ASTM D3145-01

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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An American National Standard
Designation: D 3145 – 01
Standard Test Method for
Thermal Endurance of Electrical Insulating Varnishes by the
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Helical Coil Method
This standard is issued under the fixed designation D 3145; 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.
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1. Scope Ovens for Evaluation of Electrical Insulation
D 6054 Practice for Conditioning Electrical Insulating Ma-
1.1 This test method covers the determination of the thermal
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terials for Testing
endurance of electrical insulating varnishes alone or in com-
2.2 International Electrotechnical Commission Publica-
binations with wire insulation. Changes in the helical coil bond
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tions:
strength are used as the test criteria. The coils can be made
IEC 60216 Guide for the Determination of Thermal Endur-
from bare aluminum or copper wire, or from film- or fiber-
ance Properties of Electrical Insulation Materials (Part 1)
insulated magnet wire.
1.2 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.1.1 bond strength, n—a measure of the force required to
priate safety and health practices and determine the applica-
separate surfaces which have been bonded together.
bility of regulatory limitations prior to use. For a specific
3.1.2 magnet wire, n—a metal electrical conductor, covered
precautionary statement, see Section 7.
with electrical insulation, for use in the assembly of electrical
1.3 The values stated in SI units are the standard. The values
inductive apparatus such as coils for motors, transformers,
given in parentheses are for information only.
generators, relays, magnets, etc.
NOTE 1—There is no similar or equivalent IEC standard.
3.1.2.1 Discussion—The electrical insulation is usually
composed of a film covering formed from a magnet wire
2. Referenced Documents
enamel applied over a bare conductor. In some specific
2.1 ASTM Standards:
applications, fibrous coverings, either taped or linear filament
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D 1711 Terminology Relating to Electrical Insulation
served, are also used as electrical insulation.
D 1932 Test Method for Thermal Endurance of Flexible
3.1.3 varnish, electrical insulating, n— a liquid resin sys-
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Electrical Insulating Varnishes
tem that is applied to and cured on electrical components
D 2307 Test Method for Relative Thermal Endurance of
providing electrical, mechanical and environmental protection.
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Film-Insulated Round Magnet Wire
3.1.3.1 Discussion—There are two types of electrical insu-
D 2519 Test Method for Bond Strength of Electrical Insu-
lating varnishes—solvent-containing and solventless. Solvent-
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lating Varnishes by the Helical Coil Test
containing types are solutions, dispersions or emulsions of a
D 3251 Test Method for Thermal-Aging Characteristics of
polymer or a mixture of polymers in a volatile, nonreactable
Electrical Insulating Varnishes Applied Over Film-
liquid. Solventless types are liquid resin systems free of
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Insulated Magnet Wire
volatile, nonreactable solvents.
D 3850 Test Method for Rapid Thermal Degradation of
3.1.4 Refer to Terminology D 1711 for definitions of other
Solid Electrical Insulating Materials by Thermogravimet-
terms.
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ric Method
D 5423 Specification for Forced Convection Laboratory
4. Summary of Test Method
4.1 Flexural strength of the helical coils is measured peri-
odically after exposure to several aging temperatures. The time
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This test method is under the jurisdiction of ASTM Committee D09 on
to reach an arbitrarily selected value of bond strength at each
Electrical and Electronic Insulating Materials and is the direct responsibility of
aging temperature is determined. The logarithms of these times
Subcommittee D09.01 on Electrical Insulating Varnishes, Powders, and Encapsu-
lating Compounds.
Current edition approved Nov. 10, 2001. Published January 2002. Originally
published as D 3145 – 73. Last previous edition D 3145 – 97.
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Annual Book of ASTM Standards, Vol 10.01. Available from American National Standards Institute, 25 W. 43rd St., 4th
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Annual Book of ASTM Standards, Vol 10.02. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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