1.1 本试验方法确定了在电晕作用下，在商业电源频率下使用的固体电绝缘材料的耐压性（见 注1 ). 该试验方法对于评定材料在电晕条件下对长期交流应力的耐受性更具意义，用于材料之间的比较评估。 注1: 术语“电晕”几乎仅用于本试验方法中，而不是“局部放电”，因为它是局部放电导致的电极界面边缘的可见辉光。电晕，定义见术语 D1711 ，是“导体附近气体中的可见局部放电。 ” 1.2 以国际单位制表示的数值应视为标准值。括号中给出的值是英寸-磅单位的数学转换，仅供参考，不被视为标准值。 1.3 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。 有关具体的危险说明，请参阅第节 7. . 1.4 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 该测试方法有助于评估绝缘材料和系统的研究和质量控制，因为它们提供了用于比较不同材料与外表面电晕作用的耐久性测量。本试验的不良结果并不表明该材料在高压或无表面电晕的高压应力下使用时的选择较差；表面电晕与内腔中发生的电晕不同。（见试验方法 D3382 .) 5.2 该试验方法也适用于相同相对厚度材料之间的比较。 如果买卖双方达成一致，可以在相对故障时间或电压应力大小（kV/mm或kV/in）方面表达任何差异需要在指定的小时数内产生故障。 5.3 本试验方法也可用于检查不同工艺参数对同一绝缘材料的影响，如淬火产生的残余应变、高结晶度或控制充气腔浓度和尺寸的成型工艺。 5.4 数据以一组电压下的寿命值的形式生成。使用以下方法之一分析故障时间的离散度: 5.4.1 威布尔概率图。 5.4.2 统计（更多信息请参见IEEE/IEC 62539-2007），以得出分布中心值及其标准差的估计值。 5.4.3 在一组九个测试中的第五个失败时截断测试，并将该时间用作中心趋势的度量。中描述了两种此类技术 10.2 . 5.5 该试验方法强化了一些更常见的电晕腐蚀条件，因此能够在与设备寿命相比相对较短的时间内对材料进行评估。与大多数加速寿命试验一样，在现场各种操作条件下，从指示寿命推断到实际寿命时，需要谨慎。 5.6 与电晕产生的故障相关的可能因素有: 5.6.1 电晕侵蚀绝缘层，直到剩余绝缘层无法再承受施加的电压。 5.6.2 电晕导致绝缘表面因碳化而导电，因此故障很快发生。 5.6.3 形成草酸晶体等化合物，导致表面电导率随环境湿度变化。在中等湿度条件下，电导可能足以降低电极边缘的电位梯度，从而导致电晕量减少或电晕停止，从而延缓故障。 5.6.4 电晕在绝缘层内造成“树枝状”，从而加速故障时间。 5.6.5 绝缘层内释放的气体会改变其物理尺寸。 5.6.6 绝缘材料物理性能的变化；例如，脆化或开裂，导致材料失去弹性或开裂，或两者兼而有之，从而使其无用。 5.7 测试通常在室外进行，相对湿度为50%。在买卖双方约定的情况下，可以获得在相对湿度为20%或更低的循环空气中进行测试的某些材料的附加信息（见 附录X1 ). 5.7.1 如果在封闭环境中进行测试，气流中的限制会捕获臭氧并影响结果（参见 附录X2 ). 5.7.2 当在标准条件外进行试验时，报告应注明偏差和替代条件。 5.8 失效时间的可变性是测试参数一致性的函数，如应监测的电压水平。建议使用威布尔斜率因子β作为可变性的度量。β是在威布尔概率纸上绘制失效百分比与失效时间的关系图时获得的斜率。这种图称为威布尔概率图（参见 图1 ). 图1 代表性威布尔图显示了九个样本组的前五个故障。 注1: 绘图百分比是（n）平均值的100倍 − 1. / 2. )/N和N/（N） + 1). 将人工数据放置在绘制的线（虚线）上，以说明β为4的威布尔线。第二行（非虚线）说明了失效时间的分布，这是电压-时间曲线非常平坦的材料的特征，例如云母复合材料。该线的β值为0.7。 5.9 威布尔概率图的形状可以提供额外的信息。非直线图可能指示一种以上的失效机制。 例如，该组中的一些不可解释的短时间故障表明，一小部分有缺陷的样本具有与该批次其余部分不同的故障机制。

1.1 This test method determines the voltage endurance of solid electrical insulating materials for use at commercial power frequencies under the action of corona (see Note 1 ). This test method is more meaningful for rating materials with respect to their resistance to prolonged ac stress under corona conditions for comparative evaluation between materials. Note 1: The term “corona” is used almost exclusively in this test method instead of “partial discharge,” because it is a visible glow at the edge of the electrode interface that is the result of partial discharge. Corona, as defined in Terminology D1711 , is “visible partial discharges in gases adjacent to a conductor.” 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard. 1.3 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. For specific hazard statements, see Section 7 . 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. ====== Significance And Use ====== 5.1 This test method is useful in research and quality control for evaluating insulating materials and systems since they provide for the measurement of the endurance used to compare different materials to the action of corona on the external surfaces. A poor result on this test does not indicate that the material is a poor selection for use at high voltage or at high voltage stress in the absence of surface corona; surface corona is not the same as corona that occurs in internal cavities. (See Test Methods D3382 .) 5.2 This test method is also useful for comparison between materials of the same relative thickness. When agreed upon between the buyer and the seller, it is acceptable to express any differences in terms of relative time to failure or the magnitude of voltage stress (kV/mm or kV/in.) required to produce failure in a specified number of hours. 5.3 It is possible for this test method to also be used to examine the effects of different processing parameters on the same insulating material, such as residual strains produced by quenching, high levels of crystallinity or molding processes that control the concentration and sizes of gas-filled cavities. 