1、Designation: D3145 13Standard Test Method forThermal Endurance of Electrical Insulating Varnishes by theHelical Coil Method1This standard is issued under the fixed designation D3145; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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 This test method co
3、vers the determination of the thermalendurance of electrical insulating varnishes alone or in com-binations with magnet wire insulation. Changes in the helicalcoil bond strength are used as the test criteria. The coils aremade from bare aluminum or copper wire, or from film- orfiber-insulated magnet
4、 wire.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.NOTE 1There is no similar or equivalent IEC standard.1.3 This standard does not
5、 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-bility of regulatory limitations prior to use. For a specificprecautionary statement, s
6、ee Section 7.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD1711 Terminology Relating to Electrical InsulationD1932 Test Method for Thermal Endurance of FlexibleElectrical Insulating VarnishesD2307 Test Method for Thermal Endurance of Film-Insulated Ro
7、und Magnet WireD2519 Test Method for Bond Strength of Electrical Insulat-ing Varnishes by the Helical Coil TestD3251 Test Method for Thermal Endurance Characteristicsof Electrical Insulating Varnishes Applied Over Film-Insulated Magnet WireD5423 Specification for Forced-Convection Laboratory Ov-ens
8、for Evaluation of Electrical Insulation2.2 International Electrotechnical Commission Publica-tions:3IEC 60216-1 Guide for the Determination of Thermal En-durance Properties of Electrical Insulation Materials (Part1)3. Terminology3.1 Definitions3.1.1 For definitions of terms used in the test method,
9、referto Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 bond strength, na measure of the force required toseparate surfaces which have been bonded together.3.2.2 magnet wire, na metal electrical conductor, coveredwith electrical insulation, for use in the assembly of elect
10、ricalinductive apparatus such as coils for motors, transformers,generators, relays, magnets, etc.3.2.2.1 DiscussionThe electrical insulation is usuallycomposed of a film covering formed from a magnet wireenamel applied over a bare conductor. In some specificapplications, fibrous coverings, either ta
11、ped or linear filamentserved, are also used as electrical insulation.3.2.3 varnish, electrical insulating, n a liquid resin systemthat is applied to and cured on electrical components providingelectrical, mechanical and environmental protection.3.2.3.1 DiscussionThere are two types of electrical ins
12、u-lating varnishessolvent-containing and solventless. Solvent-containing types are solutions, dispersions or emulsions of apolymer or a mixture of polymers in a volatile, nonreactableliquid. Solventless types are liquid resin systems free ofvolatile, nonreactable solvents.1This test method is under
13、the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Varnishes, Powders and Encapsulat-ing Compounds.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved i
14、n 1973. Last previous edition approved in 2008 as D3145 08. DOI:10.1520/D3145-13.2For 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
15、 onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.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
16、19428-2959. United States14. Summary of Test Method4.1 Flexural strength of the helical coils is measured peri-odically after exposure to several exposure temperatures. Thetime to reach an arbitrarily selected value of bond strength ateach exposure temperature is determined. The logarithms ofthese t
17、imes in hours are plotted as a function of the reciprocaltemperature (1/K) to give an Arrhenius plot.5. Significance and Use5.1 This test method is used to determine the effect ofexposure to elevated temperatures on the bond strength ofcombinations of magnet wire insulations and electrical insu-lati
18、ng varnishes. The results are used as a guide for thecomparison and selection of varnishes and combinations ofvarnishes and magnet wire insulation for specific applications.Test Methods D1932 and D3251describe additional tests fordetermining the thermal endurance of insulating varnishes. Acomprehens
19、ive evaluation of thermal characteristics includes acomparison of the thermal endurance determined in thesedifferent ways.5.2 This test method is useful for research and productqualifications purposes.6. Apparatus6.1 Testing Machine, see Test Method D2519.6.2 Test Fixture, see Test Method D2519.6.3
20、Ovens, see Specification D5423, Type II.7. Hazards7.1 It is unsafe to use varnish at temperatures above flashpoint without adequate ventilation, especially if the possibilityexists that flames or sparks are present. Store varnish in sealedcontainers.8. Test Specimen8.1 Prepare 60 or more specimens f
21、or each exposuretemperature, following the procedure specified in Test MethodD2519.9. Selection of Test Temperatures9.1 Expose the material to at least three temperatures.Choose the lowest temperature such that it is not more than25C higher than the estimated temperature index. Separateexposure temp
