ANSI C29.11

ANSI

C29.11-1989

996)

American American National Standard

for Com posite Suspension Insulators for Overhead Overhead Transmission Lines Tests

Secretariat:

National Electrical Manufacturers Association Associ ation

1300 North 17th Street, Suite Suite 1847 Rosslyn, VA 22209

Copyright 2001 by the National Electrical Manufacturers Association. All rights including translation translation into other languages, languages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection Literary Literary and Artistic W orks, and the International International and Pa American C opyright Conventions.

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Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA

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NOTICE AND DISCLAIMER

The inform ation in this pu blication was considered techn ically 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 developm ent of th is document. The Nationa l Electrical Man ufacturers Association (NEM A) 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 have an interest in the topic covered by this publication. Wh ile NEMA adm inisters th e process and establishes rules to promote fairness in the developme nt of consensus, it does n ot write the document and it does not 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. NEM A disclaims liability for any pe rsonal injury, property, or other damage s of any nature whatsoever, 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, expressed or implied, as to the accuracy or completeness of any inform ation published herein, and disclaims and makes no warranty that the information in this document will fulfill any of your particular purposes or needs. NEMA does not undertake to guarantee the pe rformance of any individual manufacturer or seller’s products or services by virtue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render or on behalf of any person or entity, nor is NEMA professional or other services unde rtaking to perform any duty owed by any person entity to someone else. Anyone using this documen t should rely on his or her ow n indepe nden t judgm ent or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. Inform ation and other standards on the topic covered by this p ublication may be available fro m othe r sources, which the user may wis to con sult for additional views information not c overe d 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 safety or health purposes. Any certificatio or other statement of compliance with any health or safety-related information in this document shall no be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement.

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Approval of a n American National Stan dard requires verification by ANSI that the re quirements for d ue process, consensus, and o ther criteria for approval have been m et by the standards developer

American Nationa] Standard Consensus is established when, in t he judgment o f the ANSI Board of S tandards Review,

substantial agreement has been reached by directly and materially affected interes ts. Sub stantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. The use of American National Standard s is completely voluntary; their existence does no in any respect preclude anyo ne, whether he has approved the standards or no t, from man ufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Stand ard. Moreover, no person shall have the right or authority to issue an interpretation o f an American N ational Standard in th e name of t he American National Standards Institute. Requests for interpretations should be addressed to th e secretariat or sponsor whose name appears on th title page of this standard. CAUTION NOTICE: This American N ational Standard may be revise or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodicall to reaffirm. revise, or withdraw this standard. P urchasers of American National Standards may receive current information o n all standards by calling or writing th e American N ational Stan dards Institute.

Published by

American National Standards Institute 1430 Broadway, New York, Ne w Y ork

10018

Copyright 1989 by American National Standards institute, All rights reserved. No

part of this publication may be reproduced in any form,

an electron ic retrieval syste or otherwise, without the prior written permission of the publisher.

Printed in th e United States of America A5C1189112

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Foreword

(This oreword is not part of American National Standard C29.11-1989.)

This standard comprises a manual of procedures to be followed in making tests to determine the characteristics of insulators used on electric power systems. This ne American National Standard is not an insulator specification,but rather sets forth a test method to be used in conjunction with insulator specifications. American National Standard for Wet-Process Porcelain Insulators Composite Suspension Insulators for Overhead Transmission Lines Tests, ANSI C29.11-1989, was prepared by Accredited Standards Committee C29, which is in charge of this work. Suggestions for improvement of this standard will be welcome. They should be sent to the National Electrical Manufacturers Association, 2101 L Street, NW, Washington, DC 20037. This standard was processed and approved for submittal to ANSI by Accredited Standards Committee on Insulators for Electric Power Lines, C29. Committee approval of the standard does not necessarily imply that all members voted for its approval. At the time it approved this standard, the C29 Committee had the following members J. Nicholls, Chairman N. Spaulding, Vice-chairman

C. White, Secretary

Name

Organization Represented

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Representative

Association of American Railroads ....................................................... Representation Vacant) R. Brown Bonneville Power Administration ....................................................... Electric Light and Power Gro up .......................................................... R. Bush G. Cook A. Jagtiani J. Karcher W. K osakowski E. Marchbank Institute of Electrical and Electronics Engineers ................................ National Electrical Manufacturers Association ..................................

