1、Designation: D 877 02 (Reapproved 2007)Standard Test Method forDielectric Breakdown Voltage of Insulating Liquids UsingDisk Electrodes1This standard is issued under the fixed designation D 877; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test met
3、hod describes two procedures, A and B, fordetermining the electrical breakdown voltage of insulatingliquid specimens. The breakdown test uses ac voltage in thepower-frequency range from 45 to 65 Hz.1.2 This test method is used to judge if the disk electrodebreakdown voltage requirements are met for
4、insulating liquids,as delivered from the manufacturer, that have never beenfiltered or dried. See Specification D 3487, SpecificationD 4652, and Guide D 5222 for the minimum specified electri-cal breakdown. This test method should be used as recom-mended by professional organization standards such a
5、s IEEEC57.106.1.3 Limitations of the Procedures:1.3.1 The sensitivity of this test method to the generalpopulation of contaminants present in a liquid sample de-creases as applied test voltages used in this test method becomegreater than approximately 25 kV rms.1.3.2 If the concentration of water in
6、 the sample at roomtemperature is less than 60 % of saturation, the sensitivity ofthis test method to the presence of water is decreased. Forfurther information refer to RR: D27-1006.21.3.3 The suitability for this test method has not beendetermined for a liquids viscosity higher than 900 cSt at 40C
7、.1.4 Procedure Applications1.4.1 Procedure A:1.4.1.1 Procedure A is used to determine the breakdownvoltage of liquids in which any insoluble breakdown productseasily settle during the interval between the required repeatedbreakdown tests. These liquids include petroleum oils, hydro-carbons, and aska
8、rels (PCB) used as insulating and coolingliquids in transformers, cables, and similar apparatus.1.4.1.2 Procedure A may be used to obtain the dielectricbreakdown of silicone fluid as specified in Test MethodsD 2225, provided the discharge energy into the sample is lessthan 20 mJ (milli joule) per br
9、eakdown for five consecutivebreakdowns.1.4.2 Procedure B:1.4.2.1 This procedure is used to determine the breakdownvoltage of liquids in which any insoluble breakdown productsdo not completely settle from the space between the disksduring the 1min interval required in Procedure A. ProcedureB, modifie
10、d in accordance with Section 17 of Test MethodsD 2225, is acceptable for testing silicone dielectric liquids ifthe requirements of 1.4.1.2 can not be achieved.1.4.2.2 Procedure B should also be applied for the determi-nation of the breakdown voltage of liquid samples containinginsoluble materials th
11、at settle from the specimen during testing.These may include samples taken from circuit breakers, loadtap changers, and other liquids heavily contaminated withinsoluble particulate material. These examples representsamples that may have large differences between replicatetests. The use of Procedure
12、B will result in a more accuratevalue of breakdown voltage when testing such liquids.1.4.2.3 Use Procedure B to establish the breakdown voltageof an insulating liquid where an ASTM specification does notexist or when developing a value for an ASTM guide orstandard. Procedure A may be used once the s
13、ingle operatorprecision of 13.1 has been demonstrated.1.5 Both the SI and inch-pound units are equally acceptable.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate s
14、afety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 923 Practices for Sampling Electrical Insulating LiquidsD 1816 Test Method for Dielectric Breakdown Voltage ofInsulating Oils of Petroleum Origin Using VDE
15、Electrodes1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.05 on Electrical Test.Current edition approved Oct. 1, 2007. Published October 2007. Originallyapproved in 1946. Last previous e
16、dition approved in 2002 as D 87702e2.2RR: D271006, Round-Robin Data Using Modified VDE Electrode Cell forDielectric Strength Tests on Oil, is available from ASTM Headquarters.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
17、 Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 2225 Test Methods for Silicone Fluids Used for ElectricalInsulationD
18、2864 Terminology Relating to Electrical Insulating Liq-uids and GasesD 3487 Specification for Mineral Insulating Oil Used inElectrical ApparatusD 4652 Specification for Silicone Fluid Used for ElectricalInsulationD 5222 Specification for High Fire-Point Mineral ElectricalInsulating Oils2.2 IEEE Stan
19、dards:4Standard 4, IEEE Standard Techniques for High-VoltageTestingC57.106 Guide for Acceptance and Maintenance of Insu-lating Oil in Equipment3. Significance and Use3.1 The dielectric breakdown voltage is a measure of theability of an insulating liquid to withstand electrical stress. Thepower-frequ
