ASTM_D_3755_-_20.pdf

Designation:D375520Standard Test Method forDielectric Breakdown Voltage and Dielectric Strength ofSolid Electrical Insulating Materials Under Direct-VoltageStress1This standard is issued under the fixed designation D3755;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.Scope*1.1 This test method covers the determination of dielectricbreakdown voltage and dielectric strength of solid electricalinsulating materials under direct-voltage stress.1.2 Since some materials require special treatment,refer-ence shall also be made to ASTM specifications or to the testmethod directly applicable to the material to be tested.See TestMethod D149 for the determination of dielectric strength ofelectrical insulating materials at commercial power frequen-cies.1.3 This test method is similar to IEC Publication 243-2.Allprocedures in this test method are included in IEC 243-2.Differences between this test method and IEC 243-2 are largelyeditorial.1.4 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific precaution statements are given in Section 7.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD176 Test Methods for Solid Filling and Treating Com-pounds Used for Electrical Insulation(Withdrawn 2013)3D877 Test Method for Dielectric Breakdown Voltage ofInsulating Liquids Using Disk ElectrodesD1711 Terminology Relating to Electrical InsulationD2436 Specification for Forced-Convection Laboratory Ov-ens for Electrical Insulation(Withdrawn 1994)3D3487 Specification for Mineral Insulating Oil Used inElectrical Apparatus2.2 ANSI Standard:4ANSI C68.1 Techniques for Dielectric Tests,IEEE StandardNo.4.2.3 IEC Standard:IEC 243-2 Methods of test for electric strength of solidinsulating materialsPart 2:Additional requirements fortests using direct voltage43.Terminology3.1 Definitions:3.1.1 creepage distance,nshortest distance between twoconductive parts(typically metal),measured along the surfaceof the dielectric insulator.3.1.2 dielectric breakdown voltage,nRefer to Terminol-ogy D1711.3.1.3 dielectric strength,nRefer to Terminology D1711.3.1.4 flashover(as related to electrical),nan electricaldischarge between two electrodes which occurs around thesurface of a solid dielectric in the surrounding medium.4.Summary of Test Method4.1 The specimen,held in a properly designed electrodesystem,is electrically stressed by the application of an increas-ing direct voltage until internal breakdown occurs.The test1This 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 Jan.1,2020.Published January 2020.Originallyapproved in 1979.Last previous edition approved in 2014 as D3755 14.DOI:10.1520/D3755-20.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.voltage is applied at a uniform rate of increase.The directvoltage is obtained from a high-voltage supply of adequatecurrent capacity and regulation,reasonably ripple-free,withfacilities for measuring and controlling the output voltage.5.Significance and Use5.1 This test method is intended for use as a control andacceptance test for direct-voltage applications.It can also beused in