Cei Iec 62231 Edition 1.0 (2006-02) 5m1913

NORME INTERNATIONALE INTERNATIONAL STANDARD

cEr rEc 62231 PremiCre edition Firstedition 2006-02

lsolateurss compositesrigides d socle destin6saux postesi courant alternatif de tensions sup6rieuresa 1 000 V jusqu'd 245 kV D6finitions,m6thodesd'essaiet critdres d'acceptation Compositestation post insulatorsfor substations with a.c. voltagesgreaterthan 1 000 V up to 245 kV - Definitions,test methodsand acceptancecriteria

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NORME INTERNATIONALE INTERNATIONAL STANDARD

c El

rEc

62231 Premidre6dition First edition 2006-o2

lsolateurss compositesrigides d socle destin6saux postesi courantalternatif de tensionssup6rieuresA 1 000 V jusqu'd 245 kV D6finitions,m6thodesd'essaiet critdres d'acceptation Gompositestation post insulatorsfor substations with a.c. voltagesgreaterthan 1 000 V up to 245 kV - Definitions,test methodsand acceptancecriteria

Num6ro de r6f6rence Referencenumber cElllEC 62231:2006

62231 @ IEC:2006

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CONTENTS FOREWORD..... TNTRODUCTION

..........-.-.7 '.'.'......11

I

4 5 o

7

10

1'l

...'.....'.'...""'-'53 Annex A (informative)Noteson the mechanicalloadsand tests ... ............... Annex B (informative) Determinationof the equivalentbending moment caused by .. . . .....'."57 combinedcantileverand compression(tension)loads.......'.....-... ...'. ....""'61 Annex C (informative)Exampleof torsionload test arrangement ...'.'.'."""" 63 Annex D (normative)Tolerancesof form and position............. .'" ""69 Annex E (informative)Noteson the compressionand bucklingtest..'...............'...""" Bibliography......

.." """71

62231@ IEC:2006 pre-stressing Figure1 - Thermal-mechanical test- Typicalcycles.......................................51 Figure8.1 - Combinedloadsappliedto stationpost insulators... ................59 FigureD.1- Parallelism, coaxiality and concentricity...... ............................63 'l FigureD.2- Angulardeviation of fixingholes;Example ........,............................................65 FigureD.3- Angulardeviation of fixingholes:Example 2.....................................................65 FigureD.4 - Tolerancesaccordingto standarddrawingpractice .................67 Tabfe1 - Teststo be carriedout afterdesignchanges. Table2 - Numberof samplesfor sampldtests...-..............

."............................27 ..........................45

-7 -

62231 @ IEC:2006

IN T E R N A T ION A E L L ECTROTECHNICAL COMM ISSION COMPOSITESTATIONPOST INSULATORSFOR SUBSTATIONS WITI{ AC VOLTAGES GREATER THAN IOOOV UP TO 245 KV DEFINITIONS,TEST METHODSAND ACCEPTANCEGRITERIA FOREWORD 1) The lnternationaiElectrotechnicalCommission(lEC) is a worldwideorganizationfor standardizationcomprising all national electrotechnical committees (lEC National Committees). The object of IEC is to promote internationalco-operationon all questionsconcerningstandardizationin the electricaland electronicfields. To this end and in addition to other activities, IEC publishes InternationalStandards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as "lEC Publication(s)").Their preparationis entrustedto technicalcommitteesiany IEC NationalCommitteeinterested in the subject dealt with may participate in this preparatory work. International,governmental and nongovernmentalorganizationsliaisjng with the IEC also participatein this preparation.IEC collaboratesclosely with the International Organizationfor Standardization(lSO) in accordance with conditions determined by agreementbetween the two organizations. 2) lhe formal decisionsor agreementsof IEC on technicalmatters expresl, as nearly as possible,an international consensus of opinion on the relevant subjects since each technical committee has representationfrom all interestedIEC NationalCommittees. 3) IEC Publicationshave the form of recommendationsfor internationaluse and are accepted by IEC National Committees in that sense. While all reasonableefforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpfetationby any end . 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence betwoen any IEC Publicationand the correspondingnationaior regionalpublicationshall be clearly indicatedin the latter. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipmentdeclaredto be in conformitywith an IEC Publication. 6) All s should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors,employees,servants or agents including individualexperts and of its technical committeesand IEC NationalCommitteesfor any personal injury, propertydamage or other damage of any nalure whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative referencescited in this publication.use of the referencedpublicationsis indispensablefor the correct applicationof this publication. 9) Attention is drawn to the possibilitythat some of the elements of this IEC Publicationmay be the subject of patent rights. IEC shall not be held responsiblefor identifyingany or all such patent rights.

InternationalStandardIEC 62231 has been preparedby subcommittee36C: Insulatorsfor substations, of IECtechnicalcommittee36: Insulators. Thisbilingual version(2006-04) replaces the Englishversion. The text of this standardis basedon the followinodocuments: FDI S

36Ci159/FDtS

Reporton voting 36Ci160/RVD

Full informationon the voting for the approval of this standard can be found in the report on voling indicated in the above table. The French version of this standard has not been voted uoon. This publicationhas been drafted in accordancewith the ISO/IEC Directives,Part 2.

'f

62231@ IEC:2006

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This standard is to be read in conjunctionwith IEC 62217:2005,Polymeric insulators for indoor and outdoor use with a nominal voltage >1 000 V - Generaldefinitions,test methods and acceDtancecriteria. The committeehas decidedthat the contentsof this publicationwill remainunchangeduntil the maintenanceresult date indicatedon the IEC web site under "http://webstore. iec.ch"in the data relatedto the specifiublication. At this date,the publication will be . . . .

reconfirmed; withdrawn: replacedby a revisededition,or amended.

