1、Designation: D150 11An American National StandardStandard Test Methods forAC Loss Characteristics and Permittivity (DielectricConstant) of Solid Electrical Insulation1This standard is issued under the fixed designation D150; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the 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.This standard has been approved for use by agencies of the Department of Def
3、ense.1. Scope*1.1 These test methods cover the determination of relativepermittivity, dissipation factor, loss index, power factor, phaseangle, and loss angle of specimens of solid electrical insulatingmaterials when the standards used are lumped impedances.Thefrequency range addressed extends from
4、less than 1 Hz toseveral hundred megahertz.NOTE 1In common usage, the word relative is frequently dropped.1.2 These test methods provide general information on avariety of electrodes, apparatus, and measurement techniques.Areader interested in issues associated with a specific materialneeds to consu
5、lt ASTM standards or other documents directlyapplicable to the material to be tested.2,31.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices
6、 and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see 7.2.6.1 and 10.2.1.2. Referenced Documents2.1 ASTM Standards:4D374 Test Methods for Thickness of Solid Electrical Insu-lationD618 Practice for Conditioning Plastics for TestingD1082 Test Meth
7、od for Dissipation Factor and Permittivity(Dielectric Constant) of MicaD1531 Test Methods for Relative Permittivity (DielectricConstant) and Dissipation Factor by Fluid DisplacementProceduresD1711 Terminology Relating to Electrical InsulationD5032 Practice for Maintaining Constant Relative Humid-ity
8、 by Means of Aqueous Glycerin SolutionsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous SolutionsE197 Specification for Enclosures and Servicing Units forTests Above and Below Room Temperature53. Terminology3.1 Definitions3.1.1 Use Terminology D1711 for definitions of term
9、s usedin these test methods and associated with electrical insulationmaterials.3.2 Definitions of Terms Specific to This Standard:3.2.1 capacitance, C, nthat property of a system ofconductors and dielectrics which permits the storage of elec-trically separated charges when potential differences exis
10、tbetween the conductors.3.2.1.1 DiscussionCapacitance is the ratio of a quantity,q, of electricity to a potential difference, V.Acapacitance valueis always positive. The units are farads when the charge isexpressed in coulombs and the potential in volts:C 5 q/V (1)3.2.2 dissipation factor, (D), (los
11、s tangent), (tan d), ntheratio of the loss index (k9) to the relative permittivity (k8)which is equal to the tangent of its loss angle (d)orthecotangent of its phase angle (u) (see Fig. 1 and Fig. 2).D 5k9/k8 (2)3.2.2.1 Discussiona:D 5 tan d5cot u5Xp/Rp5 G/vCp5 1/vCpRp(3)1These test methods are unde
12、r the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.12 on Electrical Tests.Current edition approved Aug. 1, 2011. Published August 2011. Originallyapproved in 1922. Last previous edition approved in 2004 as D1
13、50 98R04. DOI:10.1520/D0150-11.2R. Bartnikas, Chapter 2, “Alternating-Current Loss and Permittivity Measure-ments,” Engineering Dielectrics, Vol. IIB, Electrical Properties of Solid InsulatingMaterials, Measurement Techniques, R. Bartnikas, Editor, STP 926, ASTM,Philadelphia, 1987.3R. Bartnikas, Cha
14、pter 1, “Dielectric Loss in Solids,” Engineering Dielectrics,Vol IIA, Electrical Properties of Solid Insulating Materials: Molecular Structure andElectrical Behavior, R. Bartnikas and R. M. Eichorn, Editors, STP 783, ASTMPhiladelphia, 1983.4For referenced ASTM standards, visit the ASTM website, www.
