1、Designation:D 3277 95(Reapproved 2001)e1Standard Test Methods forMoisture Content of Oil-Impregnated Cellulosic Insulation1This standard is issued under the fixed designation D 3277;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、 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.e1NOTEEditorial changes were made in April 2001.1.Scope1.1 These test methods cover the determination of theweight percent o
3、f water in new or aged,oil-impregnatedelectrical insulation.These test methods depend on solventextraction of the water at room temperature.The range from0.1 to 7.0%water has been explored.1.2 There are four test methods,A,B,C,and D.Methods Aand B for thin paper and dense materials,respectively,arem
4、anual methods for solvent extraction of water from thespecimens.Titration is used to determine the amount of water.Method C uses automatic titration to determine the amount ofwater.Method D is a direct automated method for extractionand detection of the water.1.3 This standard does not purport to ad
5、dress 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.2.Referenced Documents2.1 ASTM Standards:D 1533 Test Metho
6、ds for Water in Insulating Liquids(KarlFischer Reaction Method)23.Summary of Test Methods3.1 These test methods depend on solvent extraction of themoisture at room temperature and Karl Fischer titration(seeTest Methods D 1533).For paper insulation 0.010 in.(0.25mm)thick and less,extraction is accomp
7、lished by stirring thesolvent with small pieces of insulation.In the special case ofdense,thick sections,such as pressboard,the extraction rate isincreased by delaminating thick sections and pulping thesample in a blender.4.Significance and Use4.1 Moisture has an adverse effect on the dielectric str
8、ength,dielectric loss,dc resistivity,and aging characteristics ofoil-impregnated cellulosic insulating materials.4.2 When cellulosic insulation such as paper and pressboardare impregnated with and immersed in oil,there is an inter-change of moisture between the cellulose and oil until theyattain equ
9、ilibrium with respect to their relative saturations withmoisture.4.3 Considerable care should be taken in using these testmethods to measure the water content of dry(0.5%)paperand board.Contamination of material by water from thesurroundings during sampling and handling may be both rapidand signific
10、ant in the case of dry test specimens.This is an evengreater concern with cellulose insulation prior to oil impreg-nation.5.Apparatus5.1 Karl Fischer Electrometric Titration Apparatus.5.2 Magnetic Stirrer and TFE-Fluorocarbon Coated Stir-ring Bars.5.3 Erlenmeyer Flasks,glass-stoppered,250-mL.5.4 Gra
11、duate,glass,100-mL.5.5 Bchner Funnel,small porcelain.5.6 Micro-Syringe,total capacity 0.2 mL,0.01-mL divi-sions.5.7 Blender,industrial type.5.8 Syringe,10 mL,ground glass.5.9 Drying Oven,1106 5C.5.10 Laboratory Desiccator.5.11 Analytical Balance.6.Reagents6.1 Karl Fischer ReagentCommercially availab
12、le stabi-lized solution,diluted from approximately 5 mg of water per 1mL to 2.5 to 3.0 mg of water per 1 mL by adding absoluteacetone-free methanol(Methods A and B).For Methods C andD,prepare commercially available solutions for use in auto-matic titrators in accordance with the manufacturers instru
13、c-tions.6.2 Titration SolventMix 2 volumes of acetone-freemethanol and 1 volume of dry chloroform.Keep the solutiontightly capped to prevent moisture absorption from the atmo-sphere.6.3 Purity of ReagentsUse reagent grade chemicals in alltests.Unless otherwise indicated,it is intended that all reage
14、ntsshall conform to the Committee on Analytical Reagents of theAmerican Chemical Society,where such specifications are1These test methods are under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gasesand are the direct responsibility of Subcom-mittee D27.06on Chemical Tes
15、t.Current edition approved June 15,1995.Published August 1995.Originallypublished as D 3277 73.Last previous edition D 3277 94.2Annual Book of ASTM Standards,Vol 10.03.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.available.Other grades may be used,provided that
16、 it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.6.4 Methanol,acetone-free with no more than 0.001%acetone.7.Sampling7.1 The sampling procedure is not defined since it would bedifferent for different apparatus,whether the samples were newor aged.Sample storage may also vary depending uponexpected water content and time between sampling and testing.The assumption is made that the sample is representative