1、Designation: D1458 13Standard Test Methods forFully Cured Silicone Rubber-Coated Glass Fabric and Tapesfor Electrical Insulation1This standard is issued under the fixed designation D1458; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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 These test met
3、hods cover procedures for testing fullycured silicone rubber-coated glass fabric and tapes to be usedfor electrical insulation.1.2 The procedures appear in the following order:Procedure SectionsASTMReferencesBreaking Strength 7 D828Breaking Strength After Creasing 8 .Conditioning 5 .Dielectric Break
4、down Voltage 9 D149, D295,D6054Dielectric Proof-Voltage 10 D1389Dissipation Factor and Relative Permittivity 11 D150Sampling 4 .Thermal Endurance 15 D1830Thickness 6 D374Thread Count 14 .Volume Resistivity 12 D257Weight 13 .1.3 The values stated in inch-pound units are to be regardedas the standard.
5、 The values given in parentheses are forinformation only.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-bili
6、ty of regulatory limitations prior to use. See 9.5.1 for aspecific warning statement.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD150 Test Methods for AC Los
7、s Characteristics and Permit-tivity (Dielectric Constant) of Solid Electrical InsulationD202 Test Methods for Sampling and Testing UntreatedPaper Used for Electrical InsulationD257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD295 Test Methods for Varnished Cotton Fabrics Used
8、 forElectrical InsulationD374 Test Methods for Thickness of Solid Electrical Insu-lation (Withdrawn 2013)3D828 Test Method for Tensile Properties of Paper andPaperboard Using Constant-Rate-of-ElongationApparatus(Withdrawn 2009)3D1389 Test Method for Proof-Voltage Testing of Thin SolidElectrical Insu
9、lating Materials (Withdrawn 2013)3D1711 Terminology Relating to Electrical InsulationD1830 Test Method for Thermal Endurance of FlexibleSheet Materials Used for Electrical Insulation by theCurved Electrode MethodD5032 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Glycerin So
10、lutionsD6054 Practice for Conditioning Electrical Insulating Mate-rials for Testing (Withdrawn 2012)3E104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, see Terminology D1711.4. Sampling
11、4.1 Sample shipments of material as specified below, andwhere possible take only one sample from any package.4.1.1 FabricOver 3 in. (75 mm) in width.4.1.1.1 RollsSelect one roll from each ten rolls or fractionthereof in a shipment of full-width fabric. Cut off not less than1These test methods are un
12、der the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.07 on Flexible and Rigid Insulating Materials.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1957. Last previous edi
13、tion approved in 2007 as D1458 01 (2007).DOI: 10.1520/D1458-13.2For 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 websit
14、e.3The last approved version of this historical standard is referenced onwww.astm.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 States1two turns of fabric from each roll
15、selected from sampling, andselect sample material for the preparation of test specimensfrom the remaining layers of the roll.4.1.1.2 SheetsSelect one sheet from each 50 sheets orfraction thereof in a shipment of sheeted fabric. Remove notless than six sheets from the outer layers of each package ofs
16、heets selected from sampling, and then select sample materialfor the preparation of test specimens from the remainingsheets.4.1.2 Tapes and Strips3 in. (75 mm) and less in width.4.1.2.1 TapesCut off not less than six turns of tape fromeach roll selected for sampling, and then select sample materialf
17、or the preparation of test specimens from the remaining layersof the roll. Select rolls of tape in accordance with the followingschedule:Number of Rolls in ShipmentMinimum Number of SampleRollsOver 10 000 1 per 10005001 to 10 000 102001 to 5000 5Less than 2000 24.1.2.2 StripsSelect three strips from
18、 each 100 strips orfraction thereof in a shipment of strips. Remove not less thansix strips from the outer layers of each package of stripsselected for sampling, and then select sample material for thepreparation of test specimens from the remaining strips.4.2 Prepare the test specimens from samples
19、 selected asspecified in 4.1, and as provided for in the individual testmethods.5. Conditioning5.1 Significance and UseThe properties of the materialdescribed in these test methods are affected by the temperatureand moisture content of the material to a greater or lesserextent, depending on the spec
