1、Designation: D3145 13D3145 18Standard 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 re
2、vision, 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 m
3、ethod covers the determination of the thermal endurance of electrical insulating varnishes alone or incombinations with magnet wire insulation. Changes in the helical coil bond strength are used as the test criteria. The coils are madefrom bare aluminum or copper wire, or from film- or fiber-insulat
4、ed magnet wire.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not considered standard.NOTE 1There is no similar or equivalent IEC standard.1.3 This standa
5、rd does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. Fo
6、r a specific precautionary statement, see Section 7.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby t
7、he World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD1711 Terminology Relating to Electrical InsulationD1932 Test Method for Thermal Endurance of Flexible Electrical Insulating Varnishes
8、D2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet WireD2519 Test Method for Bond Strength of Electrical Insulating Varnishes by the Helical Coil TestD3251 Test Method for Thermal Endurance Characteristics of Electrical Insulating Varnishes Applied Over Film-InsulatedMagnet WireD
9、5423 Specification for Forced-Convection Laboratory Ovens for Evaluation of Electrical Insulation2.2 International Electrotechnical Commission Publications:3IEC 60216-1 Guide for the Determination of Thermal Endurance Properties of Electrical Insulation Materials (Part 1)3. Terminology3.1 Definition
10、s3.1.1 For definitions of terms used in the test method, refer to Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 bond strength, na measure of the force required to separate surfaces which have been bonded together.1 This test method is under the jurisdiction of ASTM Commi
11、ttee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of SubcommitteeD09.01 on Electrical Insulating Varnishes, Powders and Encapsulating CompoundsProducts.Current edition approved Nov. 1, 2013Nov. 1, 2018. Published December 2013November 2018. Originally approv
12、ed in 1973. Last previous edition approved in 20082013as D3145 08.D3145 13. DOI: 10.1520/D3145-13.10.1520/D3145-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to th
13、e standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of w
14、hat changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered t
15、he official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2 magnet wire, na metal electrical conductor, covered with electrical insulation, for use in the
16、 assembly of electricalinductive apparatus such as coils for motors, transformers, generators, relays, magnets, etc.and so forth.3.2.2.1 DiscussionThe electrical insulation is usually composed of a film covering formed from a magnet wire enamel applied over a bare conductor.In some specific applicat
17、ions, fibrous coverings, either taped or linear filament served, are also used as electrical insulation.3.2.3 varnish, electrical insulating, n a liquid resin system that is applied to and cured on electrical components providingelectrical, mechanical and environmental protection.3.2.3.1 DiscussionT
18、here are two types of electrical insulating varnishessolvent-containing and solventless. Solvent-containing types are solutions,dispersions or emulsions of a polymer or a mixture of polymers in a volatile, nonreactable liquid. Solventless types are liquid resinsystems free of volatile, nonreactable
19、solvents.4. Summary of Test Method4.1 Flexural strength of the helical coils is measured periodically after exposure to several exposure temperatures. The time toreach an arbitrarily selected value of bond strength at each exposure temperature is determined. The logarithms of these times inhours are
20、 plotted as a function of the reciprocal temperature (1/K) to give an Arrhenius plot.5. Significance and Use5.1 This test method is used to determine the effect of exposure to elevated temperatures on the bond strength of combinationsof magnet wire insulations and electrical insulating varnishes. Th
21、e results are used as a guide for the comparison and selection ofvarnishes and combinations of varnishes and magnet wire insulation for specific applications. Test Methods D1932 andD3251describe additional tests for determining the thermal endurance of insulating varnishes. A comprehensive evaluatio
22、n ofthermal characteristics includes a comparison of the thermal endurance determined in these different ways.5.2 This test method is useful for research and product qualifications purposes.6. Apparatus6.1 Testing Machine, see Test Method D2519.6.2 Test Fixture, see Test Method D2519.6.3 Ovens, see
23、Specification D5423, Type II.7. Hazards7.1 It is unsafe to use varnish at temperatures above flash point without adequate ventilation, especially if the possibility existsthat flames or sparks are present. Store varnish in sealed containers.8. Test Specimen8.1 Prepare 60 or more specimens for each e
24、xposure temperature, following the procedure specified in Test Method D2519.9. Selection of Test Temperatures9.1 Expose the material to at least three temperatures. Choose the lowest temperature such that it is not more than 25C higherthan the estimated temperature index. Separate exposure temperatu
