1、Designation: D5288 10D5288 14Standard Test Method forDetermining the Tracking Index of Electrical InsulatingMaterials Using Various Electrode Materials (ExcludingPlatinum)1This standard is issued under the fixed designation D5288; the number immediately following the designation indicates the year o
2、foriginal 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. Scope*1.1 This test method was developed using copper electrodes to
3、 evaluate the low-voltage (up to 600 V) tracking resistance ofmaterials in the presence of aqueous contaminants.2NOTE 1At this time, only industrial laminates have been examined using this method, which was developed at the National Manufacturers ElectricalAssociation (NEMA) laboratory located at th
4、e University of Cincinnati. It was found that a closer end point (less scatter) was obtained than with platinumelectrodes, and materials tested tended to be ranked by resin system.1.1.1 It is acceptable to consider other electrode materials for use with this test method depending upon the applicatio
5、n of theinsulating material.1.2 This test method is similar to Test Method D3638, which determines the comparative tracking index of materials usingplatinum electrodes to produce the tracking on the specimen surface.1.3 The values stated in metric (SI) units are the standard. The inch-pound equivale
6、nts of the metric units are approximate.1.4 This standard is used to measure and describe the response of materials, products, or assemblies to heat and flame undercontrolled conditions, but does not by itself incorporate all factors required for fire hazard or fire risk assessment of the materials,
7、products, or assemblies under actual fire conditions.1.5 Fire testing is inherently hazardous. Adequate safeguards for personnel and property shall be employed in conducting thesetests.2. Referenced Documents2.1 ASTM Standards:3D618 Practice for Conditioning Plastics for TestingD1711 Terminology Rel
8、ating to Electrical InsulationD3636 Practice for Sampling and Judging Quality of Solid Electrical Insulating MaterialsD3638 Test Method for Comparative Tracking Index of Electrical Insulating Materials2.2 IEC Publication:4IEC 11260112 RecommendedStandard Method for Determining the ComparativeTrack I
9、ndexthe Determination of the Proof andthe Comparative Tracking Indices of Solid Insulating Materials Under Moist Conditions, 1971 Second EditionMaterials, 20033. Terminology3.1 DefinitionsIn addition to the definitions listed below, terminology as defined in For definitions of terms used in this tes
10、tmethod and associated with electrical and electronic insulating materials, use Terminology D1711 is assumed. .3.2 Definitions:Definitions of Terms Specific to This Standard:1 This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is th
11、e direct responsibility of SubcommitteeD09.12 on Electrical Tests.Current edition approved Jan. 15, 2010Nov. 1, 2014. Published February 2010December 2014. Originally approved in 1992. Last previous edition approved in 20042010as D5288 97D5288 10.(2004). DOI: 10.1520/D5288-10.10.1520/D5288-14.2 Math
12、es, K. N., Chapter 4, “Surface Failure Measurements,” Engineering Dielectrics, Vol IIB, Electrical Properties of Solid Insulating Materials, MeasurementTechniques, R. Bartnikas, Editor, ASTM STP 926, ASTM, Philadelphia, 1987.3 For referencedASTM standards, visit theASTM website, www.astm.org, or con
13、tactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from International Electrotechnical Commission (IEC), 3 rueRue de Varemb, Case postale 131, CH-1211, Geneva 20, Switzerland,
14、 http:/www.iec.ch.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users
15、 consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho
16、cken, PA 19428-2959. United States13.2.1 track, na partially conducting path of localized deterioration on the surface of an insulating material.3.2.2 tracking, nthe process that produces tracks as a result of the action of electric discharges on or close to an insulationsurface.3.2.3 tracking, cont
17、amination, ntracking caused by scintillations that result from the increased surface conduction due tocontamination.3.2.4 tracking index, TI, nan index for electrical insulating materials which is arbitrarily defined as the numerical value of thatvoltage which will cause failure by tracking when the
18、 number of drops of contaminant required to cause failure is equal to 50.3.2.4.1 DiscussionThis value is obtained from a plot of the number of drops required to cause failure by tracking versus the applied voltage.3.2.5 tracking indexcopper electrodes, TI-Cu, na tracking index test using copper elec