20、ific property.5.2 ConditioningUnless otherwise specified in the indi-vidual test method, condition test specimens as described in5.2.1 or 5.2.2, and in matters of dispute, consider 5.2.1 as thereferee method.5.2.1 Condition the test specimens for 48 h in the StandardLaboratory Atmosphere of 50 6 2 %
21、 relative humidity at atemperature of 23 6 1 C (73.4 6 1.8 F), and conduct the testsunder these conditions.5.2.2 Condition the test specimens for 48 h in the StandardLaboratory Atmosphere of 50 6 2 % relative humidity at atemperature of 23 6 1 C (73.4 6 1.8 F), and conduct the testsimmediately upon
22、removal of the specimens from the condi-tioning room or chamber.6. Thickness6.1 Significance and Use:6.1.1 The importance of space factor in the design ofelectrical equipment makes proper determination of thicknessessential.6.1.2 Some properties, such as dielectric strength and di-electric breakdown
23、, vary with the thickness of the material, andcertain properties, such as thermal conductivity and dielectricconstant, cannot be determined without a knowledge of thick-ness.6.2 Test SpecimensCut specimens prepared from fabricsamples 1 in. (25 mm) wide across the entire width of thefabric, while spe
24、cimens prepared from tape and strip samplesshall be the width of the sample and 36 in. (910 mm) long.Where the specimen is 36 in. or longer (full-width fabric 36 in.or more in width, or where the length of a strip is 36 in. orlonger), only one specimen will be required unless otherwisespecified. Whe
25、re the specimen is less than 36 in. (full-widthfabric less than 36 in. wide, or strips less than 36 in. long), asmany specimens as are needed to obtain the equivalent 36 in.linear measure will be required.6.3 ConditioningIt is not necessary to condition the speci-mens for this test. Conduct tests at
26、 the Standard LaboratoryTemperature of 23 6 1 C (73.4 6 1.8 F).6.4 ProcedureMake ten measurements, equally spacedalong 36 in. (910 mm) of the specimen or specimens inaccordance with Method C of Test Methods D374 modified asfollows:6.4.1 Allow the presser foot to remain on the test specimenfor 2 s, a
27、t the end of which read the dial gage.6.4.2 Use a presser foot 0.250 in. (6.35 mm) in diameter,and an anvil surface upon which the specimen rests at least 2in. (51 mm) in diameter. The force exerted on the specimenshall be 3 ozf (85 g).6.4.3 Method C is not considered interchangeable withMethod A.6.
28、5 ReportReport the average, maximum, and minimumthickness to the nearest 0.0001 in. (0.003 mm).7. Breaking Strength7.1 Significance and UseThe breaking strength of finishedfabric or tape is of importance as a measure of the tension itwill withstand without failure while being applied in service.7.2
29、ApparatusUse a power-driven tensile testing machinemeeting the requirements specified for Tensile Properties inTest Methods D202, except that the means for determiningelongation and for recording applied load and elongation arenot required. The machine shall be equipped with specimen-gripping device
30、s as described in 7.2.1 or 7.2.2.7.2.1 Provide two flat-jawed clamps, in which case crocuscloth will be required for holding specimens between the jaws,or7.2.2 Provide two gripping devices of the drum type asdescribed in Fig. 1, in which case pins as indicated will berequired for securing specimens
31、on the cylinders.7.3 Test SpecimensThe test specimen shall be of sufficientlength to provide positive gripping in the jaws with a separa-tion of approximately 6 in. (150 mm). In the case of theflat-jawed clamps, this will require a minimum specimenlength of 8 in. (200 mm) and a desirable length of 1
32、0 in. (250mm). Where drum-type gripping devices are used, a specimenno less than 20 in. (500 mm) long will be required. Prepare thespecimens from each sample as follows:D1458 1327.3.1 FabricsCut five specimens, 1 in. (25.4 mm) wide(Note 1), with sides parallel to the warp threads, and cut fivespecim
33、ens of similar width with sides perpendicular to thewarp threads (Note 2).NOTE 1Where specimens 1 in. (25.4 mm) in width have ultimatebreaking loads exceeding the capacity of the machine, it is permissible toreduce the width of the specimen to not less than 0.5 in. (13 mm).NOTE 2Frequently the fill
34、threads of glass fabrics used to manufacturesilicone rubber-coated glass fabrics do not run in a straight line and are notperpendicular to the warp threads. Breaking strength from specimens cutperpendicular to the warp threads has the potential, therefore, to be highlyvariable.7.3.2 Tapes and Strips
35、Cut five specimens, 1 in. (25.4 mm)wide (see Note 2), from each sample. Where tapes or strips aremanufactured in widths less than 1 in. (25.4 mm), use thespecimen width as manufactured.7.4 ConditioningIt is not necessary to condition speci-mens for this test. Conduct tests at the Standard Laboratory
