1、Designation:D116911Standard Test Method forSpecific Resistance(Resistivity)of Electrical InsulatingLiquids1This standard is issued under the fixed designation D1169;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last rev
2、ision.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.Scope1.1 This test method covers the determination of s
3、pecificresistance(resistivity)applied to new electrical insulatingliquids,as well as to liquids in service,or subsequent toservice,in cables,transformers,circuit breakers,and otherelectrical apparatus.1.2 This test method covers a procedure for making refereetests with dc potential.1.3 When it is de
4、sired to make routine determinationsrequiring less accuracy,certain modifications to this testmethod are permitted as described in Sections 19 26.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purp
5、ort 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 17.6 for aspecific warning statement.2.Refere
6、nced Documents2.1 ASTM Standards:2D150 Test Methods for AC Loss Characteristics and Permit-tivity(Dielectric Constant)of Solid Electrical InsulationD257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD923 Practices for Sampling Electrical Insulating LiquidsD924 Test Method for D
7、issipation Factor(or Power Factor)and Relative Permittivity(Dielectric Constant)of Electri-cal Insulating Liquids3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 specific resistance(resistivity),nthe ratio of the dcpotential gradient in volts per centimetre paralleling the curre
8、ntflow within the specimen,to the current density in amperes persquare centimetre at a given instant of time and underprescribed conditions.This is numerically equal to the resis-tance between opposite faces of a centimetre cube of the liquid.The units are ohm-centimetres.4.Significance and Use4.1 T
9、he resistivity of a liquid is a measure of its electricalinsulating properties under conditions comparable to those ofthe test.High resistivity reflects low content of free ions andion-forming particles,and normally indicates a low concentra-tion of conductive contaminants.5.General Considerations5.
10、1 Theory and measuring equipment pertaining to thismethod shall be in accordance with Test Methods D257.5.2 Where both ac loss characteristic(dissipation factor orpower factor)and resistivity measurements are to be madeconsecutively on the same specimen,make the ac measurementbefore applying the dc
11、potential to the specimen,and shortcircuit the cell electrodes for 1 min immediately prior tomaking the resistivity measurements.5.3 Make referee tests for resistivity in an atmosphere ofless than 50%relative humidity.For repeatable results makethese tests under carefully controlled atmospheric cond
12、itions.5.4 Aside from the adverse influence of contamination onresults of the resistivity test,there are other factors that cancontribute to variations in the test results as follows:5.4.1 The use of an instrument not having an adequate rangefor accurately measuring the current flowing in the circui
13、t.(SeeSection 6 for two types of recommended instruments.)5.4.2 When the time of electrification is not exactly thesame for every test.Upon the application of voltage,thecurrent flow through the specimen decreases asymptotically1This test method is under the jurisdiction of ASTM Committee D27 onElec
14、trical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.05 on Electrical Test.Current edition approved May 1,2011.Published May 2011.Originallyapproved in 1951 as as D1169 51 T.Last previous edition approved in 2009 asD1169 09.DOI:10.1520/D1169-11.2For referenced AS
15、TM 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
16、19428-2959.United States1 toward a limiting value.Variation in the time of electrificationcan result in appreciable variation in the test results.5.4.3 Undue length of time required for the test specimen inthe cell to attain the desired test temperature.This is one of themain sources of erroneous results.For optimum results,attainthe test temperature within 20 min.5.4.4 Fluctuations in the test voltage(see 6.1.4).6.Instrumentation6.1 Instrumentation listed in Test Methods D257 is suitable,with t