19、trodes.3.2.5.1 DiscussionThis test is comparable to comparative tracking index, Test Method D3638, with the following exceptions: (1) copper electrodesare used instead of platinum, and (2) the electrodes may have to be re-ground after every test because of the softness of copper.3.2.6 tracking resis
20、tance, nthe quantitative expression of the voltage and the time required to develop a track under specifiedconditions.4. Summary of Test Method4.1 The surface of a specimen of electrical insulating material is subjected to a low-voltage alternating stress combined witha low current which results fro
21、m an aqueous contaminant (electrolyte) which is dropped between two opposing copper electrodesevery 30 s. The voltage applied across these electrodes is maintained until the current flow between them exceeds a predeterminedvalue which constitutes failure. Additional specimens are tested at other vol
22、tages so that a relationship between applied voltageand number of drops to failure can be established through graphical means.The numerical value of the voltage which causes failurewith the application of 50 drops of the electrolyte is arbitrarily called the tracking index. This value provides an in
23、dication of therelative track resistance of the material.5. Significance and Use5.1 Electrical equipment has the potential to fail as a result of electrical tracking of insulating material that is exposed to variouscontaminating environments and surface conditions. A number of ASTM and other tests h
24、ave been designed to quantify behaviorof materials, especially at relatively high voltages.This method is an accelerated test which, at relatively low test voltages, providesa comparison of the performance of insulating materials under wet and contaminated conditions. The Tracking IndexCopperElectro
25、des test is not related directly to the suitable operating voltage in service.5.2 When organic electrical insulating materials are subjected to conduction currents between electrodes on their surfaces, manyminute tree-like carbonaceous paths or tracks are developed near the electrodes. These tracks
26、are oriented randomly, but generallypropagate between the electrodes under the influence of the applied potential difference. Eventually a series of tracks spans theelectrode gap, and failure occurs by shorting of the electrodes.5.3 As in other tracking test methods, for example, IEC 112 and Test Me
27、thod D3638, this test method specifies test proceduresthat are intended to promote the formation of surface discharges which will produce carbon tracks in a reproducible manner. Sincethese conditions rarely reproduce the actual conditions encountered in service, the results of tracking tests cannot
28、be used to infereither direct or relative service behavior of a material in a specific design application. Tracking tests can be used for screeningpurposes only. Suitability is verified through testing of the material in actual end use or under conditions that closely simulateactual end use.5.4 The
29、use of copper electrodes in this type of test was developed at the University of Cincinnati, NEMA laboratory. It is feltby the members of the Industrial Laminates Section of NEMA that using copper electrodes gives a more realistic value for atracking index, related to the resin system used to reinfo
30、rce the substrate of a laminate. In general, tracking tests made with copperelectrodes tend to give lower values than platinum electrodes in the same type of test. It is a fact that copper is more widely usedthan platinum for electrical conductors.55 Middendorf, W. H. and Vemuri, R., “Report on Copp
31、er vs. Platinum Electrodes,” 1990, Availableavailable from National Electrical Manufacturers Association, 2101L St. N.W., Suite 300, Washington, D.C. 20037-8400.D5288 1426. Apparatus6.1 The simplified electrical circuitry used in this test is illustrated in Fig. 1. For necessary information on the c
32、leanliness ofapparatus, see Annex A1. The essential components are:6.1.1 Variable Power Source, consisting of a transformer type transformer-type supply, such as the combination T1 and T2 inFig. 1, with a variable output of 0 to 1000 V, 60 Hz capable of maintaining a current of 1 A (1 kVA).6.1.2 Vol
33、tmeter (V1), capable of measuring the varying ac output of the power source. A0 A 0- to 600-V voltmeter with anaccuracy of at least 60.5 % of full scale.6.1.3 Ammeter (A1), with a range of 0 to 1 A ac and an accuracy of at least 610 % of full scale.6.1.4 Current Limiting Resistor (R1), continuously
34、variable, wire wound, rated at greater than 1 A.6.1.5 Shorting Switch (S1), single-pole single-throw rated at 1000 V and greater than 1 A.NOTE 2The need for a shorting switch is optional. It is possible to couple the variable resistor with the autotransformer which gives an automaticsetting of the c
