1、Designation: D 3300 00 (Reapproved 2006)Standard Test Method forDielectric Breakdown Voltage of Insulating Oils ofPetroleum Origin Under Impulse Conditions1This standard is issued under the fixed designation D 3300; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of 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.1. Scope1.1 This test method covers the determination of the dielec-tric breakdown v
3、oltage of insulating oils in a highly divergentfield under impulse conditions.1.2 The values stated in inch-pound units are to be regardedas the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t
4、his standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 923 Practices for Sampling Electrical Insulating LiquidsD 2864 Terminology Relating to Electrical Insulating Liq-uid
5、s and Gases2.2 IEEE Documents:IEEE Standard 4-1995 Techniques for High-Voltage Test-ing33. Significance and Use3.1 This test method is most commonly performed using anegative polarity point opposing a grounded sphere (NPS). TheNPS breakdown voltage of fresh unused oils measured in thehighly divergen
6、t field in this configuration depends on oilcomposition, decreasing with increasing concentration of aro-matic, particularly polyaromatic, hydrocarbon molecules.3.2 This test method may be used to evaluate the continuityof composition of an oil from shipment to shipment. The NPSimpulse breakdown vol
7、tage of an oil can also be substantiallylowered by contact with materials of construction, by serviceaging, and by other impurities. Test results lower than thoseexpected for a given fresh oil may also indicate use orcontamination of that oil.3.3 Although polarity of the voltage wave has little or n
8、oeffect on the breakdown strength of an oil in uniform fields,polarity does have a marked effect on the breakdown voltage ofan oil in nonuniform electric fields.3.4 Transient voltages may also vary over a wide range inboth the time to reach crest value and the time to decay to halfcrest or to zero m
9、agnitude. The IEEE standard lightningimpulse test (see 2.2) specifies a 1.2 by 50-s negative polaritywave.4. Apparatus4.1 Impulse Generator, capable of producing a standard 1.2by 50-s full wave adjustable to positive or negative polarity.The generator shall have a nominal voltage rating of at least3
10、00 kV adjustable in 10-kV steps. Generators having acapability of 1000 Ws (1000 J) at 300 kV have been foundsatisfactory.4.2 Voltage-Control EquipmentThe controls shall includea suitable measuring device for predetermining the crestvoltage to within 65 %. A voltage stabilizer is desirable at theinpu
11、t to the d-c power supply used for charging the impulse-generator capacitors.4.3 Electrodes:4.3.1 The electrodes shall consist of a polished steel or brasssphere of 0.5 in. (12.7 mm) diameter and a steel point. Thepoint may be an ordinary steel phonograph needle with a 0.06mm 6 20 % radius of curvat
12、ure of point or a No. 18 FilterPoint needle.4Needles with drawn tips are not recommended.4.3.2 The effect of variation in the radius of curvature ofpoint is subject to further investigation. Both electrodes shallbe easily replaceable.4.4 Test Cell:4.4.1 The test cell shall be made of a material of h
13、ighdielectric strength and of such dimensions that the electricalbreakdown is restricted to the electrode gap. Test cell materialsshall resist attack by, and be insoluble in, any of the cleaning1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gase
14、s and is the direct responsibility of Subcom-mittee D27.05 on Electrical Test.Current edition approved Nov. 1, 2006. Published January 2007. Originallyapproved in 1974. Last previous edition approved in 2000 as D 3300 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
15、 ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from the Institute of Electrical and Electronics Engineers, 445 HoesLane, Piscataway, NJ 08855-1331.4The following steel needle h
16、as been found satisfactory for this method: DeanNo. 18 Filter Point Needle, available from John Dean, Inc., 20 Mechanic St.,Putnam, CT 06260.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.or test liquids used. Test cells such as tho
17、se shown in Fig. 1 andFig. 2 have been found satisfactory.4.4.2 The sphere electrode shall be rigidly fixed and thepoint electrode mounted such that the gap may be adjustedfrom zero to the required value.5. Sampling5.1 Obtain a sample of the liquid to be tested usingappropriate ASTM sampling apparat
18、us in accordance withPractices D 923.6. Adjustments and Care of Electrodes and Test Cell6.1 Electrode Spacing:6.1.1 For the cell shown in Fig. 1, reduce the electrode gapto zero spacing. Proceed very carefully to avoid damaging thepoint. The point of contact shall be established electrically withan
19、ohmmeter. Open the gap to the specified spacing using a dialmicrometer or other suitable method.6.1.2 For the cell shown in Fig. 2, the gap may be set witha go-no-go gage.6.1.3 The gap spacings shall be 1.0 in. (25.4 mm) forpoint-to-sphere and 0.15 in. (3.8 mm) for sphere-to-sphereelectrode configur
20、ation.6.2 CleaningDegrease the cell and electrodes by rinsingthem with reagent grade petroleum ether, washing with deter-gent and hot water, rinsing thoroughly in hot tap water, andthen rinsing them with distilled water. Dry the cell andhardware in an oven for 2 h at approximately 105 to 110C,remove
21、, and store in a desiccator until needed.6.3 Daily UseUse new or polished sphere electrodes atthe beginning of each days testing. Discard the point electrodeand replace it after each breakdown; replace the sphereelectrodes after every five breakdowns when testing point-to-sphere. More frequent repla