62231 @ IEC:2006

INTRODUCTION Composite station post insulators consist of a cylindrical solid insulating core made of resin impregnated fibres, bearing the mechanical load, protected by an elastomer housing, the loads being transmitted to ihe core by metal fittings. Despite these common features, the materials used and the construction details employed by different manufacturers may be d ifferent. Some tests have been grouped together as "design tests" to be performed only once for insulators of the same design. The design tests are performed in order to eliminate insulator designs, materials and manufacturingtechnologiesnot suitable for high-voltageapplications. The lnfluence of time on the electrical and mechanicalpropertiesof the complete composite station post insulator and its components (core material, housing material, interfaces, etc.) has been considered in specifying the design tests in order to ensure a satisfactorylifeiime under normal service conditions. The approachfor mechanicaltesting under bendingloads used in this Standardis based on IEC 61952+Thisapproach uses the concept of a damage limit that is the maximum stress that can be developed in the insulator before damage begins to occur. Work is underway to. validate the acoustic emission techniqueto delerminethe inptionof damage.:' In some cases, station post insulatorscan be subjectedto a combinationof loads. In order to give some guidance,Annex B explains how to calculatethe equivalentbending moment in the insulatorsresultingfrom the combinationof bending,tensileand compressionloads. Polluiiontests, as specifiedin IEC 60507 and IEC 61)45, are not includedin ihis document, their applicabilityto composite station post insulatorshaving not been proven. Such polluiion tests performed on composite insulators do not correlate with experience obtained from service. Specific pollutiontests for compositeinsulatorsare under consideration. It has not been considered useful to specify a power arc test as a mandatorytest The test parameters are manifold and can have very different values depending on the configurations of the network and the s and on the design of arc-protectiondevices. The heating effect of power arcs should be considered in the design of metal fittings. critical damage to the metal fittings, resultingfrom the magnitudeand durationof the short-circuitcurrent can be avoided by properly designed arc-protection devices. This standard, however, does not exclude the possibility of a power arc test by agreement between the and the manufacturer. IEC 61467 gives details of a.c. power arc testing of insulatorsets.

lmpulse (mechanical)loads in substationare typically caused by shorl-circuits.Postr insulators'are affected by forces due' torihe interactionof the currents circulatingin edby insulators.' conductors/busbars The impulse load or peak load may be evaluatedusing guidancefound in the IEC 60865 serieg.

62231 @ IEC:2006

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Work is in progressin CIGREESCQ(Effectsof Short-Circuit Currents)task fqrc{to review impulseloads caused by short-circuitcurrentsin substations.The aim of tlfis work is to introducea new concept:the ESL factor (EquivalentStaticLoad fact6fi which is frequency dependent.The actualpeak load may be replaced,in a first approximation, by the peak load times the ESL factoF.This new value may be used as the MDCEin lhis documentfor the determination of the cantileverstrenoth. Radio interferenceand corona tests are not soecifiedin this standardsince the radio interference and coronaperformances are not characteristics of the insulatoralone. Compositehollowcore stationpost ingulatorsare currentlynot dealt with in this standard. IEC 61462gives detailsof tests on hollowcore compositeinsulators,many of whichcan be appliedto suchstationpost insulators.

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FORSUBSTATIONS STATIONPOSTINSULATORS COMPOSITE V UP TO 245 KVWITHAC VOLTAGESGREATERTHAN1 OOO AND ACCEPTANCE CRITERIA DEFINITIONS, TESTMETHODS

1

Scope and object

This International Standardappliesto compositestationpost insulatorsconsistingof a load fibres,a housing(outside bearingcylindricalinsulatingsolid core madeof resin impregnated and the insulatingsolidcore)madeof elastomermaterial(e.9.siliconeor ethylene-propylene) end fittingsattachedto the insulatingcore. Composilestationpost insulatorscoveredby this standardare subjectedto cantilever,torsion, tension and compressionloads. They are with a.c.voltagesgreaterthan 1 000 V up to 245 kV. intendedfor substations The objectof this standardis -

to definethe used, to orescribetest methods, to prescribeacceptance or failurecriteria.

dealingwith the choiceof insulatorsfor specific This standarddoes not includerequirdments conditions. operating 2

Normative references

for the applicationof this document. The followingreferenceddocumentsare indispensable the latestedition only the editioncitedapplies.For undatedreferences, For datedreferences, (including anyamendments) applies. of the referenced document IEC 60050-471, lnternationalElectrotechnicalVocabulary(IEV)- Chapter471: lnsulators IEC 60060-1,High-voltagetest techniques- Part 1: Generaldefinitionsand test requirements IEC 60168:1994,Iesfs on indoorand outdoorpostinsulatorsof ceramicmaterialor glassfor sysfemswith nominalvoltagesgreaterthan 1 000 V IEC 62217, Polymericinsulators for indoor and outdoor use with a nominal voltage greater than 1000 V - Generaldefinitions.test methodsand acceptancecriteria ISO 1101, Technicaldrcwings- Geometricaltolerancing- Tolerancingof form, orientation, locationand run-out- Generalities,definitions,symbols,indicationson drawings fSO 3452, Non-destructivetesting- Penetrantinspection- Generalprinciples

62231 @ IEC:2006

3

- 't7-

and definitions

Forthe purposesof this document,the followingand definitionsapply. 3 .1 compositestation post insulator postinsulator consisting of a solidloadbearingcylindrical insulating core,a housingand end fittingsattachedto the insulatingcore 3.2 cord (of an insulator) centralinsulatingpartof an insulatorwhichprovidesthe mechanical characteristics NOTE Thehousingand shedsare not partof the coie.

IEV 47 1 - 01-031 3.3 housing externalinsulatingpart of compositeinsulatorprovidingnecessarycreepagedistanceand protectingcorefrom environment NOTE An intermediatesheath made of insulatingmaterialmay be part of the housing.

ilEV471-01-091 3.4 housing pr ofile shape and dimensionsof the housingof the composite following: - shed overhang(s) - shed thicknessat the base and at the tip - shed spacing - shed repetition - shed inclination(s)

oost insulatorwhich includethe

3.5

shed (ofan insulator) insulatingpart,projectingfromthe insulatortrunk,intendedto increasethe creepagedistance. The shedcan be with or withoutribs !EV 47 1 - 01-151 3.6 insulatortrunk centralinsulatingpartof an insulatorfromwhichthe shedsproject NOTE Also known as shank on smaller insulators.

ltEv 471-01-111 3.7 creepagedistance shortestdistanceor the sum of the shortestdistancesalong the surfaceon an insulator betweentwo conductivepartswhichnormallyhavethe operatingvoltagebetweenthem NOTE 1 lhe surface of cement or of any other non-insulatingting materialis not consideredas forming part of the creepagedistance.

