1、Designation: D2307 07a (Reapproved 2013)Standard Test Method forThermal Endurance of Film-Insulated Round Magnet Wire1This standard is issued under the fixed designation D2307; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 covers determination of the thermalendurance of film-insulated round magnet wire in air atatmo
3、spheric pressure. It is not applicable to magnet wire withfibrous insulation, such as cotton or glass.1.2 This test method covers the evaluation of thermalendurance by observing changes in response to ac proofvoltage tests. The evaluation of thermal endurance by observ-ing changes in other propertie
4、s of magnet wire insulationrequires the use of different test methods.1.3 It is possible that exposure of some types of filminsulated wire to heat in gaseous or liquid environments in theabsence of air will give thermal endurance values differentfrom those obtained in air. Consider this possibility
5、wheninterpreting the results obtained by heating in air with respectto applications where the wire will not be exposed to air inservice.1.4 It is possible that electric stress applied for extendedperiods at a level exceeding or even approaching the dischargeinception voltage will change significantl
6、y the thermal endur-ance of film insulated wires. Under such electric stressconditions, it is possible that comparisons between materialswill also differ from those developed using this method.1.5 This test method is similar to IEC 60172. Differencesexist regarding specimen preparation.1.6 The value
7、s stated in inch-pound units are to be regardedas the standard. The SI units in parentheses are provided forinformation only.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish app
8、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1676 Test Methods for Film-Insulated Magnet WireD1711 Terminology Relating to Electrical InsulationD3251 Test Method for Thermal Endurance Charact
9、eristicsof Electrical Insulating Varnishes Applied Over Film-Insulated Magnet WireD5423 Specification for Forced-Convection Laboratory Ov-ens for Evaluation of Electrical Insulation2.2 Other Standards:IEC 60172 Statistical Analysis of Thermal Life Test Data3IEEE 101 Statistical Analysis of Thermal L
10、ife Test Data43. Terminology3.1 Definitions:3.1.1 temperature index, na number which permits com-parison of the temperature/time characteristics of an electricalinsulating material, or a simple combination of materials, basedon the temperature in degrees Celsius which is obtained byextrapolating the
11、 Arrhenius plot of life versus temperature to aspecified time, usually 20 000 h.3.1.2 thermal endurance, nan expression for the stabilityof an electrical insulating material, or a simple combination ofmaterials, when maintained at elevated temperatures for ex-tended periods of time.3.2 Definitions o
12、f Terms Specific to This Standard:3.2.1 specimen failure time, nthe hours at the exposuretemperature that have resulted in a specimen failing the prooftest (see 9.1).3.2.2 thermal endurance cycle, none oven exposure pe-riod followed by a proof voltage test.3.2.3 time to failure, nthe log average hou
13、rs calculated fora set of specimens, calculated from the individual specimenfailure times at an exposure temperature (see 9.2).1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.17 on
14、Fire and Thermal Properties.Current edition approved April 1, 2013. Published April 2013. Originallyapproved in 1964. Last previous edition approved in 2007 as D2307 07a. DOI:10.1520/D2307-07AR13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Electrotechnical Commission (IEC), 3 rue deVaremb, Case postale 131, CH-1211, Geneva 20, Switzerland, http:/www.iec.ch.4Available from
16、Institute of Electrical and Electronics Engineers, Inc. (IEEE),445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http:/www.ieee.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 19428-295
17、9. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical B
18、arriers to Trade (TBT) Committee.13.3 For definitions of terms related to electrical insulation,see Terminology D1711.4. Summary of Test Method4.1 This test method specifies the preparation of specimens,the exposure of these specimens at elevated temperatures, andthe periodic testing of the specimen
19、s by applying a preselectedproof voltage.4.2 The cyclic exposure to temperature is repeated until asufficient number of specimens have failed to meet the prooftest, and the time to failure is calculated in accordance withSection 9. The test is carried out at three or more temperatures.A regression l
