NEMA HV 2-2014 Suspension and Post Type Insulators for Electric Power Overhead Lines General Use Information.pdf

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1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA HV 2-2014Suspension and Post TypeInsulators for Electric Power Overhead Lines General Use InformationNEMA HV 2-2014 Suspension and Post Type Insulators for Electric Power Overhead Lines General Use Information Published by:

2、National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2014 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Berne Convention for

3、 the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. HV 2-2014 Page ii 2014 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by a consensus among persons e

4、ngaged in its development at the time it was approved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document h

5、erein is one, are developed through a voluntary standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. Although NEMA administers the process and establishes rules to promote fairness

6、in the development of consensus, it does not write the documents, nor does it independently test, evaluate, or verify the accuracy or completeness of any information or the soundness of any judgments contained in its standards and guideline publications. NEMA disclaims liability for any personal inj

7、ury, property, or other damages of any nature, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on this document. NEMA disclaims and makes no guaranty or warranty, express or implied, as to the accuracy

8、 or completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any particular purpose(s) or need(s). NEMA does not undertake to guarantee the performance of any individual manufacturers or sellers products or services by v

9、irtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services 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 do

10、cument should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance. Information and other standards on the topic covered by this publication may be available from other sou

11、rces, which the user may wish to consult for additional views or information not covered by this publication. NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test, or inspect products, designs, or installations for s

12、afety or health purposes. Any certification or other statement of compliance with any health- or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. HV 2-2014 Page iii 2014 National Electrical Manu

13、facturers Association FOREWORD This document is intended to provide guidelines for the proper use of insulators and to suggest precautions to be taken against improper usage that may not be readily apparent to the user. However, it is stressed that these are only guidelines and direct consultation b

14、etween the user and the manufacturer is recommended. This edition of the document is a revision of NEMA HV 2-1991. The need for this guide was indicated by the knowledge of customers experiences which manufacturers of suspension insulators gained over many years. Your comments are welcomed and shoul

15、d be submitted to: Senior Technical Director, Operations National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, VA 22209 Member Companies Hubbell Power Systems Columbia, SC K-Line Insulators USA Inc. Rochester, NY Lapp Insulators LLC LeRoy, NY NGK-Locke Virginia Bea

16、ch, VA MacLean Power Systems Fort Mill, SC Seves Canada Inc. Quebec, Canada Seves USA Spring, TX Victor Insulators, Inc. Victor, NY HV 2-2014 Page iv 2014 National Electrical Manufacturers Association TABLE OF CONTENTS Page FOREWORD iii 1 INTRODUCTION 1 2 MATERIALS 1 2.1 General 1 2.2 Chipping/Break

17、age/Tearing . 1 2.3 Abrasion . 1 2.4 Corrosion 2 2.5 High Frequency 2 3 HANDLING 2 3.1 General 2 3.2 Handling of Ceramic Insulators 2 3.3 Handling of Composite Insulators 2 4 FIELD INSPECTION 3 4.1 General 3 4.2 Inspection of Ceramic Insulators 3 4.3 Inspection of Composite Insulators 3 4.4 Tests be

18、fore Installation . 4 5 SUSPENSION TYPE INSULATOR INSTALLATION . 4 5.1 General 4 5.2 Coupling and Uncoupling . 4 5.3 Re-coupling 4 6 ELECTRICAL AND MECHANICAL RATINGS . 4 6.1 General 4 6.2 Electrical Ratings . 5 6.3 Mechanical Ratings 5 6.3.1 Ceramic Suspension Insulator Mechanical Rating 5 6.3.2 Ce

19、ramic Post Insulator Mechanical Rating 5 6.3.3 Analysis of Results for Ceramic Insulator Tests 5 6.3.4 Composite Suspension Insulator Mechanical Rating 6 6.3.5 Composite Post Insulator Mechanical Rating 6 6.3.6 Analysis of Results for Composite Insulator Tests 6 7 ROUTINE PROOF TESTS. 6 7.1 General