62231 @ IEC:2006

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NOTE 2 lf a high resistance coating is applied to parts of the insulating part of an insulator, such parts are consideredto be;ffective insulatings-urfacesand the distanceover them is includedin the creepagedistance.

ilEV471-01-041 3 .8 arcing distance shortestdistancein air externalto the insulatorbetweenthe metalliarts which normally havethe operatingvoltagebetweenthem IEV 4 7 1 - 0 1-011 NOTE The term "dry arcing distance"is also used

3.9 interfaces surfacebetweenthe differentmaterials NOTE Various interfacesoccur in most compositeinsulators'e.g. -

between housing and fixing devices,

-

between various parts of the housing,e.g. betweensheds, or betweensheath and sheds, between core and housing.

ltEc 622171 3.10 end fitting inlegral componentor formed part of in insulatorihtendedto connect it to a ing structure,or to a conductor,or to an itemof equipment,or to anotherinsulator NoTE

Where the end fitting is metallic,the term "metal fitting" is normallyused.

EV 471-01-06,modifiedl 3.11 connection zone zone where the mechanicalload is transmittedbetweenthe insulatingbody and the end fitting llEC 622171 3.12 coupling part of the fixing device which transmits load to the hardwareexternal to the insulator IIEC 622171 3.13 tracking orocesJ which forms irreversible degradation by formation of conductive paths (tracks) starting and developingon the surface of an insulatingmaterial NOTE These oaths are conductiveeven under dry conditions.

ltEc 622171

62231@ IEC:2006 ?.14 erosion irreversibleand non-conductingdegradationof the surface of the insulatorthat occurs by loss of materialwhich can be uniform.localizedor tree-shaDed NOTE Lightsurface traces,commonly tree-shaped, canoccuron composite insulators as on ceramic insulators,

after partialflashover.Thesetracesare not considered to be objectionable as long as they are non-conductive. Whentheyare conductive they are classified as tracking.

IIEC 622171 3.15 delamination (of the core) loss of bonding between fibres and matrix 3.16 crack any internal fracture or surface fissure of depth greater than 0,1 mm

ltEc 622171 3.'17 specified cantilever load SCL cantilever load which can be withstood by the insulator when tested under the prescribed conditlons 3.18 maximum design cantilever load MDCL cantilever load level above which damage to the insulatorbegins lo occur and that should nonf be exceeded in service 3.19 specified torsion load SToL torsion load level which can be withstood by the insulator when tested under the prescribed conditions 3.20 maximum design torsion load MDToL torsion load level above which damage to the insulatorbegins to occur and that should not be exceeded in service 3.2'l specified tension load STL tension load which can be withstood by the insulator when tested under the prescribed conditions 3.22 maximum design tension load MDTL tension load level above which damaoe to the insulatorbeoins to occur and that should not be exceeded in service

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3.23 specified compression load SCoL compression load which can be withstood by the insulator when tested under the prescribed conditions 3.24 buckling load compressionload that induces bucklingof the insulatorcore 3.25 maximum design compression load MDCoL load level above which damage to the insulator begins to occur and that should not be exceeded in service 3.26 failing load (of a compositestation post insulator) maximum load that is reached when tested under the orescribedconditions NOTE Damage to the core is likely to occur at loads lower than the insulatorfailing load.

3.27 overallIength distancefromflangefaceto flangeface of the end fitting 3.28 puncture(of an insulator) permanentloss of dielectricstrengthdue to a disruptivedischargeingthroughthe solid insulating material of an insulator ltEv 471-01-141 3.29 residual deflection the differencebetweenthe initialdeflection,if any,of the tip of the insulatormeasuredpriorto cantileverloadapplicationand the final deflectionmeasuredafterloadrelease NOTE The residual deflection may depend on the duration of applicationof the load and on the time duration betweenthe load release and the measurementof the deflection.

3.30 residualangulardisplacement. the differencebetweenthe initial angulardisplacement, if any, of one of the insulatorend fitting with respectto the other insulalorend fitting measuredpriorto the applicationof the torsionloadandthefinalangulardisplacement measured aftertorsionloadrelease NOTE The residual angular displacementmay depend on the duration of applicationof the torsion load and on the time duration betweenthe torsion load release and the measurementof the displacement.

4

ldentification

The manufacturer'sdrawing shall show the relevant dimensions and values necessary for identifying and testing the insulator in accordancewith this standard. The drawing shall also show applicablemanufacturingtolerances.In addition,the relevant IEC designation,when available,shallfigureon the drawing.

62231 @ IEC:2006

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Each insulator shall be marked with the name or trademark of the manufacturerand the year of manufacture.In addition, each insulatorshall be marked with ai least the Maximum Design CantileverLoad (NIDCL)(example:MDCL: 4 kN) or, when available,with the relevant IEC designation.These markingsshall be legibleand indelible. postinsulators. givingdesignations NOTE At present thereis no IECstandard of composite station

5

Environmentalconditions

See descriDtionin IEC 62217.

6

Informationon transport, storage and installation

See descriptionin IEC 62217.

7

Classificationof tests

The tests are divided into four groups as follows: 7.'l

Design tests

These tests are intended to the suitabilityof the design, materials and manufacturing technology(see Annex A for notes on the concept of damage limit). A compositestation post insulatordesign is defined by -

materialsof the core, housing and manufacturingmethod;

-

material of the end fittings, their design and method of attachment;

-

layer thickness of the housing over the core (includinga sheaih where used);

-

diameter of the core.

When changes in the design occur, re-qualificationshall be done accordingto Table 1.

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62231 @ IEC:2006

Table 1 - Tests to be carried out after design changes lF the insulatordesign changes the..

THEN the followingdesign tests shall be repeatedl

8.2

(!9,^ @xi ;

8.3

8.4

9o

6

I

X

X

Housingmaterials

8.4

8.4

8.5

= .o

E

E

;i : 6( !

<;

X

8.5

,a

3s

;9!

<6

8.4

X

o=

EF

ig

X

2

Housingprofile 1)

3

Core material

X

X

X

4

Core diameter

X

X

X

X X

5

M anufa c tu ri n g p ro c e s s ,Ab r' W

X X X,.

X X X X

X

X

X

End fitting material 7a

End fitting connectionzone design ^/,"(^_

7b

End fitting coupling design

7c

Core-housing-endfitting interfacedesign

8

End fittino method of attachmentto core

X X

X

X

X

X

1) The followingvariationof the housing profilewithin followingtolerancesdo not constitutea changel Spacing:

!10 Vo

Diameter:

! 10 % +15 o/o,-0 o/o

IVIeaninclination:

t3"

Thicknessat base and tipr

i15 %

Shed repetitionr

identical

Overhang:

When a composile station post insulator is submittedto the design tests, it becomes a parent insulatorfor a given design and the results shall be consideredvalid for that design only. This tested parent insulator defines a particular design of insulators which have all the following characleristics: a) same materialsfor the core and housingand same manufacturingmethod; b) same material of the fittings, the same design, and the same method of attachment; c) same or greater minimum layer thickness of the housing over the core (includinga sheath where used)within a toleranceof t15 %; d) same or smallerslress under mechanicalloads; e) same or greater cross-diameterof the core; f)

same housing profile parameters,see the table footnote in Table 1.

