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ASTM D150-22
Standard Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
Přeložit název
NORMA vydána dne 1.9.2022
Informace o normě:
Označení normy: ASTM D150-22
Datum vydání normy: 1.9.2022
Kód zboží: NS-1087127
Počet stran: 20
Přibližná hmotnost: 60 g (0.13 liber)
Země: Americká technická norma
Kategorie: Technické normy ASTM
Kategorie - podobné normy:
Anotace textu normy ASTM D150-22 :
Keywords:
ac loss, capacitance: parallel, series, fringing, stray, conductance, contacting electrodes, dielectric, dielectric constant, dissipation factor, electrical insulating material, electrode, fluid displacement, frequency, fringing capacitance, guarded electrode, Hz, loss angle, loss factor, loss tangent, non-contacting electrodes, permittivity, phase angle, phase defect angle, power factor, Q, quality factor, reactance: parallel, series, relative permittivity, resistance: parallel, series
Doplňující informace
| Significance and Use | ||||||||||||||||
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5.1?PermittivityInsulating materials are used in general in two distinct ways, (1) to support and insulate components of an electrical network from each other and from ground, and (5.2?AC LossFor both cases (as electrical insulation and as capacitor dielectric) the ac loss generally needs to be small, both in order to reduce the heating of the material and to minimize its effect on the rest of the network. In high frequency applications, a low value of loss index is particularly desirable, since for a given value of loss index, the dielectric loss increases directly with frequency. In certain dielectric configurations such as are used in terminating bushings and cables for test, an increased loss, usually obtained from increased conductivity, is sometimes introduced to control the voltage gradient. In comparisons of materials having approximately the same permittivity or in the use of any material under such conditions that its permittivity remains essentially constant, it is potentially useful to consider also dissipation factor, power factor, phase angle, or loss angle. Factors affecting ac loss are discussed in Appendix X3. 5.3?CorrelationWhen adequate correlating data are available, dissipation factor or power factor are useful to indicate the characteristics of a material in other respects such as dielectric breakdown, moisture content, degree of cure, and deterioration from any cause. However, it is possible that deterioration due to thermal aging will not affect dissipation factor unless the material is subsequently exposed to moisture. While the initial value of dissipation factor is important, the change in dissipation factor with aging is often much more significant. 5.4?Capacitance is the ratio of a quantity,
5.5?Dissipation factor ((D), (loss tangent), (tan ?)) is the ratio
of the loss index (?") to the relative permittivity (?') which is
equal to the tangent of its loss angle (?) or the cotangent of its
phase angle (?) (see Fig. 1
and Fig. 2). 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 parallel representations as follows: The relationships between series and
parallel components are as follows: 5.5.2?Series RepresentationWhile the parallel representation of an insulating material having a dielectric loss (Fig. 3) is usually the proper representation, it is always possible and occasionally desirable to represent a capacitor at a single frequency by a capacitance, FIG. 3 Parallel Circuit FIG. 4 Series Circuit 5.6?Loss angle ((phase defect angle), (?)) is the angle whose tangent is the dissipation factor or arctan ?"/?' or whose cotangent is the phase angle. 5.6.1?The relation of phase angle and loss angle is shown in Fig. 1 and Fig. 2. Loss angle is sometimes called the phase defect angle. 5.7?Loss
index (?" (?5.7.1?The loss index is expressed as: When the power loss is in watts, the applied voltage is in volts per centimeter, the frequency is in hertz, the volume is the cubic centimeters to which the voltage is applied, the constant has the value of 5.556 ? 10?13. Note 2:?Loss index is the term agreed upon internationally. In
the United States, ?" was formerly called the loss
factor.
5.8?Phase angle (?) is the angle whose cotangent is the dissipation factor, arccot ?"/?' and is also the angular difference in the phase between the sinusoidal alternating voltage applied to a dielectric and the component of the resulting current having the same frequency as the voltage. 5.8.1?The relation of phase angle and loss angle is shown in Fig. 1 and Fig. 2. Loss angle is sometimes called the phase defect angle. 5.9?Power factor (PF) is the ratio of the power in watts, 5.9.1?Power factor is expressed as the cosine of the phase angle ? (or the sine of the loss angle ?). When the dissipation factor is less than
0.1, the power factor differs from the dissipation factor by less
than 0.5 %. Their exact relationship is found from the
following: 5.10?Relative permittivity ((relative
dielectric constant) (SIC) ?'(?r)) is
the real part of the relative complex permittivity. It is also the
ratio of the equivalent parallel capacitance, Cp, of a
given configuration of electrodes with a material as a dielectric
to the capacitance, C?, of the same configuration of
electrodes with vacuum (or air for most practical purposes) as the
dielectric: Note 3:?In common usage the word relative is frequently
dropped.
Note 4:?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 Note 5:?Note 6:?The series capacitance is larger than the parallel
capacitance by less than 1 % for a dissipation factor of 0.1, and
by less than 0.1 % for a dissipation factor of 0.03. If a measuring
circuit yields results in terms of series components, the parallel
capacitance must be calculated from Eq 5 before the corrections and
permittivity are calculated.
Note 7:?The permittivity of dry air at 23 ?C and standard
pressure at 101.3 kPa is 1.000536 (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 addressed extends from less than 1
Hz to several hundred megahertz.
Note 1:?In 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. A reader interested in issues associated with a specific material needs to 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. |
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