1、Designation: D 2413 99 (Reapproved 2005)An American National StandardStandard Practice forPreparation of Insulating Paper and Board Impregnated witha Liquid Dielectric1This standard is issued under the fixed designation D 2413; the number immediately following the designation indicates the year ofor
2、iginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the preparation of insulating paperand
3、board impregnated with a liquid dielectric. Where 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(
4、14 in.) when care is taken to ensure the specimen 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
5、are to be regarded as thestandard.2. Referenced Documents2.1 ASTM Standards:2D117 Guide for Sampling, Test Methods, and Specifica-tions for Electrical Insulating Oils of Petroleum OriginD 149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materials
6、at Commercial Power FrequenciesD 150 Test Methods for A-C Loss Characteristics andPermittivity (Dielectric Constant) of Solid Electrical Insu-lationD 202 Test Methods for Sampling and Testing UntreatedPaper Used for Electrical InsulationD 257 Test Methods for D-C Resistance or Conductance ofInsulati
7、ng MaterialsD 924 Test Method for Dissipation Factor (or Power Factor)and Relative Permittivity (Dielectric Constant) of Electri-cal Insulating LiquidsD 1711 Terminology Relating to Electrical InsulationD 1816 Test Method for Dielectric Breakdown Voltage ofInsulating Oils of Petroleum Origin Using V
8、DE ElectrodesD 1933 Specification for Nitrogen Gas as an ElectricalInsulating MaterialD 3394 Test Methods for Sampling and Testing ElectricalInsulating BoardD 3426 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating MaterialsUsing Impulse Waves3. Termin
9、ology3.1 DefinitionsUse Terminology D 1711 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 el
10、ectrodes. The liquid dielectric 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 o
11、n the apparent density 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 equi
12、pment such as cables, transformers, insulators,etc. The numerical product of these two properties of adielectric system is proportional to the energy loss converted toheat, and is called its loss index (see Terminology D 1711). Theenergy loss reduces the efficiency of electrical equipment. Theheat p
13、roduced tends to 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. Dissipationfactor,
14、particularly at elevated temperatures, is often changedsignificantly by the presence of a small quantity of impurities1This practice is under the jurisdiction of ASTM Committee D09 on Electricaland Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.19 on Dielectric S
15、heet and Roll Products.Current edition approved May 10, 1999. Published June 1999. Originallyapproved in 1965. Last previous edition approved in 1998 as D 2413 87 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annu
16、al Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.in either the liquid or the paper. This practice is useful in thecomparison
17、of materials and in evaluating the effects ofdifferent papers on a given liquid. Judicious analysis of resultswith respect to time, temperature, and field strength should beuseful in predicting the performance and capabilities of sys-tems using the paper and the liquid. For additional informationon
18、the significance of dissipation factor and relative permittiv-ity, see Test Methods D 150.5.2 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 thedielect
19、ric strength test as applied to solid, semi-solid, andliquid materials is given in Appendix X1 of Test MethodD 149. Other factors peculiar to high-quality composite insu-lations, such as oil-impregnated papers, are considered in thefollowing:5.2.2 In tests involving high electrical stresses, immersi
20、onof critical 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
21、occur whether 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 the number of edge breakdowns,implying discharge-initiated breakdowns, sho
22、uld be consid-ered.NOTE 1Two techniques are in use in the industry for testing speci-mens for dielectric breakdown voltage. In one, the test is made with theelectrodes and test specimen submerged in the impregnating liquid whilein the other the electrodes are not submerged, that is, the specimen ist
23、ested in air. Much data has been accumulated using the latter technique.These techniques yield different values of breakdown voltage. TestMethod D 149 states preference for testing materials in the medium inwhich they are used. The use of submerged electrodes follows thispreference. When testing thi
24、ck insulating boards, the 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
