1、Designation: D2275 01 (Reapproved 2008)1D2275 14Standard Test Method forVoltage Endurance of Solid Electrical Insulating MaterialsSubjected to Partial Discharges (Corona) on the Surface1This standard is issued under the fixed designation D2275; the number immediately following the designation indica
2、tes the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1 NOTEThe units statement in subsection 1.2 was correcte
3、d and old footnote ten deleted to conform to ASTM guide-lines on sole source editorially in July 2008.1. Scope1.1 This test method differentiates among determines the voltage endurance of solid electrical insulating materials for use atcommercial power frequencies with respect to their voltage endur
4、ance under the action of corona (see Note 1). In general, this Thistest method is more meaningful for rating materials with respect to their resistance to prolonged a-cac stress under coronaconditions than is dielectric strength. for comparative evaluation between materials.NOTE 1The term “corona” i
5、s used almost exclusively in this test method instead of “partial discharge”,discharge,” because it is a visible glow at theedge of the smaller electrode. This is a difference in location,electrode interface that is the result of partial discharge. Corona, as defined in TerminologyD1711not in kind.
6、Partial discharges also occur at the edges of electrodes, and in general corona describes an electrical discharge irrespective of itslocation. , 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 pare
7、ntheses are mathematical conversionsto 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 responsibilityof the user of this standard to establish
8、appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insula
9、ting Materials atCommercial Power FrequenciesD618 Practice for Conditioning Plastics for TestingD1711 Terminology Relating to Electrical InsulationD1868 Test Method for Detection and Measurement of Partial Discharge (Corona) Pulses in Evaluation of Insulation SystemsD5032D3382 Practice for Maintaini
10、ng Constant Relative Humidity by Means of Aqueous Glycerin SolutionsTest Methods forMeasurement of Energy and Integrated Charge Transfer Due to Partial Discharges (Corona) Using Bridge TechniquesD6054 Practice for Conditioning Electrical Insulating Materials for Testing (Withdrawn 2012)3E41 Terminol
11、ogy Relating To ConditioningE104 Practice for Maintaining Constant Relative Humidity by Means of Aqueous SolutionsE171 Practice for Conditioning and Testing Flexible Barrier Packaging2.2 Special Technical Publications:Symposium on Corona, STP 198, ASTM, 1956.19562Corona Measurement and Interpretatio
12、n,Engineering Dielectrics, Vol 1, STP 669, ASTM, 1979.197921 This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.12 on Electrical Tests.Current edition approved May 1, 2008Nov. 1, 2014.
13、 Published July 2008December 2014. Originally approved in 1964. Last previous edition approved in 20012008 asD2275 01.D2275 01 (2008)1. DOI: 10.1520/D2275-01R08E01.10.1520/D2275-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org
14、. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit m
15、ay not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Har
16、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.3 International Electrotechnical Commission (IEC) Documents:IEC Publication 60343 Recommended test methodsTest Methods for determiningDetermining the relative resistance ofinsulating materials to breakdown by surface discharge
17、sRelative Resistance of Insulating Materials to Breakdown by SurfaceDischarges32.4 Institute of Electrical and Electronic Engineers (IEEE) Document:IEEE SS 11205-TBR930-1987 Guide for the Statistical Analysis of Electrical Insulation Voltage Endurance Data, 1987Data43. Terminology3.1 DefinitionsFor
18、definitions of other terms used in this standard, refer to Terminology D1711 and Test Method D1868.3.2 Definitions of Terms Specific to This Standard:3.2.1 surface corona, ncorona that exists in the electrically stressed gas where electrodes are near insulation surfaces.3.2.2 threshold voltageThatth
19、at voltage below which failure will not occur under the test conditions irrespective of theduration of the test.3.2.1.1 DiscussionDemonstration of a threshold is difficult when the slope of a volt-time curve is small, and failure times are long. High frequencytests are often an aid in demonstration,
20、 by reducing the time required to reach a necessary number of voltage cycles.3.2.3 voltage endurance, nThethe time that an insulating material can withstand a prolonged alternating voltage stress underthe action of surface corona.3.2.4 voltage stress-time curve, nAa plot of the logarithm of the mean
21、 or median time to failure of a material against voltagestress (or the logarithm of voltage stress) for a particular set of test conditions.3.2.4.1 DiscussionThe plot is the quantitative depiction of the voltage stress endurance over a range of voltage stress for the conditions of test, andfor the t
22、hickness tested. The curves of a material obtained at two thicknesses are different.3.2.5 volt-time curve, nAa plot of the logarithm of the mean or median time to failure of a material against voltage (or thelogarithm of voltage) for a particular set of test conditions.3.2.5.1 DiscussionThe plot is
23、the quantitative depiction of the voltage endurance over a range of voltage for the conditions of the test, which includesthe particular thickness tested.4. Summary of Test Method4.1 In this test method, voltage sufficient to produce surface corona is applied to the nine samples from the same specim
24、en untilfailure occurs. ComparativeThe voltage endurance is the relative time to failure of two different materials of the same thicknesswhen tested with similar electrodes at the same voltage. Comparison is also possible in terms of the magnitude of voltage stress(kV/mm or kV/in.) required to produ
25、ce failure in a specified number of hours.failure, determined by the voltage-time curve orWeibull Probability Plot.4.2 Surface corona exists in the electrically stressed gas where electrodes are near insulation surfaces.4.2 As with most tests at constant stress, there may be When there is a large di
26、spersion of times to failure for a given sample.The sample, it is acceptable to use the median time of nine specimens (time of fifth failure) may be used as the failure time forthe sample. This removes the necessity of waiting for the last few to fail. The mean maycan also be determined statisticall
27、y (seeIEEE SS 11205-TBRIEEE 930-1987 for additional information).4.4 Under the proper conditions, the test may be accelerated by increasing the frequency of the applied voltage (see AppendixX1).4.3 Standardized Under the conditions outlined in Appendix X2test conditions and conditioning prior to tes
