ASTM_D_2526_-_02.pdf

Designation:D 2526 02An American National StandardStandard Specification forOzone-Resisting Silicone Rubber Insulation for Wire andCable1This standard is issued under the fixed designation D 2526;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers an ozone-resisting crosslinkedsilicone rubber insulating compound for electrical wires andcables.1.2 This type of insulation is considered suitable for con-tinuous operation at conductor temperatures up through 125Cfor power cable applications.It is considered suitable forconductor sizes up to and including 1000 kcmil(507 mm2)ata maximum of 5000 V for both single-and-multiple-conductorcables.Minimum conductor sizes and insulation thicknessesare given in Table 1.1.3 Whenever two sets of values are presented,in differentunits,the values in the first set are the standard,while those inparentheses are for information only.1.4 In many instances the insulation material cannot betested unless it has been formed around a conductor or cable.Therefore,tests done on insulated wire or cable in thisdocument are solely to determine the relevant property of theinsulation material and not to test the insulated conductor orcompleted cable.2.Referenced Documents2.1 ASTM Standards:D 470 Test Methods for Crosslinked Insulations and Jacketsfor Wire and Cable2D 1711 Terminology Relating to Electrical Insulation22.2ICEA Standard:T-24-380 Guide for Partial-Discharge Procedure33.Terminology3.1 Definitions:For definitions of terms used in this speci-fication,refer to Terminology D 1711.3.2 Definition of Term Specific to This Standard:3.2.1 aging(act of),nexposure of material to air at 200 62C for 168 h.4.Physical Properties Requirements4.1 The crosslinked insulation shall conform to the require-ments for physical properties listed in Table 2.5.Electrical Requirements5.1 Order of TestingPerform the partial discharge,acvoltage,insulation resistance,and dc voltage tests in that orderwhen any of these tests are specified.The sequence of othertesting is not specified.5.2 Partial-Discharge(Corona)Extinction LevelWhentested in accordance with ICEA T-24-380 as modified in TestMethods D 470,each length of completed power cable ratedfor service at 2001 to 5000 V with insulation shielding on theindividual conductors shall have a partial discharge(corona)extinction level of 4.0 kV for an insulation level of 100%(grounded neutral)and 5.0 kV for an insulation level of 133%(ungrounded neutral).5.3 AC Voltage TestEach insulated conductor in the com-pleted cable shall withstand for 5 min the ac test voltagespecified in Table 1.Unless otherwise specified,omit this testif the dc voltage test described in 5.5 is to be performed.5.4 Insulation ResistanceThe insulated conductor shallhave an insulation-resistance value equal to or greater than thatcorresponding to a constant of 4000 M V-1000 ft(305 m)at60F(15.6C).When the temperature of the water in which theinsulation is tested differs from 60F,apply a correction factor.Table 2,titled“Temperature Correction Factors for InsulationResistance at 60F,”of Test Methods D 470 contains thecorrection factors.Each insulation manufacturer can furnishthe 1F coefficient for the insulation material by using theprocedure given in Test Methods D 470.Multiply the measuredvalue by the correction factor to obtain the insulation resistancevalue corrected to 60F.5.4.1 Where a nonconducting separator is applied betweenthe conductor and insulation,or where an insulated conductoris covered with a nonmetallic sheath so that the insulationresistance can be measured only on the completed assembly,1This specification is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.18 on Solid Insulations,Non-metallic Shieldings,and Coveringsfor Electrical and Telecommunication Wires and Cables.Current edition approved March 10,2002.Published June 2002.Originallypublished as D 2526 66 T.Last previous edition D 2526 97.2Annual Book of ASTM Standards,Vol 10.01.3Available from Insulated Cable Engineers Association,PO Box 440,SouthYarmouth,MA 02664.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.the required insulation resistance shall be at least 60%of thatrequired for the primary insulation based on the thickness ofthat insulation.5.5 DC Voltage TestUpon completion of the insulationresistance test,each insulated conductor in the completed cableshall withstand for 5 min the dc test voltage specified in Table1.Unless otherwise specified,omit this test if the ac voltagetest described in 5.3 has been performed.5.6 Capacitance and Dissipation FactorTest a specimenof insulated con