Stone Webster Engineering Corporation ........................................ U.S. Department of the Army (Liaison, with Vote) ...........................

offrin (Alt)

K. Labbe

Pinkham

N. Spaulding A. Baker J. Carter Harap R.Harmon B. Kingsbury J. Nicholls A. Schwaim H. Van Herk Zimmerman Davidson H. nyder

Individual Members

G. Amburgey J. Buchanan



Th C2 Working Group on Nonceramic Insulators, which was responsible for the development of this standard, had the follow ing members:

Robert Brown, Chairman

A. Akhtar H. Brown E. Chemey C. deTourrei

Karady B. Kingsbury J. Kise

Gaibrois Harap Harmon A. Jagtiani

J. Nicholls

Essig

A. Knotos

Lusk

R.Robarge E. Wheeler ` , , ` , ` , , ` , , ` ` , , , ` , ` ` , ` ` , ` ` ` , ` , , ` ` , ` , ` , ` , , ` -



Contents

PAGE

SECTION

Scope and Application................................................................................................ 1.1 Scope ................................................................................................................. 1.2 Application ....................................................................................................... Referenced and Related Standard ............................................................................. 2.1 Referenced American National Standards ........................................................ 2.2 Other Referenced Standard ............................................................................... 2.3 Related Amencan National Standard ............................................................... Definitions .................................................................................................................. 3.1 Insulators and Parts ........................................................................................... 3.2 Terms Related to Exposure ............................................................................... 3.3 Mechanical Terms .............................................................................................

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Classification f Tests ................................................................................................ 4.1 Prototype Tests ................................................................................................. 4.2 Design Tests ...................................................................................................... 4.3 Sample Tests ..................................................................................................... 4.4 Routine Tests .................................................................................................... Dimensions ................................................................................................................. Marking ...................................................................................................................... Prototype Tests ........................................................................................................... Tests on Interfaces and Connection of End Fittings ......................................... 7. Core Time-Load Test ........................................................................................ 7.3 Housing Tracking and Erosion Tes ................................................................. Core MaterialTest ........................................................................................... 7.

10

Design Tests ............................................................................................................... 8.1 Lightning Critical-ImpulseFlashover Test ....................................................... Alternating-VoltageRated Dry Flashover Test ................................................ 8.3 Switching Critical-Impulse Flashover Test ......................................................

10 10 11 11

Sample Tests ............................................................................................................... 9.1 Sample Selection............................................................................................... 9.2 Verification of Dimension ............................................................................... 9.3 Verification of the Locking System .................................................................. 9.4 Mechanical Load Tes ....................................................................................... 9.5 Galvanizing Test ............................................................................................... Retest Procedure for Sample Tests ................................................................... 9.

11 11 11 11 12 12 12

Routine Tests ......................................................................................................... 10.1 Mechanical Test ................................................................................................ 10.2 Visual Examination...........................................................................................

12

10

Figures Figure Figure

Copyright National Electrical Manufacturers Association Provided by IHS under license with NEMA No reproduction or networking permitted without license from I HS

Thermal Mechanical Test ........................................................................... Electrodes for High-Voltage Test ...............................................................


12

11

American National Standard

fo Co posite Suspen sion Insulator Ove rhead Transmission Lines Tests

1. Scop e and Applicatio

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1.1 Scope. This standard describes the tests to be prepared composite insulators for applications above 70kV, and defines the acceptance criteria for such tests. See 3.1.1 for the definition of composite insulator. All hitherto published American National Standards in the 29 series are for insulators made of wet-process porcelain or toughened glass. The standard includes definitions pertinent to composite insulators. It introduces a new category tests called prototype tests, designed to evaluate th materials and construction of composite insulators. Prototype tests are expected to be be performed on representative samples but ma be performed prior to the start of production. 1.2 Application. This standard is applicable to composite insulators used on transmission lines as suspension or tension insulators.