20、ine is calculated in accordance with Section 10,and the time to failure values plotted on thermal endurancegraph paper (see Fig. 6) as a function of the exposuretemperature.5. Significance and Use5.1 This test method is useful in determining the thermalendurance characteristics and thermal indices o
21、f film-insulatedround magnet wire in air (see 1.3) (see Test Method D3251).This test method is used as a screening test before making testsof more complex systems or functional evaluation. It is alsoused where complete functional systems testing is not feasible.5.2 Experience has shown that film-ins
22、ulated wire andelectrical insulating varnishes or resins can affect one anotherduring the thermal exposure process. Test Method D3251provides indications on the thermal endurance for a combina-tion of insulating varnish or resin and film insulated wire. It ispossible that interaction between varnish
23、 or resin and filminsulation will increase or decrease the relative thermal life ofthe varnish and film insulated wire combination compared withthe life of the film insulated wire tested without varnish.5.3 The conductor type or the surface condition of theconductor will affect the thermal endurance
24、 of film-insulatedmagnet wire. This test method is used to determine the thermalendurance characteristics of film insulation on various kinds ofconductors. The use of sizes other than those specified in 7.1.1is permissible but is not recommended for determining thermalendurance characteristics.5.4 T
25、he temperature index determined by this test method isa nominal or relative value expressed in degrees Celsius at20 000 h. It is to be used for comparison purposes only and isnot intended to represent the temperature at which the filminsulated wire could be operated.5.5 There are many factors that i
26、nfluence the results ob-tained with this test method. Among the more obvious are thefollowing:5.5.1 Wire size and film thickness.5.5.2 Moisture conditions during proof voltage tests.5.5.3 Oven construction:5.5.3.1 Velocity of air.5.5.3.2 Amount of replacement air.5.5.3.3 Elimination of products of d
27、ecomposition duringthermal exposure.5.5.3.4 Oven loading.5.5.3.5 Accuracy with which the oven maintains tempera-ture.5.5.4 In most laboratories, the number of thermal enduranceovens is limited and, therefore, many different sets of speci-mens are thermally exposed in the same oven. All specimensare
28、not necessarily removed each time the oven is opened. Thisextra temperature cycling will possibly have a degradinginfluence.5.5.5 Care with which specimens are handled, especiallyduring latter cycles when the insulation becomes brittle.5.5.6 Vibration of specimens will have a degrading effectduring
29、the later thermal endurance cycles.5.5.7 Electrical characteristics of dielectric test instrument.Refer to 8.4 and 8.5.5.5.8 Environmental factors such as moisture, chemicalcontamination, and mechanical stresses, or vibration are factorsthat will possibly result in failure after the film insulated w
30、irehas been weakened by thermal deterioration and are moreappropriately evaluated in insulation system tests.FIG. 1 Device for Preparing Twisted Pair Specimens,Motorized UnitFIG. 2 Device for Preparing Twisted Pair Specimens,Hand-Operated UnitD2307 07a (2013)26. Apparatus6.1 Voltage Source (see 8.3,
31、 8.4, and 8.5).6.2 Oven (see Specification D5423 Type 2).6.3 Device for Preparing Twisted Pair Specimens (see Figs.1 and 2).6.4 Specimen Holders (see Figs. 3-5).7. Test Specimens7.1 Preparation:7.1.1 Film-insulated round magnet wire having bare wirediameters ranging from 0.0113 to 0.1019 in. (0.287
32、to 2.588mm) 10 to 29 AWG inclusive are evaluated as described in thistest method. If the dimensions of the magnet wire are notknown, determine them using Test Methods D1676.Metric Equivalentsin. mm in. mm in. mm0.03 0.8 0.38 9.7 1.25 31.80.046 1.2 0.44 11.2 2.00 50.80.064 1.6 0.50 12.7 3.00 76.20.12
33、 3.0 0.62 15.7 4.75 120.70.140 3.6 0.88 22.4 4.88 124.00.250 6.4 1.00 25.4 6.81 173.00.30 7.6 1.12 28.4FIG. 3 A Specimen HolderD2307 07a (2013)37.1.2 Form a length of wire approximately 16 in. (400 mm)long into a U shape and twist together for a distance of 4.75 60.25 in. (120 6 6 mm) with a device
34、similar to those shown inFigs. 1 and 2. The winding weight applied to the wire specimenwhile being twisted and the number of twists (full 360rotations of the head of the twist maker) are given in Table 1.7.1.3 If specimens are to evaluated with a varnish, see TestMethod D3251.7.2 Number of Test Spec
35、imensThe accuracy of the testresults depends largely upon the number of test specimensexposed at each temperature. A greater number of test speci-mens is required to achieve an acceptable degree of accuracy ifthere is a wide spread in results among the specimens exposedat each temperature. Use a min