20、ency breakdown voltage of a liquid is reduced bythe presence of contaminants such as cellulosic fibers, conduct-ing particles, dirt, and water. A low result in this test methodindicates the presence of significant concentrations of one ormore of these contaminants in the liquid tested. See AppendixX
21、1.3.2 A high breakdown voltage measured in this test methoddoes not necessarily indicate that the amount of the contami-nants present in a liquid from which the sample was taken aresufficiently low for the sampled liquid to be acceptable in allelectrical equipment. Test Method D 877 is not sensitive
22、 to lowlevels of these contaminants. Breakdown in this test method isdominated by events occurring at the electrode edges. Thevoltage stress distribution between the parallel disk electrodesused in this test method are quasi-uniform and there issubstantial stress concentration at the sharp edges of
23、the flatdisk faces.3.3 This test method may be used for evaluation of insulat-ing liquids in equipment that is designed to be filled withunprocessed liquids as delivered by a vendor.3.4 This test method is not recommended for evaluation ofthe breakdown voltage of liquids used in equipment thatrequir
24、es the application of vacuum and filtering of the oilbefore being placed into service. Test Method D 1816 shouldbe used to determine the breakdown voltage of filtered anddegassed liquids.3.5 This test method is used in laboratory or field tests. Forfield breakdown results to be comparable to laborat
25、ory results,all criteria including room temperature (20 to 30C) must bemet.4. Electrical Apparatus4.1 In addition to this section, use IEEE Standard 4 todetermine other requirements necessary for conducting testmethods and making measurements using alternating voltages.Procedures to ensure accuracy
26、should follow the requirementsof IEEE Standard 4. Calibration(s) shall be traceable tonational standards and should be conducted annually or moreoften.4.1.1 Test VoltageThe test voltage shall be an alternatingvoltage having a frequency in the range from 45 to 65 Hz,normally referred to as power-freq
27、uency voltage. The voltagewaveshape should approximate a sinusoid with both half cyclesclosely alike, and it should have a ratio of peak-to-rms valuesequal to the square root of 2 within 65%.4.1.2 Generation of the Test Voltage The test voltage isgenerally supplied by a transformer or resonant circu
28、it. Thevoltage in the test circuit should be stable enough to bepractically unaffected by varying current flowing in the capaci-tive and resistive paths of the test circuit. Nondisruptivedischarges in the test circuit should not reduce the test voltageto such an extent, and for such a time, that the
29、 disruptivedischarge (breakdown) voltage of the test specimen is signifi-cantly affected. In the case of a transformer, the short-circuitcurrent delivered by the transformer should be sufficient tomaintain the test voltage within 3 % during transient currentpulses or discharges, and a short circuit
30、current of 0.1 A maysuffice.4.1.3 Disruptive Voltage Measurement Design the mea-surement circuit so the voltage recorded at the breakdown isthe maximum voltage across the test specimen immediatelyprior to the disruptive breakdown with an error no greater than3%.4.2 Circuit-Interrupting EquipmentDesi
31、gn the circuitused to interrupt the disruptive discharge through the specimento operate when the voltage across the specimen has collapsedto less than 100 V. It is recommended that the circuit designlimit the disruptive current duration and magnitude to lowvalues that will minimize damage to the dis
32、ks and limitformation of non-soluble materials resulting from the break-down, but consistent with the requirements of 4.1.1.4.3 Voltage Control EquipmentUse a rate of voltage riseof 3 kV/s. The tolerance of the rate of rise should be 5 % forany new equipment. Automatic equipment should be used tocon
33、trol the voltage rate of rise because of the difficulty ofmaintaining a uniform voltage rise manually. The equipmentshould produce a straight-line voltage-time curve over theoperating range of the equipment. Calibrate and label auto-matic controls in terms of rate-of-rise.4.4 Measuring SystemsThe vo
34、ltage shall be measured bya method that fulfills the requirements of IEEE Standard No. 4,giving rms values.4.5 Connect the electrode such that the voltage measuredfrom each electrode with respect to ground during the test isequal within 5 %.5. Electrodes5.1 The electrodes shall have parallel faces a