35、urrent throughout the range of the instrument. Then whenever it is necessary to check the calibration of the instrument, the shorting actioncan be accomplished by a jumper wire placed across the electrodes. This coupling of the autotransformer with the variable resistor is another option.6.1.6 Over-
36、CurrentOver-current Relay (R0), shall not trip at currents up to 0.1 A 0.1 A, and the tripping time on short circuitshall be a minimum of 0.5 s (the current shall be limited on short circuit to 1 A 1 A, with a tolerance of 610 % at a power factorof 0.9 to 1.0).NOTE 3Some instruments have used a Hein
37、emann breaker, which is probably the closest standard commercial breaker to that described in the IECMethod.6 Also the tripping action can be accomplished with electronic circuitry.6.1.7 Testing Fixture (J1)adjustable platform which supports the specimen and electrode setup.6.1.8 Copper Electrodes,
38、of electrolytic copper having a rectangular cross section measuring 5 by 2 mm (0.2 by 0.08 in.),extending 20 mm (0.8 in.) minimum from suitable mounting shanks (Fig. 2). The end of each electrode is machined to form a 30chisel-point edge, having a radius from 0.05 to 0.10 mm, extending along the 5-m
39、m (0.2-in.) side of the electrode.This is the radiusthat generally results from polishing a “0 mm” radius electrode. Since the direction of polish has the potential to influence theresults, polish all electrodes in a direction perpendicular to the long dimension of the electrode face.6.1.9 Dropping
40、Apparatus, which shall drop the electrolyte precisely as specified. It is important to also include a means ofelectrically starting and stopping the dropping of the electrolyte as well as a counting device for monitoring the numberof drops.The orifice diameter of the drop mechanism is approximately
41、1.5 mm. However, if necessary, adjust this diameter somewhat soas to obtain the proper drop size in accordance with 9.2.7. Reagents7.1 Electrolyte Solution of Ammonium Chloride in Water:7.1.1 Prepare a solution of ammonium chloride at an approximate concentration of 0.1 % by dissolving 1 g of reagen
42、t gradeammonium chloride in 1 L of water. The water used shall have a volume resistivity of no less than 0.5 M-cm at 23C. Allowthe solution to stand overnight in a covered, but not sealed, container.7.1.2 Measure the resistivity of the solution using a conductivity cell and an ac bridge, or meter, f
43、ollowing the manufacturersinstructions. If the resistivity is 385 6 5 -cm at 23 6 5-cm at 23 6 12 C, the solution is suitable for use in the test. If theresistivity is outside the above limits, adjust the concentration until these limits are observed. Adjustment is accomplished byadding water or NH4
44、Cl.6 The sole source of supply of the apparatus known to the committee at this time is the Heinemann Model Series JA, Curve 2. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting o
45、f the responsible technical committee,1which you may attend.FIG. 1 Electrical Circuit ComponentsD5288 1437.1.3 Calibrate the conductivity cell with 0.01 N potassium chloride calibrating solution which is available from the cellmanufacturer.8. Test Specimens8.1 Select samples in accordance with Pract
46、ice D3636.8.2 Typical test specimens are 50 mm (2 in.) or 100 mm (4 in.) (4 in.) diameter disks or any other similar shape. The minimumthickness is 2.5 mm (0.100 in.). Test five specimens of each sample.8.3 Variations in values can result from a lack of uniformity of dispersion of the material throu
47、ghout the molded specimen orfrom surface imperfections. Take care to prepare specimens that are as uniform as possible, both within the particular specimenand from one specimen to another.8.4 Condition samples in accordance with Procedure A of Practice D618.8.5 Specimens must be clean of dust, dirt,
48、 oil, or other contaminants. The molded surface must be smooth and scratch-free.9. Calibration and Standardization9.1 Partially support the electrodes by adjustable pivot arms and rest on the test specimen as shown in Fig. 2, exerting a forceof 100 g (3.5 oz).9.2 The drop height for the electrolyte
49、is a maximum of 40 mm (1.6 in.) 40 mm (1.6 in.) above the electrode gap. The holdingdevice is designed to store an aqueous solution and deliver periodically a measured drop to the specimen. The drop size is20 + 5 0 mm20 + 5 0 mm3 (0.0015 in. (0.0015 in.3) and the drop rate is 1 drop/30 6 5 s. (The drop size can be measured byusing a small calibrated graduate to accumulate a number of drops to obtain an accurate reading.)9.3 Allow approximately 15 drops of electrolyte to drop from the apparatus into a beaker or other container so as to removeany so
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