62231@ IEC:2006 7.2

_29_

Type tests

These tests are intended to the main characteristics of a composite station post insulator, which depend mainly on its shape and size. Type tests shall be applied t o composite insulators belonging to an already qualified design. The type tests shall be repeatedonly when the type of the compositeinsulatoris changed. Electrically,an insulatortype is defined by the -

arcing distance,

-

creepage distance,

-

housingprofile.

The electrical type tests shall be performed only once on insulators satisfying the above design criteria for one type and shall be performed with arcing and field grading devices, if they are an integral part of the insulatortype. The electricaltype tests shall be repeatedonly when one or more of the above characteristics is changed. Mechanically, an insulatortype is definedby the: -

length(onlyfor the compressionand bucklingwithstandload test),

-

core diameter and material

-

design and method of attachmentof the end fittings.

The mechanical type tests shall be performed only once on insulators satisfying the above criteria for each lype. The mechanicaltype tests shall be repeated only when one or more of the above characteristics is changed. 7.3

Sample tests

These tests are intended to the characteristicsof composite station post insulalors, which depend on the quality of manufacture and materials used. They shall be made on insulatorstaken at random from lots offeredfor acceotance. 7.4

Routine tests

These tests are intended to eliminate composite station post insulators with manufacturing defects.They shall be made on every compositestation post insulatorto be supplied.

8 8.1

Designtests General

The design tests shall be performed only once and the results shall be recorded in a test report. Each lest can be performed independentlyon new test specimens where appropriate. The composite station post insulator of a particular design shall be deemed qualified only when the insulatorsor test specimens all the design tests.

_ 2,4 _

62231 @ IEG:2006

8.2

Tests on interfacesand connectionsof end fil

Se e IEC6 2 2'17. 8.2.'l

8.2.2

--) *\

Testspecimens

see IEC6 2 217. (,L

\

I

1'2 /

4

Referencevoltage and temperaturefor veril

seelEc62217. 7. Z 2 8.2.3

Referencedry powerfrequencytest

Se er EC 6 2217. q,7.] 8.2.4

0'

Therma l-mechan ica I pre-stressing

The three specimens shall be submitted to a mechanicalload in two opposite directions and to temperaturecycles as describedin Figure 1.Ihe 24 h temperaturecycle shall be repeated twice. Each temperature cycle has two temperaturelevels with a duration of at least 8 h, one at +50 "C + 5 K, the other at -35'C * 5 K. The cold period shall be at a temperatureat least 85 K below the value actually applied in the hot period. The pre-stressingcan be conducted in air or any other suitablemedium. The load appliedto the specimensshallcorrespondto the MDCL. The load shall be applied perpendicularlyto the insulator's axis as near as possible to the normal load applicationpoint, either directly at the normal conductor position or at a hardware attachment point. When the load is not applied at the normal application point, it shall be corrected to oroduce the same bendino momeni at the base of the insulator as the one exerted by the MDCL. The direction of the cantilever load applied to the specimens shall be reversed once, generallyat the coolingagethrough ambienttemperatureas describedin Figure 1. The cycles may be interrupted for the load direction reversal and for maintenance of the test equipment for a total duration of 2 h. The starting point after any interruption shall be the beginningof the interruptedcycle. NOTE The temperaturesand loads in this pre-stressingare not intended to representservice conditions;they are designedto producespecificreproduciblestressesin the interfaceson the insulator.

8.2.5

Waterimmersionpre-stressing

See IEC 62217. 8.2.6

Verificationtests

s e e t Ec 6 2 2 1 7 . 8.3

lrqt-

S '2 '6

Assembled core load tests

Extreme service temperaturesmay affect the mechanicalbehaviourof composite insulators"

62231@ IEC:2006

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A general rule to define "extreme high or low" insulator temperaturesis not available at this time; for this reason the supplier should always specify service temperaturelimitations. NOTE Whenever the insulators are subjected to very high or low temperaturesfor long periods of time, it is advisable that customer and supplier agree on a mechanical test at higher or lower temperatures than that mentionedin this standard.

8.3,1 8.3.1.1

Test for the verification of the maximum design cantilever load (MDCL) Test procedure

Three insulatorsmade on the productionline using the standard end fittings shall be selected. The overall length of the insulatorsshall'be at least 8 times the diameter of the cote, unless the manufacturerdoes not have facili tiesto make such a length. In this case, the length of insulatorshall be as near as possibleto the prescribedlengthrange. The base end-fitting has to be fixed rigidly. The insulators shall be gradually loaded to 1,1 times the MDCL ratingat a temperatureof 20 "C i 10 K and held for 96 h. The load shall be applied to the insulators at the conductor position, perpendicularto the direction of the conductor,and perpendicular to the core of the insulators. At 24 h, 48 h, 72 h and 96 h, the deflectionof the insulatorsat the point of applicationof the Ioad shall be recorded,as additionalinformation. After removal of the load, the steps below shall be followed: -

visually inspect the base end fitting for cracks or permanentdeformation,

-

check that threads of the end fitting are re-usable,

-

if required,measure the residualdeflection.

Cut each insulator90' to the axis of the core and about 50 mm from the base of the end fitting, then cut the base end fitting part of the insulator longitudinallyinto two halves in the plane of the previously applied cantilever load. The cut surfaces shall be smoothed by means of fine abrasivecloth (grainsize 180). -

visually inspect the cut halves for cracks and delaminations,

-

perform a dye penetrationtest accordingto ISO 3452 to the cut surfaces to reveal cracks.

8,3.1,2

Acceptancecriteria

Observationof any cracks, permanentdeformationor delaminationsshall constitutefailure of the test8,3,2 8.3.2.1

Test for the verification of the maximum design torsion load (MDToL) Test procedure

Three insulalorsmade on the productionline using the standard end fittings shall be selected. The overall length of the insulatorsshall be at least 8 times the diameter of the core, unless lhe manufacturerdoes not have facilities to make such a length. In this case, the length of insulatorsshall be as near as possibleto the prescribedlength range.