28、ting are important.In particular, tests with specified air flow at both low and moderate humidities may be informative. In special cases, it is permissiblefor the test to be accelerated by increasing the frequency of the applied voltage. In cases agreed upon between the buyer and theseller, or requi
29、red in relevant specifications to perform testing on specific specimens where a service condition is thought to alter3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.4 Available from Institute of Electrical and Electroni
30、cs Engineers, Inc. (IEEE), 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http:/www.ieee.org.D2275 142the corona endurance, this factor shouldshall be introduced as part of the test and reported. Such conditions might includeelongation, elevated temperature, high humidity, other gases besid
31、es air, pollution, etc.4.4 Additional It is possible to obtain additional information from the test may be obtained if corona-voltage levels and coronaintensity are measured at the start of the test and monitored at various stages of deterioration of the insulation. The voltage levelsinclude corona-
32、inception voltage, corona-extinction voltage, and corona intensity using Test Method D1868.NOTE 2Comparative measurements of corona power or energy by bridge and oscilloscope techniques can also be informative.Also, comparativemeasurements of corona power or energy by bridge and oscilloscope techniq
33、ues can be informative (seeASTM STP 198 and STP669).4.7 If elevated frequencies are used to accelerate the test, it is recommended that the corona-discharge pulse heights and energyper cycle at the test frequency be compared with these values at rated power frequency. If the energy per cycle is the
34、same, it canbe concluded that failure time is inversely proportional to frequency.5. Significance and Use5.1 This test method is useful in research and quality control for evaluating insulating materials and systems since they providefor the measurement of the endurance used to compare the endurance
35、 of different materials to the action of corona on the externalsurfaces. A poor result on this test does not indicate that the material is a poor selection for use at high voltage or at high voltagestress in the absence of surface corona. Surface corona should be distinguished from corona; surface c
36、orona is not the same ascorona that occurs in internal cavities for which nocavities. (See Test Methods D3382standardized test has been developed.Evaluation of endurance by comparison of data on specimens of different thickness is not valid)5.2 This test method is also useful for comparison between
37、materials of the same relative thickness. When agreed upon betweenthe buyer and the seller, it is acceptable to express any differences in terms of relative time to failure or the magnitude of voltagestress (kV/mm or kV/in.) required to produce failure in a specified number of hours.5.3 The processi
38、ng of the material may affect the results obtained. For instance, It is possible for this test method to also be usedto examine the effects of different processing parameters on the same insulating material, such as residual strains produced byquenching, or high levels of crystallinity caused by slo
39、w cooling may affect the result.Also, the type of molding process, injectionor compression, may be important especially if the mixing of fillers or the or molding processes that control the concentration andsizes of gas-filled cavities are controlled in any degree by the process. Indeed, this test m
40、ethod may be used to examine the effectsof processing.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 can be analyzedusing Weibull or extreme value statistics to yield an estimate of the central value of the distribution a
41、nd its standard deviation. Thisis particularly recommended when the dispersion of failure times is large, and a comparison of lifetimes of two materials must bemade at a specified level of confidence. is analyzed using one of the methods below:5.4.1 Weibull Probability Plot.5.4.2 Statistically (see
42、IEEE 930-1987 for additional information), to yield an estimate of the central value of the distributionand 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
43、 10.2.5.4 This test is often used to demonstrate the differences between different classes of materials, and to illustrate the importanceof eliminating corona in any application of a particular material. When the test is used for such purposes or other similar ones, theneed for precision is reduced,
44、 and certain time saving techniques, such as truncating a test at the time of the fifth failure of a setof nine, and using that time as the measure of the central tendency, are recommended. Two such techniques are described in 10.2.Both techniques remove the necessity of testing beyond median failur
45、e, and reduce the required testing time to approximately halfof that required to obtain failures on all specimens.5.5 Insulating materials operating in a gaseous medium are subjected to corona attack at operating voltage on some types ofelectrical apparatus in those regions where the voltage gradien
46、t in the gas exceeds the corona inception level. On other types ofequipment, where detectable corona is absent initially, it may appear later due to transient over-voltages or changes in insulationproperties attending aging. Certain inorganic materials can tolerate corona for a long time. Many organ
47、ic materials are damagedquickly by corona, and for these, operation with no detectable corona is imperative. This test method intensifies some of the morecommonly met conditions of corona attack so that materials may are able to be evaluated in a time that is relatively short comparedto the life of
48、the equipment. As with most accelerated life tests, caution is necessary in extrapolation from the indicated life toactual life under various operating conditions in the field.5.6 The failure possible factors related to failures produced by corona may be due to one of several possible factors. The c
49、oronamay erode the insulation until the remaining insulation can no longer withstand the applied voltage. The corona may cause theinsulation surface to become conducting. For instance, carbonization may occur, so that failure occurs quickly. On the other hand,compounds such as oxalic acid crystals may be formed, as with polyethylene, in which case the surface conductance will vary withambient humidity, and at moderate humidities the conductance may be at the proper level to reduce the potential gradient at theD2275 143electrode edge, and thus cause either a re
