1、Designation: D149 09An American National StandardStandard Test Method forDielectric Breakdown Voltage and Dielectric Strength ofSolid Electrical Insulating Materials at Commercial PowerFrequencies1This standard is issued under the fixed designation D149; the number immediately following the designat
2、ion indicates 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.This standard has been approved for use by age
3、ncies of the Department of Defense.1. Scope*1.1 This test method covers procedures for the determina-tion of dielectric strength of solid insulating materials atcommercial power frequencies, under specified conditions.2,31.2 Unless otherwise specified, the tests shall be made at 60Hz. However, this
4、test method is suitable for use at anyfrequency 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 conjunctionwith any ASTM standard or other document that refers to thistest method. References to this document need
5、 to specify theparticular options to be used (see 5.5).1.4 It is suitable for use at various temperatures, and in anysuitable gaseous or liquid surrounding medium.1.5 This test method is not intended for measuring thedielectric strength of materials that are fluid under the condi-tions of test.1.6 T
6、his test method is not intended for use in determiningintrinsic dielectric strength, direct-voltage dielectric strength,or thermal failure under electrical stress (see Test MethodD3151).1.7 This test method is most commonly used to determinethe dielectric breakdown voltage through the thickness of a
7、 testspecimen (puncture). It is also suitable for use to determinedielectric breakdown voltage along the interface between asolid specimen and a gaseous or liquid surrounding medium(flashover). With the addition of instructions modifying Sec-tion 12, this test method is also suitable for use for pro
8、oftesting.1.8 This test method is similar to IEC Publication 243-1.Allprocedures in this method are included in IEC 243-1. Differ-ences between this method and IEC 243-1 are largely editorial.1.9 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
9、 is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 7. Also see 6.4.1.2. Referenced Documents2.1 ASTM Standards:4D374 Test Meth
10、ods for Thickness of Solid Electrical Insu-lationD618 Practice for Conditioning Plastics for TestingD877 Test Method for Dielectric Breakdown Voltage ofInsulating Liquids Using Disk ElectrodesD1711 Terminology Relating to Electrical InsulationD2413 Practice for Preparation of Insulating Paper andBoa
11、rd Impregnated with a Liquid DielectricD3151 Test Method for Thermal Failure of Solid ElectricalInsulating Materials Under Electric Stress5D3487 Specification for Mineral Insulating Oil Used inElectrical ApparatusD5423 Specification for Forced-Convection LaboratoryOvens for Evaluation of Electrical
12、Insulation2.2 IEC Standard:Pub. 243-1 Methods of Test for Electrical Strength of SolidInsulating MaterialsPart 1: Tests at Power Frequencies61This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommit
13、tee D09.12 on Electrical Tests.Current edition approved Oct. 1, 2009. Published November 2009. Originallyapproved in 1922. Last previous edition approved in 2004 as D149 97a(2004).DOI: 10.1520/D0149-09.2Bartnikas, R., Chapter 3, “High Voltage Measurements,” Electrical Proper-ties of Solid Insulating
14、 Materials, Measurement Techniques ,Vol. IIB, EngineeringDielectrics, R. Bartnikas, Editor, ASTM STP 926, ASTM, Philadelphia, 1987 .3Nelson, J. K., Chapter 5, “Dielectric Breakdown of Solids,” ElectricalProperties of Solid Insulating Materials: Molecular Structure and ElectricalBehavior, Vol. IIA, E
15、ngineering Dielectrics, R. Bartnikas and R. M. Eichorn,Editors, ASTM STP 783, ASTM, Philadelphia, 19834For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards
16、Document Summary page onthe ASTM website.5Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.6Available from International Electrotechnical Commission (IEC), 3 rue deVaremb, Case postale 131, CH-1211, Geneva 20, Switzerland, http:/www.iec.ch.1*A Summary of
17、Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.3 ANSI Standard:C68.1 Techniques for Dielectric Tests, IEEE Standard No.473. Terminology3.1 Definitions:3.1.1 dielectric breakdown v
18、oltage (electric breakdownvoltage), nthe potential difference at which dielectric failureoccurs under prescribed conditions in an electrical insulatingmaterial located between two electrodes. (See also AppendixX1.)3.1.1.1 DiscussionThe term dielectric breakdown voltageis sometimes shortened to “brea