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The torsion load shall be applied to the insulatorsperpendicularlywith the axis of the core of the insulator.No bendingmomentshould be applied.The insulatorsshall be graduallyloaded to 1,1 times the MDToL rating at a temperatureof 20 'C t 10 K and held for 30 min. The angular displacementshall be measured at 30 min as additional information.An acceptable value of the angular displacementshall be agreed between manufacturerand . NOTE In a torsion test, the angular displacementis proportionalto the length of the core between the end littings.

An example of a test arrangementcan be found in Annex C. After removal of the load, the steps below shall be followed: -

if required,measurethe residualangulardisplacement,

-

visually inspect the end fittings for cracks or permanentdeformation,

-

check that threads of the end fitting are re-usable,

-

cut each insulator 90' to the axis of the core at about 50 mm from the end fittings, and in the middle part of this cut section,

-

polish the cut surfaces by means of fine abrasive cloth (grain size 180),

-

visually inspect the cut surfacesfor cracks and delaminations,

-

perform a dye penetrationtest accordingto ISO 3452 to the cut surfaces to reveal cracks or delaminations.

8,3.2,2

Acceptancecriteria

Observationof any cracks, permanent deformationor delaminationsshall constitutefailure of the test. 8.3.3 8.3.3.1

Verification of the specified tension load (STL) Test procedure

Three insulatorsmade on the productionline using the standard end fittings shall be selected. The overall length of the insulatorsshall be at least 8 times the diameter of the core, unless the manufacturerdoes not have facilities to make such a length. In this case, the length of insulatorshall be as near as possibleto the prescribedlength range. The tensile load shall be applied to the insulators in line with the axis of the core of the insulatorat a temperalureof 20'C i 10 K. The load shall be increasedrapidlybut smoothly from zero to approximately 75 % of the specified tensile load and shall then be gradually increased in a time between 30 s and 90 s until the soecifiedtensile load is reached. lf 100 % of the STL is reached in less than 90 s, the load (100 % of STL) shall be maintainedfor the remainderof the 90 s. 8.3.3.2

Acceptancecriteria

The test shall be regardedas ed if there is no evidence of -

pullout or slip of the core from the end fitting, or

-

breakage of the end fitting.

62231 @ IEC:2006 8.4

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Tests on shed and housing material

See IEC 62217. 8.5

Tests on the core material

See IEC 62217. These tesls can be carried out on specimenseither wlth or without housing material.

9

Type tests

Insulatorsmade on the productionline usingthe standardend fittingsshall be selected. 9.1

Verification of dimensions

Unless otherwiseagreed, a tolerance of f (0,04x d + 1,5) mm when d S 300 mm, or I (0,025x d + 6,0) mm when d > 300 mm with a maximumtoleranceof O0 mm shall be allowed on all dimensions for which specific tolerances are not requested (d being the dimensionsin millimetres). The measurement of creepage distance shall be related to the design dimensions ano tolerances as determined from the insulator drawing, even though this dimension may be greater than the value originally specified by the purchaser.when the creepage distanie rs specifiedas a minimum value, the negativetoleranceis zero.

Tolerancesof parallelism, eccentricity, angulardeviationare givenin AnnexD. 9.2

Electricaltests

Testsin accordancewith 9.2-1 and 9.2.2shall be performedwith the insulatorin the Dosition in which it will be used in service(verticalor horizontal).lf field-grading devicesare used rn servicethey shallbe usedin the tests. Interpolation of electricaltest resultsmay be usedfor insulatorsof intermediate lengthas long as the factorbetweenthe arcingdistancesof the insulatorswhoseresultsform thelnd points of the interpolation rangeis lessthan or equalto 1,5.Extrapolation is not allowed. 5.2.1

Dry lightningimpulsevottagetest

The post insulatorshall be testedunderthe conditions prescribed in 4.1,4.2 and 4.4.1of lEg 99168 The impulsegeneratorsha be adjustedto producea 1,2tSOimputse(see lEc 60060-1). lmpulses of both positive and negative polarity shall be used. However, when it is evident which polarity will give the lower flashover voltage, it shall be sufficient to test with that polarity.

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Two test procedures are in commonusefor the lightningimpulsetest: -

the withstandvoltageprocedurewith 15 impulses; the 50 7oflashovervoltageprocedure.

NOTE The 50 % flashovervoltage proceduregives more jnformation.

The test procedureselectedshallbe agreedbetweenthe purchaserand the manufacturer. 9.2.1.1

Withstandvoltagetest usingthe withstandvoltageprocedure

The withstandvoltagetest shall be performedat the specifiedvoltage correctedfor the atmospheric conditionsat the time of test (see4.2.2of IEC60168).Fifteenimpulsesshall be appliedto the postinsulator. The acceotancecriteriaare as follows: -

the stationpost insulatoresthe test if the numberof flashoversdoes not exceedtwo for eachseriesof 15 imoulses.

The stationpost insulatorshallnot be damagedby thesetestsbut slightmarkson the surface of the housingshallbe permitted. 9.2.1.2

Voltagetest usingthe 50 % flashovervoltageprocedure

The lightningimpulsewithstandvoltageshall be calculatedfrom the 50 % lightningimpulse methoddescribed in IEC60060-1. flashover voltage,determined by the up-and-down in accordance wilh4.2.2of IEC60168. The 50 % lightning impulsevoltageshallbe corrected The acceotance criteriaare as follows: the stationpost insulatoresthe iest if the 50 % lightningimpulseflashovervoltageis not fess than (11(1- 1,3 d )) = 1,040timesthe specifiedlightningimpuisewithstandvoltage, whereo is the standarddeviation(assumedequalto 3 %). The station post insulatorshall not be damagedby these tests, but slight marks on the surfaceof the housingshallbe permitted. 9.2.2 9.2.2.1

Wet power frequencywithstandvoltage test Test procedure

with IEC 60060-1. The test circuitshallbe in accordance prescribed in 4.1,4.2,4.3and The stationpostinsulator shallbe testedunderthe conditions 4.4.1of IEC60168. The test voltageto be appliedto the stationpost insulatorshall be the specifiedwet power conditionsat the time of test (see frequencywithstandvoltagecorrectedfor the atmospheric at thisvaluefor 1 min.As additional 4.2.2of IEC60168).Thetestvoltageshallbe maintained information, the voltagecan be raiseduntilthe flashoveroccurs.

