1、Designation: D 150 98 (Reapproved 2004)An American National StandardStandard Test Methods forAC Loss Characteristics and Permittivity (DielectricConstant) of Solid Electrical Insulation1This standard is issued under the fixed designation D 150; the number immediately following the designation indica
2、tes the year oforiginal 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.This standard has been approved for use by agencies of
3、the Department of Defense.1. Scope1.1 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 th
4、at can be covered extends from less than 1Hz to several 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.The reader should also consult ASTM standards o
5、r otherdocuments directly applicable 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 and determine the
6、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:4D 374 Test Methods for Thickness of Solid Electrical Insu-lationD 618 Practice for Conditioning Plastics for TestingD 1082 Test Methods for Dissipat
7、ion Factor and Permittiv-ity (Dielectric Constant) of MicaD 1531 Test Method for Relative Permittivity (DielectricConstant) and Dissipation Factor by Fluid DisplacementProceduresD 1711 Terminology Relating to Electrical InsulationD 5032 Practice for Maintaining Constant Relative Humid-ity by Means o
8、f Aqueous Glycerin SolutionsE 104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous SolutionsE 197 Specifications for Enclosures and Servicing Units forTests Above and Below Room Temperature.53. Terminology3.1 Definitions:3.1.1 capacitance, C, nthat property of a system ofconduc
9、tors and dielectrics which permits the storage of elec-trically separated charges when potential differences existbetween the conductors.3.1.1.1 DiscussionCapacitance is the ratio of a quantity,q, of electricity to a potential difference, V. A capacitance valueis always positive. The units are farad
10、s when the charge isexpressed in coulombs and the potential in volts:C 5 q/V (1)3.1.2 dissipation factor, (D), (loss 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.
11、 1 and Fig. 2).D 5k9/k8 (2)3.1.2.1 Discussiona:D 5 tan d5cot u5Xp/Rp5 G/vCp5 1/vCpRp(3)where:G = equivalent ac conductance,Xp= parallel reactance,Rp= equivalent ac parallel resistance,Cp= parallel capacitance, andv =2pf (sinusoidal wave shape assumed).The reciprocal of the dissipation factor is the
12、quality factor,Q, sometimes called the storage factor. The dissipation factor,1These test methods are under 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 Mar
13、ch 1, 2004. Published March 2004. Originallyapproved in 1922. Last previous edition approved in 1998 as D 150 98.2R. Bartnikas, Chapter 2, “Alternating-Current Loss and Permittivity Measure-ments”, Engineering Dielectrics, Vol. IIB, Electrical Properties of Solid InsulatingMaterials, Measurement Tec
14、hniques, R. Bartnikas, Editor, STP 926, ASTM,Philadelphia, 1987.3R. Bartnikas, Chapter 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, A
15、STMPhiladelphia, 1983.4For 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.5Withdrawn.1Copyright ASTM Internationa
16、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 parallel componentsare as follows:Cp5 Cs/1 1 D2! (5)Rp/Rs5 1 1 D2
17、!/D25 1 1 1/D2! 5 1 1 Q2(6)3.1.2.2 Discussionb: Series RepresentationWhile theparallel representation of an insulating material having adielectric loss (Fig. 3) is usually the proper representation, it isalways possible and occasionally desirable to represent acapacitor at a single frequency by a ca
18、pacitance, Cs, in serieswith a resistance, Rs(Fig. 4 and Fig. 2).3.1.3 loss angle (phase defect angle), (d), nthe anglewhose tangent is the dissipation factor or arctan k9/k8 or whosecotangent is the phase angle.3.1.3.1 DiscussionThe relation of phase angle and lossangle is shown in Fig. 1 and Fig.
