Significance and Use
A major factor affecting the life of insulating materials is thermal degradation. Other factors, such as moisture and vibration, may cause failures after the material has been weakened by thermal degradation.
Electrical insulation is effective in electrical equipment only as long as it retains its physical and electrical integrity. Thermal degradation may be characterized by weight change, porosity, crazing, and generally a reduction in flexibility, and is usually accompanied by an ultimate reduction in dielectric breakdown voltage.
1.1 This test method provides a procedure for evaluating thermal endurance of flexible sheet materials by determining dielectric breakdown voltage at room temperature after aging in air at selected elevated temperatures. Thermal endurance is expressed in terms of a temperature index.
1.2 This test method is applicable to such solid electrical insulating materials as coated fabrics, dielectric films, composite laminates, and other materials where retention of flexibility after heat aging is of major importance (see Note 4).
1.3 This test method is not intended for the evaluation of rigid laminate materials nor for the determination of thermal endurance of those materials which are not expected or required to retain flexibility in actual service.
1.4 The values stated in acceptable metric units are to be regarded as the standard. The values in parentheses are for information only.
1.5 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. For a specific hazard statement, see 10.1.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies
D374 Test Methods for Thickness of Solid Electrical Insulation
D5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation
Institute of Electrical and Electronics Engineers Publications
IEEENo.101A Guide for the Statistical Analysis of Thermal Life Test Data (including Appendix A)
IEC216 Guide for the Determination of Thermal Endurance Properties of Electrical Insulating Materials (Parts 1 and 2) Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
curved electrode; dielectric breakdown voltage; flexible sheets; temperature index; thermal endurance; thermal endurance graph; thermal life; thermal life curve ; Curved electrode method; Dielectric breakdown voltage; Electrical insulating plastics; Electrical insulating solids; Flexible sheets; Sheet materials (general)--electrical insulating; Temperature index; Thermal endurance--electrical insulating materials; Thermal life curve;
ICS Number Code 83.140.10 (Films and sheets)
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Citing ASTM Standards
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