ASTM D1932-03

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An American National Standard
Designation: D 1932 – 03
Standard Test Method for
Thermal Endurance of Flexible Electrical Insulating
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Varnishes
This standard is issued under the fixed designation D 1932; 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 Dielectric Strength of Solid Electrical Insulating Materials
at Commercial Power Frequencies
1.1 This test method covers the determination of the relative
D 374 Test Methods for Thickness of Solid Electrical Insu-
thermal endurance of flexible electrical insulating varnishes by
lation
determining the time necessary at elevated temperatures to
D 580 Specification for Greige Woven Glass Tapes and
decrease the dielectric breakdown of the varnish to an arbi-
Webbings
trarily selected value when applied to a standard glass fiber
D 1346 Methods of Testing Electrical Insulating Varnishes
fabric.
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for 180°C and Above
1.2 This test method does not apply to varnishes that lose a
D 1711 Terminology Relating to Electrical Insulation
high percentage of their dielectric breakdown voltage when
D 2518 Specification for Woven Glass Fabrics for Electrical
flexed before elevated temperature exposure as prescribed in
Insulation
the screening test (Section 9). Examples of such varnishes are
D 5423 Specification for Forced-Convection Laboratory
those used for high speed armatures and laminated structures.
Ovens for Evaluation of Electrical Insulation
Also, this test method is not applicable to varnishes which
D 6054 Practice for Conditioning Electrical Insulating Ma-
distort sufficiently during thermal elevated temperature expo-
terials for Testing
sure so that they cannot be tested using the curved electrode
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2.2 IEEE Publications:
assembly.
IEEE No. 101A Guide for the Statistical Analysis of Ther-
1.3 Thermal endurance is expressed in terms of a tempera-
mal Life Test Data (including Appendix A)
ture index.
2.3 IEC Publications:
1.4 This standard does not purport to address all of the
IEC 60216 Guide for the Determination of Thermal Endur-
safety concerns, if any, associated with its use. It is the
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ance Properties of Electrical Insulating Materials (Part 1)
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3. Terminology
bility of regulatory limitations prior to use. For specific hazard
3.1 Definitions:
statements, see Section 7.
3.1.1 temperature index (TI), n—a number which permits
1.5 The values stated in SI units are the standard.
comparison of the temperature/time characteristics of an elec-
NOTE 1—There is no equivalent IEC or ISO standard.
trical insulating material, or a simple combination of materials,
based on the temperature in degrees Celsius which is obtained
2. Referenced Documents
by extrapolating the Arrhenius plot of endpoint time versus
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2.1 ASTM Standards:
temperature to a specified time, usually 20 000 h.
D 149 Test Method for Dielectric Breakdown Voltage and
3.1.2 thermal endurance graph, n—an Arrhenius plot.
3.1.3 thermal endpoint time, n—the time necessary for a
specific property of a material, or a simple combination of
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This test method is under the jurisdiction of ASTM Committee D09 on
materials, to degrade to a defined end point when aged at a
Electrical and Electronic Insulating Materials and is the direct responsibility of
specified temperature.
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders, and Encapsu-
lating Compounds.
Current edition approved Oct. 1, 2003. Published October 2003. Originally
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approved in 1967. Last previous edition approved in 2001 as D 1932 – 01. Withdrawn.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from the Institute of Electrical and Electronics Engineers, 1828 L St.,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM NW, Suite 1202, Washington, DC 20036–5104.
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Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute, 25 West 43rd St., 4th
the ASTM website. Floor, New York, NY 10036.
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D1932–03
3.1.4 thermal life endpoint time, n—a graphical representa- dielectric strength, which is therefore used as the failure
tion of thermal endpoint time at a specified exposure tempera- criterion for this test method.
ture in which the value of
...