15、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.5Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes sec
16、tion appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where:G = equivalent ac conductance,Xp= parallel reactance,Rp= equivalent ac parallel resistance,Cp= parallel capacitance, andv =2pf (sinusoidal
17、wave shape assumed).The reciprocal of the dissipation factor is the quality factor,Q, sometimes called the storage factor. The dissipation factor,D, of the capacitor is the same for both the series and parallelrepresentations as follows:D 5vRsCs5 1/vRpCp(4)The relationships between series and parall
18、el componentsare as follows:Cp5 Cs/1 1 D2! (5)Rp/Rs5 1 1 D2!/D25 1 1 1/D2! 5 1 1 Q2(6)3.2.2.2 Discussionb: Series RepresentationWhile theparallel representation of an insulating material having adielectric loss (Fig. 3) is usually the proper representation, it isalways possible and occasionally desi
19、rable to represent acapacitor at a single frequency by a capacitance, Cs, in serieswith a resistance, Rs(Fig. 4 and Fig. 2).3.2.3 loss angle (phase defect angle), (d), nthe anglewhose tangent is the dissipation factor or arctan k9/k8 or whosecotangent is the phase angle.3.2.3.1 DiscussionThe relatio
20、n of phase angle and lossangle is shown in Fig. 1 and Fig. 2. Loss angle is sometimescalled the phase defect angle.3.2.4 loss index, k9 (r9), nthe magnitude of the imaginarypart of the relative complex permittivity; it is the product of therelative permittivity and dissipation factor.3.2.4.1 Discuss
21、ionaIt may be expressed as:k9 5k8 D5 power loss/E23 f 3 volume 3 constant! (7)When the power loss is in watts, the applied voltage is involts per centimetre, the frequency is in hertz, the volume is thecubic centimetres to which the voltage is applied, the constanthas the value of 5.556 3 1013.3.2.4
22、.2 DiscussionbLoss index is the term agreed uponinternationally. In the U.S.A. k9 was formerly called the lossfactor.3.2.5 phase angle, u, nthe angle whose cotangent is thedissipation factor, arccot k9/k8 and is also the angular differ-ence in the phase between the sinusoidal alternating voltageappl
23、ied to a dielectric and the component of the resultingcurrent having the same frequency as the voltage.3.2.5.1 DiscussionThe relation of phase angle and lossangle is shown in Fig. 1 and Fig. 2. Loss angle is sometimescalled the phase defect angle.3.2.6 power factor, PF, nthe ratio of the power in wa
24、tts,W, dissipated in a material to the product of the effectivesinusoidal voltage, V, and current, I, in volt-amperes.3.2.6.1 DiscussionPower factor may be expressed as thecosine of the phase angle u (or the sine of the loss angle d).PF 5 W/VI 5 G/=G21 vCp!25 sin d5cos u (8)When the dissipation fact
25、or is less than 0.1, the power factordiffers from the dissipation factor by less than 0.5 %. Theirexact relationship may be found from the following:PF 5 D/=1 1 D2(9)D 5 PF/=1 2 PF!23.2.7 relative permittivity (relative dielectric constant) (SIC)k8(r), nthe real part of the relative complex permitti
26、vity. Itis also the ratio of the equivalent parallel capacitance, Cp,ofagiven configuration of electrodes with a material as a dielectricto the capacitance, Cy, of the same configuration of electrodeswith vacuum (or air for most practical purposes) as thedielectric:k8 5 Cp/Cv(10)3.2.7.1 DiscussionaI
27、n common usage the word “rela-tive” is frequently dropped.3.2.7.2 DiscussionbExperimentally, vacuum must bereplaced by the material at all points where it makes aFIG. 1 Vector Diagram for Parallel CircuitFIG. 2 Vector Diagram for Series CircuitFIG. 3 Parallel CircuitFIG. 4 Series CircuitD150 112sign
28、ificant change in capacitance. The equivalent circuit of thedielectric is assumed to consist of Cp, a capacitance in parallelwith conductance. (See Fig. 3.)3.2.7.3 DiscussioncCxis taken to be Cp, the equivalentparallel capacitance as shown in Fig. 3.3.2.7.4 DiscussiondThe series capacitance is large
29、rthan the parallel capacitance by less than 1 % for a dissipationfactor of 0.1, and by less than 0.1 % for a dissipation factor of0.03. If a measuring circuit yields results in terms of seriescomponents, the parallel capacitance must be calculated fromEq 5 before the corrections and permittivity are
30、 calculated.3.2.7.5 DiscussioneThe permittivity of dry air at 23Cand standard pressure at 101.3 kPa is 1.000536 (1).6Itsdivergence from unity, k8 1, is inversely proportional toabsolute temperature and directly proportional to atmosphericpressure. The increase in permittivity when the space issatura
31、ted with water vapor at 23C is 0.00025 (2, 3), and variesapproximately linearly with temperature expressed in degreesCelsius, from 10 to 27C. For partial saturation the increase isproportional to the relative humidity4. Summary of Test Method4.1 Capacitance and ac resistance measurements are madeon
32、a specimen. Relative permittivity is the specimen capaci-tance divided by a calculated value for the vacuum capacitance(for the same electrode configuration), and is significantlydependent on resolution of error sources. Dissipation factor,generally independent of the specimen geometry, is alsocalcu