5.4 The data are generated in the form of a set of values of lifetimes at a voltage. The dispersion of failure times is analyzed using one of the methods below: 5.4.1 Weibull Probability Plot. 5.4.2 Statistically (see IEEE/IEC 62539-2007 for additional information), to yield an estimate of the central value of the distribution and its standard deviation. 5.4.3 Truncating a test at the time of the fifth failure of a set of nine and using that time as the measure of the central tendency. Two such techniques are described in 10.2 . 5.5 This test method intensifies some of the more commonly met conditions of corona attack so that materials are able to be evaluated in a time that is relatively short compared to the life of the equipment. As with most accelerated life tests, caution is necessary in extrapolation from the indicated life to actual life under various operating conditions in the field. 5.6 The possible factors related to failures produced by corona are: 5.6.1 Corona eroding the insulation until the remaining insulation can no longer withstand the applied voltage. 5.6.2 Corona causing the insulation surface to become conducting due to carbonization, so that failure occurs quickly. 5.6.3 Forming of compounds such as oxalic acid crystals causing the surface conductance to vary with ambient humidity. It is possible conductance will be at a sufficient level to reduce the potential gradient at the electrode edge at moderate humidities, and thus cause either a reduction in the amount of corona, or its cessation, thus retarding failure. 5.6.4 Corona causing “treeing” within the insulation and consequently accelerating the time to failure. 5.6.5 Gases released within the insulation that change its physical dimensions. 5.6.6 Changes in the physical properties of an insulating material; embrittlement or cracking, for instance, causing the material to lose flexibility or crack, or both, and thus make it useless. 5.7 Tests are often made in open air, at 50 % relative humidity. In cases agreed upon between the buyer and the seller, additional information can be obtained for some materials with tests in circulating air at 20 % relative humidity or less (see Appendix X1 ). 5.7.1 If tests are made in an enclosure, the restriction in the flow of air can trap ozone and influence the results (see Appendix X2 ). 5.7.2 When tests are done outside the standard conditions, the report shall note the deviation and the alternative conditions. 5.8 The variability of the time to failure is a function of the consistency of the test parameters, such as voltage levels, which shall be monitored. The Weibull slope factor, β, is recommended as a measure of variability. β is the slope obtained when percent failure is plotted against failure time on Weibull probability paper. Such a plot is called a Weibull Probability Plot (see Fig. 1 ). FIG. 1 Representative Weibull Plot Showing the First Five Failures of a Group Specimen of Nine. Note 1: Plotting percentage are 100 times the average of (n − 1 / 2 )/N and n/(N + 1). Artificial data were placed on a line (dashed) drawn to illustrate a Weibull line with a β of 4. A second line (not dashed) illustrates the distribution of failure times which are characteristic of materials with very flat volt-time curves, such as mica composites. This line has a β value of 0.7. 5.9 The shape of the Weibull Probability Plot can provide additional information. It is possible that a non-straight-line plot will indicate more than one mechanism of failure. For instance, a few unaccountably short time failures in the set indicating a small portion of defective specimens with a different failure mechanism from the rest of the lot.