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9.2.2.2

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Acceptancecriteria

The stationpost insulatoresthe test if no flashoveror punctureoccursduringthe test. NoTE lf flashover occurs on the insulatortested, then a second test on the same unit may be performed,after ingthe rain conditions.

9.2.2,3

Wet power frequency flashover voltage

To provide information,when agreed between the purchaser and the manufacturer,the wet flashover voltage of the station post insulator may be determined by increasing the voltage gradually,from about 75 o/oof lhe wet power-frequencywithstandvoltige with a iate of rise of about 2 96of this voltage per second. The wet flashover voltage is the irithmetic mean of ftve consecutivereadings, and ihe value, after correctionto standard atmosphericconditions (see 4.2.2 ol IEC 60168),shattbe recorded.

9.3

Mechanical tests

9.3.1

Cantileverfaitingloadtest

Interpolation of test resultsmay be used for insuratorsof intermediate rengthas rongas the factor betweenlhe momentarm of the insulatorswhose resultsfrom the-end pointi of the interpolation rangeis lessthan or equalto 1,5.Extrapolation is not allowed. This test shall be performed at 20 "c * 10 K and is used to determine the failing load of a complete station post insulator. 9,3.1.1

Test specimens

Three insulatorsmade on the productionline using the standard base fitting shall be selecteo. 9.3.1.2

Test procedure

It may be necessary to use special bolts to hold securerythe base plate to the test jig. The canlilever load shall be increasedrapidly but smoothly from zero to approximately7s 6/o-oftne specified cantilever load (SCL) of the post insulatorsand then shall be gradually increased in a time between 30 s and 300 s until breakage of either the core or the metal fitting occurs. Precautionsshall be taken to keep the direction of applicationof the load as perpend"icular as possibleto the axis of the unloadedinsulator. 9.3.1.3

Acceptancecriteria

The three failingload valuesshall be greaterthan the SCL. NoTE . The mechanicalfailing load of a composjtestation post insulatoris defined as the maximum load thar rs reached dlring the test. The failure mode is recordedin the test report.

9.3.2

Specified tension toad test

This test shall be performed at 20 'c t l0 K and is used to determine the specified tension Ioad of a complete station post insurator.short insuratorsmay be used for this test.

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Testspecimens

Three insulatorsmade on the producti online usingthe standardend-fittingsshall be selected. 9.3.2,2

Test procedure

The tension load shall be applied in the direction of the longitudinalaxis of the insulator.The load shall be increased relatively quickly, but smoothly, from 0 kN to approximately75 % of the srl. The load shall then be gradually increased to the srl in a period of no less than 30 s but no greater than 90 s. lt 100 % of the STL is reached in less than g0 s, the loao (1O0o/'ol STL) shall be mainlainedfor the remainderof the g0 s.

9.3.2.3

Acceptancecriteria

No evidenceof partial,or complete,pulloutof the corefromthe end fitting(s). No evidenceof end fittingbreakage. 9.3.3

Compression and buckling w ithstand load test

This test is only required if compression is a major componenl of the overall service mechanical loads and shall be performed by agreement between the manufacturerand the . This test shall be performedat 20'c I 1.0K and is used to determinethe withstand load of a complete station post insulator. 9.3.3.1

Test specimen

one insulatormade on the productionline usingthe standardend fittingsshall be selected. 9.3.3.2

Test procedure

In service, the coupling of the slation posl insulator belongs to one of the cases 1 to 4 In Annex E. In the laboratory,the post insulator shall be subjected to a compresslonload along their axis, accordingto any one of the cases 1 to 4 in Annex E. The test load is given by SCoL multipliedby the correctionfacior CF given in Annex E. The load applied to the insulator shall be increased rapidty but smoothly (within 90 s) from zero to approximalely75 o/oof the test load of the post insulatorsand then shall be gradually increasedin a time between 30 s and 300 s up to the test load. Precaulionsshall be taken to keep the direction of the load as close as gossibleto the axis of lhe unloaded insulator. lt may be necessary to use special bolts or fixing arrangementslo hold securely both end fittings to the test sefup. 9.3.3.3

Acceptancecriteria

The insulatorshall withstandthe test load withoulvisualdamaoe.

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10 Sample tests 10.1 General rules For the sample tests, two groups of samples shall be used, E'l and E2. The sizes of these samples are indicated in Table 2. lf more than 2 000 insulators are concerned,they shall be divided into an ootimum number of lols of less than 2 000 insulators.The results of the tests shall be evaluatedseparatelyfor each lot. The insulatorsshall be selected from the lot at random. The purchaser has the right to make the selection.The samplesshall be subjectedto the applicablesampletests. The samole tests are as follows: -

verificationof the dimensions

-

galvanizingtest

(E1 + Ez\l (E1 + E2\:

-

verificationof the specifiedmechanicalloads

(E1).

ln the event of a failure of the sample to satisfy a test, the re-testing procedure shall be appliedas prescribedin 10.5. Table 2 - Number of samples for sample tests '. Sample size

Lot size

w

E1

E2

Ns100

By agreement

By agreement

100 <300

2

1

300 <2000

4

3

Insulatorsof sample E2 only can be used in service only if the galvanisingtest is performed with the magnetic method. 10.2 Verification of dimensions (E1 + E2) On all selected insulators,the dimensionsof the compositestation post insulator shall comply with the values shown on the drawing, within specified tolerances for geometry, form and position. Unless otherwise specified, the tolerances given in Annex D and in 9.1 of this document shall be used. The drawing can show points between which the creepage distance is specified. The measurement of creepage distance shall be related to the design dimensions as determined from the insulator drawing, even though this dimension may be greater than the value originallyspecified by the purchaser.When the creepagedistance is specifiedas a minimum value, the negativetolerance is zero. 10.3 Galvanizingtest (El + E2) This test shall be performedon all galvanisedparts in accordancewith IEC 60168.

