ASTM D150-98(2004)
(Test Method)Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
SCOPE
1.1 These test methods cover the determination of relative permittivity, dissipation factor, loss index, power factor, phase angle, and loss angle of specimens of solid electrical insulating materials when the standards used are lumped impedances. The frequency range that can be covered extends from less than 1 Hz to several hundred megahertz. Note 1In common usage, the word relative is frequently dropped.
1.2 These test methods provide general information on a variety of electrodes, apparatus, and measurement techniques. The reader should also consult ASTM standards or other documents directly applicable to the material to be tested.,
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 7.2.6.1 and 10.2.1.
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Standards Content (Sample)
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An American National Standard
Designation:D150–98 (Reapproved 2004)
Standard Test Methods for
AC Loss Characteristics and Permittivity (Dielectric
Constant) of Solid Electrical Insulation
This standard is issued under the fixed designation D150; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope (Dielectric Constant) of Mica
D1531 Test Methods for Relative Permittivity (Dielectric
1.1 These test methods cover the determination of relative
Constant) and Dissipation Factor by Fluid Displacement
permittivity, dissipation factor, loss index, power factor, phase
Procedures
angle,andlossangleofspecimensofsolidelectricalinsulating
D1711 Terminology Relating to Electrical Insulation
materialswhenthestandardsusedarelumpedimpedances.The
D5032 Practice for Maintaining Constant Relative Humid-
frequency range that can be covered extends from less than 1
ity by Means of Aqueous Glycerin Solutions
Hz to several hundred megahertz.
E104 Practice for Maintaining Constant Relative Humidity
NOTE 1—In common usage, the word relative is frequently dropped.
by Means of Aqueous Solutions
1.2 These test methods provide general information on a E197 Specification for Enclosures and Servicing Units for
variety of electrodes, apparatus, and measurement techniques. Tests Above and Below Room Temperature
The reader should also consult ASTM standards or other
,
23 3. Terminology
documents directly applicable to the material to be tested.
1.3 This standard does not purport to address all of the 3.1 Definitions:
3.1.1 capacitance, C, n—that property of a system of
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- conductors and dielectrics which permits the storage of elec-
trically separated charges when potential differences exist
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For specific hazard between the conductors.
3.1.1.1 Discussion—Capacitance is the ratio of a quantity,
statements, see 7.2.6.1 and 10.2.1.
q,ofelectricitytoapotentialdifference, V.Acapacitancevalue
2. Referenced Documents
is always positive. The units are farads when the charge is
2.1 ASTM Standards: expressed in coulombs and the potential in volts:
D374 Test Methods for Thickness of Solid Electrical Insu-
C 5 q/V (1)
lation
3.1.2 dissipation factor, (D), (loss tangent), (tan d), n—the
D618 Practice for Conditioning Plastics for Testing
ratio of the loss index (k9) to the relative permittivity (k8)
D1082 Test Method for Dissipation Factor and Permittivity
which is equal to the tangent of its loss angle (d)orthe
cotangent of its phase angle (u) (see Fig. 1 and Fig. 2).
D5k9/k8 (2)
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
3.1.2.1 Discussion—a:
Subcommittee D09.12 on Electrical Tests.
Current edition approved March 1, 2004. Published March 2004. Originally D 5tand5cotu5 X /R 5 G/vC 51/vC R (3)
p p p p p
approved in 1922. Last previous edition approved in 1998 as D150–98. DOI:
10.1520/D0150-98R04.
where:
R. Bartnikas, Chapter 2, “Alternating-Current Loss and Permittivity Measure-
G = equivalent ac conductance,
ments”, Engineering Dielectrics, Vol. IIB, Electrical Properties of Solid Insulating
X = parallel reactance,
p
Materials, Measurement Techniques, R. Bartnikas, Editor, STP 926, ASTM,
R = equivalent ac parallel resistance,
Philadelphia, 1987. p
C = parallel capacitance, and
R. Bartnikas, Chapter 1, “Dielectric Loss in Solids”, Engineering Dielectrics,
p
VolIIA,ElectricalPropertiesofSolidInsulatingMaterials:MolecularStructureand
v =2pf (sinusoidal wave shape assumed).
Electrical Behavior, R. Bartnikas and R. M. Eichorn, Editors, STP 783, ASTM
Philadelphia, 1983.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Withdrawn. The last approved version of this historical standard is referenced
the ASTM website. on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D150–98 (2004)
FIG. 4 Series Circuit
FIG. 1 Vector Diagram for Parallel Circuit
3.1.4.1 Discussion—a—It may be expressed as:
k95k8 D
5powerloss/~E 3 f 3 volume 3constant! (7)
When the power loss is in watts, the applied voltage is in
voltspercentimetre,thefrequencyisinhertz,thevolumeisthe
cubic centimetres to which the voltage is applied, the constant
−13
has the value of 5.556 310 .