2.

Referenced an d Related Standards

2.1 Referenced American National Standards. This standard is intended to be used conjunction with the following American National Standards. When these standards are superseded by a revision approved by the American National Standards, Inc, the revision shall apply.

ANSI C29.1-1988, Electrical Power Insulators, Test Methods for ANSIDEEE 4- 1978, Techniques for High-Voltage Testing 2.2 Other Referenced Standard. This standard is also intended to be used in conjunction with Tests on Insulators of Ceramic Material or Glass for Overhead


Lines with Nominal Voltage Greater Than 1000 V, IEC 383-1983.' 2.3 Related American National Standard.- The standard listed here is for information only and is not essential for the completion of the requirements o this standard.

ANSIDEEE 100-1984, Dictionary of Electrical and Electronics Terms 3.

Definitions

NOTE: Definitions as given in this section apply specifically to the subjects treated in thi s standard. For additional definitions, see ANSIAEEE 100-1984.

3.1 Insulators and Parts composite insula3.1.1 Comp osite Insulator. tor is made of at least two insulating parts core and housing. It is equipped with end fittings. 3.1.2 Core. The core is the internal insulating part of a composite insulator. It is intended to carry the mechanical load. It consists mainly of glass fiber positioned in a resin matrix so as to achieve maximum tensile strength. 3.1.3 Housing. The housing is external to the core and protects it from the weather. It may be equipped with weathersheds. Some designs of composite insulators employ a sheath made of insulating material between th weathersheds and the core. This sheath is part of the housing. 3.1.4 Weathersheds. Weathersheds are insulating parts, projecting from the housing or sheath, intended to increase the leakage distance and to provide an interrupted path for water drainage. 3.1.5 End Fittings. End fittings transmit th me chanical load to the core. They are usually made o metal. 'Available from the American National Standards Institute.


3.1.6 Coupling Zone. The coupling zone is the part of the end fitting that transmits the load to the line, to the tower, or to another insulator. It does not include the interface between core and the end fitting. 3.1.7 Interfaces. An interface is the surface between different materials. Examples of interfaces in composite insulators are as follows: (1) Glass fiber/impregnating resin (2) Filler/polymer (3) Core/housing (4) Weathershed/weathershed (5) Weathershed/shea (6) Housinglend fittings (7 Core/end fittings 3.2 Terms Related to Exposure 3.2.1 Tracking. Tracking is the formation of electrically conducting paths starting and developing on the surface of an insulating material. These paths are conductive even under conditions. Tracking can occur on surfaces contact with air and also on the interfaces between insulating materials. 3.2.2 Treeing. Treeing is the formation of microchannels within the material. The microchannels ca be either conducting or nonconducting and can progress through the bulk of the material until electrical failure occurs. 3.2.3 Erosion. Erosion is nonconductive loss of material from the insulating surface. It can be uniform, localized, or tree-shaped. Shallow surface traces, commonly tree-shaped, can occur on composite insulators, as on ceramic insulators, after arcing. These traces do not affect the operating characteristics of the insulator. 3.2.4 Chalking. Chalking is a surface condition wherein some particles of the filler become apparent during weathering, forming a powdery surface. 3.2.5 Crazing. Crazing is the formation surface microfractures of depths up to 0. 3.2.6 Cracking. Cracking is any surface fracture of a depth greater than 0.1 mm. 3.2.7 Hydrolysis. Hydrolysis is a chemical process involving th reaction of a material with water in liquid or vapor form. It can lead to electrical or mechanical degradation. 3.3 Mechanical Term 3.3.1 Specified Mechanical Load (S.M.L.). The S.M.L. is load specified by the manufacturer that as to be verified during a Mechanical Load Test (see 9.4). It forms the basis for selection of an insulator. 3.3.2 Routine Test Load (R.T.L.). The R.T.L. is a rating equal 50% of the S.M.L.

