1、BRITISH STANDARD BS 5689-2: 1979 IEC 394-2: 1972 Varnished fabrics for electrical purposes Part 2: Methods of test UDC 621.315.614.72:677.077.625.17 + 621.315.614.72:621.317 + 677.077.625.17:620.1BS5689-2:1979 This British Standard, having been prepared under the directionof the General Electrotechn
2、ical Engineering Standards Committee, was published under the authority ofthe Executive Board on 31January1979 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference GEL/16 Draft for comment 77/31724 DC ISBN 0 580 10566 0 Cooperating organizations The Gener
3、al Electrotechnical Engineering Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Associated Offices Technical Committee British Approvals Service for Elect
4、ric 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 Contractors Association of
5、Scotland Electrical, Electronic, Telecommunications and Plumbing Union Electrical Research Association* Electricity Supply Industry in England and Wales* Electronic Components Industry Federation* Engineering Equipment Users Association Health and Safety Executive Home Office Institution of Electric
6、al Engineers 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 committ
7、ee entrusted with the preparation of this British Standard: Adhesive Tape Manufacturers Association British Paper and Board Industry Federation (PIF) British Plastics Federation Department of Industry (British Calibration Service) Department of Industry (National Physical Laboratory) Electrical and
8、Electronic and Insulation Association (BEAMA) Rotating Electrical Machines Association (BEAMA) Transmission and Distribution Association (BEAMA) Amendments issued since publication Amd. No. Date of issue CommentsBS5689-2:1979 BSI 09-1999 i Contents Page Cooperating organizations Inside front cover N
9、ational foreword ii Introduction 1 1 General notes on tests 1 2 Thickness 1 2.1 Test apparatus 1 2.2 Test specimens 1 2.3 Procedure 1 2.4 Results 1 3 Resistance against hydrolysis 1 3.1 Test specimens 1 3.2 Procedure 2 3.3 Results 2 4 Effect of fabric on oil 2 4.1 Procedure 2 4.2 Results 2 5 Effect
10、of oil or other liquid on varnished fabric 3 5.1 Test specimens 3 5.2 Procedure 3 5.3 Results 3 6 Tensile strength and extension 3 6.1 Test apparatus 3 6.2 Test specimens 3 6.3 Procedure 3 6.4 Results 3 7 Internal tearing resistance 4 7.1 Test apparatus 4 7.2 Test specimens 4 7.3 Procedure 4 7.4 Res
11、ults 4 8 Edge tearing resistance 4 8.1 Apparatus 4 8.2 Test specimens 4 8.3 Procedure 5 8.4 Results 5 9 Electric strength 5 9.1 Apparatus 5 9.2 Test specimens and number of tests 5 9.3 Procedure 5 9.4 Results 6 10 Thermal endurance test 6 Figure 1 7 Figures 2a, 2b Diagram of an Elmendorf tear tester
12、 (initial position) 8 Figure 2c Diagram of an Elmendorf tear tester (position at end of test) 8 Figure 3 9 Figure 4 Typical example of electrode apparatus for tests on tape 9 Figure 5 Apparatus for stretching and testing extended slit material for electric strength 10 Publications referred to Inside
13、 back coverBS5689-2:1979 ii BSI 09-1999 National foreword This British Standard is identical with IEC Publications 394-2 “Specification for varnished fabrics for electrical purposes” Part2 “Methods of test” published in1972 by the International Electrotechnical Commission (IEC). It is published unde
14、r the direction of the General Electrotechnical Engineering Standards Committee. Other Parts of this standard are: Part 1: Definitions and general requirements; Part 3: Specifications for individual materials (in course of preparation). It is the intention that this standard will ultimately replace
15、BS419:1966 “Varnished fabrics and tapes for electrical purposes”. A decision on withdrawal of this standard will be taken when the specification sheets for the respective individual materials have been issued in Part3 of this standard. Terminology and conventions. The text of the International Stand
16、ard has been approved as suitable for publication without deviation, as a British Standard. Some terminology and certain conventions are not identical with those used in British Standards; attention is especially drawn to the following. Where the word “recommendation” appears, referring to this stan
17、dard, it should be interpreted as “British Standard”. In the second paragraph of the “Introduction”, the word “series” should be interpreted as “British Standard”. NOTEIt should be noted that the preferred SI unit for pressure is the pascal. Therefore in2.1.1 “10N/cm 2to20N/cm 2 ” should be interpre
18、ted as “100kPa to200kPa”, and in2.1.2 “10 N/cm 2 ” should be interpreted as “100kPa”. In 9.3.5 the unit symbols in the title should be read as if printed in upright type. NOTEAt present there is no corresponding British Standard for IEC Publication243. Although BS2918 is a related standard, it diffe
