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定价: 345元 / 折扣价: 294

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4.1 The dielectric breakdown voltage and dielectric strength of an insulating gas in a uniform field depends primarily on the molecular structure of the gas. As different gases are mixed either by plan or by contamination, any change in dielectric breakdown voltage and dielectric strength will depend on both the nature and proportion of the individual gases. This test method uses plane and spherical electrodes which provide a nearly uniform field (see Appendix) in the area of electrical discharge. It is suitable for determining the dielectric breakdown voltage and dielectric strength of different gases and mixtures thereof for research and application evaluations and also as a field test. A more complete discussion of the significance of the dielectric strength test is given in the Appendix.1.1 This test method covers the determination of the dielectric breakdown voltage and dielectric strength of insulating gases used in transformers, circuit breakers, cables, and similar apparatus as an insulating medium. The test method is applicable only to gases with boiling points below room temperature at atmospheric pressure.1.2 This standard may involve hazardous materials, operations, and equipment. 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.1.3 Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA's website — http://www.epa.gov/mercury/faq.htm for additional information. Users should be aware that selling mercury and/or mercury containing products into your state may be prohibited by state law.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.

定价: 590元 / 折扣价: 502 加购物车

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4.1 Dielectric withstand voltage testing is useful for design verification, quality control of materials, and workmanship.4.2 This test method is used to verify that the membrane switch or printed electronic device can operate safely at its rated voltage, and withstand momentary overpotentials due to switching, surges and other similar electrical phenomena.4.3 Specific areas of testing are, but not limited to:4.3.1 Conductor/dielectric/conductor crossing point,4.3.2 Close proximity of conductors, and4.3.3 Any other conductive surface such as shielding or metal backing panel.4.4 Dielectric withstand voltage testing may be destructive and units that have been tested should be considered unreliable for future use.4.5 Testing using ac voltage may be useful for switches intended for control circuits powered by ac voltages.1.1 This test method covers the verification of a specified dielectric withstand voltage or dielectric breakdown voltage of a membrane switch or printed electronic device.

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5.1 In many cases, equipment failure modes are identified by wear debris that is not captured in used lubricating oil samples but captured on chip detectors, filters or by other means. Users of this technique include, but are not limited to, original equipment manufacturers (OEMs), commercial airlines, civil aerospace operators, maintenance repair and overhaul (MRO) facilities, and military maintenance personnel.1.1 This test method describes a means for quantitative determination of wear debris found in in-service lubricants by laser-induced breakdown spectroscopy (LIBS). LIBS is an analytical technology that uses short laser pulses to create micro hot-plasma ablation of a material and then employs spectroscopic tools for analysis.21.2 This method covers the means for alloy classification and sizing of wear debris. Wear debris sources can include, but are not limited to: (1) chip collector and chip detector devices, (2) filters, (3) ferrograms, and (4) loose particles. The 23 tested alloys and metals included in the default material library of the instrument are listed in Table 1.1.3 The method for alloy classification and sizing of wear debris is not limited to the list of alloys in Table 1. The instrument has the capability of including additional alloys and metals as required.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 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.

定价: 590元 / 折扣价: 502 加购物车

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3.1 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 X1.3.2 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 is sufficiently low for the sampled liquid to be acceptable in all electrical equipment. Test Method D877 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.3.3 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.3.4 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 D1816 should be used to determine the breakdown voltage of filtered and degassed liquids.3.5 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.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 determine the electrical discharge voltage of in-use electrical liquids. It is no longer applicable to new insulating liquids upon receipt, in which case Test Method D1816 shall be used.NOTE 1: It is understood that long-term histories for this test method exist, but this test method is no longer considered applicable as numerous deficits exist that affect its usefulness. It is recommended to move all new and in-service electrical discharge voltage testing of electrical insulating liquids to Test Method D1816.1.3 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:D27-1006.21.3.3 The suitability for this test method has not been determined for a liquid's viscosity higher than 900 cSt at 40 °C.1.4 Procedure Applications 1.4.1 Procedure A: 1.4.1.1 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, natural and synthetic esters, and askarels (PCB) used as insulating and cooling liquids in transformers, cables, and similar apparatus.1.4.1.2 Procedure A may be used to obtain the dielectric breakdown of silicone fluid as specified in Test Methods D2225, provided the discharge energy into the sample is less than 20 mJ (milli joule) per breakdown for five consecutive breakdowns.1.4.2 Procedure B: 1.4.2.1 This 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 D2225, is acceptable for testing silicone dielectric liquids if the requirements of 1.4.1.2 can not be achieved.1.4.2.2 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.1.4.2.3 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 13.1 has been demonstrated.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.1.6 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.1.7 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.