4. Classification of Tests 4.1 Prototype Tests. The purpose of these tests is to verify the suitability of the prototype design, materials, and method of manufacture. The prototype tests are described in Section 7. When a composite insulator is submitted to the prototype tests, the results shall be considered valid for the whole class of insulators represented. class of insulators is defined as those: (1) Having a core and weathersheds of the same materials and method of manufacture (2) Having the end fittings of the same design, materials, and method of attachment to he core (3) Having the same or greater housing thickness (4) Having the same or smaller ratio f S.M.L. to the smallest core radial cross-sectional area between end fittings (5) Having the same core diameter The prototype test report shall include a drawing of the insulator tested, with dimensions. These dimensions shall at a minimum include those dimensions that define a class. To allow for subsequent manufacturing or design variations, the term “same” in 4.1(3), 4.1(4), and 4.1(5) may vary up to 15% before the prototype tests must be repeated. See Section 5 for tolerances on dimensions. 4.2 Design Tests. The purpose of these tests is to verify those characteristics of a composite insulator which depend on its size and shape. The requirements are given in Section 8. 4.2.1 Electrical Design. The electrical design of a composite insulator is defined y the followin characteris ics: (1) arcing distance (2) Leakage distance (3 Weathershed inclination (4) Weathershed diameter (5) Weathershed spacing The electrical design tests shall be performed only once on insulators of a specific electrical design. 4.2.2 Mechanical Design. The mechanical design of a composite insulator is defined by the following characteristics: (1) Core diameter (2) Method of attachment of the end fittings 4.3 Sample Tests. These tests verify the conformance of composite insulators to requirement given in Section 9. They are to be made on insulators taken at random from a production lot. 4.4 Routine Tests. These tests are for the purpos of eliminating insulators with manufacturing defects.

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AMERICAN NATIONAL STA NDARD C29.11-1989

They are to be made on every insulator according to the requirements of Section 10

5.

Dimensions

The following tolerances are allowed on all dimensions for which special tolerances do not apply. is the dimension in millimeters.

300 mm 300 mm with a 6) mm, when maximum tolerance of 50

? (0.04~ 1.5) mm when x

(0.02%

Marking ‘Each insulator shall be clearly and indelibly marked with the name or trademark of the manufacturer, the year of manufacture, the specified mechanical load (S.M.L.), and the routine test load (R.T.L.). The routine test load shall be identified by the word “TEST”.

7. Prototype Tests Prototype testing is done in four parts as described i Sections 7.1.7.2,7.3, and 7.4. Each part ay be performed independently on new test specimens. The test specimens shall pass the tests in each part in sequence. Prototype tests are to be performed only once for each class of insulator. The results shall be recorded in a test report. The test report shall constitute the evidence of successful completion of the prototype tests. Tests on Interfaces and Connectio of End Fittings 7.1.1 Test Specimen. Three insulators shall be tested. The insulation length (metal-to-metal spacing) shall be at least 800 in length to be valid for all lengths. If insulators less than 800 in length are tested, the tests are only considered valid for insulators up to the length tested. The end fittings and end weathershed geometry shall be representative o production insulators. The insulators shall be subjected to the mechanical test of 10.1 prior to testing. 7.1.2 Power Frequency Voltage Test. The dry power frequency flashover voltage shall be obtained by averaging five flashover voltages on each of the three test specimens. The flashover voltage shall be corrected to standard conditions in accordance with


ANSIDEEE 4-1978. The flashover voltage shall be reached within 1 minute by increasing he voltage linearly from zero. 7.1.3 Sudden Load Release Test. Each test specimen shall be subjected to five sudden load releases. The load shall be 30% the S.M.L. The insulator temperature shall be -2 C to -25°C. 7.1.4 Thermal Mechanical Test. The insulators shall be loaded at ambient temperature to at least 5% th S.M.L. for minute. During this time, the length of the insulators shall be measured. The measurement accuracy shall be at least 0.5 mm. This will be th reference length. The insulators shall be submitted to thermal variations from -35’C o +50’C while under a permanen mechanical load of 0.5 S.M.L. shown in Figure The time at each temperature shall be at least hours per cycle. The tests may be conducted in suitable medium. the end of thermal cycling, the insulators shall allowed to reach ambient temperature and the length shall again be measured using th same load as for the reference length. NOTE: The test may be nterrupted for maintenance for a total duration of hours.

