ASTM_D_352_-_97_2016.pdf

Designation:D35297(Reapproved 2016)Standard Test Methods forPasted Mica Used in Electrical Insulation1This standard is issued under the fixed designation D352;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 These test methods cover the testing of bonded micasplittings and bonded mica paper to be used for commutatorinsulation,hot molding,heater plates,and other similar insu-lating purposes.1.2 These test methods appear in the following sections:TestSectionsCompressive Creep4 10Dielectric Strength38 41Mica or Binder Content19Molding Test31 36Organic Binder20 24Resistivity42 46Silicone Binder25 30Stability Under Heat and Pressure11 181.3 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.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.See 40.1 and 45.1for specific hazard statements.2.Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD1711 Terminology Relating to Electrical Insulation3.Terminology3.1 Definitions:3.1.1 For definitions of terms relating to electricalinsulation,refer to Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 binder content,n,(of pasted mica)the percent byweight of binder relative to the original weight of a specimenas determined by procedures specified herein.3.2.1.1 DiscussionBinder content includes any residualsolvent.Pasted mica materials not fully cured(such as moldingand flexible plates)may contain appreciable quantities ofsolvent in the binder.This solvent is usually later removedwhen the material is cured in the manufacture of electricalequipment.In such cases,the binder content after cure is less(by the amount of solvent removed)than would be determinedby this method.To determine the binder content after cure ofmaterials that are not fully cured,but subsequently will be,it isnecessary,before initially weighing the specimen,to heat thespecimen for a time and at a temperature that depends upon thematerial from which the specimen is prepared.3.2.2 compressive creep,nthe change in thickness of abonded micaceous material resulting from exposure to elevatedtemperature for a specified time while a specimen is under aspecified compressive load.3.2.3 mica content,n,(of pasted mica)the percent byweight of mica relative to the original weight equal to 100%minus the binder content as determined by procedures specifiedherein.COMPRESSIVE CREEP4.Significance and Use4.1 This test determines the compressive creep under labo-ratory conditions or under conditions that may be encounteredduring manufacture of electrical equipment.It has specialsignificance if the material to be tested is applied as commu-tator segment insulation.It serves as a measure under specifiedconditions of the ability of the material to resist deformationwhile under compressive load,during exposure to elevatedtemperature for a specified time.This test is suitable foracceptance tests and for manufacturing control.1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Products.Current edition approved May 15,2016.Published May 2016.Originallyapproved in 1932.Last previous edition approved in 2008 as D352 97(2008)1.DOI:10.1520/D0352-97R16.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Apparatus5.1 Hydraulic PressA hydraulic press having temperaturecontrolled,electrically heated platens,or a press with otherprovisions for heating the specimen and controlling the tem-perature.The platens shall be at least 4 by 4 in.(102 by 102mm)in size.The press shall be capable of exerting a force ofat least 4000 lb(18 kN).The apparatus shall be capable ofmaintaining a specimen temperature of at least 200 6 5C.Itis preferable that the apparatus have platens with water ducts orother provisions for cooling the specimen.(See Note 1 in 7.3.)5.2 Pressu