1、Designation: D2413 16Standard Practice forPreparation of Insulating Paper and Board Impregnated witha Liquid Dielectric1This standard is issued under the fixed designation D2413; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the preparation of insulating paperand board impregnated with a liquid dielectric. Where
3、thispractice states only “paper,” the same procedure shall apply toboard.1.2 This practice has been found practicable for papershaving nominal thickness of 0.05 mm (2 mil) and above. It hasbeen used successfully for insulating board as thick as 6 mm(14 in.) when care is taken to ensure the specimen
4、geometrynecessary for valid measurement of dielectric properties. Suit-able geometry depends on the electrode system used. Rigidsolid opposing electrodes require flat specimens that haveessentially parallel surfaces.1.3 The values stated in SI units are to be regarded asstandard. No other units of m
5、easurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2D117 Guide for Sampling, Test Methods, and Specificationsfor Electrical Insulating Oils of Petroleum OriginD149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materi
6、alsat Commercial Power FrequenciesD150 Test Methods for AC Loss Characteristics and Permit-tivity (Dielectric Constant) of Solid Electrical InsulationD202 Test Methods for Sampling and Testing UntreatedPaper Used for Electrical InsulationD257 Test Methods for DC Resistance or Conductance ofInsulatin
7、g MaterialsD924 Test Method for Dissipation Factor (or Power Factor)and Relative Permittivity (Dielectric Constant) of Electri-cal Insulating LiquidsD1711 Terminology Relating to Electrical InsulationD1816 Test Method for Dielectric Breakdown Voltage ofInsulating Liquids Using VDE ElectrodesD1933 Sp
8、ecification for Nitrogen Gas as an Electrical Insu-lating MaterialD3394 Test Methods for Sampling and Testing ElectricalInsulating BoardD3426 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating MaterialsUsing Impulse Waves3. Terminology3.1 DefinitionsUs
9、e Terminology D1711 for definitions ofterms used in this practice and associated with electrical orelectronic materials.4. Summary of Practice4.1 The paper is heated and vacuum dried and the liquiddielectric degassed. The paper may be dried in loose form orassembled between electrodes. The liquid di
10、electric may beheated and degassed prior to introducing it into the chambercontaining the dried paper or it may be degassed as it isintroduced into the evacuated chamber containing the driedpaper. A sufficient length of time is allowed for the impregnat-ing process depending on the apparent density
11、of the paper andmethod of impregnation. The impregnated specimens aresubsequently tested for various selected electrical properties.5. Significance and Use5.1 Dissipation Factor and Relative PermittivityKnowledge of these properties is important in the design ofelectrical equipment such as cables, t
12、ransformers, insulators,and so forth. The numerical product of these two properties ofa dielectric system is proportional to the energy loss convertedto heat, and is called its loss index (see Terminology D1711).The energy loss reduces the efficiency of electrical equipment.The heat produced tends t
13、o chemically degrade the dielectricmaterial and may even lead to thermal runaway. Test results ofimpregnated specimens can disclose significant differencesbetween combinations of papers and oils that appear similarwhen the papers and the oils are tested separately. Dissipation1This practice is under
14、 the jurisdiction of ASTM Committee D09 on Electricaland Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.01 on Electrical Insulating Products.Current edition approved Nov. 1, 2016. Published November 2016. Originallyapproved in 1965. Last previous edition approved
15、 in 2009 as D2413 99 (2009).DOI: 10.1520/D2413-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright A
16、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1factor, particularly at elevated temperatures, is often changedsignificantly by the presence of a small quantity of impuritiesin either the liquid or the paper. This practice is useful in thecompar
17、ison of materials and in evaluating the effects ofdifferent papers on a given liquid. Judicious analysis of resultswith respect to time, temperature, and field strength are usefulin predicting the performance and capabilities of systems usingthe paper and the liquid. For additional information on th
18、esignificance of dissipation factor and relative permittivity, seeTest Methods D150.5.2 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materials atCommercial Power Frequencies:5.2.1 A comprehensive discussion of the significance of thedielectric st
