ASTM D374/D374M-16
(Test Method)Standard Test Methods for Thickness of Solid Electrical Insulation
Standard Test Methods for Thickness of Solid Electrical Insulation
SIGNIFICANCE AND USE
5.1 Some electrical properties, such as dielectric strength, vary with the thickness of the material. Determination of certain properties, such as relative permittivity (dielectric constant) and volume resistivity, usually require a knowledge of the thickness. Design and construction of electrical machinery require that the thickness of insulation be known.
SCOPE
1.1 These test methods cover the determination of the thickness of several types of solid electrical insulating materials employing recommended techniques. Use these test methods except as otherwise required by a material specification.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, each system shall be used independently of the other. It is possible that combining values from the two systems will result in non-conformance with the standard.
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.
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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.
Designation:D374/D374M −16
Standard Test Methods for
1
Thickness of Solid Electrical Insulation
This standard is issued under the fixed designation D374/D374M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 3. Terminology
1.1 These test methods cover the determination of the 3.1 Refer to Terminology D1711 for definitions pertinent to
thickness of several types of solid electrical insulating materi- this standard.
als employing recommended techniques. Use these test meth-
3.2 Definitions of Terms Specific to This Standard:
ods except as otherwise required by a material specification.
3.2.1 1 micron, µm, n—a dimension equivalent to
1.2 The values stated in either SI units or inch-pound units 0.03937 mils.
are to be regarded separately as standard. The values stated in
3.2.2 1 mil, n—a dimension equivalent to 0.0010 in.
each system may not be exact equivalents; therefore, each
3.2.3 absolute uncertainty (of a measurement), n—the
system shall be used independently of the other. Combining
smallestdivisionabletobereaddirectlyontheinstrumentused
values from the two systems may result in non-conformance
for measurement.
with the standard.
3.2.4 micrometer, n—an instrument for measuring any di-
1.3 This standard does not purport to address all of the
mension with absolute uncertainty of 1 mil [25 µm] or smaller.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Methods
priate safety, health, and environmental practices and deter-
4.1 This standard provides eight different test methods for
mine the applicability of regulatory limitations prior to use.
the measurement of thickness of solid electrical insulation
1.4 This international standard was developed in accor-
materials. The test methods (identified as Test Methods A
dance with internationally recognized principles on standard-
through H) employ different micrometers that exert various
ization established in the Decision on Principles for the
pressures for varying times upon specimens of different geom-
Development of International Standards, Guides and Recom-
etries. Tables 1 and 2 display basic differences of each test
mendations issued by the World Trade Organization Technical
method and identify test methods applicable for use on various
Barriers to Trade (TBT) Committee.
categories of materials.
2. Referenced Documents
5. Significance and Use
2
2.1 ASTM Standards:
5.1 Some electrical properties, such as dielectric strength,
D1711 Terminology Relating to Electrical Insulation
vary with the thickness of the material. Determination of
D6054 Practice for Conditioning Electrical Insulating Mate-
certain properties, such as relative permittivity (dielectric
3
rials for Testing (Withdrawn 2012)
constant) and volume resistivity, usually require a knowledge
E252 Test Method for Thickness of Foil, Thin Sheet, and
of the thickness. Design and construction of electrical machin-
Film by Mass Measurement
ery require that the thickness of insulation be known.
6. Apparatus
1
These test methods are under the jurisdiction of ASTM Committee D09 on
4
Electrical and Electronic Insulating Materials and are the direct responsibility of
6.1 Apparatus A—Machinist’s Micrometer Caliper with
Subcommittee D09.12 on Electrical Tests.
Calibrated Ratchet or Friction Thimble:
Current edition approved June 1, 2016. Published August 2016. Originally
6.1.1 ApparatusAis a micrometer caliper without a locking
approved in 1933. Last previous edition approved in 2004 as D374 – 99 (2004)
which was withdrawn January 2013 and reinstated in June 2016. DOI: 10.1520/
device but is equipped with either a calibrated ratchet or a
D0374_D0374M-16.
friction thimble. By use of a proper manipulative procedure
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
andacalibratedspring(seeAnnexA1),thepressureexertedon
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 the specimen is controllable.
the ASTM website.