25、test results toequipment design and service requires particular caution andskill (see Appendix X1 of Test Method D 149).5.3 Dielectric Breakdown Voltage and Dielectric StrengthUnder Impulse ConditionsTesting impregnated paper orboard under impulse conditions can yield useful data for thedesigner of
26、electrical equipment. The test results are useful inthe comparison of materials and for research studies. For amore general treatise on the significance of impulse testing seeTest Method D 3426.6. Apparatus6.1 Drying and Impregnating Equipment:6.1.1 Impregnating ChamberThe chamber shall beequipped w
27、ith a thermal control unit capable of maintainingselected temperatures as high as 115 C. 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 conn
28、ection to the chamber separate 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 Equipm
29、entFor the liquid, if Proce-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 dry
30、ing and degassing effect ofheat 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 D 924.6.3 Equipment for Measuring Dielectric Str
31、ength at Com-mercial Power Frequencies:6.3.1 The equipment for measuring the dielectric strength ofthe paper shall be as described in Test Method D 149, exceptthat the electrodes shall be as specified in Test Methods D 202or D 3394, as applicable.6.3.2 The equipment for testing the dielectric streng
32、th of theliquid shall be as described in Test Method D 1816.6.4 Equipment for measuring impulse withstand strengthand impulse breakdown dielectric strength shall be that whichis specified in Test Method D 3426.7. General Considerations7.1 When undertaking an investigation into the electricalproperti
33、es of various papers that are to be 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 b
34、e used.7.1.3 Whether the liquid dielectric 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 a
35、re 80 C and 100 C.7.2 Determine the 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 SpecificationD 1933.8. Test Specim
36、ens8.1 Take great care to prevent either the untreated paper orthe liquid dielectric from being contaminated or degraded byimproper handling or from being subjected to laboratoryfumes, dirt, oxidation, or ultraviolet light.8.2 Before impregnation, cut the paper specimens to a sizesuitable to the geo
37、metry of the electrodes to be used. Test atD 2413 99 (2005)2least five specimens for each procedure used. Test at least fivespecimens for each procedure used.9. Impregnating Procedure9.1 Vacuum Drying the PaperTwo procedures are usedfor drying the paper: Procedure A, in which the paper is inloose fo
38、rm in either sheets or strips and Procedure B, in whichthe paper 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 1156 5C and an absolute pressure of 75 Pa (0.5 Torr) or less for atleast 16 h. This period h
39、as been found adequate for dryingpapers having 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 ele
40、ctrodes and place the assembly in the impregnatingchamber. 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 th
41、e assembly to the same treatment as that described 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
42、paper is in equilibrium with the test chamber, but does notnecessarily mean that the paper is dry. When resistivity ismeasured instead of dissipation factor, do so in accordancewith Test Methods D 257.9.2 Vacuum Treating the Liquid DielectricTwo proce-dures are used for drying and degassing the liqu
43、id: Procedure1, in which the liquid is treated in a separate chamber beforebeing introduced into the impregnating chamber containing thedried paper, and Procedure 2, in which the liquid is introduceddirectly into the impregnating chamber. Procedure 1 is recom-mended for referee testing and for use w
44、ith low viscosityimpregnants such as transformer 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 3 10-6m2/s (50 cSt) or higher at 40 C, as may be usedwit
45、h paper for cables, the same conditions as used for the paperdrying have been found to be satisfactory. For transformer oilswith a viscosity in the order of 12 3 106m2/s (12 cSt) at 40C, conditions of 60 C and 40 Pa (0.3 Torr) have been foundto be adequate. Other liquids may require other conditions
46、 aslearned by experience. To obtain good degassification, intro-duce the liquid, warmed to the temperature chosen, slowly intothe separate 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 l
47、iquid, as outlined in 9.2.1.To obtain good degassification, 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 wil
48、l impregnate the paper from the bottom. After theliquid 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
49、nitrogen, may be applied to the impreg-nating chamber. The 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 Impregnated specimens should not be removed fromimmersion in the liquid dielectric even momentarily, where asmoisture reabsorption will occur into the specimen. This isparticularly important if