3.1.4.2 Discussion—b—Loss index is the term agreed upon
internationally. In the U.S.A. k9 was formerly called the loss
factor.
3.1.5 phase angle, u, n—the angle whose cotangent is the
dissipation factor, arccot k9/k8 and is also the angular differ-
FIG. 2 Vector Diagram for Series Circuit
ence in the phase between the sinusoidal alternating voltage
applied to a dielectric and the component of the resulting
The reciprocal of the dissipation factor is the quality factor,
current having the same frequency as the voltage.
Q, sometimes called the storage factor. The dissipation factor,
3.1.5.1 Discussion—The relation of phase angle and loss
D, of the capacitor is the same for both the series and parallel
representations as follows: angle is shown in Fig. 1 and Fig. 2. Loss angle is sometimes
called the phase defect angle.
D5vR C 51/vR C (4)
s s p p
3.1.6 power factor, PF, n—the ratio of the power in watts,
W, dissipated in a material to the product of the effective
The relationships between series and parallel components
sinusoidal voltage, V, and current, I, in volt-amperes.
are as follows:
3.1.6.1 Discussion—Power factor may be expressed as the
C 5 C /~1 1 D ! (5)
p s cosine of the phase angle u (or the sine of the loss angle d).
2 2
PF 5 W/VI 5 G/ G 1 ~vC ! 5sind5cos u (8)
=
p
2 2 2 2
R /R 5 ~1 1 D !/D 51 1 ~1/D ! 51 1 Q (6)
p s
Whenthedissipationfactorislessthan0.1,thepowerfactor
3.1.2.2 Discussion—b: Series Representation—While the
differs from the dissipation factor by less than 0.5%. Their
parallel representation of an insulating material having a
exact relationship may be found from the following:
dielectric loss (Fig. 3) is usually the proper representation, it is
always possible and occasionally desirable to represent a
PF 5 D/=1 1 D (9)
capacitor at a single frequency by a capacitance, C , in series
s 2
D 5 PF/=1 2 ~PF!
with a resistance, R (Fig. 4 and Fig. 2).
s
3.1.7 relativepermittivity(relativedielectricconstant)(SIC)
3.1.3 loss angle (phase defect angle), (d), n—the angle
k8(´ ), n—the real part of the relative complex permittivity. It
whosetangentisthedissipationfactororarctan k9/k8orwhose
r
is also the ratio of the equivalent parallel capacitance, C,ofa
cotangent is the phase angle.
p
givenconfigurationofelectrodeswithamaterialasadielectric
3.1.3.1 Discussion—The relation of phase angle and loss
to the capacitance, C , of the same configuration of electrodes
angle is shown in Fig. 1 and Fig. 2. Loss angle is sometimes
y
with vacuum (or air for most practical purposes) as the
called the phase defect angle.
dielectric:
3.1.4 loss index, k9 (´ 9), n—themagnitudeoftheimaginary
r
partoftherelativecomplexpermittivity;itistheproductofthe
k8 5 C /C (10)
p v
relative permittivity and dissipation factor.
3.1.7.1 Discussion—a—In common usage the word “rela-
tive” is frequently dropped.
3.1.7.2 Discussion—b—Experimentally, vacuum must be
replaced by the material at all points where it makes a
significant change in capacitance.The equivalent circuit of the
dielectric is assumed to consist of C , a capacitance in parallel
p
with conductance. (See Fig. 3.)
3.1.7.3 Discussion—c—C istakentobeC ,theequivalent
x p
FIG. 3 Parallel Circuit parallel capacitance as shown in Fig. 3.
D150–98 (2004)
3.1.7.4 Discussion—d—The series capacitance is larger have a high value of permittivity, so that the capacitor may be
than the parallel capacitance by less than 1% for a dissipation physically as small as possible. Intermediate values of permit-
factor of 0.1, and by less than 0.1% for a dissipation factor of tivity are sometimes used for grading stresses at the edge or
0.03. If a measuring circuit yields results in terms of series end of a conductor to minimize ac corona. Factors affecting
components, the parallel capacitance must be calculated from permittivity are discussed in Appendix X3.
