ASTM D2304-10
(Test Method)Standard Test Method for Thermal Endurance of Rigid Electrical Insulating Materials
Standard Test Method for Thermal Endurance of Rigid Electrical Insulating Materials
SIGNIFICANCE AND USE
Thermal degradation is often a major factor affecting the life of insulating materials and the equipment in which they are used. The temperature index provides a means for comparing the thermal capability of different materials in respect to the degradation of a selected property (the aging criterion). This property needs to directly or indirectly represent functional needs in application. For example, it is possible that a change in dielectric strength will be of direct, functional importance. However, more often it is possible that a decrease in dielectric strength will indirectly indicate the development of undesirable cracking (embrittlement). A decrease in flexural strength has the potential to be of direct importance in some applications, but also has the potential to indirectly indicate a susceptibility to failure in vibration. Often, it is necessary that two or more criteria of failure be used; for example, dielectric strength and flexural strength.
Other factors, such as vibration, moisture and contaminants, have the potential to cause failure after thermal degradation takes place. In this test method, water absorption provides one means to evaluate such considerations.
For some applications, the aging criteria in this test method will not be the most suitable. Other criteria, such as elongation at tensile or flexural failure, or resistivity after exposure to high humidity or weight loss, have the potential to serve better. The procedures in this test method have the potential to be used with such aging criteria. It is important to consider both the nature of the material and its application. For example, it is possible that tensile strength will be a poor choice for glass-fiber reinforced laminates, because it is possible that the glass fiber will maintain the tensile strength even when the associated resin is badly deteriorated. In this case, flexural strength is a better criterion of thermal aging.
When dictated by the needs of the application, it...
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1.1 This test method provides procedures for evaluating the thermal endurance of rigid electrical insulating materials. Dielectric strength, flexural strength, or water absorption are determined at room temperature after aging for increasing periods of time in air at selected-elevated temperatures. A thermal-endurance graph is plotted using a selected end point at each aging temperature. A means is described for determining a temperature index by extrapolation of the thermal endurance graph to a selected time.
1.2 This test method is most applicable to rigid electrical insulation such as supports, spacers, voltage barriers, coil forms, terminal boards, circuit boards and enclosures for many types of application where retention of the selected property after heat aging is important.
1.3 When dielectric strength is used as the aging criterion, it is also acceptable to use this test method for some thin sheet (flexible) materials, which become rigid with thermal aging, but is not intended to replace Test Method D1830 for those materials which must retain a degree of flexibility in use.
1.4 This test method is not applicable to ceramics, glass, or similar inorganic materials.
1.5 The values stated in metric units are to be regarded as standard. Other units (in parentheses) are provided for information.
1.6 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. A specific warning statement is given in 10.3.4.
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Designation: D2304 − 10
Standard Test Method for
1
Thermal Endurance of Rigid Electrical Insulating Materials
This standard is issued under the fixed designation D2304; 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.
1. Scope 2. Referenced Documents
2 3
1.1 Thistestmethod providesproceduresforevaluatingthe 2.1 ASTM Standards:
thermal endurance of rigid electrical insulating materials. D149 Test Method for Dielectric Breakdown Voltage and
DielectricStrengthofSolidElectricalInsulatingMaterials
Dielectric strength, flexural strength, or water absorption are
determined at room temperature after aging for increasing at Commercial Power Frequencies
D229 Test Methods for Rigid Sheet and Plate Materials
periods of time in air at selected-elevated temperatures. A
thermal-endurance graph is plotted using a selected end point Used for Electrical Insulation
D570 Test Method for Water Absorption of Plastics
at each aging temperature. A means is described for determin-
ing a temperature index by extrapolation of the thermal D790 Test Methods for Flexural Properties of Unreinforced
and Reinforced Plastics and Electrical Insulating Materi-
endurance graph to a selected time.
als
1.2 This test method is most applicable to rigid electrical
D1830 Test Method for Thermal Endurance of Flexible
insulation such as supports, spacers, voltage barriers, coil
Sheet Materials Used for Electrical Insulation by the
forms, terminal boards, circuit boards and enclosures for many
Curved Electrode Method
types of application where retention of the selected property
D5423 Specification for Forced-Convection Laboratory Ov-
after heat aging is important.
ens for Evaluation of Electrical Insulation
4
1.3 When dielectric strength is used as the aging criterion, it
2.2 IEEE:
is also acceptable to use this test method for some thin sheet
No. 1 General Principles Upon Which Temperature Limits
(flexible) materials, which become rigid with thermal aging,
Are Based in the Rating of Electric Equipment
but is not intended to replace Test Method D1830 for those
No. 98 Guide for the Preparation of Test Procedures for the
materials which must retain a degree of flexibility in use.
Thermal Evaluation of Electrical Insulating Materials
1.4 This test method is not applicable to ceramics, glass, or No. 101 Guide for the Statistical Analysis of Test Data
similar inorganic materials.
