5.1 The levels of tensile properties obtained when testing aramid paper are dependent on the age and history of the specimen and on the specific conditions used during the test. Among these conditions are rate of stretching, type of clamps, gauge length of specimen, temperature and humidity of the atmosphere, rate of airflow across the specimen, and temperature and moisture content of the specimen. Testing conditions accordingly are specified precisely to obtain reproducible test results on a specific sample.5.2 Tensile strength is used in engineering calculations when designing various types of products.5.3 Elongation of the paper is taken into consideration in the design and engineering of reinforced products because of its effect on uniformity of the finished product and its dimensional stability during service.5.4 Stiffness is a measure of the resistance of the paper to extension as a force is applied.5.5 Tensile Energy Absorption is dependent on the relationship of force to elongation. It is a measure of the ability of a textile structure to absorb mechanical energy. Tensile Energy Absorption is work-to-break per area.5.6 It should be emphasized that, although the preceding parameters are related to the performance of the product, the actual configuration of the product is significant. Shape, size, and internal construction also can have appreciable effects on product performance. It is not possible, therefore, to evaluate the performance of the end product in terms of the reinforcing material alone.5.7 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate test results were obtained, and that are randomly assigned in equal numbers to each laboratory for testing. Other materials with established test values may be used for this purpose. The test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results must be adjusted in consideration of the known bias.1.1 This test method covers the tensile testing of aramid paper with thickness less than 1 mm. This test method includes testing procedures only and includes no specifications or tolerances.1.2 The procedures given in this test method are for use with computer-controlled constant-rate-of-elongation tensile testing equipment.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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.1.5 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.

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5.1 Dissipation Factor and Relative Permittivity—Knowledge of these properties is important in the design of electrical equipment such as cables, transformers, insulators, and so forth. The numerical product of these two properties of a dielectric system is proportional to the energy loss converted to heat, and is called its loss index (see Terminology D1711). The energy loss reduces the efficiency of electrical equipment. The heat produced tends to chemically degrade the dielectric material and may even lead to thermal runaway. Test results of impregnated specimens can disclose significant differences between combinations of papers and oils that appear similar when the papers and the oils are tested separately. Dissipation factor, particularly at elevated temperatures, is often changed significantly by the presence of a small quantity of impurities in either the liquid or the paper. This practice is useful in the comparison of materials and in evaluating the effects of different papers on a given liquid. Judicious analysis of results with respect to time, temperature, and field strength are useful in predicting the performance and capabilities of systems using the paper and the liquid. For additional information on the significance of dissipation factor and relative permittivity, see Test Methods D150.5.2 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies: 5.2.1 A comprehensive discussion of the significance of the dielectric strength test as applied to solid, semi-solid, and liquid materials is given in Appendix X1 of Test Method D149. Other factors peculiar to high-quality composite insulations, such as oil-impregnated papers, are considered in the following:5.2.2 In tests involving high electrical stresses, immersion of critical parts of a test circuit in oil is a widely used technique for inhibiting corona. However, it has limitations that must be recognized when using the submerged electrode option of this practice (Note 1). Attack on the paper by corona generated in the surrounding fluid at electrode edges can occur whether the fluid is air or oil. Corona occurs at considerably higher voltages in oil than in air. Thick and dense papers are more likely to cause discharge-initiated breakdowns. For interpretation of breakdown measurements consider the number of edge breakdowns, implying discharge-initiated breakdowns.NOTE 1: Two techniques are in use in the industry for testing specimens for dielectric breakdown voltage. In one, the test is made with the electrodes and test specimen submerged in the impregnating liquid while in the other the electrodes are not submerged, that is, the specimen is tested in air. Much data has been accumulated using the latter technique. These techniques yield different values of breakdown voltage. Test Method D149 states preference for testing materials in the medium in which they are used. The use of submerged electrodes follows this preference. When testing thick insulating boards, the use of submerged electrodes is greatly preferred.5.2.3 The results of power frequency tests on oil impregnated papers are useful for screening, research, and quality control, provided that considerable judgment is exercised in interpreting the results. The application of the test results to equipment design and service requires particular caution and skill (see Appendix X1 of Test Method D149).5.3 Dielectric Breakdown Voltage and Dielectric Strength Under Impulse Conditions—Testing impregnated paper or board under impulse conditions can yield useful data for the designer of electrical equipment. The test results are useful in the comparison of materials and for research studies. For a more general treatise on the significance of impulse testing see Test Method D3426.1.1 This practice covers the preparation of insulating paper and board impregnated with a liquid dielectric. Where this practice states only “paper,” the same procedure shall apply to board.1.2 This practice has been found practicable for papers having nominal thickness of 0.05 mm (2 mil) and above. It has been used successfully for insulating board as thick as 6 mm (1/4 in.) when care is taken to ensure the specimen geometry necessary for valid measurement of dielectric properties. Suitable geometry depends on the electrode system used. Rigid solid opposing electrodes require flat specimens that have essentially parallel surfaces.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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.

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