IEEE 56-1977 - IEEE Guide for Insulation Maintenance of Large Alternating-Current Rotating Machinery (10,000 kVA and Larger).pdf

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1、ANSI/IEEE Std 56-1997(Revision of IEEE Std 56-1958)An American National StandardIEEE Guide for Insulation Maintenance of Large Alternating-Current Rotating Machinery (10 000 kVA and Larger)SponsorRotating Machinery Committeeof theIEEE Power Engineering SocietyApproved June 3, 1976Reaffirmed Septembe

2、r 26, 1991IEEE Standards BoardApproved July 19, 1990Reaffirmed April 20, 1992American National Standards InstituteThe Institute of Electrical and Electronics Engineers, IncNo part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without theprior writ

3、ten permission of the publisher.iiWhen the IEEE Standards Board approved this standard on June 3, 1976, it had the following membership:William R. Kruesi, Chair Irvin N. Howell, Jr., Vice Chair Ivan G. Easton, Secretary William E. AndrusJean Jacques ArchambaultDale R. CochranWarren H. CookLouis Cost

4、rellJay ForsterJoseph L. KoepfingerIrving KolodnyBenjamin J. LeonAnthony C. LordiJohn P. MarkeyThomas J. MartinDonald T. MichaelVoss A. MooreWilliam S. MorganWilliam J. NeiswenderGustave ShapiroRalph M. ShowersRobert A. SodermanLeonard W. Thomas, Sr.Charles L. WagnerWilliam T. Wintringham DeceasedFo

5、rewordThis foreword is not a part of IEEE Std 56-1977, IEEE Guide for Insulation Maintenance of Large Alternating-Current RotatingMachinery (10 000 kVA and Larger).The present revision was prepared by a Working Group of the Insulation Subcommittee of the IEEE RotatingMachinery Committee. Working Gro

6、up personnel were:R. F. Sharrow, Chair J. M. BrownA. W. W. CameronE. B. CurdtsN.V. GjajaR.J. HillenW.J. SheetsA. W. ZwienerThe original document was prepared by a similar working group whose personnel were:G. L. Moses, Chair P. L. AlgerJ. S. AskeyL. J. BeberichO. D. ButlerE. B. CurdtsJ. F. DexterP.

7、A. EmmonsW. T. GordonG. L. HillW.R. HoughJ.W. JonesM.S. KerwenJ.L. KuehlthauH.C. MarcraftE.H. PoveyC.L. SidwayJ.B. SweringH.R. TomlinsonE.H. ToveeA.L. VanEmdenR.W. WiesemaniiiCLAUSE PAGE1. Purpose.12. Scope.13. Significance of Maintenance.14. Service Conditions Reducing Insulation Life .24.1 Thermal

8、 Aging . 24.2 Overtemperature. 24.3 Overvoltage. 24.4 Contamination. 24.5 Physical Damage. 24.6 Partial Discharge (Corona) Effects . 35. Insulation Systems in General Use .35.1 Insulated Parts. 35.2 Stator-Winding Insulation. 45.3 Rotor Winding Insulation. 45.4 Brush-Rigging Insulation. 55.5 Core an

9、d Frame-Assembly Insulation. 55.6 Stator-Winding, Embedded, Temperature-Detector Insulation . 56. Visual-Inspection Methods .56.1 Stator Windings. 56.2 Rotor Windings. 76.3 Brush Rigging . 76.4 Core Assembly. 77. Cleaning .97.1 General. 97.2 Cleaning Techniques. 98. Maintenance Tests.118.1 Stator Wi

10、nding . 128.2 Rotor Winding. 179. References.189.1 IEEE Standards . 189.2 ASTM Standard . 1910. Bibliography.19Annex A Test of Laminar Insulation in Stator Cores (Informative).23An American National StandardIEEE Guide for Insulation Maintenance of Large Alternating-Current Rotating Machinery (10 000

11、 kVA and Larger)1. PurposeThe purpose of this guide is to present information necessary to permit an effective evaluation of the insulationsystems of large alternating-current rotating electrical machines. Such an evaluation can serve as a guide to the degreeof maintenance or replacement which might

12、 be deemed necessary, and also offer some indication of the future servicereliability of the equipment under consideration.2. ScopeThis guide is intended to apply in general to large alternating-current rotating electrical machines rated at 10 000 kVAor more, and operating at voltages of 6000 V and

13、above.3. Significance of MaintenanceRotating electrical machines are complex structures which are subjected to mechanical, electrical, and thermal stressesof varying magnitude. Of the various components, the insulation systems are the most susceptible to aging or damagedue to these stresses. The ser

14、vice life of an electrical machine will, therefore, largely depend on the serviceability ofthe insulation systems.Where reliability is of concern, adequate inspection and testing programs are advocated to assure that the equipmentis maintained in satisfactory condition to minimize the possibility of

15、 in-service failure.The experience and data obtained from regular maintenance inspection and testing programs can, in addition toproviding an evaluation of the present condition of the equipment, give some indication of long-term trends andprobable need for future repair or replacement.The extent to

16、 which a maintenance program is pursued will depend largely on the operators own experience andphilosophy, but should also take into account the importance of service reliability of the equipment. Where highservice reliability is required, a regular maintenance program involving periodic disassembly