19、kdown voltage.”3.1.2 dielectric failure (under test), nan event that isevidenced by an increase in conductance in the dielectric undertest limiting the electric field that can be sustained.3.1.3 dielectric strength, nthe voltage gradient at whichdielectric failure of the insulating material occurs u
20、nder spe-cific conditions of test.3.1.4 electric strength, nsee dielectric strength.3.1.4.1 DiscussionInternationally, “electric strength” isused almost universally.3.1.5 flashover, na disruptive electrical discharge at thesurface of electrical insulation or in the surrounding medium,which may or ma
21、y not cause permanent damage to theinsulation.3.1.6 For definitions of other terms relating to solid insulat-ing materials, refer to Terminology D1711.4. Summary of Test Method4.1 Alternating voltage at a commercial power frequency(60 Hz, unless otherwise specified) is applied to a testspecimen. The
22、 voltage is increased from zero or from a levelwell below the breakdown voltage, in one of three prescribedmethods of voltage application, until dielectric failure of thetest specimen occurs.4.2 Most commonly, the test voltage is applied using simpletest electrodes on opposite faces of specimens. Th
23、e options forthe specimens are that they be molded or cast, or cut from flatsheet or plate. Other electrode and specimen configurations arealso suitable for use to accommodate the geometry of thesample material, or to simulate a specific application for whichthe material is being evaluated.5. Signif
24、icance and Use5.1 The dielectric strength of an electrical insulating mate-rial is a property of interest for any application where anelectrical field will be present. In many cases the dielectricstrength of a material will be the determining factor in thedesign of the apparatus in which it is to be
25、 used.5.2 Tests made as specified herein are suitable for use toprovide part of the information needed for determining suit-ability of a material for a given application; and also, fordetecting changes or deviations from normal characteristicsresulting from processing variables, aging conditions, or
26、 othermanufacturing or environmental situations. This test method isuseful for process control, acceptance or research testing.5.3 Results obtained by this test method can seldom be useddirectly to determine the dielectric behavior of a material in anactual application. In most cases it is necessary
27、 that theseresults be evaluated by comparison with results obtained fromother 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 inSection 12: Method A, Short-Time Test;
28、Method B, Step-by-Step Test; and Method C, Slow Rate-of-Rise Test. MethodAisthe most commonly-used test for quality-control tests. How-ever, the longer-time tests, Methods B and C, which usuallywill give lower test results, will potentially give more mean-ingful results when different materials are
29、being compared witheach other. If a test set with motor-driven voltage control isavailable, the slow rate-of-rise test is simpler and preferable tothe step-by-step test. The results obtained from Methods B andC are comparable to each other.5.5 Documents specifying the use of this test method shallal
30、so specify:5.5.1 Method of voltage application,5.5.2 Voltage rate-of-rise, if slow rate-of-rise method isspecified,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 curre
31、nt-sensing element, and5.5.7 Any desired deviations from the recommended proce-dures as given.5.6 If any of the requirements listed in 5.5 are missing fromthe specifying document, then the recommendations for theseveral variables shall be followed.5.7 Unless the items listed in 5.5 are specified, te
32、sts madewith such inadequate reference to this test method are not inconformance with this test method. If the items listed in 5.5 arenot closely controlled during the test, it is possible that theprecisions stated in 15.2 and 15.3 will not be obtained.5.8 Variations in the failure criteria (current
33、 setting andresponse time) of the current sensing element significantlyaffect the test results.5.9 Appendix X1. contains a more complete discussion ofthe significance of dielectric strength tests.6. Apparatus6.1 Voltage SourceObtain the test voltage from a step-uptransformer supplied from a variable
34、 sinusoidal low-voltagesource. The transformer, its voltage source, and the associatedcontrols shall have the following capabilities:6.1.1 The ratio of crest to root-mean-square (rms) testvoltage shall be equal to=2 6 5 % (1.34 to 1.48), with thetest specimen in the circuit, at all voltages greater