7.1.5 Water Penetration Test. The test specimens shall be kept immersed in boiling tap water for 42 continuous hours. the end of boiling, the insulators shall remain in the vessel until the water cools to approximately 50’C. This temperature shall be maintained until the verification tests start. 7.1.6 Verification Tests. The verification tests consist of the sequence of tests described in 7.1.6.1 through 7.1.6.3, and are used to verify that the insulators have not been damaged by the previous tests. They shall all be completed within 48 hours. 7.1.6.1 Visual. The housing shall be inspected visually. No cracks are permitted. 7.1.6.2 Steep Front Impulse Voltage Test The test specimens shall be fitted with a sharp-edged electrode. The electrode shall consist of a clip made a copper strip approximately 20 wide and less mm than 1 thick. The electrode shall lie firmly on the housing between the weathersheds forming two approximately equal test sections. If the test specimens have an insulating length equal to or less than 50 no clip is necessary; the voltage may be applied between end fittings. n impulse voltage with a front steepness at least 1000 kV/microsecond shall be applied to each test section. Each test section shall stressed with 25 impulses of positive and 25 impulses of negative polarity. Each impulse shall cause an external flashover of the test section. No puncture shall occur.


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R.T.L. S.M.L.)

(2 0.

71 I

TIME IN HOURS

AIR TEMPERATURE

TIME IN HOURS

THERMAL TEST CYCLES

Figure Thermal Mechanical Test

Following the test, the electrode used to form test sections shall be removed. 7.1.6.3 Power Frequency Voltage Test. The power frequency flashover voltages shall be determined once more for each specimen using the procedure given in 7.1.2. The average flashover voltage for each test specimen shall be at least 90% of the value determined in 7.1.2. Each test specimen shall be individually subjected to 80% its average flashover voltage as determined in 7.1.2. The voltage shall be maintained for 30 minutes. puncture shall occur and the temperature of the shank measured immediately after the test shall not be more than 20'C above ambient. Core Time-Load Test 7.2.1 Test Specimen. Six insulators shall be tested. The insulation length (metal-to-metal spacing) shall not be less than 800 mm or the longest length to be manufactured, whichever is less. The end fittings shall have a grip to the core that is representative of production insulators, but the coupling zone may be modified to avoid failure o th end fittings. 7.2


7.2.2 Determination of the Average Failing Load of the Core. Three of the test specimens shall tested in tension. The tensile load shall be increased rapidly but smoothly from to 75% of the expected mechanical failing load, and then shall be gradually increased to failure in a time of 30 to 90 seconds. Failure shall be by fracture or complete pull-out of the core. Failure an end fitting within the coupling zone shall require testing of additional test specimens until three core failures (fracture or complete pull-out) are obtained. 7.2.3 Core Time Load Test. Three test specimens shall be subjected to a tensile load of 60% of the average failing load obtained in 7.2.2. This load shall be maintained for 96 hours without failure.

Housing Tracking an d Erosion Test Test Specimen. Two insulators or tes specimens shall be tested. The specimen length shall be chosen such that the leakage distance falls between 484 and 692 mm The applied voltage shall be equal to the value obtained by dividing he leakage distance of the test specimen by 34.6, with 7.3

