ASTM D2304-18

Standard Test Method for Thermal Endurance of Rigid Electrical Insulating Materials

SIGNIFICANCE AND USE
6.1 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.  
6.2 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.  
6.3 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.  
6.4 When dictated by the needs of t...
SCOPE
1.1 This test method2 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. A specific warning statement is given in 11.3.4.  
1.7 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...

General Information

• Status: Historical
• Publication Date: 30-Apr-2018
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.07 - Electrical Insulating Materials

Standards Content (Sample)

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: D2304 − 18
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* 1.7 This international standard was developed in accor-
2 dance with internationally recognized principles on standard-
1.1 This test method provides procedures for evaluating the
ization established in the Decision on Principles for the
thermal endurance of rigid electrical insulating materials.
Development of International Standards, Guides and Recom-
Dielectric strength, flexural strength, or water absorption are
mendations issued by the World Trade Organization Technical
determined at room temperature after aging for increasing
Barriers to Trade (TBT) Committee.
periods of time in air at selected-elevated temperatures. A
thermal-endurance graph is plotted using a selected end point
2. Referenced Documents
at each aging temperature. A means is described for determin-
3
2.1 ASTM Standards:
ing a temperature index by extrapolation of the thermal
D149 Test Method for Dielectric Breakdown Voltage and
endurance graph to a selected time.
Dielectric Strength of Solid Electrical Insulating Materials
1.2 This test method is most applicable to rigid electrical
at Commercial Power Frequencies
insulation such as supports, spacers, voltage barriers, coil
D229 Test Methods for Rigid Sheet and Plate Materials
forms, terminal boards, circuit boards and enclosures for many
Used for Electrical Insulation
types of application where retention of the selected property
D570 Test Method for Water Absorption of Plastics
after heat aging is important.
D790 Test Methods for Flexural Properties of Unreinforced
1.3 When dielectric strength is used as the aging criterion, it
and Reinforced Plastics and Electrical Insulating Materi-
is also acceptable to use this test method for some thin sheet
als
(flexible) materials, which become rigid with thermal aging,
D1830 Test Method for Thermal Endurance of Flexible
but is not intended to replace Test Method D1830 for those
Sheet Materials Used for Electrical Insulation by the
materials which must retain a degree of flexibility in use.
Curved Electrode Method
D5423 Specification for Forced-Convection Laboratory Ov-
1.4 This test method is not applicable to ceramics, glass, or
ens for Evaluation of Electrical Insulation
similar inorganic materials.
4
2.2 IEEE:
1.5 The values stated in metric units are to be regarded as
No. 1 General Principles Upon Which Temperature Limits
standard. Other units (in parentheses) are provided for infor-
Are Based in the Rating of Electric Equipment
mation.
No. 98 Guide for the Preparation of Test Procedures for the
1.6 This standard does not purport to address all of the
Thermal Evaluation of Electrical Insulating Materials
safety concerns, if any, associated with its use. It is the
No. 101 Guide for the Statistical Analysis of Test Data
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use. A
3.1 Definitions:
specific warning statement is given in 11.3.4.
3.1.1 Arrhenius plot, n—a graph of the logarithm of thermal
life as a function of the reciprocal of absolute temperature.
3.1.1.1 Discussion—This is normally depicted as the best
1
This test method is under the jurisdiction of ASTM Committee D09 on
straight line fit, determined by least squares, of end points
Electrical and Electronic Insulating Materials and is the direct responsibility of
obtained at aging temperatures. It is important that the slope,
Subcommittee D09.07 on Electrical Insulating Materials.
Current edition approved May 1, 2018. Published May 2018. Originally issued
as D2304 – 64 T. Last previous edition approved in 2010 as D2304 – 10. DOI:
3
10.1520/D2304-18. 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 [e-mail]. 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 Engineers, 445 Hoes
method. Ln., P.O. Box
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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.
Designation: D2304 − 10 D2304 − 18
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 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, 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. A specific warning statement is given in 10.3.411.3.4.
1.7 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.
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
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 Electrical Insulating Materials.
Current edition approved Oct. 1, 2010May 1, 2018. Published October 2010May 2018. Originally issued as D2304 – 64 T. Last previous edition approved in 20022010
as D2304 – 97D2304 – 10.R02. DOI: 10.1520/D2304-10.10.1520/D2304-18.
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 referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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 1331, Piscataway, NJ 088
...