36、imum of 10 specimens for eachtemperature. It is permissible to evaluate a greater number ofspecimens if desired.7.3 Specimen HolderIt has been found that individualhandling of the twisted specimens will introduce prematurefailures. It is, therefore, mandatory that the specimens beplaced in a suitabl
37、e holder. Design the holder in a manner thatwill protect the twisted specimens from external mechanicaldamage and warpage.An example of a suitable holder is shownin Figs. 3 and 4. Construct the holder so as to allow for theelectrical connection of the twists for the proof testing (see Fig.5 for an e
38、xample).7.4 Electrical ConnectionProvide a suitable electricalconnection to the test specimens in the holder that will notinduce mechanical stress to the specimens. Non-mechanicalconnections are preferred. A typical device is shown in Fig. 5.The specimens are connected to a voltage source as describ
39、edin 8.3 and 8.4.8. Procedure8.1 Prior to the first exposure cycle, make sure all specimenspass the proof-voltage test (see Table 2). Expose the specimensat elevated temperatures in accordance with Table 3. Removethe specimens from the oven and cool to room temperaturebefore testing. Test by applyin
40、g the voltage specified in Table2. Take care to prevent damage to the specimens.8.2 Exposure TimesThe exposure times given in Table 3are selected to subject the test specimen to approximately tencycles before all specimens fail. It is permissible to extendTable 3 at the high end of the exposure temp
41、erature range toaccommodate special high-temperature film insulations. Thethermal endpoint time of the specimens will possibly beaffected by the number of cycles. Log average or median hourvalues, obtained from test specimens subjected to less thaneight cycles or more than twenty cycles at the expos
42、uretemperature are possibly unreliable. Therefore, to ensure thenumber of cycles to failure will be within the parameters,adjust the exposure time. For example, if a set of testspecimens has been exposed for eight cycles and less than halfhave failed, it is recommended that the exposure time shouldb
43、e approximately doubled, and if the test shows a 30 % orgreater failure rate by the fourth cycle, it is recommended thatthe exposure time should be reduced by one-half. Expose testspecimens to at least three temperatures. It is recommendedthat exposure temperatures be at least 10C apart. Select thel
44、owest test temperature to be no more than 20C above theestimated temperature index of the magnet wire. Space the testtemperatures equally so that they cover a range of at least40C. The accuracy of the time to failure predicted from theresults will increase as the exposure temperature approachesthe t
45、emperature to which the insulation is exposed in service.The end point at the lowest exposure temperature must be atFIG. 4 A Specimen HolderFIG. 5 A Specimen Holder and Electrical Connection DeviceD2307 07a (2013)4NOTE 1This graph should contain all appropriate information regarding the insulating m
46、aterials.FIG. 6 Example of a Regression Line Plot (Table 5)TABLE 1 Tension and Number of Twists for Twisted Pair ConstructionNominal Bare Wire DiameterWire SizeAWGATotalTwistsWinding Weight on Specimens ( 2%)in. mm kg lb0.102 to 0.091 2.59 to 2.30 10 to 11 3 10.8 240.081 to 0.064 2.05 to 1.63 12 to
47、14 4 5.4 120.057 to 0.045 1.45 to 1.15 15 to 17 6 2.7 60.040 to 0.032 1.02 to 0.81 18 to 20 8 1.35 30.029 to 0.023 0.72 to 0.57 21 to 23 12 0.70 1.5B0.020 to 0.016 0.51 to 0.40 24 to 26 16 0.34 .0.014 to 0.011 0.36 to 0.29 27 to 29 20 0.17 .APrepare test specimens, of intermediate diameters, in acco
48、rdance with the requirements for the next smaller AWG size.BFor weights less than 1.5 lb, use kilogram weights.D2307 07a (2013)5least 5000 h. If the log average or median hours are less than100, do not use the data. Use ovens of the forced-draft designconforming to Specification D5423 Type 2.8.3 Tes
49、t VoltagesThe voltages given in Table 2 are se-lected in order to subject the insulation to a stress of approxi-mately 300 V/mil (12 kV/mm). This value is above the airbreakdown value for the space afforded by the insulation filmsseparating the wires. These relatively high values are chosen sothat crazing, or other deterioration of the coating is readilydetected.8.4 The voltage to be applied shall be an ac voltage with anominal frequency of 50 or 60 Hz of an approximatelysine-wave form, the peak factor being within the limits of=265% (1.34 to 1.48). The test
