ASTM_D_3377_-_04_2013.pdf

Designation:D337704(Reapproved 2013)Standard Test Method forWeight Loss of Solventless Varnishes1This standard is issued under the fixed designation D3377;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 percentweight loss of cured solventless electrical varnishes whenexposed to elevated temperatures for prescribed periods oftime.1.2 Results of this test method are based on 6-mm(14-in.)thick specimens and will not be applicable to specimensappreciably thinner or thicker than 6 mm.1.3 The values stated in SI units are to be regarded as thestandard.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 and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1This standard resembles IEC 602162“Guide for the deter-mination of thermal endurance properties of electrical insulating materi-als.Part 2:Choice of test criteria”in a number of ways,but is notconsistently similar throughout.The data obtained using either standardwill possibly be technically equivalent.2.Referenced Documents2.1 ASTM Standards:2D1711 Terminology Relating to Electrical InsulationD5423 Specification for Forced-Convection Laboratory Ov-ens for Evaluation of Electrical Insulation2.2 IEC Standard:IEC 602162 Guide for the determination of thermal endur-ance properties of electrical insulating materials.Part 2:Choice of test criteria33.Terminology3.1 Definitions:3.1.1 varnish,nelectrical insulating,a liquid resin systemthat is applied to and cured on electrical components providingelectrical,mechanical,and environmental protection.3.1.1.1 DiscussionThere are two types of electrical insu-lating varnish:solvent-containing and solventless.The solvent-containing varnish is a solution,dispersion,or emulsion of apolymer or mixture of polymers in a volatile,nonreactableliquid.The solventless type is a liquid resin system free ofvolatile,nonreactable solvents.3.1.2 For definitions of other terms relating to electricalinsulation,see Terminology D1711.4.Significance and Use4.1 The amount and composition of by-products producedby exposure of insulating varnishes to elevated temperaturescan possibly:4.1.1 Deteriorate other insulations in the system,4.1.2 Cause cracking of insulation due to pressure,buildupin thick cross sections,or4.1.3 Corrode other parts in the assembly.4.2 Amount and rate of weight loss will possibly affect thethermal rating of a varnish.5.Apparatus5.1 Metal Mold,consisting of two flat sheets 300 by 300 by6 mm(12 by 12 by14in.)separated by 6.4 6 0.5-mm(1460.02-in.)thick spacers along three sides.The spacers also sealthe edges of the mold and the assembly is held together with“C”clamps or bolts.Aluminum or polished steel plates arepermissible.5.2 Laboratory Balance,with accuracy of 6 1 mg.5.3 Forced-Convection Laboratory Oven,meeting require-ments of Specification D5423,Type II for each test tempera-ture.5.4 Screening Platform,6-mm(14-in.)mesh,with 50-mm(2-in.)legs.5.5 Mold Release.NOTE2Fluorocarbon-type release agents are satisfactory.5.6 Desiccator.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materialsand is direct responsibility of Subcom-mittee D09.01 on Electrical Insulating Varnishes,Powders and EncapsulatingCompounds.Current edition approved April 1,2013.Published April 2013.Originallyapproved in 1975.Last previous edition approved in 2009 as D3377 04(2009).DOI:10.1520/D3377-04R13.2For 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 Institute,11 W.42nd St.,13thFloor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Procedure6.1 Apply a thin,uniform coating of release agent to thecontact surfaces of the mold.6.2 Assemble the mold,taking precautionary measures toavoid leaks.6.3 Pour the sample into the open edge of the mold,usingcare to avoid bubbles.NOTE3In some cases,it will be necessary to prevacuum the samplebefore pouring.6.4 Cure the sample using the recommended cure cycle.6.5 After curing,remove the mold and contents from theoven and allow to cool to room temperature.6.6 Carefully disassemble the mold and remove the castsheet.6.7 From the cast sheet,cut at least three specimensapproximately 50 by 50 mm(2 by 2 in.)for each testtemperature.6.8 Dry the specimens for 1 h 6 5 min at 110 6 2 C toremove sur