3. Terminology
1.5 The values stated in metric units are to be regarded as
3.1 Definitions:
standard. Other units (in parentheses) are provided for infor-
3.1.1 Arrhenius plot, n—a graph of the logarithm of thermal
mation.
life as a function of the reciprocal of absolute temperature.
1.6 This standard does not purport to address all of the
3.1.1.1 Discussion—This is normally depicted as the best
safety concerns, if any, associated with its use. It is the
straight line fit, determined by least squares, of end points
responsibility of the user of this standard to establish appro-
obtained at aging temperatures. It is important that the slope,
priate safety and health practices and determine the applica-
which is the activation energy of the degradation reaction, be
bility of regulatory limitations prior to use. Aspecific warning
approximately constant within the selected temperature range
statement is given in 10.3.4.
to ensure a valid extrapolation.
3.1.2 temperature index, n—a number which permits com-
parison of the temperature/time characteristics of an electrical
1
This test method is under the jurisdiction of ASTM Committee D09 on
insulatingmaterial,orasimplecombinationofmaterials,based
Electrical and Electronic Insulating Materials and is the direct responsibility of
on the temperature in degrees Celsius which is obtained by
Subcommittee D09.07 on Flexible and Rigid Insulating Materials.
Current edition approved Oct. 1, 2010. Published October 2010. Originally
issued as D2304 – 64 T. Last previous edition approved in 2002 as D2304 – 97R02.
3
DOI: 10.1520/D2304-10. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
2
This test method is a revision of a procedure written by the Working Group on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Rigid Electrical Insulating Materials of the Subcommittee on Thermal Evaluation, Standards volume information, refer to the standard’s Document Summary page on
IEEE Electrical Insulation Committee, which was presented as CP 59-113 at the the ASTM website.
4
IEEE Winter General Meeting Feb. 1–6, 1959. See references at end of this test Available from the Institute of Electrical and Electronics
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
An American National Standard
Designation:D2304–97 (Reapproved 2002) Designation: D2304 – 10
Standard Test Method for
1
Thermal Endurance of Rigid Electrical Insulating Materials
This standard is issued under the fixed designation D2304; 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.
1. Scope
2
1.1 This test method provides procedures for evaluating the thermal endurance of rigid electrical insulating materials.
Dielectric strength, flexural strength, or water absorption are determined at room temperature after aging for increasing periods of
time in air at selected-elevated temperatures. A thermal-endurance graph is plotted using a selected end point at each aging
temperature. A means is described for determining a temperature index by extrapolation of the thermal endurance graph to a
selected time.
1.2 This test method is most applicable to rigid electrical insulation such as supports, spacers, voltage barriers, coil forms,
terminal boards, circuit boards and enclosures for many types of application where retention of the selected property after heat
aging is important.
1.3 When dielectric strength is used as the aging criterion, this test method may also be usedit is also acceptable to use this test
method for some thin sheet (flexible) materials, which become rigid with thermal aging, but is not intended to replaceTest Method
D1830 for those materials which must retain a degree of flexibility in use.
1.4 This test method is not applicable to ceramics, glass, or similar inorganic materials.
1.5 The values stated in metric units are to be regarded as standard. Other units (in parentheses) are provided for information.
1.6 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. A specific warning statement is given in 10.3.4.
2. Referenced Documents
3
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D229 Test Methods for Rigid Sheet and Plate Materials Used for Electrical Insulation
D570 Test Method for Water Absorption of Plastics
D790 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials
D1830 Test Method for Thermal Endurance of Flexible Sheet Materials Used for Electrical Insulation by the Curved Electrode
Method
D5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
4
2.2 IEEE:
No. 1 General Principles Upon Which Temperature Limits Are Based in the Rating of Electric Equipment
No. 98 Guide for the Preparation of Test Procedures for the Thermal Evaluation of Electrical Insulating Materials
No. 101 Guide for the Statistical Analysis of Test Data
3. Terminology
3.1 Definitions:
3.1.1 Arrhenius plot, n—a graph of the logarithm of thermal life as a function of the reciprocal of absolute temperature.
1
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.07 on Flexible and Rigid Insulating Materials.
Current edition approved Sept. 10, 1997. Published November 1997. Originally issued as D2304–64T. Last previous edition D2304–96. DOI: 10.1520/D2304-97R02.
Current edition approved Oct. 1, 2010. Published October 2010. Originally issued as D2304 – 64 T. Last previous edition approved in 2002 as D2304 – 97R02. DOI:
10.1520/D2304-10.
2
This test method is a revision of a procedure written by the Working Group on Rigid Electrical Insulating Materials of the Subcommittee on Thermal Evaluation, IEEE
Electrical Insulation Committee, which was presented as CP 59-113 at the IEEE Winter General Meeting Feb. 1–6, 1959. See references at end of this test method.
3
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
Available from the Institute of Electrical and Electronics Engineers, 445 Hoes Ln., P.O. Box 1
...
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