25、res from each other by at least 10C, preferably 20C.9.2 Select exposure temperatures in accordance with those shown in Table 1 as indicated by the anticipated temperature indexof the material under test. It is recommended that exploratory tests be first made at the highest temperature to obtain data
26、establishing the 100 h minimum endpoint time requirement, and that this be used as a guide for the selection of the lower testtemperatures.9.3 Choose the exposure temperature so that any essentially linear portions of the Arrhenius plot (log of time to failure versusthe reciprocal of the absolute te
27、mperature) is well established; that is, confirm are well established. Confirm the suspicion ofsignificant nonlinearity by test at one or more additional temperatures. Generally the additional temperatures are lower than theones previously tested.10. Procedure10.1 Suspend at least 20 sets of coils c
28、ontaining at least 3three coils in each set vertically in each oven.D3145 18210.2 Periodically remove one set of coils and condition 2 h at standard laboratory conditions in accordance with Practice23 62C and less than 55 % D618.RH. Measure flexural strength at room temperature in accordance with Te
29、st Method D2519.10.3 The length of the exposure period and the number of coils tested per cycle will depend on the deterioration rate at eachexposure temperature. The exposure period will be longer at the start, shorter as the deterioration rate increases.10.4 Continue the test until the breaking st
30、rength reaches less than 22 N (5 lbf). The end point is that point where the curveintersects the 22-N (5-lbf) line, or other specified value.11. Calculation11.1 Plot the breaking strength value after each exposure period versus time in hours on a three-decade semilog paper with timeas the ordinate.1
31、1.2 From the curve, pick the 22-N (5-lbf) point, or specified value, and record the number of hours to reach this point. Thisis to be done for each temperature and will be known as the end point at that temperature.11.3 In order to calculate the temperature index, data must be available from a minim
32、um of three exposure temperatures. Thehighest exposure temperature must have a thermal endpoint time of at least 100 h. The endpoint time at the lowest exposuretemperature must have a thermal life of at least5000 h.11.4 Plot the end points at each temperature on graph paper having a logarithmic time
33、 scale as the ordinate and the reciprocalof the absolute temperature as the abscissa. Draw the best fit straight line through all points. For definition of how to draw the bestfit line, see the Annex of Test Method D2307 for calculation of the regression line.11.5 The temperature where the line cros
34、ses the specified hour line is the temperature index for the combination used for thetest. Unless otherwise specified, use an hour line of 20 000 h.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 sch
35、edule used,12.1.4 Exposure temperatures, and12.1.5 Temperature index.13. Precision and Bias13.1 PrecisionData from a between-laboratory study4 involving three laboratories testing a single unsaturated polyester resinyielded:Average temperature index 204Range of values 8Standard deviation 413.2 BiasT
36、his test method has no bias because the value for the thermal endurance of insulating varnish using the helical coilmethod is defined in terms of this test method.4 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D09-1033.TABLE
37、1 Suggested Exposure Temperatures and Cycle DurationsACycleDuration,dayTemperatures Corresponding to the Estimated Temperature Index Range, CB,CClass 105 Class 130 Class 155 Class 180 Class 200 Class 220100 to109110 to119120 to129130 to139140 to149150 to159160 to169170 to179180 to189190 to199200 to2
38、09210 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 150 160 170 180 190 200 210 220 230 240 250 260 270 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
39、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 240A Taken from IEC Publication 60216-1.B Exposure temperatures above and below those given are to be selected by experimentation.C Range to which the temperature is assume
40、d to correspond to an extrapolated 20 000 h time to failure.D3145 18314. Keywords14.1 electrical insulating; helical coil; magnet wire; thermal endurance; varnishSUMMARY OF CHANGESCommittee D09 has identified the location of selected changes to this test method standard since the last issue,issue (D
41、3145 08D3145 13,) that may impact the use of this test method. standard. (Approved Nov. 1,2013Nov. 1, 2018).)(1) Deleted references to Test Method D3850 and Practice D6054.(1) Removed reference to Practice D618.(2) Revised 9.3 and 10.2(2) Added reference to Practice D618.Committee D09 has identified
42、 the location of selected changes 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 nonmandatory language.ASTM International takes no position respecting the validity of any patent rights as
43、serted in connection with any item 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
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45、ive careful consideration at a meeting 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 Inte
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