20、6 7.2 Ceramic Suspension Insulator Mechanical Proof Test . 6 7.3 Ceramic Post Insulator Mechanical Proof Test . 6 7.4 Composite Suspension Insulator Mechanical Proof Test . 6 7.5 Composite Post Insulator Mechanical Proof Test . 7 8 MECHANICAL SERVICE LOADS 7 8.1 General 7 8.2 Single Valued Line Load

21、s and Strengths 7 8.3 Variable Line Loads and Strengths . 8 8.4 Dynamic Loads . 9 8.5 Construction and Maintenance Loads 9 9 ELECTRIC FIELD CONSIDERATIONS FOR COMPOSITE INSULATORS 9 9.1 Background 9 9.2 Electric Field Modeling . 10 9.3 Full Scale Laboratory Tests 10 10 REFERENCES . 11 TABLE 1 Suspen

22、sion and Post Type Insulator Damage Limits. 9 HV 2-2014 Page 1 1 INTRODUCTION High voltage line insulators of essentially the same basic designs as those made today have been providing reliable service for many years. An even greater level of reliability can be attained by recognizing that insulator

23、s are both structural members and electrical apparatus and it is equally important that they be properly handled, stored, installed, and maintained. Suspension and post type insulators for electric power overhead lines are described and defined in the voluntary C29 series of American National Standa

24、rds 1-9. The sole purpose of these product standards is to define dimensions and tests as required to ensure the interchangeability in service of one manufacturers insulator with that of another for the same type and class insulator. Conformance of a given insulator to the mechanical and electrical

25、requirements of a particular standard, when subjected to tests as described in the standard, is intended to assist users in selecting their insulators. High voltage insulators are but one component of overhead electric lines and users are assumed competent in integrating them into their systems. Nec

26、essarily, not all conditions can be anticipated in a general discussion and the proper use of information offered here is the responsibility of the user. 2 MATERIALS 2.1 General Insulators as described in the C29 series of standards are of two types: Ceramic insulators which consist of wet-process p

27、orcelain or toughened glass dielectric materials assembled together with their associated metal components using cement. Ceramic materials are hard and non-ductile 2-4. Composite insulators which consist of reinforced fiberglass resin matrix core rods, elastomeric outer-housings, and their associate

28、d metal components. The core rod provides mechanical and electrical strength, and the elastomeric housing and weathersheds protects the core rod 6-9. For both types of insulators ferrous metal components are protected with a hot-dip zinc coating. The normal operating temperature range for ceramic an

29、d composite type high voltage insulators is -40F to + 150F. If application outside this range is contemplated, the manufacturer should be consulted for guidance. 2.2 Chipping/Breakage/Tearing Ceramic insulators have high impact strength, but the dielectric material can be broken unless care is exerc

30、ised in handling. When any section of the porcelain shell has been broken off, or the toughened glass is shattered, the user should discard the insulator. Composite insulator weathersheds can be torn or cut unless care is taken in handling. Insulators with minor tears in the perimeter of the weather

31、sheds can be used provided that no tear is present in the sheath protecting the fiberglass core rod 2.3 Abrasion Excessive abrasion causing roughening of the ceramic insulator surface, will reduce the ability of the insulator to shed pollutants. Abrasion of the surface of a composite insulator, expo

32、sing the core rod, can result in a loss of strength and should be considered as a cause for the user to remove the insulator from service. Metal end-fitting zinc coatings can also be damaged by excessive abrasion, exposing the base metal to corrosion. HV 2-2014 Page 2 2014 National Electrical Manufa

33、cturers Association 2.4 Corrosion Corrosive atmospheres or chemical agents may damage ceramic or composite insulators including their associated metal components. It is advisable to discuss applications in such atmospheres with the manufacturer. 2.5 High Frequency Ceramic suspension type insulators

