1、Designation: D4881 05 (Reapproved 2012)An American National StandardStandard Test Method forThermal Endurance of Varnished Fibrous- or Film-WrappedMagnet Wire1This standard is issued under the fixed designation D4881; the number immediately following the designation indicates the year oforiginal ado
2、ption 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. Scope1.1 This test method covers the determination of thermalendurance of rectan
3、gular and square fibrous- or film-wrappedmagnet wire coated with an insulating varnish.1.2 The values given in SI units are the standard. The valuesgiven in parentheses are for information only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
4、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. A specific precau-tionary statement is given in Section 5.NOTE 1There is no similar or equivalent IEC Standard.2. Refere
5、nced Document2.1 ASTM Standards:2D1711 Terminology Relating to Electrical InsulationD2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet WireD3353 Test Methods for Fibrous-Insulated Magnet Wire3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 varnish, electrica
6、l insulating, n a liquid resin sys-tem that is applied to and cured on electrical componentsproviding electrical, mechanical, and environmental protec-tion.3.1.1.1 DiscussionThere are two types of electrical insu-lating varnishes: solvent-containing and solventless. Solvent-containing types are solu
7、tions, dispersions, or emulsions of apolymer or a mixture of polymers in a volatile, nonreactableliquid. Solventless types are liquid resin systems free ofvolatile, nonreactable solvents.3.1.2 Refer to Terminology D1711 for definitions of otherterms.4. Significance and Use4.1 Individual varnishes be
8、have differently when applied tothe same fibrous- or film-wrapped magnet wire when exposedto elevated temperatures. Likewise, a varnish does not alwaysbehave the same when applied to different types of fibrous orfilm-wrapped magnet wires and when exposed to elevatedtemperatures.5. Safety Precautions
9、5.1 It is unsafe to use varnish at temperatures above theflash point without adequate ventilation, especially if thepossibility exists that flames or sparks are present. Storevarnish in sealed containers.6. Test Specimens6.1 Construction of Test Specimens:6.1.1 Cut two 250-mm (10-in.) lengths of wir
10、e for eachspecimen to be made.6.1.2 Determine the thickness dimensions per Test MethodD3353.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical Insulating Varnishes, Po
11、wders and Encapsulat-ing Compounds.Current edition approved Jan. 1, 2012. Published January 2012. Originallyapproved in 1988. Last previous edition approved in 2005 as D4881 05. DOI:10.1520/D4881-05R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Serv
12、ice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.FIG. 1 Jig for Forming Wire1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.3 Form each l
13、ength in a fixture as shown in Fig. 1.6.1.4 Prepare a test specimen by placing the two formedwires together back to back and wrap tightly with a minimumof 6 turns of glass yarn over the middle 6-in. (150-mm) section.The glass yarn shall have a gap between turns and there mustbe intimate contact of t
14、he two wires.6.1.5 Prepare ten specimens for each test temperature.6.2 Varnishing the Test Specimens:6.2.1 Adjust the consistency of a solvent-containing varnishto give a 0.025 6 0.005-mm (0.0010 6 0.0002-in.) cured filmon each side of a 0.13-mm (0.005-in.) copper strip withdrawnat a rate of 100 mm/
15、min (4 in./min). Use solventless varnish asreceived.6.2.2 Submerge the test specimens vertically in the varnishto be tested. Withdraw them at a rate of 100 mm/min (4in./min). Drain the test specimens for 10 to 12 min. Cureaccording to the manufacturers recommendations. If asolvent-containing varnish
16、 is being tested, the test specimensshall be dipped in the reverse direction and cured as before.6.2.3 Expose12 in. of bare conductor at one end of eachwire to facilitate electrical connections.7. Procedure7.1 After selecting the test voltage from Table 1, follow theprocedure in Test Method D2307 wi
17、th the following excep-tions:7.1.1 The described specimen holder and electrical connec-tion device are not required. Instead, lay samples flat on avented tray during oven exposure.7.1.2 Test individual specimens by carefully attaching testleads to each specimen.8. Calculation8.1 After all specimens
18、have failed, calculate the endpointtime at each test temperature in accordance with Test MethodD2307.8.2 Plot the results using the endpoint time calculated foreach temperature as the ordinate on a logarithmic time scaleand the reciprocal of the absolute temperature as the abscissa.8.3 Calculate the
19、 temperature index at 20 000 and correla-tion coefficient using the procedure given in Test MethodD2307.9. Report9.1 Report the following information:9.1.1 Identification of the varnish used,9.1.2 Identification of the magnet wire used including sizeand build,9.1.3 Temperature index, and9.1.4 Correl
20、ation coefficient.10. Precision and Bias10.1 PrecisionThis test method has been in use for manyyears, but no statement of precision has been made and noactivity is planned to develop such a statement.10.2 BiasThis test method has no bias because the valuefor thermal endurance of varnished-fibrous or
21、 film-wrappedmagnet wire is defined in terms of this test method.11. Keywords11.1 electrical insulating; fibrous-wrapped wire; film-wrapped wire; thermal endurance; varnishASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
22、in 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 committee and m
23、ust be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of t
24、heresponsible 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, PO Box C7
25、00, 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). Permissi
26、on rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).TABLE 1 Test VoltagesDifference Between Bare and Insulated WireThickness, mm (in.)Test Voltage, 60Hz ac RMS0.036 0.050 ( 0.0015 0.0020) 3000.051 0.064 ( 0.0021 0.0025) 3750.065 0.076 ( 0.0026 0.0030) 4500.077 0.089 ( 0.0031 0.0035) 5500.090 0.102 ( 0.0036 0.0040) 6500.103 0.114 ( 0.0041 0.0045) 7000.115 0.127 ( 0.0046 0.0050) 7500.128 0.140 ( 0.0051 0.0055) 8000.141 0.152 ( 0.0056 0.0060) 8500.153 (0.0061) 1000D4881 05 (2012)2
