1、Designation: D 2307 07aAn American National StandardStandard Test Method forThermal Endurance of Film-Insulated Round Magnet Wire1This standard is issued under the fixed designation D 2307; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the 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.1. Scope*1.1 This test method covers determination of the thermalendurance of film-insulated round magnet wire
3、 in air atatmospheric pressure. It is not applicable to magnet wire withfibrous insulation, such as cotton or glass.1.2 The values stated in inch-pound units are to be regardedas the standard. The SI units in parentheses are provided forinformation only.1.3 This test method covers the evaluation of
4、thermalendurance by observing changes in response to ac proofvoltage tests. The evaluation of thermal endurance by observ-ing changes in other properties of magnet wire insulationrequires the use of different test methods.1.4 It is possible that exposure of some types of filminsulated wire to heat i
5、n gaseous or liquid environments in theabsence of air will give thermal endurance values differentfrom those obtained in air. Consider this possibility wheninterpreting the results obtained by heating in air with respectto applications where the wire will not be exposed to air inservice.1.5 It is po
6、ssible that electric stress applied for extendedperiods at a level exceeding or even approaching the dischargeinception voltage will change significantly the thermal endur-ance of film insulated wires. Under such electric stress condi-tions, it is possible that comparisons between materials willalso
7、 differ from those developed using this method.1.6 This test method is similar to IEC 60172. Differencesexist regarding specimen preparation.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
8、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:2D 1676 Test Methods for Film-Insulated Magnet WireD 1711 Terminology Relating to Electrical InsulationD 3251 Test Method for Therma
9、l Endurance Characteristicsof Electrical Insulating Varnishes Applied Over Film-Insulated Magnet WireD 5423 Specification for Forced-Convection LaboratoryOvens for Evaluation of Electrical Insulation2.2 Other Standards:IEC 60172 Statistical Analysis of Thermal Life Test Data3IEEE 101 Statistical Ana
10、lysis of Thermal Life 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 b
11、yextrapolating the 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
12、.3.2 Definitions of 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, nt
13、he log average hours 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 ofSubco
14、mmittee D09.10 on Magnet Wire Insulation.Current edition approved Oct. 1, 2007. Published October 2007. Originallyapproved in 1964. Last previous edition approved in 2007 as D 2307 07.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm
15、.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 Institute of
16、 Electrical and Electronics Engineers, Inc. (IEEE),445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http:/www.ieee.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
17、States.3.3 For definitions of terms related to electrical insulation,see Terminology D 1711.4. 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 specimens by applying a preselecte
18、dproof 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 line is calculated in accor
19、dance 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 of film-insulatedround magn
20、et wire in air (see 1.4) (see Test Method D 3251).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-insulated wire andelectrical
21、 insulating varnishes or resins can affect one anotherduring the thermal exposure process. Test Method D 3251provides indications on the thermal endurance for a combina-tion of insulating varnish or resin and film insulated wire. It ispossible that interaction between varnish or resin and filminsula
22、tion 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 of film-insulatedmagnet
23、 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 The temperature index det
24、ermined 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 influence the results ob-
25、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 decomposition duringtherm
26、al 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 not necessarily removed
27、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 the later thermal endura
28、nce 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 wirehas been weakened by
29、thermal deterioration and are moreappropriately evaluated in insulation system tests.6. Apparatus6.1 Voltage Source (see 8.3, 8.4, and 8.5).6.2 Oven (see Specification D 5423 Type 2).FIG. 1 Device for Preparing Twisted Pair Specimens,Motorized UnitFIG. 2 Device for Preparing Twisted Pair Specimens,H
30、and-Operated UnitD 2307 07a26.3 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 to 2.588mm) 10 to 29 AWG incl
31、usive are evaluated as described in thistest method. If the dimensions of the magnet wire are notknown, determine them using Test Methods D 1676.7.1.2 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
32、 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 D 3251.7.2 Number of Test Sp
33、ecimensThe 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 m
34、inimum 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 suita
35、ble holder. Design the holder in a manner thatwill protect the twisted specimens from external mechanicaldamage and warpage.An example of a suitable holder is shownMetric 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 3.0 0.62
36、 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 HolderD 2307 07a3in 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 example).7.4 Electrical Connection
37、Provide 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 describedin 8.3 and 8.4.8. Procedure8.1
38、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 applying the voltage specified in Table2
39、. 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 temperature range toaccommodate speci
40、al 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 exposuretemperature are possibly unrel
41、iable. 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 shouldbe approximately doubled, and if t
42、he 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 thelowest test temperature to be no m
43、ore 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 temperature to which the insulatio
44、n is exposed in service.The end point at the lowest exposure temperature must be atleast 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 D 5423 Type 2.8.3 Test VoltagesThe voltages given in Table 2 are
45、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 coatin
46、g 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=26 5 % (1.34 to 1.48). The test transformer shall have a ratedpower of at least 500 V-A and shall provide a c
47、urrent ofessentially undistorted waveform under test conditions.FIG. 4 A Specimen HolderFIG. 5 A Specimen Holder and Electrical Connection DeviceD 2307 07a48.5 To detect failure, the fault detection device shall operatewhen a current of 1.5 to 15 mA flows in the high voltagecircuit. The test voltage
48、 source shall have a capacity to supplythe detection current with a maximum voltage drop of 10 %.8.6 Apply the proof voltage to the test specimens forapproximately 1 s. A relatively short time of application of thetest voltage is desirable to minimize the effects of corona anddielectric fatigue.NOTE
49、This graph should contain all appropriate information regarding the insulating materials.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 (6 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 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 1
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