34、are designed for use at power frequencies ( 100 Hz) and temporary over-voltages aside, are unsatisfactory for use at higher frequencies because of the increased power loss and possible internal heating of the dielectric. 3 HANDLING 3.1 General High voltage insulators are subject to a wide variety of

35、 handling procedures from initial shipment to installation on power lines. Differences in materials and construction between ceramic and composite type insulators dictate some differences in handling precautions. 3.2 Handling of Ceramic Insulators Ceramic insulators should not be dropped or thrown w

36、hile still in their containers or after being unpacked. Insulators that have been dropped should be inspected for damage. Porcelain insulators should be tested prior to installation for possible internal cracks and shattered toughened glass insulators should be discarded. Insulator strings made up o

37、f coupled ceramic suspension type insulators should not be subjected to excessive bending loads as deformation of either end-fitting could occur. Such damage, if undetected, may subsequently result in mechanical or electrical failure. In the case of ball-andsocket type end-fittings, bending may caus

38、e flattening or twisting of the cotter keys legs resulting in loss of the locking feature. Line personnel should not climb upon ceramic insulators in any manner. Insulators should not be used to support line construction apparatus unless the apparatus is specifically designed for that purpose, such

39、as stringing blocks with proper adaptors for attaching the blocks. Post type insulators should not be used to support ladders. Ceramic Insulators are not designed to support loads on the dielectric surfaces and may break under such loading and cause injury to personnel. 3.3 Handling of Composite Ins

40、ulators Judgment should be used in the storage of composite insulators. If the storage location is protected from the weather, they may be stored in their original shipping cartons. If stored outdoors, consideration should be given to the construction of the original carton. If the cartons will degr

41、ade in an outdoor environment, the insulators should be removed from the packing and stored in a manner that will keep them clean without causing undue deformation of the elastomeric housing. If the composite insulators are stored in their original shipping cartons, they may be transported in those

42、same cartons. If not, care should be taken during transport to avoid impacts or external loading that could tear the elastomeric housing or adversely load the core rods. Removal of the insulators from the packing HV 2-2014 Page 3 2014 National Electrical Manufacturers Association must be done in suc

43、h a manner as to not damage the elastomeric housing. In particular if the packing is cut open, care must be taken not to cut the housing. Composite insulators should be carried only by their end-fittings and should not be lifted by their elastomeric sheds. Caution must be taken to avoid excessive be

44、nding loads during handling. For longer insulators it may be necessary to provide additional support by cradles or slings around the core between adjacent weathersheds; in such cases extreme care should be exercised to avoid abrasion or damage of the housing material or the weathersheds. Composite i

45、nsulators should not be walked on, climbed on, or used to support line construction apparatus not specifically designed for that purpose. Composite insulators can be damaged during storage by rodents chewing parts of the sheds, and should this occur the insulators should not be placed in service. 4

46、FIELD INSPECTION 4.1 General Insulators should be individually inspected during line construction before they are installed to assure that harsh shipping or handling procedures have not damaged them. The insulators should again be inspected prior to line energization to guard against damage that may

47、 have been incurred during construction. 4.2 Inspection of Ceramic Insulators Insulators with chipped or cracked shells should be discarded and companion units in the same crate or pallet should be carefully examined. If handling abuse is indicated, all the units should be tested to assure their sou

48、ndness (see subsection 4.4). For suspension type ceramic insulators, the cotter keys of units with ball-and-socket type end-fittings should be individually inspected. All cotter keys should be pushed into their locking position in the cap socket. No twisting, flattening, or indention should appear,

49、as this indicates compressive, impact, or bending loads, for which the insulator is not designed, may have occurred. Any unit with such damage should be tested before installation. All damaged cotter keys should be replaced. Cotter keys deformed or left in the un-locked position, could allow uncoupling of the string of insulators during line erection or in service. For post type ceramic insulators, the surface of the trunk sections between the sheds should be examin