1、Designation:A717/A717M12Standard Test Method forSurface Insulation Resistivity of Single-Strip Specimens1This standard is issued under the fixed designation A717/A717M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last
2、revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a means of testing the surfaceinsulation resistivity of single strips or punchings of flat-rolledelectr
3、ical steel under predetermined conditions of voltage,pressure,and temperature.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the oth
4、er.Combiningvalues from the two systems may result in non-conformancewith 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 this standard to establish appro-priate safety and health practices and
5、 determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic Materials3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 surface insulation resistivityrefers to the
6、effectiveresistivity of a single insulative layer tested between appliedbare metal contacts and the base metal of the insulated testspecimen.It is not the same as the terms interlaminar resistivityand stack resistivity,which refer to the average resistivity oftwo adjacent insulative surfaces in cont
7、act with each other.3.1.2 The apparatus is popularly known as a Franklin tester.4.Summary of Test Method4.1 Ten metallic contacts of fixed area are applied to one ofthe surfaces of the specimen and electrical contact is made withthe base metal by two drills.The effectiveness of the surfaceinsulation
8、 is then indicated by a measurement of averageelectrical current flowing between the contacts and the basemetal under specified applied voltage.This measurement canbe used directly as an indicator of insulation quality or may beconverted to an apparent surface insulation resistivity value.5.Signific
9、ance and Use5.1 This test method is particularly suitable for qualitycontrol in the application of insulating coatings.5.2 Surface insulation resistivity is evaluated from a dccurrent that can range from 0(perfect insulator)to 1 A(perfectconductor).5.3 Single readings should not be considered signif
10、icantsince the nature of the test device and specimen are such thatsuccessive measurements of a specimen often yield differentvalues.6.Apparatus6.1 The apparatus,as shown in Fig.1 and Fig.2,shallconsist of a contact unit or test head which is attached to thehead of a hydraulic press.Its associated m
11、easuring equipment,which may be remotely located,includes an ammeter,voltmeter,and voltage regulated dc power supply.Whenmeasurements are to be made at elevated temperatures,theplaten beneath the specimen is heated and controlled.Detaileddescriptions of the various components are given in AnnexA1.7.
12、Sampling7.1 Samples shall be representative of the steel and shall becut in a manner to assure representative sampling as describedin Practice A34/A34M.8.Test Specimen8.1 The width and length of a specimen strip shall be greaterthan the width and length respectively of the assembly ofcontacts.The su
13、ggested minimum specimen size is 2 by 5 in.50 by 130 mm.8.2 A minimum of five specimen strips is recommended.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved May 1,2
14、012.Published July 2012.Originally approvedin 1975.Last previous edition approved in 2006 as A717/A717M 06.DOI:10.1520/A0717_A0717M-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume informa
15、tion,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.3 By mutual agreement between the producer and theuser,tests may be run on Epstein test strips.The Epsteinspecimens may
16、 be less satisfactory than the minimum sizespecimen suggested in 8.1 because of the tilting effect due toburrs,shearing strains,and disturbances in the coating.9.Procedure9.1 To ensure correct contact button conditions,make ashort circuit test occasionally by testing a bare metal surface.When the short circuit current is less than 0.99 A,clean thecontacts.The use of solvents for cleaning is preferred toabrasives because the latter can result in rounded tips withreduced contact areas.9.2 The reco
