 Definitions and units The volume conductivity of a liquid extract ex is the difference between the volume conductivity of the extract solution and the volume conductivity of the control sample (blank sample). The
17、 SI unit of the volume conductivity is S m1. In practice, the unit S cm1 is often used. 3 Apparatus 250 ml conical flasks (Erlenmeyer) with reflux condensers having acid resistant and alkali resistant glass; conductivity cell with known cell constant k (m1) or (cm1); a bridge or other measuring devi
18、ce capable of measuring resistances with an accuracy of 5 %. In the case of aqueous extracts, this measuring device shall permit the measurement of resistances up to 1 M7 at frequencies between 50 Hz and 3 000 Hz. In the case of organic extracts, the measuring device shall permit the measurement of
19、resistances up to 1 T7 using not more than 100 V. d.c. NOTEIf unknown, the cell constant k is determined by means of a standard KCl solution of known conductivity, in accordance with Appendix B. 4 Procedure 4.1 Aqueous extract 4.1.1 Test water The quality of the test water has a considerable influen
20、ce on the result of the test. The volume conductivity of the test water preparing the aqueous extracts shall be u 2 104 S m1. The pH value of the test water shall be between 6.8 and 7.2. The test water can be made by means of an ion-exchanger or by using double distilled water of the recommended pH
21、value. NOTEAttention is drawn to the effect of carbon dioxide. The pH of newly prepared water will change to between 5.7 and 5.9 after the water has been exposed to air for a short time. If the change due to carbon dioxide has produced a pH of not less than 6.4, the water can be restored to pH = 7 b
22、y blowing pure nitrogen through it for a short time. The pH will remain within the required limits for a long time if the water is stored in polyethylene flasks from which carbon dioxide is excluded. 4.1.2 Preparation of the aqueous extract If not otherwise specified, the aqueous extract is to be pr
23、epared as follows. Take a test specimen weighing approximately 20 g into pieces of suitable dimensions. Weigh 5 0.1 g of these small pieces into three flasks fitted with reflux condensers, as described in Clause 3, and add 100 ml of test water. A fourth flask and condenser is used for the blank cont
24、rol sample. The water in the four flasks shall be kept boiling gently for 60 5 min and then cooled in the flasks to room temperature. Precautions shall be taken to avoid admission of carbon dioxide. 4.1.3 Measurements Before measuring the extracts, the resistance of the blank control sample shall be
25、 determined. The aqueous extract is decanted from the test specimens into the conductivity cell for measuring immediately. The conductivity cell shall be rinsed twice with the extract. The measurement of the resistance shall be carried out on each extract separately. The measurements shall be carrie
26、d out at 23 1 C. NOTEIt is essential to ensure that during the taking, storing and manipulation of samples, specimens and test portions intended for the conductivity test of aqueous extract are not contaminated either by the atmosphere, particularly the atmosphere of the chemical laboratory, or by h
27、andling with bare hands. 4.2 Organic extract 4.2.1 Test liquid If it is necessary to use organic liquids for the determination of ionic impurities in electrical insulating materials, trichloroethylene is suitable, and shall be used unless otherwise specified. The volume conductivity of trichloroethy
28、lene for preparing the liquid extracts shall be u 0.5 109 S m1. For special cases, 1 1011 S m1 may be achieved. The solvent is usually of laboratory reagent grade. Therefore, it shall be purified by stirring in about 1 % by weight of Fullers earth and filtering through a sintered glass filter. A fil
29、ter having a maximum pore diameter in the range of 5 4m to 15 4m is suitable. NOTE 1Fullers earth becomes ineffective if allowed to absorb moisture and may be dried by heating in clean air at a temperature not exceeding 120 C. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:50:24 GMT+00:00
30、 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 2 BSI 12-1999 NOTE 2Purified trichloroethylene is stable if kept in the dark or in a brown bottle, but its conductivity should be checked before use for an extraction. During extraction and measurement, the solvent should be shielded from strong light,
31、especially direct sunlight, and stored in the dark. NOTE 3Trichloroethylene is toxic and should be handled with the appropriate care. 4.2.2 Preparation of the trichloroethylene extract Cut a test specimen weighing approximately 20 g into pieces of suitable dimensions and heat them gently in air for
32、about 2 h at a temperature of 80 C to 100 C in order to remove any appreciable amount of absorbed water. Weigh 5 0.1 g of these small pieces into three flasks fitted with reflux condensers, as described in Clause 3, and add 100 ml of solvent. A fourth flask and condenser is used for the control samp