3
The last approved version of this historical standard is referenced on
4
www.astm.org. Hereinafter referred to as a machinist’s micrometer.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D374/D374M − 16
Standard Test Methods for
1
Thickness of Solid Electrical Insulation
This standard is issued under the fixed designation D374/D374M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 3. Terminology
1.1 These test methods cover the determination of the 3.1 Refer to Terminology D1711 for definitions pertinent to
thickness of several types of solid electrical insulating materi- this standard.
als employing recommended techniques. Use these test meth-
3.2 Definitions of Terms Specific to This Standard:
ods except as otherwise required by a material specification.
3.2.1 1 micron, µm, n—a dimension equivalent to
1.2 The values stated in either SI units or inch-pound units 0.03937 mils.
are to be regarded separately as standard. The values stated in
3.2.2 1 mil, n—a dimension equivalent to 0.0010 in.
each system may not be exact equivalents; therefore, each
3.2.3 absolute uncertainty (of a measurement), n—the
system shall be used independently of the other. Combining
smallest division able to be read directly on the instrument used
values from the two systems may result in non-conformance
for measurement.
with the standard.
3.2.4 micrometer, n—an instrument for measuring any di-
1.3 This standard does not purport to address all of the
mension with absolute uncertainty of 1 mil [25 µm] or smaller.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Methods
priate safety, health, and environmental practices and deter-
4.1 This standard provides eight different test methods for
mine the applicability of regulatory limitations prior to use.
the measurement of thickness of solid electrical insulation
1.4 This international standard was developed in accor-
materials. The test methods (identified as Test Methods A
dance with internationally recognized principles on standard-
through H) employ different micrometers that exert various
ization established in the Decision on Principles for the
pressures for varying times upon specimens of different geom-
Development of International Standards, Guides and Recom-
etries. Tables 1 and 2 display basic differences of each test
mendations issued by the World Trade Organization Technical
method and identify test methods applicable for use on various
Barriers to Trade (TBT) Committee.
categories of materials.
2. Referenced Documents
5. Significance and Use
2
2.1 ASTM Standards:
5.1 Some electrical properties, such as dielectric strength,
D1711 Terminology Relating to Electrical Insulation
vary with the thickness of the material. Determination of
D6054 Practice for Conditioning Electrical Insulating Mate-
certain properties, such as relative permittivity (dielectric
3
rials for Testing (Withdrawn 2012)
constant) and volume resistivity, usually require a knowledge
E252 Test Method for Thickness of Foil, Thin Sheet, and
of the thickness. Design and construction of electrical machin-
Film by Mass Measurement
ery require that the thickness of insulation be known.
6. Apparatus
1
These test methods are under the jurisdiction of ASTM Committee D09 on
4
Electrical and Electronic Insulating Materials and are the direct responsibility of
6.1 Apparatus A—Machinist’s Micrometer Caliper with
Subcommittee D09.12 on Electrical Tests.
Calibrated Ratchet or Friction Thimble:
Current edition approved June 1, 2016. Published August 2016. Originally
6.1.1 Apparatus A is a micrometer caliper without a locking
approved in 1933. Last previous edition approved in 2004 as D374 – 99 (2004)
which was withdrawn January 2013 and reinstated in June 2016. DOI: 10.1520/
device but is equipped with either a calibrated ratchet or a
D0374_D0374M-16.
friction thimble. By use of a proper manipulative procedure
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and a calibrated spring (see Annex A1), the pressure exerted on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the specimen is controllable.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3
The last approved version of this historical standard is referenced on
4
www.astm.org. Hereinafter referred to as a machinist’s micrometer.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D374/D374M − 16
TABLE 1 Test Methods Suitable
...
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