1.1本试验方法描述了两个程序，A和B，用于测定绝缘液体样品的击穿电压。击穿测试使用45至65 Hz工频范围内的交流电压。 1.2本试验方法用于判断从制造商处交付的未经过滤或干燥的绝缘液体是否满足盘电极击穿电压要求。有关规定的最小电气击穿，请参阅规范D 3487、规范D 4652和指南D 5222。该测试方法应按照专业组织标准（如IEEE C57.106）的建议使用。 1.3程序的限制 1.3.1当本试验方法中使用的外加试验电压大于约25 kV rms时，本试验方法对液体样品中存在的污染物总体的灵敏度降低。 1.3. 2如果室温下样品中的水浓度低于饱和度的60%，则本试验方法对水存在的敏感性降低。有关更多信息，请参阅RR:D27-1006。 1.3.3对于40℃下粘度高于900 cSt的液体，尚未确定本试验方法的适用性。 1.4程序应用 1.4.1程序A 程序A用于确定液体的击穿电压，其中任何不溶性击穿产物在所需重复击穿试验之间的间隔期间容易沉淀。这些液体包括石油、碳氢化合物和用作变压器、电缆和类似设备中的绝缘和冷却液的askarels（PCB）。 程序A可用于获得试验方法D 2225中规定的硅酮液体的介电击穿，前提是在连续五次击穿中，样品中的放电能量小于20 mJ（毫焦耳）。 1.4.2程序B该程序用于确定液体的击穿电压，其中任何不溶性击穿产物在程序A中要求的1分钟间隔内未从盘片之间的空间完全沉淀。程序B，根据试验方法D 2225第17节修改，如果无法达到的要求，则可用于测试硅介质液体。 程序B还应适用于测定含有不溶性物质的液体样品的击穿电压，这些不溶性物质在试验过程中从样品中沉淀下来。这些可能包括从断路器、负载分接开关和其他严重受不溶性颗粒物质污染的液体中采集的样本。这些示例代表了重复测试之间可能存在较大差异的样本。在测试此类液体时，使用程序B将获得更准确的击穿电压值。 在不存在ASTM规范或制定ASTM指南或标准值时，使用程序B确定绝缘液体的击穿电压。一旦证明了的单操作员精度，即可使用程序A。 1.5国际单位制和英寸-磅单位同样可以接受。 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和健康实践，并确定监管限制的适用性。 ====意义和用途====== 介电击穿电压是衡量绝缘液体承受电应力的能力。液体的工频击穿电压因存在诸如纤维素纤维、导电颗粒、污垢和水等污染物而降低。 本试验方法的结果较低，表明试验液体中存在一种或多种此类污染物的显著浓度。看见 附录X1 . 在本试验方法中测量的高击穿电压并不一定表明从中取样的液体中存在的污染物量足够低，以使取样液体在所有电气设备中均可接受。试验方法D 877对这些污染物的低水平不敏感。本试验方法中的击穿主要由电极边缘发生的事件决定。本试验方法中使用的平行圆盘电极之间的电压应力分布是准均匀的，在平圆盘表面的锐边处存在大量应力集中。 本试验方法可用于评估设备中的绝缘液体，该设备设计为填充供应商交付的未加工液体。 本试验方法不推荐用于评估设备中使用的液体的击穿电压，这些设备在投入使用之前需要应用真空和过滤油。试验方法D 1816 应用于确定过滤和脱气液体的击穿电压。 本试验方法用于实验室或现场试验。为了使现场分解结果与实验室结果具有可比性，所有标准包括室温（20至30 ° C） 必须满足。

1.1 This test method describes two procedures, A and B, for determining the electrical breakdown voltage of insulating liquid specimens. The breakdown test uses ac voltage in the power-frequency range from 45 to 65 Hz. 1.2 This test method is used to judge if the disk electrode breakdown voltage requirements are met for insulating liquids, as delivered from the manufacturer, that have never been filtered or dried. See Specification D 3487, Specification D 4652, and Guide D 5222 for the minimum specified electrical breakdown. This test method should be used as recommended by professional organization standards such as IEEE C57.106. 1.3 Limitations of the Procedures 1.3.1 The sensitivity of this test method to the general population of contaminants present in a liquid sample decreases as applied test voltages used in this test method become greater than approximately 25 kV rms. 1.3.2 If the concentration of water in the sample at room temperature is less than 60 % of saturation, the sensitivity of this test method to the presence of water is decreased. For further information refer to RR: D27-1006. 1.3.3 The suitability for this test method has not been determined for a liquid's viscosity higher than 900 cSt at 40C. 1.4 Procedure Applications 1.4.1 Procedure A Procedure A is used to determine the breakdown voltage of liquids in which any insoluble breakdown products easily settle during the interval between the required repeated breakdown tests. These liquids include petroleum oils, hydrocarbons, and askarels (PCB) used as insulating and cooling liquids in transformers, cables, and similar apparatus. Procedure A may be used to obtain the dielectric breakdown of silicone fluid as specified in Test Methods D 2225, provided the discharge energy into the sample is less than 20 mJ (milli joule) per breakdown for five consecutive breakdowns. 1.4.2 Procedure BThis procedure is used to determine the breakdown voltage of liquids in which any insoluble breakdown products do not completely settle from the space between the disks during the 1-min interval required in Procedure A. Procedure B, modified in accordance with Section 17 of Test Methods D 2225, is acceptable for testing silicone dielectric liquids if the requirements of can not be achieved. Procedure B should also be applied for the determination of the breakdown voltage of liquid samples containing insoluble materials that settle from the specimen during testing. These may include samples taken from circuit breakers, load tap changers, and other liquids heavily contaminated with insoluble particulate material. These examples represent samples that may have large differences between replicate tests. The use of Procedure B will result in a more accurate value of breakdown voltage when testing such liquids. Use Procedure B to establish the breakdown voltage of an insulating liquid where an ASTM specification does not exist or when developing a value for an ASTM guide or standard. Procedure A may be used once the single operator precision of has been demonstrated. 1.5 Both the SI and inch-pound units are equally acceptable. 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. ====== Significance And Use ====== The dielectric breakdown voltage is a measure of the ability of an insulating liquid to withstand electrical stress. The power-frequency breakdown voltage of a liquid is reduced by the presence of contaminants such as cellulosic fibers, conducting particles, dirt, and water. A low result in this test method indicates the presence of significant concentrations of one or more of these contaminants in the liquid tested. See Appendix X1 . A high breakdown voltage measured in this test method does not necessarily indicate that the amount of the contaminants present in a liquid from which the sample was taken are sufficiently low for the sampled liquid to be acceptable in all electrical equipment. Test Method D 877 is not sensitive to low levels of these contaminants. Breakdown in this test method is dominated by events occurring at the electrode edges. The voltage stress distribution between the parallel disk electrodes used in this test method are quasi-uniform and there is substantial stress concentration at the sharp edges of the flat disk faces. This test method may be used for evaluation of insulating liquids in equipment that is designed to be filled with unprocessed liquids as delivered by a vendor. This test method is not recommended for evaluation of the breakdown voltage of liquids used in equipment that requires the application of vacuum and filtering of the oil before being placed into service. Test Method D 1816 should be used to determine the breakdown voltage of filtered and degassed liquids. This test method is used in laboratory or field tests. For field breakdown results to be comparable to laboratory results, all criteria including room temperature (20 to 30 ° C) must be met.