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10,4 verification of the specified mechanical loads (E1) '10.4.1 Verification of the specified cantilever load (SCL) (El divided by 2) 10.4.1.1

Test procedure

It may be necessary to use special bolts to hold securely the base plate to the test ji9. The cantilever load shall be applied to the insulatorat the conductor position, perpendicularto the direction of the conductor,and perpendicularto the core of the insulator. The load shall be increased rapidly but smoothly from zero to approximately 75% of the specifiedcantilever load (SCL) of the post insulatorand then shall be gradually increased in a time between 30 s and 90 s uniil the SCL is reached. lf the SCL is reached in less than 90 s, the load shall be maintainedfor the remainderof the 90 s. '1O.4.1.2 Acceptance criteria The insulalor shall be regardedas ed if the SCL can be maintainedfor the requiredtime. ln order to obtain more informationfrom the test, the load may then be increased until failure of the core or breakage of the metal fitting occurs. The failing load values and the failure modes shall be recorded. 10.4.2 Verification of the specified tensile load (STL) (E1 divided by 2) '10.4.2.1 Test procedu re The tension load shall be applied in the direction of the longitudinalaxis of the insulator.The load shall be increased relatively quickly, but smoothly, from 0 kN to approximately75 % of the STL. The load shall then be gradually increased to the STL in a period of no less than 30 s but no greater than 90 s. lf 1OOo/oof the STL is reached in less than 90 s, the load (100 % of STL) shall be maintainedfor the remainderof the 90 s. '1O.4.2.2 Acceptance criteria No evidence of partial, or complete,pullout of the core from the end fitting(s). No evidence of end fitting breakage. 10,5 Re-testing procedure lf only one insulatoror metal part fails 10 comply with the sample tests, a new sample equal to twice the quantity originallysubmittedto the tests shall be subjectedto re-testing. The re-testingshall comprisethe test in which failure occurred. lf two or more insulators or metal parts fail to comply with any of the sample tests, or if any failure occurs during the re-testing,the complete lot shall be consideredas not complyingwith this standard and shall be withdrawn by the manufacturer.

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Providedthe cause of the failure can be clearly identified,the manufacturermay sort the lot to eliminate all the insulatorswith this defect. The sorted lot may then be resubmittedfor testing. The number then selected shall be three times the first quantity chosen for tests. lf any insulator fails during this re-testing,the complete lot shall be considered as not complying with this standard"

11 Routinetests 11.1 ldentification of the station post insulator Each insulator shall be marked with the name or trademark of the manufacturerand the year of manufacture. In addilion, each insulator shall be marked according to Clause 4- These markingsshall be legibleand indelible. 11.2 Visual examination The examination shall be made on each insulator. The mounting of the metal fittings on the insulating parts shall be in accordancewith the drawings.The colour of the insulator shall be approximatelyas specified in ihe drawings. The following imperfectionsshall be acceptableon the insulatorsurface: -

superficialdefects of area less than 25 mm2 (the total defective area not exceeding 0,2 % of the total insulalorsurface) and depth or height less than 1 mm.

11.3 Tens ile load test Every insulator shall be subjected,at ambient temperature,to a tensile load of at least 50 % of the specifiedtensile load (STL) for at least 10 s. lf no STL is given for the insulator,an STL of at least 10 kN shall be assumed. No pullout or slip of the core from the end fitting shall occur.

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AK temperature 'C 5015

pre-stressingtest - Typical cycles Figure I - Thermal-mechanical

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Annex A (informative) Noteson the mechanicalloads and tests

This annexoresentssomecommentson the variousmechanical testsof this standard. A.1

Design tests

For a family of stationpost insulators, the maximumdesignbendingstress or moment (generallyexpressedin megapascals, MPal or newtonmetre€,N.m, respectively) limitsthe cantileverloads.The core and the end fittingsdefinea stationpost insulatorfamilyas each familymay containinsulatorsof differentlength. The maximumdesignbendingstress(resulting fromMDCL)is the maximumuseablebending stressof the insulator.For each familyof stationpost insulators,a 96 h cdnlilever'f9ad:test verifiegfthatthe core can sustainthe maximumdesignbendingstresswithoutdamage.This test, aS a designlest, needsto be performedonly once on a representative lengthinsulator for each insulatorfamily. In applications wheretorsionloadsare the majorload component,a 30-mintorsionload test verifidsthat the corecan sustainthe maximumdesiontorsionloadwithoutdamaoe. In addition,a tensileloadtest is requiredto the designof the end fittingstogetherwith the methodof attachment.

4.2

Type tests

The core diameter, insulator coupling length and method of attachment of the end fittings mechanicallydefine a stationpost insulatortype. A maximumdesigncantileverload (MDCL), in kN (kilonewtons),is assigned to each station post insulator type usually by interpolation from the design MDCL verification test. For each station post insulator type, the assigned MDCL is the allowable ultimate limit for service loads. A test to the MDCL for each station post insulator type is not included in this standard as such a type test would be uneconomicand time consumino. The cantilever failing load is determined with a short time load type test. This standard requiresthat the cantileverfailing load shall exceed the specified cantileverload (SCL), which is the short-timewithstandstrength of the insulator.The cantileverfailing load verifies that the rod or base end fitting does not fail at the specified cantilever load, though damage to the core may occur. A compressionor buckling test may be performedto that the insulator can sustain the specified compressionload without visual damage.

62231 @ IEC:2006

A.3

Sampletest

A short-time cantilever load test has been included as a sample test to the specified cantilever load (SCL). A tension load test (STL) verifies that the end fittings are correctly fastened to the core and that they can sustain the specified load. These tests are performed on productioninsulators complete with productionend fittings. They are simple and relaiively quick to perform.

A.-4 Routinetensile test A routineiensileiest is specifiedinsteadof a routinebendingtest. This test providessome verificationof the end fittingattachmentprocessduringproductionand is similarto the routine test performedon compositesuspensioninsulators.This test is usedsince,unlikeporcelain, compositestation post insulatorsare not made with brittle materials,and consequentlya routinebendingtest at any levelbelowthe MDCLwouldnot give any usefulinformation. By contrastwith suspensioninsulators,this test may be more difficultto performwith some designsof end fittingsand mountingbases.This difficultyarisessincesome designsof end shouldbe takento ensure tensileloadon the insulator.'Care fittingsimposean unbalanced that the resultingloadis appliedin linewith the axisof the insulator.