19、rs in many respects. Additional information. For the purposes of the British Standard the following Scope is applicable: Scope This Part of this British Standard contains the methods of test for varnished fabrics for electrical purposes. A British Standard does not purport to include all the necessa
20、ry 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. Cross-references International Standard a Corresponding British Standard IEC 212:1971 BS 2844:1972 Memo
21、randum on conditioning of solid electrical insulating materials prior to and during testing (Technically equivalent) IEC 296:1969 BS 148:1972 Insulating oil for transformers and switchgear (Technically equivalent) a Not dated in the text. Summary of pages This document comprises a front cover, an in
22、side front cover, pagesi andii, pages1to10, an inside back cover and a back 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.BS5689-2:1979 BSI 09-1999 1 Introduction This recom
23、mendation is one of a series that includes varnished fabrics comprising bases woven from cotton, natural silk, or synthetic fibres (including glass) supplied in the form of full width rolls, sheets, or tapes slit to various widths. The series will have three parts describing: 1) Definitions and gene
24、ral requirements; 2) Methods of test; 3) Specifications for individual materials. 1 General notes on tests 1.1 Select test specimens which are representative of the bulk of the material. 1.2 The test specimens, after being cut, shall be conditioned for24h at23 2 C and 505% r.h. If the test is not co
25、nducted in this standard atmosphere, the test shall be made within5 minutes after removal from the standard atmosphere. 2 Thickness 2.1 Test apparatus 2.1.1 An external screw type micrometer having measuring faces of6mm to8mm diameter. The measuring faces shall be flat within0.001mm and parallel to
26、within0.003mm. The pitch of the screw shall be0.5mm and the graduations shall be50divisions of0.01mm, enabling readings to be estimated to0.002mm. The pressure exerted on the specimens shall be10N/cm 2to20N/cm 2 . 2.1.2 A dead weight dial-type micrometer having two ground and lapped concentric circu
27、lar surfaces flat to within0.001mm and parallel to within0.003mm. The upper surface shall be6mm to8mm in diameter. The lower surface shall be larger than the upper one. The upper surface shall move on the axis perpendicular to the surfaces. The dial shall be graduated to read directly to0.002mm. The
28、 frame of the micrometer shall be of such rigidity that a force of15N applied to the dial housing, out of contact with either the weight or the presser foot spindle, will produce a deflection of the frame not greater than0.002mm as indicated on the micrometer dial. The pressure exerted on the specim
29、en shall be10N/cm 2 . 2.1.3 The setting gauge used to check the instruments shall be accurate to within 0.001mm of nominal size. The indicated thickness of the instruments shall not differ by more than0.005mm from the gauge block. In case of dispute, the dead weight micrometer shall be employed. 2.2
30、 Test specimens 2.2.1 Full width material One specimen25mm wide and with its length equal to the width of the roll shall be cut across the entire width of the roll. 2.2.2 Slit material One specimen 1 m long shall be cut from the roll. 2.3 Procedure Measure the thickness of the material, when not con
31、strained in any way, at9 points spaced not less than75mm apart along the length of the test specimens. All joins or selvages shall be excluded from the area of the test. 2.4 Results The values of the 9 measurements are to be recorded. The central value is the thickness of the material. 3 Resistance
32、against hydrolysis 3.1 Test specimens A piece of varnished fabric, approximately125mm 50mm, or an equivalent area of narrower material.BS5689-2:1979 2 BSI 09-1999 3.2 Procedure Roll the test specimen and push it into a “heavy” wall thickness borosilicate test tube, approximately125mm long by16mm dia
33、meter (Figure 1, page 7). Add 2ml of distilled water to the test tube. Take a short length of tinned copper wire, approximately 0.6mm diameter, and, with the end nearest the test specimen bent into circular shape at a right angle to the length, insert the wire into the test tube. Cut the wire at suc
34、h length that it is totally within the test tube and acts as a stop to prevent the test specimen slipping into the water when the test tube is sealed and inverted. Seal the test tube, e.g., by drawing it out in a flame, taking care not to reduce unduly the wall thickness of the test tube at the seal
