ASTM_D_3145_-_13.pdf

Designation:D314513Standard Test Method forThermal Endurance of Electrical Insulating Varnishes by theHelical Coil Method1This standard is issued under the fixed designation D3145;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers the determination of the thermalendurance of electrical insulating varnishes alone or in com-binations with magnet wire insulation.Changes in the helicalcoil bond strength are used as the test criteria.The coils aremade from bare aluminum or copper wire,or from film-orfiber-insulated magnet wire.1.2 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.NOTE1There is no similar or equivalent IEC 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 determine the applica-bility of regulatory limitations prior to use.For a specificprecautionary statement,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD1711 Terminology Relating to Electrical InsulationD1932 Test Method for Thermal Endurance of FlexibleElectrical Insulating VarnishesD2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet WireD2519 Test Method for Bond Strength of Electrical Insulat-ing Varnishes by the Helical Coil TestD3251 Test Method for Thermal Endurance Characteristicsof Electrical Insulating Varnishes Applied Over Film-Insulated Magnet WireD5423 Specification for Forced-Convection Laboratory Ov-ens for Evaluation of Electrical Insulation2.2 International Electrotechnical Commission Publica-tions:3IEC 60216-1 Guide for the Determination of Thermal En-durance Properties of Electrical Insulation Materials(Part1)3.Terminology3.1 Definitions3.1.1 For definitions of terms used in the test method,referto Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 bond strength,na measure of the force required toseparate surfaces which have been bonded together.3.2.2 magnet wire,na metal electrical conductor,coveredwith electrical insulation,for use in the assembly of electricalinductive apparatus such as coils for motors,transformers,generators,relays,magnets,etc.3.2.2.1 DiscussionThe electrical insulation is usuallycomposed of a film covering formed from a magnet wireenamel applied over a bare conductor.In some specificapplications,fibrous coverings,either taped or linear filamentserved,are also used as electrical insulation.3.2.3 varnish,electrical insulating,n a liquid resin systemthat is applied to and cured on electrical components providingelectrical,mechanical and environmental protection.3.2.3.1 DiscussionThere are two types of electrical insu-lating varnishessolvent-containing and solventless.Solvent-containing types are solutions,dispersions or emulsions of apolymer or a mixture of polymers in a volatile,nonreactableliquid.Solventless types are liquid resin systems free ofvolatile,nonreactable solvents.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Varnishes,Powders and Encapsulat-ing Compounds.Current edition approved Nov.1,2013.Published December 2013.Originallyapproved in 1973.Last previous edition approved in 2008 as D3145 08.DOI:10.1520/D3145-13.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*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 States1 4.Summary of Test Method4.1 Flexural strength of the helical coils is measured peri-odically after exposure to several exposure temperatures.Thetime to reach an arbitrarily selected value of bond strength ateach exposure temperature is determined.The logarithms ofthese times in hours are plotted as a function of the reciprocaltemperature(1/K)to give an Arrhenius plot.5.Significance and Use5.1 This test method is used to determine the effect ofexposure to elevated temperatures on the bond strength ofcombinations of magnet wire insulation