1.1 本试验方法包括在直流电压应力下测定固体电绝缘材料的介电击穿电压和介电强度。 1.2 由于某些材料需要特殊处理，还应参考ASTM规范或直接适用于待测材料的试验方法。见测试方法 D149 用于测定商业电源频率下电绝缘材料的介电强度。 1.3 该试验方法类似于IEC出版物243-2。本试验方法中的所有程序均包含在IEC 243-2中。该试验方法与IEC 243-2之间的差异主要是编辑性的。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 具体预防说明见第节 7. . 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法旨在用作直流电压应用的控制和验收试验。它还可用于特定最终用途材料的部分评估，并作为检测因特定变质原因引起的材料变化的手段。 5.2 经验表明，使用直流电压获得的击穿值通常约为60 Hz交流电压击穿均方根值的2到4倍。 5.3 对于非均匀试样，试样内的电压应力分布由交流电压的阻抗（主要是电容性）决定。随着直流电压的增加，电压分布仍然很大程度上是电容性的，尽管这在一定程度上取决于电压增加的速率。稳定施加直流电压后，试样上的电压分配由电阻决定。直流电压或交流电压的选择取决于击穿试验的目的，以及在某种程度上取决于材料的预期应用。 5.4 更全面地讨论了介质击穿试验的意义 附录X1 试验方法附录X1 D149 . 试验方法的附录章节 D149 交流电压不适用于直流电压法。

1.1 This test method covers the determination of dielectric breakdown voltage and dielectric strength of solid electrical insulating materials under direct-voltage stress. 1.2 Since some materials require special treatment, reference shall also be made to ASTM specifications or to the test method directly applicable to the material to be tested. See Test Method D149 for the determination of dielectric strength of electrical insulating materials at commercial power frequencies. 1.3 This test method is similar to IEC Publication 243-2. All procedures in this test method are included in IEC 243-2. Differences between this test method and IEC 243-2 are largely editorial. 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. Specific precaution statements are given in Section 7 . 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. ====== Significance And Use ====== 5.1 This test method is intended for use as a control and acceptance test for direct-voltage applications. It can also be used in the partial evaluation of material for specific end uses and as a means for detecting changes in material due to specific deteriorating causes. 5.2 Experience indicates that the breakdown value obtained with direct voltage usually will be approximately 2 to 4 times the rms value of the 60-Hz alternating-voltage breakdown. 5.3 For a nonhomogeneous test specimen, the distribution of voltage stress within the specimen is determined by impedance (largely capacitive) with alternating voltage. With an increasing direct voltage, the voltage distribution will still be largely capacitive, although this depends partly on the rate of voltage increase. After steady application of direct voltage the voltage division across the test specimen is determined by resistance. The choice of direct or alternating voltage depends upon the purpose for which the breakdown test is to be used, and to some extent, on the intended application of the material. 5.4 A more complete discussion of the significance of dielectric breakdown tests is given in Appendix X1 of this method and in Appendix X1 of Test Method D149 . Those appendix sections of Test Method D149 that refer to alternating voltage are not applicable to the direct-voltage method.