ASTM_D_3426_-_97_2012.pdf

Designation:D342697(Reapproved 2012)Standard Test Method forDielectric Breakdown Voltage and Dielectric Strength ofSolid Electrical Insulating Materials Using Impulse Waves1This standard is issued under the fixed designation D3426;the number immediately following the designation 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.1.Scope1.1 This test method covers the determination of dielectricstrength of solid electrical insulating materials undersimulated-lightning impulse conditions.1.2 Procedures are given for tests using standard 1.2 by 50s full-wave impulses.1.3 This test method is intended for use in determining theimpulse dielectric strength of insulating materials,either usingsimple electrodes or functional models.It is not intended foruse in impulse testing of apparatus.1.4 This test method is similar to IEC Publication 243-3.Allprocedures in this test method are included in IEC 243-3.Differences between this test method and IEC 243-3 are largelyeditorial.1.5 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 safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precautionstatements are given in Section 9.2.Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD374 Test Methods for Thickness of Solid Electrical Insu-lation(Withdrawn 2013)3D2413 Practice for Preparation of Insulating Paper andBoard Impregnated with a Liquid Dielectric2.2 American National Standard:C 68.1 Techniques for Dielectric Tests(IEEE Standard No.4)42.3 IEC Standard:Pub 243-3 Methods of Test for Electric Strength of SolidInsulating MaterialsPart 3:Additional Requirements forImpulse Tests43.Terminology3.1 Definitions:3.1.1 Reference should be made to Fig.1 for the symbolsmentioned.3.1.2 full-impulse-voltage wave,nan aperiodic transientvoltage that rises rapidly to a maximum value,then falls lessrapidly to zero.3.1.3 peak value of an impulse voltage wave,n themaximum value of voltage.3.1.4 virtual-peak value of an impulse voltage wave,navalue derived from a recording of an impulse wave on whichhigh-frequency oscillations or overshoot of limited magnitudemay be present.If the oscillations have a magnitude of no morethan 5%of the peak value and a frequency of at least 0.5 MHz,a mean curve may be drawn,the maximum amplitude of whichis the virtual-peak value.If the oscillations are of greatermagnitude,the voltage wave is not acceptable for standardtests.3.1.5 virtual-front time of an impulse voltage wave,nequal to 1.67 times the interval tfbetween the instants whenthe voltage is 0.3 and 0.9 times the peak value(t1,Fig.1).3.1.6 virtual origin of an impulse voltage wave,nthe pointof intersection O1with the line of zero voltage of a line drawnthrough the points of 0.3 and 0.9 times the peak voltage on thefront of an impulse voltage wave.3.1.7 virtual time to half-value of an impulse voltage wave,nthe time interval t2between the virtual origin O1and theinstant on the tail when the voltage has decreased to half thepeak value.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.12 on Electrical Tests.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1975.Last previous edition approved in 2004 as D3426 97(2004).DOI:10.1520/D3426-97R12.2For 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 Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Summary of Test Method4.1 A series of sets-of-three voltage waves of a specifiedshape(see 5.3)is applied to the test specimen.The voltage ofsuccessive sets is increased in magnitude until breakdown ofthe test specimen occurs.4.2 The procedures for sampling and specimen preparationare as specified in the material specification or other documentcalling for the use of this test method.The surroundingmedium(air or other gas,or oil or other liquid)is also asspecified if it differs from the medium in which the specimensare finally conditioned for test.5.Significance and Use5.1 Insulating materials used in high-voltage equipmentmay be subjected to transie