33、lated from the measured values.4.2 This method provides (1) guidance for choices ofelectrodes, apparatus, and measurement approaches; and (2)directions on how to avoid or correct for capacitance errors.4.2.1 General Measurement Considerations:Fringing and Stray Capacitance Guarded ElectrodesGeometry
34、 of Specimens Calculation of Vacuum CapacitanceEdge, Ground, and Gap Corrections4.2.2 Electrode Systems - Contacting ElectrodesElectrode Materials Metal FoilConducting Paint Fired-On SilverSprayed Metal Evaporated MetalLiquid Metal Rigid MetalWater4.2.3 Electrode Systems - Non-Contacting ElectrodesF
35、ixed Electrodes Micrometer ElectrodesFluid Displacement Methods4.2.4 Choice of Apparatus and Methods for MeasuringCapacitance and AC LossFrequency Direct and Substitution MethodsTwo-Terminal Measurements Three-Terminal MeasurementsFluid Displacement Methods Accuracy considerations5. Significance and
36、 Use5.1 PermittivityInsulating materials are used in general intwo distinct ways, (1) to support and insulate components of anelectrical network from each other and from ground, and (2)tofunction as the dielectric of a capacitor. For the first use, it isgenerally desirable to have the capacitance of
37、 the support assmall as possible, consistent with acceptable mechanical,chemical, and heat-resisting properties. A low value of permit-tivity is thus desirable. For the second use, it is desirable tohave a high value of permittivity, so that the capacitor is ableto be physically as small as possible
38、. Intermediate values ofpermittivity are sometimes used for grading stresses at the edgeor end of a conductor to minimize ac corona. Factors affectingpermittivity are discussed in Appendix X3.5.2 AC LossFor both cases (as electrical insulation and ascapacitor dielectric) the ac loss generally needs
39、to be small,both in order to reduce the heating of the material and tominimize its effect on the rest of the network. In highfrequency applications, a low value of loss index is particularlydesirable, since for a given value of loss index, the dielectricloss increases directly with frequency. In cer
40、tain dielectricconfigurations such as are used in terminating bushings andcables for test, an increased loss, usually obtained fromincreased conductivity, is sometimes introduced to control thevoltage gradient. In comparisons of materials having approxi-mately the same permittivity or in the use of
41、any material undersuch conditions that its permittivity remains essentially con-stant, it is potentially useful to consider also dissipation factor,power factor, phase angle, or loss angle. Factors affecting acloss are discussed in Appendix X3.5.3 CorrelationWhen adequate correlating data are avail-
42、able, dissipation factor or power factor are useful to indicatethe characteristics of a material in other respects such asdielectric breakdown, moisture content, degree of cure, anddeterioration from any cause. However, it is possible thatdeterioration due to thermal aging will not affect dissipatio
43、nfactor unless the material is subsequently exposed to moisture.While the initial value of dissipation factor is important, thechange in dissipation factor with aging is often much moresignificant.6. General Measurement Considerations6.1 Fringing and Stray CapacitanceThese test methodsare based upon
44、 measuring the specimen capacitance betweenelectrodes, and measuring or calculating the vacuum capaci-tance (or air capacitance for most practical purposes) in thesame electrode system. For unguarded two-electrode measure-ments, the determination of these two values required tocompute the permittivi
45、ty, kx8 is complicated by the presence ofundesired fringing and stray capacitances which get included inthe measurement readings. Fringing and stray capacitances areillustrated by Figs. 5 and 6 for the case of two unguarded6The boldface numbers in parentheses refer to the list of references appended
46、 tothese test methods. FIG. 5 Stray Capacitance, Unguarded ElectrodesD150 113parallel plate electrodes between which the specimen is to beplaced for measurement. In addition to the desired directinterelectrode capacitance, Cv, the system as seen at terminalsa-a8 includes the following:Ce= fringing o
47、r edge capacitance,Cg= capacitance to ground of the outside face of eachelectrode,CL= capacitance between connecting leads,CLg= capacitance of the leads to ground, andCLe= capacitance between the leads and the electrodes.Only the desired capacitance, Cv, is independent of theoutside environment, all
48、 the others being dependent to a degreeon the proximity of other objects. It is necessary to distinguishbetween two possible measuring conditions to determine theeffects of the undesired capacitances. When one measuringelectrode is grounded, as is often the case, all of the capaci-tances described a
49、re in parallel with the desired Cv- with theexception of the ground capacitance of the grounded electrodeand its lead. If Cvis placed within a chamber with walls atguard potential, and the leads to the chamber are guarded, thecapacitance to ground no longer appears, and the capacitanceseen at a-a8 includes Cvand Ceonly. For a given electrodearrangement, the edge capacitance, Ce, can be calculated withreasonable accuracy when the dielectric is air. When a speci-men is placed between the electrodes, the value of the edgecapacitance can