19、rength test as applied to solid, semi-solid, andliquid materials is given inAppendix X1 of Test Method D149.Other factors peculiar to high-quality composite insulations,such as oil-impregnated papers, are considered in the follow-ing:5.2.2 In tests involving high electrical stresses, immersionof cri
20、tical parts of a test circuit in oil is a widely used techniquefor inhibiting corona. However, it has limitations that must berecognized when using the submerged electrode option of thispractice (Note 1). Attack on the paper by corona generated inthe surrounding fluid at electrode edges can occur wh
21、ether thefluid is air or oil. Corona occurs at considerably higher voltagesin oil than in air. Thick and dense papers are more likely tocause discharge-initiated breakdowns. For interpretation ofbreakdown measurements consider the number of edgebreakdowns, implying discharge-initiated breakdowns.NOT
22、E 1Two techniques are in use in the industry for testingspecimens for dielectric breakdown voltage. In one, the test is made withthe electrodes and test specimen submerged in the impregnating liquidwhile in the other the electrodes are not submerged, that is, the specimenis tested in air. Much data
23、has been accumulated using the latter technique.These techniques yield different values of breakdown voltage. TestMethod D149 states preference for testing materials in the medium inwhich they are used. The use of submerged electrodes follows thispreference. When testing thick insulating boards, the
24、 use of submergedelectrodes is greatly preferred.5.2.3 The results of power frequency tests on oil impreg-nated papers are useful for screening, research, and qualitycontrol, provided that considerable judgment is exercised ininterpreting the results. The application of the test results toequipment
25、design and service requires particular caution andskill (see Appendix X1 of Test Method D149).5.3 Dielectric Breakdown Voltage and Dielectric StrengthUnder Impulse ConditionsTesting impregnated paper orboard under impulse conditions can yield useful data for thedesigner of electrical equipment. The
26、test results are useful inthe comparison of materials and for research studies. For amore general treatise on the significance of impulse testing seeTest Method D3426.6. Apparatus6.1 Drying and Impregnating Equipment:6.1.1 Impregnating ChamberThe chamber shall beequipped with a thermal control unit
27、capable of maintainingselected temperatures as high as 115C. The chamber shallhave a connection, through a suitable vapor trap, to a vacuumpump capable of maintaining selected absolute pressures aslow as 75 Pa (0.5 Torr), as measured by a suitable vacuum gagehaving a connection to the chamber separa
28、te from that of thevacuum pump. It shall be constructed of materials that will notcontaminate either the liquid dielectric or the paper, and shallinclude an appropriately valved entry for the liquid plus a bafflefor the purposes indicated in 9.3.6.1.2 Vacuum Drying EquipmentFor the liquid, if Proce-
29、dure 1 (9.2.1) is to be used. This may be substantially aduplicate of the impregnating chamber except that a valvedvacuum-tight line is required for transferring dried liquid to theimpregnating chamber. Baffles may be used to expose thinfilms of incoming liquid to the drying and degassing effect ofh
30、eat and vacuum.6.2 Equipment for Measuring Dissipation Factor (PowerFactor) and Permittivity of Liquid DielectricThe equipmentand test cell shall be any three-terminal system meeting therequirements set forth in Test Method D924.6.3 Equipment for Measuring Dielectric Strength at Com-mercial Power Fr
31、equencies:6.3.1 The equipment for measuring the dielectric strength ofthe paper shall be as described in Test Method D149, exceptthat the electrodes shall be as specified in Test Methods D202or D3394, as applicable.6.3.2 The equipment for testing the dielectric strength of theliquid shall be as desc
32、ribed in Test Method D1816.6.4 Equipment for measuring impulse withstand strengthand impulse breakdown dielectric strength shall be that whichis specified in Test Method D3426.7. General Considerations7.1 When undertaking an investigation into the electricalproperties of various papers that are to b
33、e impregnated with aspecific liquid dielectric or a specific paper to be impregnatedwith various liquid dielectrics, the parties concerned shallagree to the following:7.1.1 The identification of paper to be used.7.1.2 The identification of the liquid dielectric to be used.7.1.3 Whether the liquid di
34、electric shall be treated in aseparate container or introduced directly into the evacuationchamber containing the treated paper.7.1.4 The number of sheets or strips that shall comprise eachtest specimen for the respective tests.NOTE 2Two commonly used temperatures are 80C and 100C.7.2 Determine the
