NEMA WC 72-1999 Continuity of Coating Testing for Electrical Conductors《电导体的涂层试验连续性》.pdf

1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA WC 72-1999 (R2015)Continuity of Coating Testing for ElectricalConductorsNEMA WC 72-1999 (R2004, R2015) Page i 2015 National Electrical Manufacturers Association NEMA Standards Publication WC 72-1999 (R2004, R2015) Continuity

2、 of Coating Testing for Electrical Conductors Published by: National Electrical Manufacturers Association 1300 North 17thStreet, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2015 National Electrical Manufacturers Association. All rights including translation into other languages, reserved under th

3、e Universal Copyright Convention, the Berne Convention for the Protection of Literary and Artistic Works, and the International and Pan American Copyright Conventions. NEMA WC 72-1999 (R2004, R2015) Page ii 2015 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in t

4、his publication was considered technically sound by the consensus of persons engaged in the development and approval of the document at the time it was developed. Consensus does not necessarily mean that there is unanimous agreement among every person participating in the development of this documen

5、t. National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and/or seeks out the views of persons who ha

6、ve an interest in the topic covered by this publication. While NEMA administers the process and establishes rules to promote fairness in the development of consensus, it does not write the document and it does not independently test, evaluate, or verify the accuracy or completeness of any informatio

7、n or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publi

8、cation, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, expressed or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any of you

9、r particular purposes or needs. NEMA does not undertake to guarantee the performance of any individual manufacturer or sellers products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services

10、for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this document should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercis

11、e of reasonable care in any given circumstances. Information and other standards on the topic covered by this publication may be available from other sources, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undert

12、ake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for safety or health purposes. Any certification or other statement of compliance with any health or safetyrelated information in this document shall no

13、t be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. NEMA WC 72-1999 (R2004, R2015) Page i 2015 National Electrical Manufacturers Association CONTENTS Foreword ii Section 1 General 1 1.1 Scope . 1 1.2 References 1 Section 2 Background for Development

14、 of WC 72 2 Section 3 Industry Problems and Observations 3 Section 4 The “White Card“ Continuity of Coating Test. 4 4.1 Procedure 4 4.2 Examination of Finished/Insulated Product 4 Section 5 Summary and Conclusions 5 NEMA WC 72-1999 (R2004, R2015) Page ii 2015 National Electrical Manufacturers Associ

15、ation Foreword This standard has been developed by the Polysulfide Task Force of the Aerospace Subcommittee (members as listed below) of the High Performance Wire and Cable Section of NEMA in close coordination between manufacturers, users, third party certifying agencies and others having specializ

16、ed experience. The Aerospace Subcommittee of the High Performance Wire and Cable Section of NEMA periodically reviews this standard for any revisions necessary to keep it up to date. Proposed revisions or comments should be submitted to: Senior Technical Director, Operations National Electrical Manu

17、facturers Association 1300 North 17thStreet, Suite 900 Rosslyn, Virginia 22209 Members of NEMA High Performance Wire and Cable Section that participated in the development of this standard were: AlcatelElm City, NC Barcel/CDTlrvine, CA BICC Brand-Rex CompanyWillimantic, CT Cable USANaples, FL Judd W

18、ire lnc.Turner Falls, MA Montrose/CDTAuburn, MA Phelps Dodge PHC Lexington, SC Quirk WireW. Brookfield, MA Radix WireCleveland, OH Raychem Corp.Menlo Park, CA Rockbestos-Surprenant Corp.Clinton, MA Tensolite CompanySt. Augustine, FL NEMA WC 72-1999 (R2004, R2015) Page 1 2015 National Electrical Manu

19、facturers Association Section 1 GENERAL 1.1 SCOPE This standards publication contains a review of the problems that have occurred when polysulfide testing has been improperly imposed on tin, silver and nickel coated copper and copper alloy stranded conductors or on tin, silver or nickel coated coppe

20、r and copper alloy single or stranded conductors after insulating. The Sodium Polysulfide Test is a materials inspection test, not a finished wire or cable test, and should only be imposed on a single strand/conductor prior to stranding or insulating. A new test, called the “white card“ continuity o

