1、BRITISH STANDARD BS5591:1978 IEC589:1977 Incorporating Amendment No.1 Methods of test for Determination of ionic impurities in electrical insulating materials by extraction with liquids UDC 621.315.611.001.4:543.056:543.257.5BS5591:1978 This BritishStandard, having been prepared under the directiono
2、f the General Electrotechnical Engineering Standards Committee, was published under the authorityofthe Executive Boardon 30June1978 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference GEL/16 Draft for comment 77/20330 DC ISBN 0 580 10211 4 Cooperating or
3、ganizations The General Electrotechnical Engineering Standards Committee, under whose direction this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee British Approva
4、ls Service for Electric Cables Ltd. British Electrical and Allied Manufacturers Association (BEAMA) British Radio Equipment Manufacturers Association British Steel Corporation Department of Energy (Electricity) Electric Cable Makers Confederation Electrical Contractors Association Electrical Contrac
5、tors Association of Scotland Electrical Research Association* Electricity Supply Industry in England and Wales* Electronic Components Industry Federation Electronic Engineering Association Engineering Equipment Users Association Health and Safety Executive Home Office Institution of Electrical Engin
6、eers Ministry of Defence National Coal Board Oil Companies Materials Association Post Office* Telecommunication Engineering and Manufacturing Association (TEMA) The organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrus
7、ted with the preparation of this BritishStandard: British Industrial Ceramic Manufacturers Association Electrical and Electronic and Insulation Association (BEAMA) Glass Textile Association Rotating Electrical Machines Association (BEAMA) Amendments issued since publication Amd. No. Date of issue Co
8、mments 2789 April 1979 Indicated by a sideline in the marginBS5591:1978 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii 1 Scope and object 1 2 Definitions and units 1 3 Apparatus 1 4 Procedure 1 5 Calculation 2 6 Test report 2 Appendix A Platinized plati
9、num electrodes Inside back cover Appendix B KCl Standard solutions Inside back coverBS5591:1978 ii BSI 12-1999 National foreword This BritishStandard has been prepared under the direction of the General Electrotechnical Engineering Standards Committee. It is identical with IECPublication589:1977 “Me
10、thods 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 deviation, as a BritishStan
11、dard. WARNING NOTE. Attention is drawn to the health hazard which may arise when this test is performed (seenote3 to4.2.1). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance
12、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, pagesi andii, pages1 and2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had ame
13、ndments incorporated. This will be indicated in the amendment table on the inside front cover.BS5591:1978 BSI 12-1999 1 1 Scope and object The purpose of this standard is to determine whether or not ionizable soluble organic and/or inorganic materials are present in electrical insulating materials.
14、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 electrical insulating materials which are to be immersed in coolants or impregnants. 2 Definitions and units The volume conductivity of
15、a liquid extract exis the difference between the volume conductivity of the extract solution and the volume conductivity of the control sample (blank sample). The SI unit of the volume conductivity is Sm 1 . In practice, the unit Scm 1is often used. 3 Apparatus 250ml conical flasks (Erlenmeyer) with
16、 reflux condensers having acid resistant and alkali resistant glass; conductivity cell with known cell constant k (m 1 ) or (cm 1 ); a bridge or other measuring device capable of measuring resistances with an accuracy of5%. In the case of aqueous extracts, this measuring device shall permit the meas
17、urement of resistances up to1M7 at frequencies between50Hz and3000Hz. In the case of organic extracts, the measuring device shall permit the measurement of resistances up to1T7 using not more than100V. d.c. NOTEIf unknown, the cell constant k is determined by means of a standard KCl solution of know
18、n 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 influence on the result of the test. The volume conductivity of the test water preparing the aqueous extracts shall beu210 4Sm 1 . The pH value of the test
19、 water shall be between6.8 and7.2. The test water can be made by means of an ion-exchanger or by using double distilled water of the recommended pH value. NOTEAttention is drawn to the effect of carbon dioxide. The pH of newly prepared water will change to between5.7 and5.9 after the water has been
20、exposed to air for a short time. If the change due to carbon dioxide has produced a pH of not less than6.4, the water can be restored to pH=7 by 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 fla
21、sks from which carbon dioxide is excluded. 4.1.2 Preparation of the aqueous extract If not otherwise specified, the aqueous extract is to be prepared as follows. Take a test specimen weighing approximately20g into pieces of suitable dimensions. Weigh5 0.1g of these small pieces into three flasks fit