17、 and knowledgeablevisual examination of the equipment, together with the application of electrical tests of proven significance, is stronglyrecommended.2 Copyright 1998 IEEE All Rights ReservedIEEE Std 56-1977 IEEE GUIDE FOR INSULATION MAINTENANCE OFIt should be recognized that some overpotential te

18、sts may be damaging to insulation in marginal condition. Wherethere is uncertainty, consultation with the manufacturer is recommended. This is implicit in setting up anymaintenance testing program.4. Service Conditions Reducing Insulation LifeAs has been stated, electrical machines and their insulat

19、ion systems are subjected to mechanical, electrical, andthermal stresses which give rise to many deteriorating influences, the most significant of which are the following.4.1 Thermal AgingGradual aging caused by temperatures due to normal operating loads.4.2 OvertemperatureUnusually high temperature

20、 from causes such as overload, high ambient temperature, restricted ventilation, and loss ofcooling liquid.4.3 OvervoltageUnusually high voltage such as from switching or lightning surges.4.4 ContaminationThis deteriorates electrical insulation by actually conducting current over insulated surfaces,

21、 or by attacking thematerial reducing its electrical insulating quality or its physical strength, or by thermally insulating the materialforcing it to operate at higher than normal temperatures. Included here are:Wetness or extreme humidityOil or greaseConducting dusts and particlesNonconducting dus

22、ts and particlesChemicals of industry4.5 Physical DamageThis contributes to electrical insulation failure by opening leakage paths through the insulation. Included here are:Physical shockVibrationOverspeedUnusual electromagnetic forcesCopyright 1998 IEEE All Rights Reserved 3LARGE ALTERNATING-CURREN

23、T ROTATING MACHINERY IEEE Std 56-1977Erosion by foreign matterDamage by foreign objectsThermal cycling4.6 Partial Discharge (Corona) EffectsPartial discharges which may occur at higher operating voltages may be accompanied by several undesirable effectssuch as chemical action, heating, and ionic bom

24、bardment.5. Insulation Systems in General Use5.1 Insulated PartsInsulation is present in various machine components, but the complexity of the structure is such that only a generaldescription can be given here. However, detailed information on the structure of insulation systems and modes ofinsulati

25、on failure are important to evaluation.5.1.1 Stator Winding.The stator winding with its associated leads is the main current-carrying winding of the machine. The coils of the statorwinding have strands and ground insulation and may have turn insulation.Wedges, blocks, and other insulated mechanical

26、supports are a part of the stator winding assembly.5.1.2 Rotor Winding.The rotors of ac machines are either salient pole or cylindrical type. In all cases, they have turn and ground insulation,insulated mechanical supports, and lead insulation and may have collector rings with insulation.5.1.3 Brush

27、 Rigging.Machines with collector rings will have insulated brush rigging.5.1.4 Core Assembly.The principal insulation components in this assembly are the insulation between laminations in the core and insulationon through bolts (when used).5.1.5 Other Parts.Insulation is sometimes used on bearings a

28、nd other mechanical parts such as hydrogen seals, oil seals, and pipingTemperature sensors may be applied, and these usually incorporate insulation. Refer to the manufacturers instructionbook.4 Copyright 1998 IEEE All Rights ReservedIEEE Std 56-1977 IEEE GUIDE FOR INSULATION MAINTENANCE OF5.2 Stator

29、-Winding Insulation5.2.1 Strand Insulation.The individual strands of stator-coil conductors are usually insulated with organic films, fibers bonded with resins, ormica in various forms bonded with resins. Fibers may be such materials as paper, cotton, asbestos, glass, polyester, orcombinations there

30、of.5.2.2 Turn Insulation (Conductor).In a coil with more than one turn, groups of strands forming a single-turn (conductor) may be held together andinsulated. Individual strand insulation, as described in Section 5.2.1, may also serve as turn insulation.5.2.3 Ground Insulation.Ground insulation is g

31、enerally defined as that insulation intended to insulate the current-carrying components (such asthe coils, the collector rings, and connections thereto) from one another and from the noncurrent-carrying componentswhich are usually considered to be grounded (such as the core iron, the shaft, and oth

32、er structural members).Ground insulation takes on many different forms depending on the type of machine and the manufacturers practices.Ground insulation is generally a dry-type, multilayered system comprising various insulating materials bonded andfilled. Mica or micaceous products are generally pr

33、eferred in high voltage machines for at least a part of the ground-insulation system.5.2.4 Insulation Grading System.The surface of slot portions of stator coils, including several inches of the coil beyond the core, is normallysemiconducting. The semiconducting characteristic is accomplished by the

34、 application of conducting varnish or by theuse of semiconducting tapes.5.2.5 Support Insulation.Supports may be nonmetallic or metallic in design. Nonmetallic supports are made of insulating material such aswood, molded parts, or compressed laminates of cotton, asbestos, glass, or synthetic fibers.

35、 Where necessary, metallicsupports are insulated.5.3 Rotor Winding Insulation5.3.1 Turn Insulation (Conductor).Turn insulation on wire-wound coils usually incorporates a thin insulating layer on the strand itself: for example,various materials such as asbestos, cotton, fiberglass, papers, micas, and synthetic materials.Turn insulation on strap-wound coils of both salient-pole and cylindrical-type rotors usually incorporates variousforms of tape or strip mat