21、f coating test, is presented as a solution to these problems and can also be utilized on shield wires. This new test is referenced in ANSI/NEMA WC 67. 1.2 REFERENCED STANDARDS American Society of Testing Materials 100 Barr Harbor Drive West Conshohocken, Pennsylvania 19428-2959 ASTM B33-94 Standard

22、Specification for Tinned Soft or Annealed Copper Wire for Electrical Purposes ASTM B298-94 ASTM B355-95 Standard Specification for Silver-Coated Soft or Annealed Copper Wire Standard Specification for Nickel-Coated Soft or Annealed Copper Wire National Electrical Manufacturers Association 1300 North

23、 17thStreet Suite 900 Rosslyn, Virginia 22209 ANSI/NEMA WC 67-1997 Standard for Uninsulated Conductors Used in Electrical and Electronic Applications NEMA WC 72-1999 (R2004, R2015) Page 2 2015 National Electrical Manufacturers Association Section 2 BACKGROUND FOR DEVELOPMENT OF WC 72 The Sodium Poly

24、sulfide Test is the standard continuity of coating described in ASTM Standards such as B33, B298, and B355. The only purpose of this test is to evaluate the tin, silver or nickel coating of a single strand/conductor after the drawing process. However, this test has a variety of problems and limitati

25、ons: a. This test is performed in a laboratory and is not practical for use on a production floor. b. This test uses corrosive chemicals that require special handling, safety precautions and proper hazardous waste disposal. c. The coating of stranded conductors cannot be properly evaluated. d. The c

26、oating of an insulated single or stranded conductor cannot be properly evaluated. e. The Sodium Polysulfide Test cannot be used to evaluate the coating of braided or served shields, whether round or flat. NEMA WC 72-1999 (R2004, R2015) Page 3 2015 National Electrical Manufacturers Association Sectio

27、n 3 INDUSTRY PROBLEMS AND OBSERVATIONS The Sodium Polysulfide Test for continuity of coating has been the primary method for evaluating the coatings of tin, silver, and nickel coated copper and copper alloy wires for many years. In the referenced ASTM Standards, the proper application is to test sin

28、gle strands/conductors prior to any stranding or insulating. Over the years, however, this test has been misapplied in attempts to evaluate the coating of stranded conductors, of insulated single and stranded conductors, of wires after humidity tests and of braided and served shield wires. Although

29、these wires can be physically tested, the act of preparing the samples for testing can damage the coating, thus creating false readings. In addition, the effects of lighting and reflectance on stranded conductors can be misinterpreted as failures. Magnification has also been incorrectly used to exam

30、ine wires as part of the polysulfide test. While strand/conductor coatings inherently have a degree of porosity, microscopic examination is beyond the scope of this test. To the best knowledge of those who developed this standard, there is no known evidence of microscopic coating discontinuities hav

31、ing been a source of wire failures in service. NEMA WC 72-1999 (R2004, R2015) Page 4 2015 National Electrical Manufacturers Association Section 4 THE “WHITE CARD“ CONTINUITY OF COATING TEST 4.1 PROCEDURE Check the wire in a well-lighted area (using white light whenever possible). Look at the wire on

32、 the spool with an unaided eye and also by holding a white index card against the surface of the wire. Roll the spool to make sure that the entire exposed surface of the wire is examined. Check for exposed copper or base metal along one side of the specimen. Due to excessive localized abrasion durin

33、g stranding, shielding or cabling, any patterns of exposed copper or continuous lines shall be grounds for rejection. The examination is intended to detect excessive damage. Random point failures shall not be cause for rejection. 4.2 EXAMINATION OF FINISHED/INSULATED PRODUCT If this procedure is use

34、d for examination of insulated or finished product, a 4“ test specimen of product shall be available for examination. Care should be taken to ensure that any failure pattern was not generated by the specimen preparation. Note that spurious readings can occur due to reflections from any non-white sur

35、face. NEMA WC 72-1999 (R2004, R2015) Page 5 Section 5 SUMMARY AND CONCLUSIONS The “white card“ test addresses the limitations and problems with the Sodium Polysulfide Test, as presented in Sections 2 and 3, while maintaining the expected quality of the coating continuity. Those who have utilized thi

36、s test at their facilities have found it to be simple, reliable and a valid test for stranded conductors and shields. NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITWWW.GLOBAL.IHS.COM OR CALL 1-800-854-7179/1-303-397-79565612_0514TB