62231A IEC:2006

Annex B (informative) Determinationof the equivalentbendingmomentcausedby combinedcantileverand compression(tension)loads

B.l

lntroduction

This annex providesguidancefor applicationswhere the compressionload is not dominant and will not lead to buckling of the station post insulato.. The torsion load is also deemed to have no significantinfluenceon the combinedloading of the insulator. This annex does not cover cases where the compressionand/or torsion loads are significant comparedto the bendingload. In cases where the bending load on the station post insulator is dominant, the corresponding stress may be significantly modified by the additional stress caused by the simultaneous application of a compression (or tension) Ioad. The bending moment correspondingto the combinationof these loads must not exceed the moment which corresDondsto the MDCL. The following clauses give information on calculating the approximate equivalent bending moment when station post insulatorsare submittedto combined loads. The following notation is used: applied compression,tension and cantileverloads (N); MC

resultingmomentin the post undercompression;

Mr

resultingmoment in the post under tension;

d

distance from the point of applicationof the load to the top edge of the metal base fitting in metres (m):

E

longitudinalYoung's modulus (Pa or N m-2);

I

moment of inertia of the rod (m) to the fourth power (for a solid round rod of diameterD:l=nD4/64).

NOTE The values for Young's modulus and for the moment of inertia (or the real diameter)should be supplied by the manufacturer.

8.2

Maximum allowable bending moment, rnmax

The maximumdesign cantileverload of a compositestation post insulatorinduces the maximumallowablebendingmomentmr"" = MDCLx d. The maximumstressassociatedwith thisbendingmomentmustnot produce anydamageto the insulator core. The maximumcombinedstress is the maximumstress resultingfrom the simultaneously (or tension)loads.In service,the variouscombinations appliedcantilever and compression of loadsmustnot producea bendingmomentthat is greaterthanthe bendingmomentinduced bv the MDCL.

L./

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8.3

-59-

Gombined loading of station post insulators

The followingformulaeallowthe determination of the momentin the insulatorwhensubmitted io singleor combinedloads.lt shouldbe notedthat the accuracyof theseformulaedepends on the deflection.The more the momentapproachesthe MDCL, the less accuratethey Decome. It shouldalso be notedthat the appliedloadscan inducedamagingstresslevelsin the end fittingsor accessories evenwhenthe momentin the insulatoris at an acceptablelevel.

fi ll'

tEc o22n6

Figure 8.1 - Gombined l oads applied to station post insulators A - Comoressioncase The cantilever (C) component of the load applies a cantilever moment to the insulator; the compression load (Co) is taken as being applied to the head of the insulatortoward its base. The moment resultingfrom the applicationof these two forces is given by

u "o

= lc2 Eil coll t2 tanla (cotet)ttzl

In service,Mcoshouldnot exceedmmax. B - Tensioncase The cantilever(C) componentof the load appliesa cantilevermomentto the insulator;the tensionload (IJ is takenas beingappliedto the headof the insulaiorawayfrom its base.The momentresultingfromthe application of thesetwo forcesis givenby M, = lcz E rl1t2 1,,nh ld (rtEt)1t21 In service,Mr shouldnot exceedmmax.

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62231 @ IEC:2006

Annex C (informative) Exampleof torsion load test arrangement

Top View

Disdlacement sensor

Tensilesystem

Embeddedarea

lEc 02w6

One exampleof the mountingarrangement for the torsionloadtest couldbe as follows: TorsionmomentMt: Mt = F xD.lz . Lineardisolacement d Angulardisplacement a a = 2d/Dz wherea is in radians

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Annex D (normative ) Tolerancesof form and position

The following Figures D.1 to D.3 give tolerances of form and position for composite station post insulators. Figure D.l shows a typical jig for measurement of parallelism, coaxiality, concenlricity and eccentricity along with the relative tolerances. Figures D.2 and D.3 show two examples of methods of measuring.the angular deviation of the fixing holes; Figure D.4 summarizesthe applicabletolerancesaccordingto standarddrawingpractice(lSO 1101). Guidelineson the methodsof measurementcan be found in IEC 60168. Reference diameter

Legend Parallelism of the endfaces: forh<1m, p<0,5mm forh>'1 m, p < 0,5 h mmwithh in m The tolerances of the parallelism are related to a diameterof 250 mm. C = 2 y.e Coaxi'ality and concentricity: Eccentricity: e < 2 (1 + h) mm withh in m

FigureD.1- Parallelism, coaxialityand concentricity

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-6 5 -

Precision lev€l for direct reading of angularpositiona

Pr€cisionlevelin horizontalposition

Centredpins

Tolerance of the deviation:a< * i' Figure D.2 - Angular deviationof fixing holes: Example1

Centredpins

a = Ian-l

f a") wheref* is the distancebetweenthe centresof two oppositepins

r.il

Toleranceof the deviation:u< * 1' Figure D.3 - Angular deviation of fixing holes: Example 2

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-6 7 -

Parallelism:the upper plane face is parallelto the lower referenceplane C within the indicated tolerances. Coaxialityand concentricity:the axes of the top fitting fixing holes have to be within a cylinderwith a diameteras indicatedbv the numericalvalue.

r af

valueindicates the maximumissibie unevenness of the face. Evenness: the numerical Alignmentof the fixing holesrthe line betweentwo opposite,axesof holes of the top fitting have to be in Iine with the correspondingline of the bottom fitting with two parallelsof specifieddistance

Figure D.4 - Tolerances according to gtandard drawing practice

62231A IEC:2006

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Annex E (informative ) Noteson the compressionand bucklingtest

The result of the compressionand bucklingtest is influencedby: -

rod diameter,

-

length between end fittings,

-

coupling arrangementof the end fitting (top and bottom).

Dependingon the coupling at the top and bottom of the station post insulatorthe buckling test has 4 Ioad conditions(elasticEuler-buckling). 1

TI

l.

FB

I+ Lj,k = 0,7

The correctionfactorCF is givenby: gP = (L/ Ly)zwherej corresponds to to the servicecouplingarrangement, and k Gorresponds the laboratoryarrangement. As an example,if servicecouplingarrangementcorrespondsto case 1, and the laboratory to case4, thenthe correctionfactorCF= (2lO,flz= 16. set-upcorresponds

L/

62231 @ IEC:2006

Bibliography IEC 60865 (alf parts), Short-citcuitcurrents- Calculationof effects IEC 61245,Artificialpollution tests on high-voltageinsulatorsto be used on d.c. sysferns IEC 61462, Compositeinsulators- Hollow insulatorsfor use in outdoor and indoor electrical equipment- Detinitions,test methods,acceptancecriteriaand designrecommendations IEC 61467, lnsulatorcfor overhead lines with a nominal voltage above 1 000 V - AC power arc fesls on insulatorsets fEC 60507,Artificialpollutionfesfs on high-voftageinsulatorsto be used on a.c. sysfems IEC 61952, Insulatorsfor overhead /ines - Composite line post insulators for alternative current with a nominal voltage > 1 000 V

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