33、le. The solvent in the four flasks shall be boiled gently for 60 5 min and then cooled in the flasks to room temperature. The whole process shall be carried out in the dark. NOTEThe loss of volume through evaporation should not exceed 10 % otherwise the test is to be repeated. 4.2.3 Measurements Bef
34、ore measuring the extracts, the resistance of the control sample shall be determined. The trichloroethylene extract is decanted from the test specimens into the conductivity cell for measuring immediately. The cell shall have been cleaned several times with purified trichloroethylene and dried befor
35、e filling. After the cell has been rinsed twice with extract, the measurement of the resistance shall be carried out on each extract separately. The measurement shall be carried out 1 min after application of the d.c. voltage at 23 1 C. NOTEIt is essential to ensure that during the taking, storing a
36、nd manipulation of samples, specimens and test portions intended for the conductivity test of organic extract, these are not contamined either by the atmosphere, particularly the atmosphere of the chemical laboratory, or by handling with bare hands. 5 Calculation The calculation of the volume conduc
37、tivity of the liquid extract shall be calculated by: 6 Test report The test report shall include the following information: designation of the electrical insulating material; designation of the liquid; all results; date of test. where: ex= volume conductivity of the liquid extract in S m1 (S cm1) ex
38、= volume resistivity of the liquid extract in ohms-metres (ohms-centimetres) k= cell constant in m1 (cm1) RS= resistance of the extract solution in ohms RB= resistance of the control sample in ohms ex 1 ex - -k 1 RS - - 1 RB - - = Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:50:24 GMT+0
39、0:00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 BSI 12-1999 Appendix A Platinized platinum electrodes For platinizing the electrodes, the test cell shall be dipped into a solution of: 10 ml distilled water with 3 g hexachloroplatinum (IV) acid: H2(PtCl6) 6 H2O 0.02 g lead (II) acetate: Pb(CH3COO)
40、 3 H2O. Following this 4 V d.c. shall be applied to the electrodes. The current shall be adjusted so that a slight gas generation on the surface of the electrodes can be observed. After reversing the polarization, the other electrode is platinized. Both electrodes form the cathode for an equal time.
41、 After platinizing, the electrodes have a deep-black velvet-like covering. NOTE 1Bright platinum new electrodes shall be roughened with sand-paper. They require 10 min for platinizing. NOTE 2For the regeneration of used platinized electrodes, the operating time is 1 min to 2 min. For cleaning the pl
42、atinum solution from the electrodes, the water-rinsed electrodes are dipped into a 2 % to 5 % sulphuric acid solution. Then the two electrodes are connected to the cathode and a separate platinum electrode is also dipped into the solution and connected to the anode. After a few minutes of electrolys
43、is, the electrodes must be thoroughly rinsed with water. During the time when the test cells are not in use, they should be filled with test water. Care must be taken that the electrodes are kept continuously moistened. In case of failure to do so, the electrodes may be rinsed in ethanol. Appendix B
44、 KCl Standard solutions Three standard solutions having concentrations 0.1 N, 0.01 N and 0.001 N shall be prepared. For this purpose, pulverized or cristalline KCl, pure for analysis is used. It should be dried before using at approximately 105 C for 2 h. For 0.1 N weigh 7.4555 g KCl and for 0.01 N
45、weigh 0.7456 g KCl in air at a temperature of 23 2 C. Each quantity is then placed in a 1 000 ml measuring flask which is then filled up with test water (see Sub-clause 4.1.1) to 1 litre. The 0.001 N standard solution should be prepared immediately before use only. One hundred millilitres of the 0.0
46、1 N KCl standard solution shall be placed in a 1 000 ml measuring flask which is then filled up with test water (see Sub-clause 4.1.1) to 1 litre. The conductivity of the standard solution at 23 C is for: and the cell constant k may be calculated as follows: k = KCl R where R is the resistance measu
47、red in ohms. The KCl standard solution should be stored in glass flasks with ground-glass stoppers. NOTEAll glass flasks should be made of acid-resistant and alkali-resistant hydrolytic glass. 0.1 NKCl = 1.24S m1 0.01 NKCl = 0.136S m1 0.001 NKCl = 0.0141S m1 Licensed Copy: sheffieldun sheffieldun, n
48、a, Fri Dec 01 14:50:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5591:1978 IEC 589:1977 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and
49、at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical comm