35、nd axes in acoincident horizontal line when mounted in the cup. Constructthe electrodes of polished brass as disks 25.4 mm (1.0 in.) indiameter 62.0 %, and at least 3.18 mm (18 in.) thick, and withsharp edges. The sharp edge shall have a quarter circle radiusno greater than 0.254 mm (0.010 in.). Ref
36、er to Annex A1 forillustrations of measuring edge radius.4Available from The Institute of Electrical and Electronics Engineers, Inc., POBox 1331, Piscataway, NJ 08855.D 877 02 (2007)26. Test Cup6.1 Construct the cup of a material having high dielectricstrength, that is inert to any of the cleaning o
37、r test liquids. Thecup material shall not absorb moisture or the cleaning and testliquids. The vector sum of the resistive and capacitive currentof the cup, when filled with oil meeting the requirements ofSpecification D 3487, shall be less than 200 A at 20 kV, atpower frequency. Construct the cup s
38、o that no part is less than12.7 mm (0.5 in.) from any part of the electrode disk. The cupshall be designed to permit easy removal of the electrodes forcleaning and polishing, verification that the sharp edge iswithin the specified tolerance, and to permit easy adjustment ofthe gap spacing. The top o
39、f the cup shall be maintained at least25.4 mm (1.0 in.) above the top of the electrodes.7. Adjustment and Care of Electrodes and Test Cup7.1 Daily UseAt the beginning of each days testingexamine the electrodes for scratches, pitting, and contamina-tion. If pitting or scratches of the disk faces are
40、found, examinethe electrodes in accordance with 7.4 for the proper sharp edgeand then polish in accordance with 7.5. For severe problemsresurfacing may be required. The gap shall be reset inaccordance with 7.2. Clean and prepare the cup in accordancewith 7.3.7.2 Electrode SpacingThe spacing of the e
41、lectrodes dur-ing tests is 2.54 mm (0.100 in.). The adjustment is made witha standard round gage of 2.54 mm (0.100 in.) 61.0 % or 0.1006 0.0005 in., or flat steel “go” and “no-go” gages having athickness of 2.53 mm and 2.55 mm or 0.0995 and 0.1005 in.,respectively. Recheck the spacing following any
42、disturbance ofthe cup or electrodes and at operation in the beginning of eachdays testing. Use the same gage size when conductingcomparative tests.7.3 CleaningWipe the electrodes and the cup clean withdry, lint-free tissue paper or a clean dry chamois. It is importantto avoid touching the electrodes
43、 or the cleaned gage with thefingers or with portions of the tissue paper or chamois that havebeen in contact with the hands. After adjustment of the gapspacing, the cup shall be rinsed with a dry solvent. Alow-boiling solvent should not be used as its rapid evaporationmay cool the cup, causing mois
44、ture condensation. If thisoccurs, the cup should be warmed slightly to evaporate anymoisture before use. Take care to avoid touching the electrodesor the inside of the cup after cleaning. Flush the cup using partof the sample. Fill the cup with a specimen from a sample witha known breakdown voltage.
45、 Make a voltage breakdown test asspecified in this test method. If the breakdown voltage isjudged in the proper range for the sample with a knownbreakdown value, the test cup is prepared for testing othersamples. If a value lower than expected is obtained, flush orclean the cup as necessary until te
46、st results meet the expectedvalue for the known sample.7.4 Electrode Edge VerificationUsing a 0.010-in.(0.254-mm equivalent), radius gage5or an optical comparator,verify that the radius of the edge of the electrode, on the gapside, is less than 0.010 in. (0.254 mm), verify the face of theelectrodes
47、are at 90 6 1 to the side edge of the electrode. If theedge radius is no greater than the value specified and the sidesare at 90, the electrodes are satisfactory for continued use.Check the disk in at least four locations for each criteria. If theradius exceeds the tolerance or the edges are not at
48、90, theelectrodes shall be resurfaced to the specified values. Refer toAnnex A1 for illustrations of measuring edge radius.7.5 Polishing of ElectrodesWhen examination of elec-trodes shows minor scratching or pitting, the electrodes shouldbe removed from the test cup and polished by buffing withjewel
49、ers rouge using a soft cloth or soft buffing wheel.(Resurfacing may be necessary in order to remove deep pitmarks or edge damage.) Care must be taken in resurfacing orin polishing to ensure that the electrode faces remain perpen-dicular to the axis and the edges radius does not exceed thevalue specified in 7.4. All residue from the buffing must beremoved before the electrodes are reinstalled in the test cup.This can be accomplished by repeated wiping with lint-freetissue paper saturated with a suitable solvent (such as petro-leum ether), followed by solvent ri