22、eratures from each other by at least 10C,preferably 20C.9.2 Select exposure temperatures in accordance with thoseshown in Table 1 as indicated by the anticipated temperatureindex of the material under test. It is recommended thatexploratory tests be first made at the highest temperature toobtain dat
23、a establishing the 100 h minimum endpoint timerequirement, and that this be used as a guide for the selectionof the lower test temperatures.9.3 Choose the exposure temperature so that any essentiallylinear portions of the Arrhenius plot (log of time to failureversus the reciprocal of the absolute te
24、mperature) is wellestablished; that is, confirm the suspicion of significant non-linearity by test at one or more additional temperatures.Generally the additional temperatures are lower than the onespreviously tested.10. Procedure10.1 Suspend at least 20 sets of coils containing at least 3coils in e
25、ach set vertically in each oven.10.2 Periodically remove one set of coils and condition 2 hat standard laboratory conditions in accordance with PracticeD618. Measure flexural strength at room temperature inaccordance with Test Method D2519.10.3 The length of the exposure period and the number ofcoil
26、s tested per cycle will depend on the deterioration rate ateach exposure temperature. The exposure period will be longerat the start, shorter as the deterioration rate increases.10.4 Continue the test until the breaking strength reachesless than 22 N (5 lbf). The end point is that point where thecur
27、ve intersects the 22-N (5-lbf) line, or other specified value.11. Calculation11.1 Plot the breaking strength value after each exposureperiod versus time in hours on a three-decade semilog paperwith time as the ordinate.11.2 From the curve, pick the 22-N (5-lbf) point, or speci-fied value, and record
28、 the number of hours to reach this point.This is to be done for each temperature and will be known asthe end point at that temperature.TABLE 1 Suggested Exposure Temperatures and Cycle DurationsACycleDuration,dayTemperatures Corresponding to the Estimated Temperature Index Range, CB,CClass 105 Class
29、 130 Class 155 Class 180 Class 200 Class 220100 to109110 to119120 to129130 to139140 to149150 to159160 to169170 to179180 to189190 to199200 to209210 to219220 to229230 to2391 170 180 190 200 210 220 230 240 250 260 270 280 290 3002 160 170 180 190 200 210 220 230 240 250 260 270 280 2904 150 160 170 18
30、0 190 200 210 220 230 240 250 260 270 2807 140 150 160 170 180 190 200 210 220 230 240 250 260 27014 130 140 150 160 170 180 190 200 210 220 230 240 250 26028 120 130 140 150 160 170 180 190 200 210 220 230 240 25049 110 120 130 140 150 160 170 180 190 200 210 220 230 240ATaken from IEC Publication
31、60216-1.BExposure temperatures above and below those given are to be selected by experimentation.CRange to which the temperature is assumed to correspond to an extrapolated 20 000 h time to failure.D3145 13211.3 In order to calculate the temperature index, data mustbe available from a minimum of thr
32、ee exposure temperatures.The highest exposure temperature must have a thermal end-point time of at least 100 h. The endpoint time at the lowestexposure temperature must have a thermal life of at least5000 h.11.4 Plot the end points at each temperature on graph paperhaving a logarithmic time scale as
33、 the ordinate and thereciprocal of the absolute temperature as the abscissa. Draw thebest fit straight line through all points. For definition of how todraw the best fit line, see the Annex of Test Method D2307 forcalculation of the regression line.11.5 The temperature where the line crosses the spe
34、cifiedhour line is the temperature index for the combination used forthe test. Unless otherwise specified, use an hour line of 20 000h.12. Report12.1 Report the following information:12.1.1 Identification of the varnish,12.1.2 Identification of the magnet wire insulation,12.1.3 Cure schedule used,12
35、.1.4 Exposure temperatures, and12.1.5 Temperature index.13. Precision and Bias13.1 PrecisionData from a between-laboratory study4in-volving three laboratories testing a single unsaturated polyesterresin yielded:Average temperature index 204Range of values 8Standard deviation 413.2 BiasThis test meth
36、od has no bias because the valuefor the thermal endurance of insulating varnish using thehelical coil method is defined in terms of this test method.14. Keywords14.1 electrical insulating; helical coil; magnet wire; thermalendurance; varnishSUMMARY OF CHANGESCommittee D09 has identified the location
37、 of selected changes to this test method since the last issue,D3145 08, that may impact the use of this test method. (Approved Nov. 1, 2013)(1) Deleted references to Test Method D3850 and PracticeD6054.(2) Added reference to Practice D618.Committee D09 has identified the location of selected changes
38、 to this test method since the last issue,D3145 03, that may impact the use of this test method. (Approved May 1, 2008)(1) Revised the text throughout to remove nonmandatorylanguage.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item
39、 mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical commi
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41、eting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive,
42、 PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D09-1033.D3145 133