Eq 5 before the corrections and permittivity are calculated. 5.2 AC Loss—Forbothcases(aselectricalinsulationandas
3.1.7.5 Discussion—e—The permittivity of dry air at 23°C capacitordielectric)theaclossgenerallyshouldbesmall,both
and standard pressure at 101.3 kPa is 1.000536 (1). Its in order to reduce the heating of the material and to minimize
divergence from unity, k8−1, is inversely proportional to its effect on the rest of the network. In high frequency
absolute temperature and directly proportional to atmospheric applications,alowvalueoflossindexisparticularlydesirable,
pressure. The increase in permittivity when the space is since for a given value of loss index, the dielectric loss
saturatedwithwatervaporat23°Cis0.00025(2,3),andvaries increases directly with frequency. In certain dielectric configu-
approximately linearly with temperature expressed in degrees rations such as are used in terminating bushings and cables for
Celsius, from 10 to 27°C. For partial saturation the increase is test, an increased loss, usually obtained from increased con-
proportional to the relative humidity ductivity, is sometimes introduced to control the voltage
3.2 Other definitions may be found in Terminology D1711.
gradient.Incomparisonsofmaterialshavingapproximatelythe
same permittivity or in the use of any material under such
4. Summary of Test Method
conditionsthatitspermittivityremainsessentiallyconstant,the
quantity considered may also be dissipation factor, power
4.1 Capacitance and ac resistance measurements are made
factor, phase angle, or loss angle. Factors affecting ac loss are
on a specimen. Relative permittivity is the specimen capaci-
discussed in Appendix X3.
tancedividedbyacalculatedvalueforthevacuumcapacitance
(for the same electrode configuration), and is significantly 5.3 Correlation—When adequate correlating data are avail-
able,dissipationfactororpowerfactormaybeusedtoindicate
dependent on resolution of error sources. Dissipation factor,
the characteristics of a material in other respects such as
generally independent of the specimen geometry, is also
dielectric breakdown, moisture content, degree of cure, and
calculated from the measured values.
deterioration from any cause. However, deterioration due to
4.2 This method provides (1) guidance for choices of
thermal aging may not affect dissipation factor unless the
electrodes, apparatus, and measurement approaches; and (2)
material is subsequently exposed to moisture. While the initial
directions on how to avoid or correct for capacitance errors.
value of dissipation factor is important, the change in dissipa-
4.2.1 General Measurement Considerations:
tion factor with aging may be much more significant.
Fringing and Stray Capacitance Guarded Electrodes
Geometry of Specimens Calculation of Vacuum Capacitance
Edge, Ground, and Gap Corrections
6. General Measurement Considerations
4.2.2 Electrode Systems - Contacting Electrodes
6.1 Fringing and Stray Capacitance—These test methods
Electrode Materials Metal Foil
are based upon measuring the specimen capacitance between
Conducting Paint Fired-On Silver
electrodes, and measuring or calculating the vacuum capaci-
Sprayed Metal Evaporated Metal
Liquid Metal Rigid Metal tance (or air capacitance for most practical purposes) in the
Water
same electrode system. For unguarded two-electrode measure-
ments, the determination of these two values required to
4.2.3 Electrode Systems - Non-Contacting Electrodes
computethepermittivity, k 8iscomplicatedbythepresenceof
x
Fixed Electrodes Micrometer Electrodes
Fluid Displacement Methods
undesiredfringingandstraycapacitanceswhichgetincludedin
the measurement readings. Fringing and stray capacitances are
4.2.4 Choice of Apparatus and Methods for Measuring
illustrated by Figs. 5 and 6 for the case of two unguarded
Capacitance and AC Loss
parallel plate electrodes between which the specimen is to be
Frequency Direct and Substitution Methods
placed for measurement. In addition to the desired direct
Two-Terminal Measurements Three-Terminal Measurements
Fluid Displacement Methods Accuracy considerations
interelectrode capacitance, C , the system as seen at terminals
v
a-a8 includes the following:
5. Significance and Use
5.1 Permittivity—Insulatingmaterialsareusedingeneralin
twodistinctways,(1)tosupportandinsulatecomponentsofan
electricalnetworkfromeachotherandfromground,and(2)to
function as the dielectric of a capacitor. For the first use, it is
generally desirable to have the capacitance of the support as
small as possible, consistent with acceptable mechanical,
chemical, and heat-resisting properties.Alow value of permit-
tivity is thus desirable. For the second use, it is desirable to
The boldface numbers in parentheses refer to the list of references appended to
these test methods. FIG. 5 Stray Capacitance, Unguarded Electrodes
D150–98 (2004)
exception of the ground capacitance of the grounded electrode
and its lead. If C is placed within a chamber with walls at
v
guard potential, and the leads to the chamber are guarded, the
capacitance to ground no longer appears, and the capacitance
seen at a-a8 includes C and C only. For a given electrode
v e
FIG. 6 Flux Lines Between Unguarded Electrodes
arrangement, the edge capacitance, C , can be calculated with
e
reasonable accuracy when the dielectric is air. When a speci-
men is placed between the electrodes, the value of the edge
C = fringing or edge capacitance,
e
capacitance can change requiring the use of an edge capaci-
C = capacitance to ground of the outside face of each
g
tance correction using the information fromTable 1. Empirical
electrode,
correctionshavebeenderivedforvariousconditions,andthese
C = capacitance between connecting leads,
L
are given in Table 1 (for the case of thin electrodes such
...
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