ASTM D2413-99

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An American National Standard
Designation:D2413–99
Standard Practice for
Preparation of Insulating Paper and Board Impregnated with
a Liquid Dielectric
This standard is issued under the fixed designation D 2413; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Insulating Oils of Petroleum Origin Using VDE Elec-
trodes
1.1 This practice covers the preparation of insulating paper
D 1933 Specification for Nitrogen Gas as an Electrical
and board impregnated with a liquid dielectric. Where this
Insulating Material
practice states only “paper,” the same procedure shall apply to
D 3394 Methods of Sampling and Testing Electrical Insu-
board.
lating Board
1.2 This practice has been found practicable for papers
D 3426 Test Method for Dielectric Breakdown Voltage and
having nominal thickness of 0.05 mm (2 mil) and above. It has
Dielectric Strength of Solid Electrical Insulating Materials
been used successfully for insulating board as thick as 6 mm
1 Using Impulse Waves
( ⁄4 in.) when care is taken to ensure the specimen geometry
necessary for valid measurement of dielectric properties. Suit-
3. Terminology
able geometry depends on the electrode system used. Rigid
3.1 Definitions—Use Terminology D 1711 for definitions of
solid opposing electrodes require flat specimens that have
terms used in this practice and associated with electrical or
essentially parallel surfaces.
electronic materials.
1.3 The values stated in SI units are to be regarded as the
standard.
4. Summary of Practice
2. Referenced Documents 4.1 The paper is heated and vacuum dried and the liquid
dielectric degassed. The paper may be dried in loose form or
2.1 ASTM Standards:
assembled between electrodes. The liquid dielectric may be
D117 Guide to Test Methods and Specifications for Elec-
2 heated and degassed prior to introducing it into the chamber
trical Insulating Oils of Petroleum Origin
containing the dried paper or it may be degassed as it is
D 149 Test Methods for Dielectric Breakdown Voltage and
introduced into the evacuated chamber containing the dried
Dielectric Strength of Solid Electrical Insulating Materials
3 paper.Asufficient length of time is allowed for the impregnat-
at Commercial Power Frequencies
ing process depending on the apparent density of the paper and
D 150 Test Methods for AC Loss Characteristics and Per-
method of impregnation. The impregnated specimens are
mittivity (Dielectric Constant) of Solid Electrical Insulat-
3 subsequently tested for various selected electrical properties.
ing Materials
D 202 Test Methods for Sampling and Testing Untreated
5. Significance and Use
Paper Used for Electrical Insulation
5.1 Dissipation Factor and Relative Permittivity—
D 257 Test Methods for D-C Resistance or Conductance of
Knowledge of these properties is important in the design of
Insulating Materials
electrical equipment such as cables, transformers, insulators,
D 924 TestMethodforDissipationFactor(orPowerFactor)
etc. The numerical product of these two properties of a
and Relative Permittivity (Dielectric Constant) of Electri-
2 dielectric system is proportional to the energy loss converted to
cal Insulating Liquids
3 heat,andiscalleditslossindex(seeTerminologyD 1711).The
D 1711 Terminology Relating to Electrical Insulation
energy loss reduces the efficiency of electrical equipment. The
D 1816 Test Method for Dielectric Breakdown Voltage of
heat produced tends to chemically degrade the dielectric
material and may even lead to thermal runaway. Test results of
impregnated specimens can disclose significant differences
This practice is under the jurisdiction of ASTM Committee D-9 on Electrical between combinations of papers and oils that appear similar
and Electronic Insulating Materials and is the direct responsibility of Subcommittee
when the papers and the oils are tested separately. Dissipation
D09.19 on Dielectric Sheet and Roll Products.
factor, particularly at elevated temperatures, is often changed
Current edition approved May 10, 1999. Published June 1999. Originally
published as D 2413 – 65 T. Last previous edition D 2413 – 87 (1998).
Annual Book of ASTM Standards, Vol 10.03.
3 4
Annual Book of ASTM Standards, Vol 10.01. Annual Book of ASTM Standards, Vol 10.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D2413–99
significantly by the presence of a small quantity of impurities have a connection, through a suitable vapor trap, to a vacuum
in either the liquid or the paper. This practice is useful in the pump capable of maintaining selected absolute pressures as
comparison of materials and in evaluating the effects of lowas75Pa(0.5Torr),asmeasuredbyasuitablevacuumgage
different papers on a given liquid. Judicious analysis of results having a connection to the chamber separate from that of the
with respect to time, temperature, and field strength should be vacuum pump. It shall be constructed of materials that will not
useful in predicting the performance and capabilities of sys- contaminate either the liquid dielectric or the paper, and shall
tems using the paper and the liquid. For additional information includeanappropriatelyvalvedentryfortheliquidplusabaffle
on the significance of dissipation factor and relative permittiv- for the purposes indicated in 9.3.
ity, see Test Methods D 150. 6.1.2 Vacuum Drying Equipment—For the liquid, if Proce-
5.2 Test Method for Dielectric Breakdown Voltage and dure 1 (9.2.1) is to be used. This may be substantially a
Dielectric Strength of Solid Electrical Insulating Materials at duplicate of the impregnating chamber except that a valved
Commercial Power Frequencies: vacuum-tight line is required for transferring dried liquid to the
5.2.1 Acomprehensive discussion of the significance of the impregnating chamber. Baffles may be used to expose thin
dielectric strength test as applied to solid, semi-solid, and films of incoming liquid to the drying and degassing effect of
liquid materials is given in Appendix X1 of Test Method heat and vacuum.
D 149. Other factors peculiar to high-quality composite insu-
6.2 Equipment for Measuring Dissipation Factor (Power
lations, such as oil-impregnated papers, are considered in the Factor) and Permittivity of Liquid Dielectric—The equipment
following:
and test cell shall be any three-terminal system meeting the
5.2.2 In tests involving high electrical stresses, immersion requirements set forth in Test Method D 924.
ofcriticalpartsofatestcircuitinoilisawidelyusedtechnique
6.3 Equipment for Measuring Dielectric Strength at Com-
for inhibiting corona. However, it has limitations that must be mercial Power Frequencies:
recognized when using the submerged electrode option of this
6.3.1 The equipment for measuring the dielectric strength of
practice (Note 1). Attack on the paper by corona generated in
the paper shall be as described in Test Method D 149, except
the surrounding fluid at electrode edges can occur whether the
that the electrodes shall be as specified in Test Methods D 202
fluidisairoroil.Coronaoccursatconsiderablyhighervoltages
or D 3394, as applicable.
in oil than in air. Thick and dense papers are more likely to
6.3.2 The equipment for testing the dielectric strength of the
cause discharge-initiated breakdowns. For interpretation of
liquid shall be as described in Test Method D 1816.
breakdown measurements the number of edge breakdowns,
6.4 Equipment for measuring impulse withstand strength
implying discharge-initiated breakdowns, should be consid-
and impulse breakdown dielectric strength shall be that which
ered.
is specified in Test Method D 3426.
NOTE 1—Two techniques are in use in the industry for testing speci-
7. General Considerations
mens for dielectric breakdown voltage. In one, the test is made with the
electrodes and test specimen submerged in the impregnating liquid while
7.1 When undertaking an investigation into the electrical
in the other the electrodes are not submerged, that is, the specimen is
properties of various papers that are to be impregnated with a
tested in air. Much data has been accumulated using the latter technique.
specific liquid dielectric or a specific paper to be impregnated
These techniques yield different values of breakdown voltage. Test
with various liquid dielectrics, th
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