7.3.1


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AMERICAN NATIO NAL STANDA RD C29.11-198

he result expressed in kV.The test specimen shall be fitted with end fittings representative of those used in

production. 7.3.2 Test Chamber. The volume of the test chamber shall not exceed 10 cubic meters. An aperture of not more than 80 square centimeters shall be provided for natural exhaust air. turbo sprayer or room humidifier of constant spraying capacity shall be used as the water atomizer. It shall not spray directly onto the test specimen. The contaminant shall be sodium chloride (NaCl) and deionized water. The maximum voltage drop permitted is 5% when the test circuit is loaded with a resistive current o 25 root-mean-square (r.m.s.) current of 1 ampere r.m.s. shall cause an overcurrent trip-out. The test specimen shall be cleaned with deionized water before starting the test. One test specimen shall be tested vertically and one test specimen tested horizontally. There shall be a clearance of at least 20 mm between th roof of the chamber and a test specimen and a clearance of at least 100 between the walls and a test specimen. 7.3.3 Test Conditions. The following conditions shall.be maintained for a 1000-hour duration of th test: Water flow rate Size of droplets Temperature NaCl content of water

f O . 1 (See Note 1) to 10 20'C 'C 10 kg/m3 .5 kg/m3

NOTES: 'Th e water flow rate is.defined in liters per hour per cub ic meter volume of the test chamb er. The water may not be recirculated. 'Interruptions for inspection purpo ses shall not be counted in the test duration. Each in terrup tion shall not exceed 15 minutes.

7.3.4 Evaluation. No more than three overcurrent trip-outs are allowed. No tracking is allowed. N weathershed punctures are allowed. Erosion is not allowed to reach the core. 7.4 Core Material Tests 7.4.1 Dye Penetration Test 7.4.1.1 Test Specimen. Ten samples shall be cut from an insulator. The housing material may be removed from th core but removal is not mandatory The length of th samples shall be 10 mm. They shall be cut 90 degrees to the axis of the core with a diamond-coated circular saw blade under cool running water. The cut surfaces shall be smoothed with a 180-grit abrasive cloth. The cut ends shall be clean and parallel. 7.4.1.2 Test. The samples shall be placed on layer of steel or glass balls in a glass vessel with the

fibers vertical. The balls shall be of the same diameter and in the range of to mm The dye, composed of 1 gram fuchsin in 100 grams of methanol is poured into the vessel until its level is mm to 3 above the top of the balls. 7.4.1 3 Evaluation. The time for the dye to rise throug th samples by capillarity shall be more than 15 minutes. 7.4.2 Water Diffusion Test 7.4.2.1 Test Specimen. Six samples shall be cut from an insulator. The housing material may be removed from the core, but removal is not mandatory. The length of the specimens shall be 30 mm 0. mm oval is not mandatory. The length of the 0.5 mm. They shall be cut samples shall be 10 90 degrees to the axis of the core with a diamondcoated circular saw blade under cool running water. The cut surfaces shall be smoothed with a 180-grit abrasive cloth. The cut ends shall be clean and parallel. 7.4.2.2 Prestressing. The surfaces of the specimens shall be cleaned with isopropyl alcohol and filter paper immediately before boiling. The specimens shall be boiled in deionized water with 0.1% by weight NaCl in a glass container for 100 hours .5 hours. Only one core material may be boiled at one time. After boiling, the specimens shall be removed from the salt water and placed into tap water in a glass container at room temperature for at least 15 minutes. The following test shall begin within 3 hours of removal of the specimens from the salt water. 7.4.2.3 Test. The test arrangementis shown in Figure 2. Immediately before the test, the specimens shall be removed from the water and their surfaces dried with filter paper. The specimens shall be placed between the electrodes and the voltage increased at a kV

12 kV where it shall remain for 1 minute. 7.4.2.4 Evaluation. No puncture or surface flashover is allowed. The current during the whole test shall not exceed 1 mA r.m.s

8.

Design Tests

Design tests ar performed on full insulators. 8.1 Lightning Critical-Impulse Flashover Test. This test is to be performed on one insulator in accordance with ANSIDEEE 4-1978. The specimen mounting shall be in accordance with 3.1 of ANSI C29.1-1988, except that the upper surface of the

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AMERICAN NATIONAL STANDA RD C29.11-1989

VOLTAG ELECTRODES MADE OUT OF BRASS

50 64

30

NOTE: For samples large diameters, the diameters of the electrodes must increased. Th e diam eter of th elect~od*smust be at least 20 reater than that of the samples.