36、Temperature of 23 6 1 C (73.4 6 1.8 F).7.5 Procedure:7.5.1 Clamp the ends of the specimen in the jaws betweentwo pieces of crocus cloth, the abrasive side of the cloth facingthe metal jaws. Carefully align the specimen so that thebreaking force is parallel to the length of the specimen betweenthe ja
37、ws. Adjust the clearance between jaws to 6 in. (150 mm).7.5.2 Alternatively, loop the specimen around a binding pinof suitable diameter so that the specimen fits neither too tightlynor too loosely in the hole provided. Insert the loopedspecimen and pin in the hole provided in the drum-typegripping d
38、evice. Carefully align the specimen so that thebreaking force will be parallel to the length of the specimen.Adjust the clearance between jaws to 6 in. (150 mm).7.5.3 Adjust the speed of the machine in accordance withthe requirements for Tensile Properties in Test Methods D202.7.5.4 Disregard values
39、 for breaks in or at the jaws. In thesecases, continue tests so that there are five reportable breakingstrength values per sample.7.6 Report:7.6.1 Report the average, maximum, and minimum break-ing strength in pounds per inch of width (or kilograms permillimetre of width), together with the width an
40、d nominalthickness.7.6.2 In the case of fabrics, report the breaking strength inthe warp and fill directions separately.7.7 Precision and Bias:7.7.1 The precision (repeatability within a single laboratory)of this test method has been demonstrated to be approximately17 %, expressed as a coefficient o
41、f variation of a series ofreplicate measurements on different specimens of the samesample.7.7.2 This test method has no bias because the value forbreaking strength is determined solely in terms of this testmethod itself.8. Breaking Strength After Creasing8.1 Significance and UseCreasing of silicone
42、rubber-coated glass fabric is accompanied by breaking of some of theglass fibers at the crease and a consequent reduction inbreaking strength. The extent of this damage is related to thethickness and weave of the glass fabric and the nature andthickness of the silicone rubber coating. The creasing s
43、imulatesto a degree the pinching action resulting from several succes-sive layers of tape moving relative to one another while inconfined position, such as in cables.8.2 Apparatus:8.2.1 Use a metal weight adjustable between 2.25 and 4.50lbf (10 and 20 N). Mount it suitably through guides over ametal
44、 horizontal plane to enable the weight to be lowered at auniform speed perpendicular to the horizontal plane. Thebottom of the weight shall be parallel to the top surface of thehorizontal plane at all times. The creasing surface of the weightis a rectangle of such dimensions that the side which ispe
45、rpendicular to the crease made on the specimen is 1.5 in. (40mm). Suitable apparatus is shown in Fig. 2.8.2.2 Provide suitable means for lowering the weight at auniform rate of 12 in. (300 mm)/min and of raising the weightat the end of a 2-s dwell. Accomplish this by one of thefollowing: (a) utilizi
46、ng the breaking strength machine, de-scribed in 7.2, in combination with a system of pulleys; (b)byusing a motor fitted with reducing gears and a cam, or (c)byother devices that accomplish the purpose.8.3 Test SpecimensPrepare ten specimens as described in7.3 except that specimens shall be taken fro
47、m samples of tapeor rolls of fabric only. In the case of fabric, cut the specimensin the warp direction only.8.4 Conditioning:FIG. 1 Drum-Type Gripping DevicesD1458 1338.4.1 It is usually not necessary to condition specimens forthis test. When specimens are not especially conditioned, testthem at th
48、e Standard Laboratory Temperature of 23 6 1C(73.4 6 1.8 F).8.4.2 Where it is desired to obtain the greatest degree ofreproducibility, condition specimens in accordance with 5.2.8.5 Procedure:8.5.1 Adjust the weight so that the specimens are creased bya load of 4.5 lbf (20 N)/in. of width.8.5.2 Fold
49、the specimen without creasing, and insert thelooped end under the weight so that the crease will be formedunder the center of the weight. Lower the weight at a uniformrate of 12 in. (300 mm)/min to crease the specimen.8.5.3 Allow the creased specimen to support the weight fora period of 2 s, at the end of which period lift the weight fromthe specimen.8.5.4 Determine the breaking strength of the creased speci-men in accordance with 7.5.8.6 ReportReport the following information:8.6.1 Average, maximum, and minimum breaking strengthsafter creasing, i
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