定价: 590元 / 折扣价: 502 加购物车

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3.1 This test method is most commonly performed using a negative polarity needle or a sharp defined point to an opposing grounded sphere (NPS). The NPS breakdown voltage of fresh unused liquids measured in the highly divergent field in this configuration depends on the insulating liquid composition, decreasing with increasing concentration of aromatic, particularly polyaromatic, hydrocarbon molecules in liquids of petroleum origin and decreasing with ester molecular structure, either natural or synthetic.3.2 This test method may be used to evaluate the continuity of composition of an insulating liquid from shipment to shipment. The NPS impulse breakdown voltage of an insulating liquid can also be substantially lowered by contact with materials of construction, by service aging, particulate matter, and by other impurities. Test results lower than those expected for a given fresh liquid may also indicate use or contamination.3.3 Although polarity of the voltage wave has little or no effect on the breakdown strength of an insulating liquid in uniform fields, polarity does have a marked effect on the breakdown voltage in nonuniform electric fields.3.4 Transient voltages may also vary over a wide range in both the time to reach crest value and the time to decay to half crest or to zero magnitude. The IEEE standard lightning impulse test (see 2.2) specifies a 1.2 by 50-μs negative polarity wave.1.1 This test method covers the determination of the dielectric breakdown voltage of insulating liquids in a highly divergent field under impulse conditions and has been found applicable to liquids of petroleum origin, natural and synthetic esters.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI 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.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.

定价: 515元 / 折扣价: 438 加购物车

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3.1 The dielectric breakdown voltage of an insulating liquid is of importance as a measure of the liquid's ability to withstand electric stress without failure. The dielectric breakdown voltage serves to indicate the presence of contaminating agents such as water, dirt, cellulosic fibers, or conducting particles in the liquid, one or more of which may be present in significant concentrations when low breakdown voltages are obtained. However, a high dielectric breakdown voltage does not necessarily indicate the absence of all contaminants; it may merely indicate that the concentrations of contaminants that are present in the liquid between the electrodes are not large enough to deleteriously affect the average breakdown voltage of the liquid when tested by this test method (see Appendix X1.)3.2 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.1.1 This test method covers the determination of the dielectric breakdown voltage of insulating liquids (oils of petroleum origin, silicone fluids, high fire-point mineral electrical insulating oils, synthetic ester fluids and natural ester fluids). This test method is applicable to insulating liquids commonly used in cables, transformers, oil circuit breakers, and similar apparatus as an insulating and cooling medium. Refer to Terminology D2864 for definitions used in this test method.1.2 This test method is sensitive to the deleterious effects of moisture in solution especially when cellulosic fibers are present in the liquid. It has been found to be especially useful in diagnostic and laboratory investigations of the dielectric breakdown strength of insulating liquid in insulating systems.21.3 This test method is used to judge if the VDE electrode breakdown voltage requirements are met for insulating liquids. This test method should be used as recommended by professional organization standards such as IEEE C57.106.1.4 This test method may be used to obtain the dielectric breakdown of silicone fluid as specified in Test Method D2225, Specification D4652, or Specification D6871, provided that the discharge energy into the sample is less than 20 mJ (milli joule) per breakdown for five consecutive breakdowns.1.5 Both the metric and the alternative inch-pound units are acceptable.1.6 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.1.7 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.