35、. Place the test tube (when cold) vertically, with the sealed end downward, in an oven and maintain it at105 2 C for the time prescribed in Part3 of this recommendation. 3.3 Results Examine the test specimen from time to time and at the end of the appropriate period, for signs of flow of the varnish
36、 film. The varnish shall show no well marked flow. Where the specified time is reached without well marked flow, the specimen shall be withdrawn from the test tube and its surface condition examined for tackiness, transfer of varnish during unrolling, and swelling. Report all these observations. NOT
37、EIt is essential that “heavy” wall thickness test tubes are used for this test to minimize the risk of explosion and injury to personnel. As a further safety precaution, it is recommended that the test tubes are screened from the observer. 4 Effect of fabric on oil 4.1 Procedure Approximately 10g of
38、 varnished fabric is cut into pieces with an area of approximately50mm 2and placed in a vessel with transformer oil (see note). The mass ratio of varnished fabric to oil should be1:10. The vessel is placed into a thermostatic bath at a temperature of105 2 C for72h. Simultaneously, another vessel wit
39、h the same quantity of oil without varnished fabric is placed in the thermostatic bath. 50 ml of a mixture of toluene and ethyl alcohol (2:1) is placed in a conic bulb and boiled with a reflux condenser for5min. Then 4 to 5 drops of phenolphthalein indicator are added and the contents are neutralize
40、d while hot with0.05 molar alcoholic solution of KOH till the first appearance of discolouration to pink. 8g to10g of transformer oil, which has been heated with the varnished fabric, is added into the bulb. The contents of the bulb are boiled for5min with a reflux condenser at continuous mixing. Th
41、en 4 to5 drops of phenolphthalein indicator are added and the mixture is titrated while hot with0.05 molar alcoholic solution of KOH with continuous mixing up to the first appearance of change of colour of the lower layer of the mixture to pink. The test is repeated using the oil which has been heat
42、ed without varnished fabric (blank test). NOTEThe transformer oil used shall fulfil the requirements for transformer oil Class II as given in IEC Publication296. 4.2 Results The acid number of the tested oil is calculated by the formula: The acid number is calculated as the arithmetical mean from th
43、e results of two parallel determinations of titration. where: V 1 = volume of solution of KOH used for titration of tested oil, in ml V 2 = volume of solution of KOH used for titration in the blank test in ml T = titre (molarity) of solution of KOH, in this case 0.05 mol/litre m = mass of the tested
44、 oil, in g.BS5689-2:1979 BSI 09-1999 3 5 Effect of oil or other liquid on varnished fabric 5.1 Test specimens Five specimens of about 125mm in length and 40mm in width are used. Where the material is less than40mm wide, it shall be tested in the width supplied; the length must then be chosen so that
45、 a wrapping according to Sub-clause5.2 can be produced. 5.2 Procedure Each strip shall be helically wound on to a metal rod of about 10mm to12mm diameter with an overlap of about50 per cent with the ends fixed and to cover a length of rod of100mm. The rods shall be immersed in a glass vessel filled
46、with the liquid under test and heated in an electrical drying oven at105 2 C for48h. Uncoiling shall be carried out immediately after the specimen has cooled down to room temperature. The surface condition is examined for tackiness, transfer of varnish, and swelling. 5.3 Results The character of the
47、 damage, if any, is reported. 6 Tensile strength and extension 6.1 Test apparatus Either a constant rate-of-load machine or a constant rate-of-traverse machine may be used, the machine preferably shall be power driven and graduated so that a reading of1% of the value required by the specification sh
48、eet is possible. 6.2 Test specimens Five specimens are used. The length of the test specimens shall be such, that it allows a length of200mm between the jaws of the testing machine. The width shall be15mm maximum. When testing full width straight cut material, cut five test specimens in the directio
49、n of the warp and five test specimens in the direction of the weft in such a way as to be representative of the bulk of the material and so that no two test specimens cut in the same direction contain the same longitudinal threads. When testing full width bias cut material, the specimens are cut in the lengthwise direction of the material in such a way as to be representative of the bulk of the material. Slit material is tested ill the width as delivered up to a maximum of15mm. 6.3 Procedure Fix a test specimen in the testing machine and app
