cei iec 62231 edition 1.0 (2006-02)

NORME cErINTERNATIONALE rEcINTERNATIONAL 62231

PremiCre editionFirst edition

2006-02STANDARD

lsolateurs supports composites rigides d socledestin6s aux postes i courant alternatifde tensions sup6rieures a 1 000 V jusqu'd 245 kV -D6finitions, m6thodes d'essai et critdresd'acceptation

Composite station post insulators for substationswith a.c. voltages greater than 1 000 V up to245 kV - Definitions, test methods andacceptance criteria

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Intemalional Electrol€chnical Commission, 3, rue de Varemb6, PO Box 131, CH-1211 Gensva 20, Swiz€dandTelephone: +41 229190211 rebfax: +4122919 03 00 E-maili [email protected] Web: www.i€c.ch

Commission Electrolechnique Internat ionalelnternat ional Electrotechnical CommissionMextyHapoaHae SneKrporexHh,reo€i KoMrccrc

CODE PRIXPRICE CODE

Pour N* voft calalague en vigueurFor pice, see cunent calalogue

NORME cElrEc

62231Premidre 6di t ion

First edition2006-o2

INTERNATIONALE

INTERNATIONALSTANDARD

lsolateurs supports composites rigides d socledestin6s aux postes i courant alternatifde tensions sup6rieures A 1 000 V jusqu'd 245 kV -D6finitions, m6thodes d'essai et critdresd'acceptation

Gomposite station post insulators for substationswith a.c. voltages greater than 1 000 V up to245 kV - Definitions, test methods andacceptance criteria

Num6ro de r6f6renceReference number

cElllEC 62231:2006

62231 @ IEC:2006

CONTENTS

FOREWORD... . . . . . . . . . . . . - . - .7

TNTRODUCTION ' . ' . ' . . . . . .11

-3-

I

4

5

o

7

10

1'l

Annex A ( informat ive) Notes on the mechanical loads and tests . . . . . . . . . . . . . . . . . . . . . ' . . . . . ' . ' . . . "" ' - '53

Annex B (informative) Determination of the equivalent bending moment caused bycombined cant i lever and compression ( tension) loads.. . . . . . ' . . . . . - . . . . . . . . . . . . ' . "57

Annex C ( informat ive) Example of tors ion load test arrangement . . . ' . . . . . "" '61

Annex D (normat ive) Tolerances of form and posi t ion. . . . . . . . . . . . . . . . ' . ' . ' . " """ 63

Annex E ( informat ive) Notes on the compression and buckl ing test . . ' . . . . . . . . . . . . . . . ' . . . """ . ' " ""69

Bibl iography.. . . . . . . " """71

62231 @ IEC:2006

Figure 1 - Thermal-mechanical pre-stressing test - Typical cycles .......................................51Figure 8.1 - Combined loads applied to station post insulators... ................59Figure D.1 - Paral le l ism, coaxial i ty and concentr ic i ty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63Figure D.2 - Angular deviat ion of f ix ing holes; Example ' l . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Figure D.3 - Angular deviat ion of f ix ing holes: Example 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65Figure D.4 - Tolerances according to standard drawing practice .................67

Tabfe 1 - Tests to be carr ied out af ter design changes. ." . . . . . . . . . . . . . . . . . . . . . . . . . . . .27Table 2 - Number of samples for sampld tests. . . - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

62231 @ IEC:2006 -7 -

INTERNATIONAL ELECTROTECHNICAL COMMISSION

COMPOSITE STATION POST INSULATORS FOR SUBSTATIONSWITI{ AC VOLTAGES GREATER THAN IOOO V UP TO 245 KV -DEFINITIONS, TEST METHODS AND ACCEPTANCE GRITERIA

FOREWORD

1) The lnternationai Electrotechnical Commission ( lEC) is a worldwide organization for standardization comprisingal l national electrotechnical committees ( lEC National Committees). The object of IEC is to promoteinternational co-operation on al l questions concerning standardization in the electr ical and electronic f ields. Tothis end and in addit ion to other act ivi t ies, IEC publishes International Standards, Technical Specif icat ions,Technical Reports, Publicly Avai lable Specif icat ions (PAS) and Guides (hereafter referred to as " lECPublication(s)"). Their preparation is entrusted to technical committeesi any IEC National Committee interestedin the subject dealt with may part icipate in this preparatory work. International, governmental and non-governmental organizations l iaisjng with the IEC also part icipate in this preparation. IEC col laborates closelywith the International Organization for Standardization ( lSO) in accordance with condit ions determined byagreement between the two organizations.

2) lhe formal decisions or agreements of IEC on technical matters expresl, as nearly as possible, an internationalconsensus of opinion on the relevant subjects since each technical committee has representation from al linterested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC NationalCommittees in that sense. While al l reasonable efforts are made to ensure that the technical content of IECPublications is accurate, IEC cannot be held responsible for the way in which they are used or for anymisinterpfetat ion by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publicationstransparently to the maximum extent possible in their national and regional publ icat ions. Any divergencebetwoen any IEC Publication and the corresponding nationai or regional publ icat ion shal l be clearly indicated inthe latter.

5) IEC provides no marking procedure to indicate i ts approval and cannot be rendered responsible for anyequipment declared to be in conformity with an IEC Publication.

6) Al l users should ensure that they have the latest edit ion of this publ icat ion.

7) No l iabi l i ty shal l attach to IEC or i ts directors, employees, servants or agents including individual experts andmembers of i ts technical committees and IEC National Committees for any personal injury, property damage orother damage of any nalure whatsoever, whether direct or indirect, or for costs ( including legal fees) andexpenses arising out of the publication, use of, or rel iance upon, this IEC Publication or any other IECPublications.