Figure Electrodes for High-Voltage Test energized electrode shall be 10 to 200 connection point of the lower end fitting.

from the

8. Alternating-Voltage Rated ry Flashover Test. This test is to be performed on one insulator in accordance with ANSIDEEE 4-1978,2.3.3.2. The specimen mounting shall be in accordance with 3.1 ANSI C29.1-1988, except that the upper surface of the energized electrode shall be 100 to 200 mm from th connection point of the lower end fitting. 8.3 Switching Critical-Impulse Flashover Test. This test is to be performed only when the intended service voltage is in excess of 300 kV phase-tophase. It is to be performed on one insulator in accordance wit 2. of ANSI/IEEE 4-1978. The specimen mounting shall be in accordance with 18.1.3 or 18. 383-1983.

9. Sample Tests Sample Selection. The insulators shall be selected from the lot at random. The purchaser has the

9.

right to make the selection. The insulators shall be subjected to the applicable sample tests. Tests Verification of dimensions Verification of locking system Mecha nical load tes Galvanizing test

Number Samples 7

In the event of a failure of the sample to satisfy a test, the retest procedure 9.6 shall be applied. 9. Verification Dimensions. The insulators in the sample shall be checked for dimensions against th dimensions on th manufacturer’sdrawing. If tolerances are not given on the drawing, the tolerances given in Section shall apply. 9. Verification the Locking System. For ball and socket insulators, the specified samples shall be tested for disengagement force of th cotter key. It shall be between 111 and 667 newtons force for three locking-to-unlockingoperations.

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AMERICAN NATIONAL STANDAR D C29.11-i98

Mechanical Load Test. The sample insulators shall be subjected to a tensile load that shall be increased rapidly but smoothly from zero to 75% of the S.M.L. and then gradually be increased to the S.M.L. in a time between 30 and 90 seconds. If 100% of th S.M.L. s reached in less than 90 seconds, the load shall be sustained at S.M.L. or the remainder of the 90 seconds. The test is passed if no failure occurs. The load shall then be increased until the insulator fails. The failure load shall be recorded. The historical failure loads shall justify the manufacturer’s choice of S.M.L.

9.4

Galvanizing Test. The specified size of sample shall be tested in accordance with Section of ANSI C29.1-1988. Five to ten measurements shall be uniformly and randomly distributed over the entire surface. Both the average thickness value for each individual specimen and the average of the entire sample shall equal or exceed the following: 9.5

Average of Entire Sample (mil) Hardware ( ex ce p t n u t s h l t s Nutshlts

3.4

Average Individual Specimen (mil) 3. 1.

Retest Procedure for Sample Tests. If only one insulator or metal part fails to comply with the requirements of a sample test, a new sample equal to twice the quantity originally submitted to that test shall be subjected to retesting. The retesting shall comprise the test in which failure occurred, preceded 9.6

by those tests that may be considered as having influenced the results of the original test. If two or more insulators or metal parts fail to comply with of the sample tests or if any failure occurs during the retesting, the complete lot is considered no complying with the standard and shall be withdrawn for examination by the manufacturer. The number then selected shall be three times the first quantity chosen for tests. The retesting shall comprise the test in which failure occurred, preceded by those tests that may be considered as having influenced the results of the original test. If any insulator fails during the retesting, the complete lot is considered as not complying with this standard.

10.

Routine Tests

Routine tests are to be performed on every insulator produced. 10.1 Mechanical Test. Every insulator shall withstand for at least seconds a tensile load equal to or greater than the R.T.L. rating. Visual Examination. The mounting of the metallic parts shall be in conformance with the manufacturer’s drawing. The color of the insulator shall be approximately as specified the drawing. The following imperfections shall acceptable on he insulator surface: Superficial defects of area less than 25 square millimeters (the total defective area not to exceed 2% of the total insulator surface) and depth less than mm 10.2

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12



ANSI C29.11

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