22、cement may be necessary whentesting sphere-to-sphere. Sphere electrodes may be cleaned andpolished for reuse in point-to-sphere testing. However, the useof polished spheres is not recommended for sphere-to-spheretesting. When not in use, clean and store the cell in accordancewith 6.2.FIG. 1 Test Cel
23、lD 3300 00 (2006)27. Test Temperature7.1 Conduct the tests with the specimen at room tempera-ture as defined in Terminology D 2864. Testing liquids attemperatures lower than that of the room may give variable andunsatisfactory results. Record the test temperature.8. Procedure8.1 Set the electrode sp
24、acing to the desired value.8.2 Rinse the test cell with a portion of the sample anddiscard this liquid. Slowly fill the cell with the test liquid, beingcareful to avoid entraining air bubbles. Allow it to set undis-turbed for 2 min prior to testing.8.2.1 For the test cell shown in Fig. 1, unscrew th
25、e upperelectrode holding assembly to fill it with the sample oil whileholding the cell at an angle to prevent splashing, which couldcreate air bubbles. Screw the top portion down until the metalflange seats firmly.8.3 Connect the fixed electrode to ground and the movableelectrode to the impulse gene
26、rator.8.4 Apply the impulse wave of specified polarity startingapproximately 40 kV below the expected breakdown level.Apply three impulse waves at each voltage level. Allow aminimum of 30 s between each test.8.5 Increase the voltage level in steps of 10 kV or less untilbreakdown occurs, noting the c
27、rest voltage level at breakdown.It is necessary to have at least three withstand levels prior tobreakdown.8.5.1 Measure the breakdown voltage using techniquesspecified in IEEE Standard 4.8.6 After each breakdown, change the point electrode andfollow 8.1 and 8.2.8.7 Make five breakdown tests on five
28、specimens from thesame sample. Maintain at least two significant digits in theresults.8.8 Criterion for Statistical Consistency:8.8.1 Calculate the mean and standard deviation of the fivebreakdowns as follows:X 5 n1(i51nXi! (1)where:X= mean of the five individual values,Xi= ith breakdown voltage, an
29、dn = number of breakdowns either 5 or 10.8.8.2 Using the impulse crest voltage breakdown valuesdetermined in 8.7, calculate the mean value using the equationin 8.8.1. Determine that the range of the five breakdowns is nogreater than 33.3 % of the mean value. If the range isacceptable, report this me
30、an value as the impulse breakdownvoltage. If the range exceeds 33.3 % of the mean value of thefive breakdowns, then conduct five additional breakdowns andobtain a new mean breakdown value for the ten breakdowns.Determine the range of the ten breakdowns and if the range isless than 54.6 % of the mean
31、 of the ten breakdowns, report thismean value as the impulse breakdown voltage. If the allowablerange is exceeded, the error is too large. Investigate the causeof the error and repeat the tests.NOTE 1The criterion for statistical consistency specified apply only tonegative polarity waves if point-to
32、-sphere electrodes are used.8.9 It may be necessary to partially immerse the test cell inoil to prevent external flashover. This is necessary with the cellshown in Fig. 1.FIG. 2 Test CellD 3300 00 (2006)38.10 If a second insulating liquid is to be tested, thoroughlyclean the test cell in accordance
33、with 6.2.9. Report9.1 Report the following information:9.1.1 Sample identification,9.1.2 Electrode configuration, polarity, and electrode spac-ing,9.1.3 Impulse crest voltage for each breakdown (do notdiscard any data),9.1.4 Wave shape identification,9.1.5 Starting voltage crest level, voltage steps
34、, and highestvoltage withstand level,9.1.6 Mean impulse breakdown value,9.1.7 Sample water content,9.1.8 Barometric pressure, and9.1.9 Date of test.10. Precision and Bias10.1 This precision statement applies to new oil receivedfrom a supplier. Using the point-to-sphere electrode configu-ration, the
35、following precision statements are applicable toboth positive and negative polarity:10.1.1 Single Operator PrecisionThe single operator %coefficient of variance of a single test result comprised of fivebreakdowns has been found to be 3.9 %. Therefore, results oftwo properly conducted tests by the sa
36、me operator on the samesample should not differ by more than 11 % of the average ofthe two tests. The maximum allowable range for the series offive breakdowns comprising the test result should be less than33.3 % of the average of the five breakdowns. In the casewhere a ten-breakdown average is used,
37、 the maximum allow-able range of the individual tests comprising the result shouldbe less than 54.6 % of the average of the ten breakdowns.10.1.2 Multilaboratory PrecisionThe multilaboratory %coefficient of variance has been found to be 5.43 %. Therefore,results of two properly conducted tests in di
38、fferent laboratorieson the same sample of oil should not differ by more than15.4 % of the average of the two results.10.2 No statement can be made about the bias of this testmethod because a standard reference material is not available.11. Keywords11.1 dielectric breakdown; impulse voltage; insulati
39、ng oilsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such righ
40、ts, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional
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42、Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 3300 00 (2006)4