19、2. Loss angle is sometimescalled the phase defect angle.3.1.4 loss index, k9 (er9), nthe magnitude of the imaginarypart of the relative complex permittivity; it is the product of therelative permittivity and dissipation factor.3.1.4.1 DiscussionaIt may be expressed as:k9 5k8 D5 power loss/E23 f 3 vo
20、lume 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 1013.3.1.4.2 DiscussionbLoss index is the term agreed uponinternatio
21、nally. In the U.S.A. k9 was formerly called the lossfactor.3.1.5 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 voltageapplied to a dielectric and the component of the resultingcurr
22、ent having the same frequency as the voltage.3.1.5.1 DiscussionThe relation of phase angle and lossangle is shown in Fig. 1 and Fig. 2. Loss angle is sometimescalled the phase defect angle.3.1.6 power factor, PF, nthe ratio of the power in watts,W, dissipated in a material to the product of the effe
23、ctivesinusoidal voltage, V, and current, I, in volt-amperes.3.1.6.1 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 factor is less than 0.1, the power factordiffers from the diss
24、ipation 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!23.1.7 relative permittivity (relative dielectric constant) (SIC)k8(er), nthe real part of the relative complex permittivity. Itis also the ratio of the equivalent parallel capa
25、citance, 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)3.1.7.1 DiscussionaIn common usage the word “rela-tive” is frequently dropped
26、.3.1.7.2 DiscussionbExperimentally, vacuum must bereplaced by the material at all points where it makes asignificant change in capacitance. The equivalent circuit of thedielectric is assumed to consist of Cp, a capacitance in parallelwith conductance. (See Fig. 3.)3.1.7.3 DiscussioncCxis taken to be
27、 Cp, the equivalentparallel capacitance as shown in Fig. 3.3.1.7.4 DiscussiondThe series capacitance is largerthan the parallel capacitance by less than 1 % for a dissipationFIG. 1 Vector Diagram for Parallel CircuitFIG. 2 Vector Diagram for Series CircuitFIG. 3 Parallel CircuitFIG. 4 Series Circuit
28、D 150 98 (2004)2factor 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 calculated.3.1.7.5 DiscussioneThe permittivity o
29、f 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 issaturated with water vapor at 23C is 0.00025 (2, 3), an
30、d variesapproximately linearly with temperature expressed in degreesCelsius, from 10 to 27C. For partial saturation the increase isproportional to the relative humidity3.2 Other definitions may be found in Terminology D 1711.4. Summary of Test Method4.1 Capacitance and ac resistance measurements are
31、 madeon 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 a
32、lsocalculated 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 Electrodes
33、Geometry 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 Ele
34、ctrodesFixed 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. Signific
35、ance and 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 capaci
36、tance of 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 may bephysically as small as possibl
37、e. Intermediate values of permit-tivity are sometimes used for grading stresses at the edge orend 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 sho
38、uld be small, bothin order to reduce the heating of the material and to minimizeits effect on the rest of the network. In high frequencyapplications, a low value of loss index is particularly desirable,since for a given value of loss index, the dielectric lossincreases directly with frequency. In ce
39、rtain dielectric configu-rations such as are used in terminating bushings and cables fortest, an increased loss, usually obtained from increased con-ductivity, is sometimes introduced to control the voltagegradient. In comparisons of materials having approximately thesame permittivity or in the use
40、of any material under suchconditions that its permittivity remains essentially constant, thequantity considered may also be dissipation factor, powerfactor, phase angle, or loss angle. Factors affecting ac loss arediscussed in Appendix X3.5.3 CorrelationWhen adequate correlating data are avail-able,
41、 dissipation factor or power factor may be used to indicatethe characteristics of a material in other respects such asdielectric breakdown, moisture content, degree of cure, anddeterioration from any cause. However, deterioration due tothermal aging may not affect dissipation factor unless themateri
42、al is subsequently exposed to moisture. While the initialvalue of dissipation factor is important, the change in dissipa-tion factor with aging may be much more significant.6. General Measurement Considerations6.1 Fringing and Stray CapacitanceThese test methodsare based upon measuring the specimen
43、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 permittivity, kx8 is complicated b
44、y 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 unguardedparallel plate electrodes between which the specimen is to beplaced for measurement. In addition to t
45、he desired directinterelectrode capacitance, Cv, the system as seen at terminalsa-a8 includes the following:6The boldface numbers in parentheses refer to the list of references appended tothese test methods. FIG. 5 Stray Capacitance, Unguarded ElectrodesD 150 98 (2004)3Ce= fringing or edge capacitan
46、ce,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 the others bein
47、g 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 are in parallel w
48、ith 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 Ce
49、only. 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 change requiring the use of an edge capaci-tance correction using the information from Table 1. Empiricalcorrections have been derived for various conditions, and theseare given in Table 1 (for the case of thin electrodes such asfoil). In routine work, where best accuracy is not required itmay be convenient to use uns
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