35、physical and electrical properties of theliquid dielectric in accordance with the applicable methodsoutlined in Guide D117 (see 6.3.2).7.3 Use dry nitrogen in these procedures meeting therequirements of Type 1 listed in Table 1 of SpecificationD1933.8. Test Specimens8.1 Take great care to prevent ei
36、ther the untreated paper orthe liquid dielectric from being contaminated or degraded byimproper handling or from being subjected to laboratoryfumes, dirt, oxidation, or ultraviolet light.D2413 1628.2 Before impregnation, cut the paper specimens to a sizesuitable to the geometry of the electrodes to
37、be used. Test atleast five specimens for each procedure used. Test at least fivespecimens for each procedure used.9. Impregnating Procedure9.1 Vacuum Drying the PaperTwo procedures are used fordrying the paper: Procedure A, in which the paper is in looseform in either sheets or strips and Procedure
38、B, in which thepaper is assembled between electrodes.9.1.1 Procedure APile the paper loosely in the impregnat-ing chamber and thoroughly dry it at a temperature of 115 65C and an absolute pressure of 75 Pa (0.5 Torr) or less for atleast 16 h. This period has been found adequate for dryingpapers havi
39、ng an apparent density of up to 1.2 g/cm3. Forpapers of greater apparent density, increase the drying time toat least 24 h. Procedure A is preferred for drying specimens ofthick insulating board.9.1.2 Procedure BAssemble the paper insulation betweenthe electrodes and place the assembly in the impreg
40、natingchamber. Connect shielded leads to the electrodes and bringthem out of the chamber to permit measurements of dissipationfactor or of resistivity to be made as an indication of thedryness of the paper during the treating process (see 9.2.2).Subject the assembly to the same treatment as that des
41、cribed in9.1.1 except that the duration of the heating and vacuumtreatment will be dependent on the results obtained when theelectrical measurements are made. A constant value of dissi-pation factor or resistivity indicates that the moisture content ofthe paper is in equilibrium with the test chambe
42、r, but does notnecessarily mean that the paper is dry. When resistivity ismeasured instead of dissipation factor, do so in accordancewith Test Methods D257.9.2 Vacuum Treating the Liquid DielectricTwo proceduresare used for drying and degassing the liquid: Procedure 1, inwhich the liquid is treated
43、in a separate chamber before beingintroduced into the impregnating chamber containing the driedpaper, and Procedure 2, in which the liquid is introduceddirectly into the impregnating chamber. Procedure 1 is recom-mended for referee testing and for use with low viscosityimpregnants such as transforme
44、r oils.9.2.1 Procedure 1Maintain the separate container (6.1.2)at a temperature and absolute pressure suitable for the impreg-nating liquid to be used. For oil having a viscosity in the orderof 50 10-6m2/s (50 cSt) or higher at 40C, as may be usedwith paper for cables, the same conditions as used fo
45、r the paperdrying have been found to be satisfactory. For transformer oilswith a viscosity in the order of 12 106m2/s (12 cSt) at 40C,conditions of 60C and 40 Pa (0.3 Torr) have been found to beadequate. Other liquids may require other conditions as learnedby experience. To obtain good degassificati
46、on, introduce theliquid, warmed to the temperature chosen, slowly into theseparate container.9.2.2 Procedure 2Adjust the impregnating chamber con-taining the dried paper to conditions of pressure and tempera-ture suitable for the impregnating liquid, as outlined in 9.2.1.To obtain good degassificati
47、on, slowly introduce the liquiddirectly into the chamber.9.3 Impregnating ProcedureWhen introducing the liquidinto the chamber containing the paper it is generally consideredgood practice to arrange a baffle over the paper so that theliquid will impregnate the paper from the bottom. After theliquid
48、has completely covered the paper, break vacuum withdesiccated air or dry nitrogen. Allow8hormore at atmo-spheric pressure for the paper to become completely impreg-nated. To accelerate the process, positive pressure, usingdesiccated air or dry nitrogen, may be applied to the impreg-nating chamber. T
49、he time required for thorough impregnationis dependent on the rate of liquid penetration of the paper,which in turn is an inverse function of the paper density, thethickness, and the liquid viscosity. Loose pieces of paperimpregnate more quickly than multiple layers tightly as-sembled in an insulation structure.9.4 Do not remove impregnated specimens from immersionin the liquid dielectric even momentarily, where as moisturereabsorption will occur into the specimen. This is particularlyimportant if dielectric tests are to be conducted.10. Calculation10.1 D
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