ASTM_D_3251_-_04_2013.pdf

Designation:D325104(Reapproved 2013)Standard Test Method forThermal Endurance Characteristics of Electrical InsulatingVarnishes Applied Over Film-Insulated Magnet Wire1This standard is issued under the fixed designation D3251;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 the thermalendurance characteristics of electrical insulating varnishes andfilm-insulated magnet wire in combination.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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.NOTE1This test method is equivalent to IEC 60172.2.Referenced Documents2.1 ASTM Standards:2D115 Test Methods for Testing Solvent Containing Var-nishes Used for Electrical InsulationD1711 Terminology Relating to Electrical InsulationD2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet Wire2.2 IEC Standard:IEC 60172 Test Procedure for the determination of thetemperature index of enameled winding wires33.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method referto Terminology D1711.4.Summary of Test Method4.1 A varnish is applied to twisted pairs of film-insulatedmagnet wire and exposed to elevated temperatures.Life testresults are compared to those of unvarnished twisted pairs.5.Significance and Use5.1 Different combinations of varnishes and film-insulatedmagnet wire behave differently when exposed to elevatedtemperatures.This includes different varnishes tested with thesame film-insulated magnet wire and a single varnish testedwith different film-insulated magnet wire.5.2 This test method is used to determine the effect on theelectrical properties of a varnish applied to film-insulatedmagnet wire when the combination is exposed to prescribedelevated temperatures.6.Hazards6.1 It is unsafe to use varnish at temperatures above theflash point without adequate ventilation,especially if thepossibility exists that flames or sparks are present.Storevarnish in sealed containers.This also applies to specifiedreagents and solvents.(WarningLethal voltages are a po-tential hazard during the performance of this test.It is essentialthat the test apparatus,and all associated equipment electricallyconnected to it,be properly designed and installed for safeoperation.Solidly ground all electrically conductive partswhich it is possible for a person to contact during the test.Provide means for use at the completion of any test to groundany parts which were at high voltage during the test or have thepotential for acquiring an induced charge during the test orretaining a charge even after disconnection of the voltagesource.Thoroughly instruct all operators as to the correctprocedures for performing tests safety.When making highvoltage tests,particularly in compressed gas or in oil,it ispossible for the energy released at breakdown to be sufficient toresult in fire,explosion,or rupture of the test chamber.Designtest equipment,test chambers,and test specimens so as tominimize the possibility of such occurrences and to eliminatethe possibility of personal injury.If the potential for fire exists,have fire suppression equipment available.)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 April 1,2013.Published April 2013.Originallyapproved in 1973.Last previous edition approved in 2009 as D3251 04(2009).DOI:10.1520/D3251-04R13.2For 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 Association,25 W.43rd St.,4thFloor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Sampling7.1 Sample the varnish in accordance with Test MethodsD115.8.Test Specimen8.1 Twist two pieces of film-insulated magnet wire inaccordance with Table 1 on Tension and Number of Twists forTwisted Pair Construction in Test Method D2307.8.2 Use the specimen holder described in Test MethodD2307.8.3 Use one set,consisting of a minimum of ten varnishedand ten unvarnished test specimens,for each test temperature(Note 2).Eleven specimens are re