定价: 590元 / 折扣价: 502 加购物车

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5.1 The dielectric strength of an electrical insulating material is a property of interest for any application where an electrical field will be present. In many cases the dielectric strength of a material will be the determining factor in the design of the apparatus in which it is to be used.5.2 Tests made as specified herein are suitable for use to provide part of the information needed for determining suitability of a material for a given application; and also, for detecting changes or deviations from normal characteristics resulting from processing variables, aging conditions, or other manufacturing or environmental situations. This test method is useful for process control, acceptance or research testing.5.3 Results obtained by this test method can seldom be used directly to determine the dielectric behavior of a material in an actual application. In most cases it is necessary that these results be evaluated by comparison with results obtained from other functional tests or from tests on other materials, or both, in order to estimate their significance for a particular material.5.4 Three methods for voltage application are specified in Section 12: Method A, Short-Time Test; Method B, Step-by-Step Test; and Method C, Slow Rate-of-Rise Test. Method A is the most commonly-used test for quality-control tests. However, the longer-time tests, Methods B and C, which usually will give lower test results, will potentially give more meaningful results when different materials are being compared with each other. If a test set with motor-driven voltage control is available, the slow rate-of-rise test is simpler and preferable to the step-by-step test. The results obtained from Methods B and C are comparable to each other.5.5 Documents specifying the use of this test method shall also specify:5.5.1 Method of voltage application,5.5.2 Voltage rate-of-rise, if slow rate-of-rise method is specified,5.5.3 Specimen selection, preparation, and conditioning,5.5.4 Surrounding medium and temperature during test,5.5.5 Electrodes,5.5.6 Wherever possible, the failure criterion of the current-sensing element, and5.5.7 Any desired deviations from the recommended procedures as given.5.6 If any of the requirements listed in 5.5 are missing from the specifying document, then the recommendations for the several variables shall be followed.5.7 Unless the items listed in 5.5 are specified, tests made with such inadequate reference to this test method are not in conformance with this test method. If the items listed in 5.5 are not closely controlled during the test, it is possible that the precisions stated in 15.2 and 15.3 will not be obtained.5.8 Variations in the failure criteria (current setting and response time) of the current sensing element significantly affect the test results.5.9 Appendix X1 contains a more complete discussion of the significance of dielectric strength tests.1.1 This test method covers procedures for the determination of dielectric strength of solid insulating materials at commercial power frequencies, under specified conditions.2,31.2 Unless otherwise specified, the tests shall be made at 60 Hz. However, this test method is suitable for use at any frequency from 25 to 800 Hz. At frequencies above 800 Hz, dielectric heating is a potential problem.1.3 This test method is intended to be used in conjunction with any ASTM standard or other document that refers to this test method. References to this document need to specify the particular options to be used (see 5.5).1.4 It is suitable for use at various temperatures, and in any suitable gaseous or liquid surrounding medium.1.5 This test method is not intended for measuring the dielectric strength of materials that are fluid under the conditions of test.1.6 This test method is not intended for use in determining intrinsic dielectric strength, direct-voltage dielectric strength, or thermal failure under electrical stress (see Test Method D3151).1.7 This test method is most commonly used to determine the dielectric breakdown voltage through the thickness of a test specimen (puncture). It is also suitable for use to determine dielectric breakdown voltage along the interface between a solid specimen and a gaseous or liquid surrounding medium (flashover). With the addition of instructions modifying Section 12, this test method is also suitable for use for proof testing.1.8 This test method is similar to IEC Publication 243-1. All procedures in this method are included in IEC 243-1. Differences between this method and IEC 243-1 are largely editorial.1.9 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 hazard statements are given in Section 7. See also 6.4.1.1.10 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 It is possible for insulating materials used in high-voltage equipment to be subjected to transient voltage stresses, resulting from such causes as nearby lightning strokes. This is particularly true of apparatus such as transformers and switchgear used in electrical-power transmission and distribution systems. The ability of insulating materials to withstand these transient voltages is important in establishing the reliability of apparatus insulated with these materials.5.2 Transient voltages caused by lightning will be of either positive or negative polarity. In a symmetrical field between identical electrodes, the polarity has no effect on the breakdown strength. However, with dissimilar electrodes there can be a pronounced polarity effect. It is common practice when using dissimilar electrodes, to make negative that electrode at which the higher gradient will appear. When asymmetrical electrodes are used for testing materials with which the tester has no previous experience or knowledge, it is recommended that he make comparative tests with positive polarity and negative polarity applied to the higher gradient, or smaller electrode, to determine which polarity produces the lower breakdown voltage.5.3 The standard wave shape is a 1.2 by 50-μs wave, reaching peak voltage in approximately 1.2 μs and decaying to 50 % of peak voltage in approximately 50 μs after the beginning of the wave. This wave is intended to simulate a lightning stroke that strikes a system without causing failure on the system.5.4 For most materials, the impulse dielectric strength will be higher than either its power frequency alternating voltage or its direct voltage dielectric strengths. Because of the short time involved, dielectric heating and other thermal effects are largely eliminated during impulse testing. Thus, the impulse test gives values closer to the intrinsic breakdown strength than do longer time tests. From comparisons of the impulse dielectric strength with the values obtained from longer time tests, it is possible to draw inferences as to the modes of failures under the various tests for a given material. Refer to Appendix X1 of Test Method D149 for further information on this subject.1.1 This test method covers the determination of dielectric strength of solid electrical insulating materials under simulated-lightning impulse conditions.1.2 Procedures are given for tests using standard 1.2 by 50 μs full-wave impulses.1.3 This test method is intended for use in determining the impulse dielectric strength of insulating materials, either using simple electrodes or functional models. It is not intended for use in impulse testing of apparatus.1.4 This test method is similar to IEC Publication 243-3. All procedures in this test method are included in IEC 243-3. Differences between this test method and IEC 243-3 are largely editorial.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precaution statements are given in Section 9.1.6 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.

定价: 515元 / 折扣价: 438 加购物车

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