22、ted with reflux condensers, as described in Clause3, and add100ml of test water. A fourth flask and condenser is used for the blank control sample. The water in the four flasks shall be kept boiling gently for60 5min and then cooled in the flasks to room temperature. Precautions shall be taken to av
23、oid admission of carbon dioxide. 4.1.3 Measurements Before measuring the extracts, the resistance of the blank control sample shall be determined. The aqueous extract is decanted from the test specimens into the conductivity cell for measuring immediately. The conductivity cell shall be rinsed twice
24、 with the extract. The measurement of the resistance shall be carried out on each extract separately. The measurements shall be carried out at23 1 C. NOTEIt is essential to ensure that during the taking, storing and manipulation of samples, specimens and test portions intended for the conductivity t
25、est of aqueous extract are not contaminated either by the atmosphere, particularly the atmosphere of the chemical laboratory, or by handling 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 insula
26、ting materials, trichloroethylene is suitable, and shall be used unless otherwise specified. The volume conductivity of trichloroethylene for preparing the liquid extracts shall beu 0.510 9Sm 1 . For special cases,110 11Sm 1may be achieved. The solvent is usually of laboratory reagent grade. Therefo
27、re, it shall be purified by stirring in about1% by weight of Fullers earth and filtering through a sintered glass filter. A filter having a maximum pore diameter in the range of54m to154m is suitable. NOTE 1Fullers earth becomes ineffective if allowed to absorb moisture and may be dried by heating i
28、n clean air at a temperature not exceeding120 C.BS5591:1978 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 s
29、trong light, 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 approximately20g into pieces of suitable dimensions and heat them gently
30、in air for about2h at a temperature of80 C to100 C in order to remove any appreciable amount of absorbed water. Weigh5 0.1g of these small pieces into three flasks fitted with reflux condensers, as described in Clause3, and add100ml of solvent. A fourth flask and condenser is used for the control sa
31、mple. The solvent in the four flasks shall be boiled gently for605min 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 exceed10%otherwise the test is to be repeated. 4.2.3 Measurements Before
32、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 before fi
33、lling. 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 out1min after application of the d.c. voltage at23 1 C. NOTEIt is essential to ensure that during the taking, storing and mani
34、pulation 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 conductivity
35、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 m 1(S cm 1 ) ex =vol
36、ume resistivity of the liquid extract in ohms-metres (ohms-centimetres) k =cell constant in m 1(cm 1 ) R S =resistance of the extract solution in ohms R B =resistance of the control sample in ohms ex 1 ex -k 1 R S - 1 R B - =BS5591:1978 BSI 12-1999 Appendix A Platinized platinum electrodes For plati
37、nizing the electrodes, the test cell shall be dipped into a solution of: 10ml distilled water with 3g hexachloroplatinum (IV) acid: H 2 (PtCl 6 ) 6H 2 O 0.02g lead (II) acetate: Pb(CH 3 COO) 3H 2 O. Following this4V d.c. shall be applied to the electrodes. The current shall be adjusted so that a sli
38、ght 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. After platinizing, the electrodes have a deep-black velvet-like covering. NOTE 1Bright platinum new electrodes
39、 shall be roughened with sand-paper. They require10min for platinizing. NOTE 2For the regeneration of used platinized electrodes, the operating time is1min to2min. For cleaning the platinum solution from the electrodes, the water-rinsed electrodes are dipped into a2% to5% sulphuric acid solution. Th
40、en 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 electrolysis, the electrodes must be thoroughly rinsed with water. During the time when the test cells are not in use, they should
41、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 KCl Standard solutions Three standard solutions having concentrations0.1N,0.01N and0.001N shall be prepared. For this pu
42、rpose, pulverized or cristalline KCl, pure for analysis is used. It should be dried before using at approximately105 C for2h. For0.1N weigh7.4555g KCl and for0.01N weigh0.7456g KCl in air at a temperature of23 2 C. Each quantity is then placed in a1000ml measuring flask which is then filled up with
43、test water (seeSub-clause4.1.1) to1litre. The0.001N standard solution should be prepared immediately before use only. One hundred millilitres of the0.01N KCl standard solution shall be placed in a1000ml measuring flask which is then filled up with test water (seeSub-clause4.1.1) to1litre. The conduc
44、tivity of the standard solution at23 C is for: and the cell constant k may be calculated as follows: k = KCl R where R is the resistance measured 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
45、alkali-resistant hydrolytic glass. 0.1N KCl=1.24 S m 1 0.01N KCl=0.136 S m 1 0.001N KCl=0.0141 S m 1BS5591:1978 IEC589:1977 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view
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