35、than 50 % ofthe breakdown voltage.6.1.2 The capacity of the source shall be sufficient tomaintain the test voltage until dielectric breakdown occurs. Formost materials, using electrodes similar to those shown inTable 1, an output current capacity of 40 mA is usuallysatisfactory. For more complex ele
36、ctrode structures, or for7Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.D149 092testing high-loss materials, it is possible that higher currentcapacity will be needed. The power rating for most tests willvary from 0.5 kV
37、A for testing low-capacitance specimens atvoltages up to 10 kV, to 5 kVA for voltages up to 100 kV.6.1.3 The controls on the variable low-voltage source shallbe capable of varying the supply voltage and the resultant testvoltage smoothly, uniformly, and without overshoots or tran-sients, in accordan
38、ce with 12.2. Do not allow the peak voltageto exceed 1.48 times the indicated rms test voltage under anycircumstance. Motor-driven controls are preferable for makingshort-time (see 12.2.1) or slow-rate-of-rise (see 12.2.3) tests.6.1.4 Equip the voltage source with a circuit-breakingdevice that will
39、operate within three cycles. The device shalldisconnect the voltage-source equipment from the powerservice and protect it from overload as a result of specimenbreakdown causing an overload of the testing apparatus. Ifprolonged current follows breakdown it will result in unnec-essary burning of the t
40、est specimens, pitting of the electrodes,and contamination of any liquid surrounding medium.6.1.5 It is important for the circuit-breaking device to havean adjustable current-sensing element in the step-up trans-former secondary, to allow for adjustment consistent with thespecimen characteristics an
41、d arranged to sense specimen cur-rent. Set the sensing element to respond to a current that isindicative of specimen breakdown as defined in 12.3.6.1.6 The current setting is likely to have a significant effecton the test results. Make the setting high enough that transients,such as partial discharg
42、es, will not trip the breaker but not sohigh that excessive burning of the specimen, with resultantelectrode damage, will occur on breakdown. The optimumcurrent setting is not the same for all specimens and dependingupon the intended use of the material and the purpose of thetest, it is often desira
43、ble to make tests on a given sample atmore than one current setting. The electrode area is likely tohave a significant effect upon the choice of current setting.6.1.7 It is possible that the specimen current-sensing ele-ment will be in the primary of the step-up transformer.Calibrate the current-sen
44、sing dial in terms of specimen current.6.1.8 Exercise care in setting the response of the currentcontrol. If the control is set too high, the circuit will notrespond when breakdown occurs; if set too low, it is possiblethat it will respond to leakage currents, capacitive currents, orpartial discharg
45、e (corona) currents or, when the sensing ele-ment is located in the primary, to the step-up transformermagnetizing current.6.2 Voltage MeasurementA voltmeter must be providedfor measuring the rms test voltage. If a peak-reading voltmeteris used, divide the reading by=2 to get rms values. Theoverall
46、error of the voltage-measuring circuit shall not exceed5 % of the measured value. In addition, the response time ofthe voltmeter shall be such that its time lag will not be greaterthan 1 % of full scale at any rate-of-rise used.6.2.1 Measure the voltage using a voltmeter or potentialtransformer conn
47、ected to the specimen electrodes, or to aseparate voltmeter winding, on the test transformer, that isunaffected by the step-up transformer loading.6.2.2 It is desirable for the reading of the maximum appliedtest voltage to be retained on the voltmeter after breakdown sothat the breakdown voltage can
48、 be accurately read and re-corded.6.3 ElectrodesFor a given specimen configuration, it ispossible that the dielectric breakdown voltage will vary con-siderably, depending upon the geometry and placement of thetest electrodes. For this reason it is important that the elec-trodes to be used be describ
49、ed when specifying this testmethod, and that they be described in the report.TABLE 1 Typical Electrodes for Dielectric Strength Testing of Various Types of Insulating MaterialsAElectrodeTypeDescription of ElectrodesB,CInsulating Materials1 Opposing cylinders 51 mm (2 in.) in diameter, 25 mm (1 in.) thick withedges rounded to 6.4 mm (0.25 in.) radiusflat sheets of paper, films, fabrics, rubber, molded plastics, laminates,boards, glass, mica, and ceramic2 Opposing cylinders 25 mm (1 in.) in diameter, 25 mm (1 in.) thick withedges rounded to 3.2 mm (0.125 in.) radiussame
