ASTM D257-99
(Test Method)Standard Test Methods for DC Resistance or Conductance of Insulating Materials
Standard Test Methods for DC Resistance or Conductance of Insulating Materials
SCOPE
1.1 These test methods cover direct-current procedures for the determination of dc insulation resistance, volume resistance, volume resistivity, surface resistance, and surface resistivity of electrical insulating materials, or the corresponding conductances and conductivities.
1.2 These test methods are not suitable for use in measuring the electrical resistivity/conductivity of moderately conductive materials. Use Test Method D4496 to evaluate such materials.
1.3 The test methods and procedures appear in the following sections: Test Method or Procedure Section Calculation 13 Choice of Apparatus and Test Method 7 Cleaning Solid Specimens 10.1 Conditioning of Specimens 11 Effective Area of Guarded Electrode X2 Electrode Systems 6 Factors Affecting Insulation Resistance or Conductance X1 Measurements Humidity Control 11.2 Liquid Specimens and Cells 9.4 Precision and Bias 15 Procedure for the Measurement of Resistance or Conductance 12 Referenced Documents 2 Report 14 Sampling 8 Significance and Use 5 Specimen Mounting 10 Summary of Test Methods 4 Terminology 3 Test Specimens for Insulation, Volume, and Surface 9 Resistance or Conductance Determination Typical Measurement Methods X3
1.3 This standard does not purport to address all of the safety problems, 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 a specific hazard statement, see Note 1.
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An American National Standard
Designation: D 257 – 99
Standard Test Methods for
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DC Resistance or Conductance of Insulating Materials
This standard is issued under the fixed designation D 257; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2. Referenced Documents
1.1 These test methods cover direct-current procedures for 2.1 ASTM Standards:
the determination of dc insulation resistance, volume resis- D 150 Test Methods for AC Loss Characteristics and Per-
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tance, volume resistivity, surface resistance, and surface resis- mittivity Dielectric Contant of Solid Electrical Insulation
tivity of electrical insulating materials, or the corresponding D 374 Test Methods for Thickness of Solid Electrical Insu-
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conductances and conductivities. lation
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1.2 These test methods are not suitable for use in measuring D 618 Practice for Conditioning Plastics for Testing
the electrical resistivity/conductivity of moderately conductive D 1169 Test Method for Specific Resistance (Resistivity) of
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materials. Use Test Method D 4496 to evaluate such materials. Electrical Insulating Liquids
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1.3 The test methods and procedures appear in the follow- D 1711 Terminology Relating to Electrical Insulation
ing sections: D 4496 Test Method for DC Resistance or Conductance of
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Moderately Conductive Materials
Test Method or Procedure Section
Calculation 13
D 5032 Practice for Maintaining Constant Relative Humid-
Choice of Apparatus and Test Method 7
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ity by Means of Aqueous Glycerin Solutions
Cleaning Solid Specimens 10.1
Conditioning of Specimens 11 E 104 Practice for Maintaining Constant Relative Humidity
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Effective Area of Guarded Electrode X2
by Means of Aqueous Solutions
Electrode Systems 6
Factors Affecting Insulation Resistance or Conductance X1
3. Terminology
Measurements
Humidity Control 11.2
3.1 Definitions—The following definitions are taken from
Liquid Specimens and Cells 9.4
Terminology D 1711 and apply to the terms used in these test
Precision and Bias 15
methods.
Procedure for the Measurement of Resist- 12
ance or Conductance
3.1.1 conductance, insulation, n—the ratio of the total
Referenced Documents 2
volume and surface current between two electrodes (on or in a
Report 14
specimen) to the dc voltage applied to the two electrodes.
Sampling 8
Significance and Use 5
3.1.1.1 Discussion—Insulation conductance is the recipro-
Specimen Mounting 10
cal of insulation resistance.
Summary of Test Methods 4
Terminology 3 3.1.2 conductance, surface, n—the ratio of the current
Test Specimens for Insulation, Volume, and Surface 9
betweentwoelectrodes(onthesurfaceofaspecimen)tothedc
Resistance or Conductance Determination
voltage applied to the electrodes.
Typical Measurement Methods X3
3.1.2.1 Discussion—(Some volume conductance is un-
1.4 This standard does not purport to address all of the
avoidably included in the actual measurement.) Surface con-
safety concerns, if any, associated with its use. It is the
ductance is the reciprocal of surface resistance.
responsibility of the user of this standard to establish appro-
3.1.3 conductance,volume,n—the ratio of the current in the
priate safety and health practices and determine the applica-
volume of a specimen between two electrodes (on or in the
bility of regulatory limitations prior to use. For a specific
specimen) to the dc voltage applied to the two electrodes.
hazard statement, see 6.1.8.
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These test methods are under the jurisdiction of ASTM Committee D-9 on Annual Book of ASTM Standards, Vol 10.01.
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Electrical and Electronic Insulating Materials and are the direct responsibility of Annual Book of ASTM Standards, Vol 08.01.
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Subcommittee D09.12 on Electrical Tests. Annual Book of ASTM Standards, Vol 10.03.
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Current edition approved Oct. 10, 1999. Published November 1999. Originally Annual Book of ASTM Standards, Vol 10.02.
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published as D 257 – 25 T. Last previous edition D 257 – 93 (1998). Annual Book of ASTM Standards, Vol 11.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 257
3.1.3.1 Discussion—Volume conductance is the reciprocal 3.1.11.1 Discussion—Volume resistivity is usually ex-
of volume resistance. pressed in ohm-centimetres (preferred) or in ohm-metres.
Volume resistivity is the reciprocal of volume conductivity.
3.1.4 conductivity, surface, n—the surface conductance
multiplied by that ratio of specimen surface dimensions (dis-
...
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