1、Designation: D 4880 08An American National StandardStandard Test Method forSalt Water Proofness of Insulating Varnishes OverEnamelled Magnet Wire1This standard is issued under the fixed designation D 4880; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 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. Scope*1.1 This test method covers the performance in a specifiedwater solution of an insulat
3、ing varnish applied over enamelledmagnet wire.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.3 This standard does not purport to
4、 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. Specific precau-tionary statements are given in Sec
5、tion 6.NOTE 1There is no IEC method equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D 1676 Test Methods for Film-Insulated Magnet WireD 1711 Terminology Relating to Electrical Insulation3. Terminology3.1 Definitions: For definitions of terms used in this testmethod refer to Te
6、rminology D 1711.3.1.1 varnish, electrical 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 varnish solventcontaining and solventle
7、ss. Thesolvent-containing varnish is solution, dispersion, or emulsionof a polymer or a mixture of polymers in a volatile, nonre-actable liquid. The solventless type is a liquid resin system freeof volatile, nonreactable solvents.3.1.2 varnished, adjreferring to any item on to whichvarnish has been
8、applied and cured.4. Significance and Use4.1 This test method is useful in determining the perfor-mance of varnishes over enamelled magnet wire when sub-jected to the specified sodium chloride solution. It is useful inevaluating the resistance of varnished magnet wire to a dilutedsodium chloride sol
9、ution under applied voltage.5. Apparatus5.1 Description of Electrical Apparatus:5.1.1 The apparatus shall contain devices for limiting orinterrupting the current to each specimen whenever a failureoccurs. In particular, 7.5 W light bulbs or110 Afuses have beenused. Lighting of the bulb or “blowing”
10、of the fuse indicatesfailure.5.1.2 The power supply shall provide a source of filtered120 6 2 V dc which drops by less than 2 V when a current of0.5 A is drawn.5.1.3 A positive polarity of 120 V dc is applied to thespecimens. The surrounding sodium chloride solution is atground potential. The ground
11、 connection, using an immersedelectrode, is made using Nichrome, stainless steel, or othernon-corrosive wire. Do not use iron, carbon steel, copper, orbrass (see Fig. 1).5.2 An appropriate container shall be selected for thesodium chloride solution. Fit it with a cover to preventevaporation of the s
12、olution.6. Safety Precautions6.1 Do not use varnish at temperatures above the flash pointwhen inadequate ventilation, and possibility of flames orsparks exist. Store varnish in sealed containers. These precau-tions shall also apply to the handling of the reagents andsolvents called for in this test
13、method.6.2 WarningLethal voltages are a potential hazard duringthe performance of this test. It is essential that the testapparatus, and all associated equipment electrically connectedto it, be properly designed and installed for safe operation.1This test method is under the jurisdiction of ASTM Com
14、mittee 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 May 1, 2008. Published June 2008. Originallyapproved in 1988. Last previous edition app
15、roved in 2003 as D 4880 03.2For 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 onthe ASTM website.1*A Summary of Changes section app
16、ears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Solidly ground all electrically conductive parts which it ispossible for a person to contact during the test. Provide meansfor use at the completion of a
17、ny test to ground any parts whichwere at high voltage during the test or have the potential foracquiring an induced charge during the test or retaining acharge even after disconnection of the voltage source. Thor-oughly instruct all operators as to the correct procedures forperforming tests safely.
18、When making high voltage tests,particularly in compressed gas or in oil, it is possible for theenergy released at breakdown to be sufficient to result in fire,explosion, or rupture of the test chamber. Design test equip-ment, test chambers, and test specimens so as to minimize thepossibility of such
19、 occurrences and to eliminate the possibilityof personal injury. If the potential for fire exists, have firesuppression equipment available.7. Test Specimens Preparation7.1 Selection of Enamelled Magnet Wire The type ofenamelled magnet wire used for this test shall be agreed uponbetween interested p
20、arties. Seven of the nine unvarnished testspecimens shall fail within the specified test time.7.2 Twist a section of 1.02-mm (0.0403-in.) (18-AWG)enamelled magnet wire with the appropriate number of twistsand tension as described in Test Methods D 1676 (see Fig. 2).Note however, that one end of the
21、specimen is a continuousloop instead of two loose ends.7.3 Prepare 18 specimens in the manner described in 7.2.7.4 Dipping:7.4.1 Adjust the consistency of the solvent-containing var-nish to give a 0.025 6 0.005-mm (0.0010 6 0.0002-in.) curedfilm on each side of a 0.13-mm (.005-in.) copper stripwithd
22、rawn at a rate of approximately 100 mm/min (4 in./min).Use solventless varnish as received.7.4.2 Dip nine twisted specimens in the varnish to be tested.After the specimens are submerged in the varnish, withdrawthem at a rate of approximately 100 mm/min (4 in./min). Drainthe specimens for a minimum o
23、f 10 min. Cure according to themanufacturers specifications. Dip the specimens again in thereverse direction if a solvent-containing varnish was used.When testing solventless varnishes, dip test specimens onlyonce.8. Procedure8.1 Perform the following for nine unvarnished specimensand nine varnished
24、 specimens.8.2 Remove the enamel from the loose ends of the twistedspecimens. Use these legs to make the electrical connections.8.3 For each test, prepare a solution of distilled water andsodium chloride in which the sodium chloride is at a concen-tration of 3.5 6 0.1 % by weight.8.4 Set up the appr
25、opriate circuit as outlined in Section 5.Connect the specimen to the electrical circuit. Then submergethe specimens so that approximately 76 mm (3 in.) of thetwisted sections of the specimens are submerged in the sodiumchloride solution.8.5 Apply 120 6 5 V dc between the specimen and thesodium chlor
26、ide solution.8.6 Check for failures daily or more often if possible andthen record the total elapsed time from the application of thetest voltage to when failures are detected. The length of time ofthe test is 100 h unless otherwise agreed upon between the userand the manufacturer.8.7 if seven of th
27、e nine unvarnished test specimens do notfail within the test time, repeat the test with a differentenamelled magnet wire as specified in 7.1.9. Report9.1 Report the following information:9.1.1 Identification of the varnish used,9.1.2 Identification and film build of the magnet wire used,9.1.3 The nu
28、mber of unvarnished specimens failed at theend of the test time and the elapsed time when each failure wasdetected,9.1.4 The number of unvarnished specimens that did not failat the end of the test time,9.1.5 The number of varnished specimens that failed at theend of the test time and the elapsed tim
29、e when each failure wasdetected, and9.1.6 The number of varnished specimens that did not fail atthe end of the test time.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 stateme
30、nt.10.2 BiasThis test method has no bias because the valuefor salt water proofness is defined in terms of this method.11. Keywords11.1 electrical insulating; enamelled wire; magnet wire; saltwater; varnishFIG. 1 Typical Test ApparatusFIG. 2 Test SpecimenD4880082SUMMARY OF CHANGESCommittee D09 has id
31、entified the location of selected changes to this test method since the last issue,D 4880 03, that may impact the use of this test method. (Approved May 1, 2008)(1) Revised 7.1.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item ment
32、ionedin 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
33、and must 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
34、 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, PO B
35、ox 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).D4880083