8) Attention is drawn to the Normative references cited in this publ icat ion. use of the referenced publications isindispensable for the correct appl icat ion of this publ icat ion.

9) Attention is drawn to the possibi l i ty that some of the elements of this IEC Publication may be the subject ofpatent r ights. IEC shall not be held responsible for identi fying any or al l such patent r ights.

International Standard IEC 62231 has been prepared by subcommittee 36C: Insulators forsubstations, of IEC technical committee 36: Insulators.

This bi l ingual version (2006-04) replaces the Engl ish version.

The text of this standard is based on the followino documents:

FD IS Report on voting

36Ci 159/FDtS 36Ci 160/RVD

Full information on the voting for the approval of this standard can be found in the report onvoling indicated in the above table.

The French version of this standard has not been voted uoon.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

' f

62231 @ IEC:2006 -9-

This standard is to be read in conjunction with IEC 62217:2005, Polymeric insulators forindoor and outdoor use with a nominal voltage >1 000 V - General definitions, test methodsand acceDtance criteria.

The committee has decided that the contents of this publication will remain unchanged untilthe maintenance result date indicated on the IEC web site under "http://webstore. iec.ch" inthe data related to the specific publication. At this date, the publication will be

. reconfirmed;

. withdrawn:

. replaced by a revised edition, or

. amended.

62231 @ IEC:2006

INTRODUCTION

typically caused by shorl-circuits. Postrinteraction of the currents circulating in

The impulse load or peak load may be evaluated using guidance found in the IEC 60865serieg.

Composite station post insulators consist of a cylindrical solid insulating core made of resinimpregnated fibres, bearing the mechanical load, protected by an elastomer housing, theloads being transmitted to ihe core by metal fittings. Despite these common features, thematerials used and the construction details employed by different manufacturers may bed ifferent.

Some tests have been grouped together as "design tests" to be performed only once forinsulators of the same design. The design tests are performed in order to eliminate insulatordesigns, materials and manufacturing technologies not suitable for high-voltage applications.The lnfluence of time on the electrical and mechanical properties of the complete compositestation post insulator and its components (core material, housing material, interfaces, etc.)has been considered in specifying the design tests in order to ensure a satisfactory lifeiimeunder normal service conditions.

The approach for mechanical test ing under bending loads used in th is Standard is based onIEC 61952+This approach uses the concept of a damage limit that is the maximum stress thatcan be developed in the insulator before damage begins to occur. Work is underway to.validate the acoustic emission technique to delermine the incpption of damage.:'

In some cases, station post insulators can be subjected to a combination of loads. In order togive some guidance, Annex B explains how to calculate the equivalent bending moment in theinsulators resul t ing f rom the combinat ion of bending, tensi le and compression loads.

Pol lu i ion tests, as speci f ied in IEC 60507 and IEC 61)45, are not included in ih is document,their applicability to composite station post insulators having not been proven. Such polluiiontests performed on composite insulators do not correlate with experience obtained fromservice. Specific pollution tests for composite insulators are under consideration.

It has not been considered useful to specify a power arc test as a mandatory test The testparameters are manifold and can have very different values depending on the configurationsof the network and the supports and on the design of arc-protection devices. The heatingeffect of power arcs should be considered in the design of metal fittings. critical damage tothe metal fittings, resulting from the magnitude and duration of the short-circuit current can beavoided by properly designed arc-protection devices. This standard, however, does notexclude the possibility of a power arc test by agreement between the user and the manu-facturer. IEC 61467 gives details of a.c. power arc testing of insulator sets.

lmpulse (mechanical) loads in substation areinsulators' are affected by forces due' toriheconductors/busbars supported by insulators.'

62231 @ IEC:2006 - 13 -

Work is in progress in CIGRE ESCQ (Effects of Short-Circuit Currents) task fqrc{to reviewimpulse loads caused by short-circuit currents in substations. The aim of tlfis work is tointroduce a new concept: the ESL factor (Equivalent Static Load fact6fi which is frequencydependent. The actual peak load may be replaced, in a first approximation, by the peak loadtimes the ESL factoF. This new value may be used as the MDCE in lhis document for thedetermination of the cantilever strenoth.

Radio interference and corona tests are not soecified in this standard since the radiointerference and corona performances are not characteristics of the insulator alone.

Composite hollow core station post ingulators are currently not dealt with in this standard.IEC 61462 gives details of tests on hollow core composite insulators, many of which can beapplied to such station post insulators.

62231 @ IEC:2006 - 15 -

COMPOSITE STATION POST INSULATORS FOR SUBSTATIONSWITH AC VOLTAGES GREATER THAN 1 OOO V UP TO 245 KV -DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA

1 Scope and object

This International Standard applies to composite station post insulators consisting of a loadbearing cylindrical insulating solid core made of resin impregnated fibres, a housing (outsidethe insulating solid core) made of elastomer material (e.9. silicone or ethylene-propylene) andend fittings attached to the insulating core. Composile station post insulators covered by thisstandard are subjected to cantilever, torsion, tension and compression loads. They areintended for substations with a.c. voltages greater than 1 000 V up to 245 kV.

The object of this standard is

- to define the terms used,

- to orescribe test methods,

- to prescribe acceptance or failure criteria.

This standard does not include requirdments dealing with the choice of insulators for specificoperat ing condit ions.

2 Normative references

The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies. For undated references, the latest editionof the referenced document ( including any amendments) appl ies.

IEC 60050-471 , lnternational Electrotechnical Vocabulary (IEV) - Chapter 471: lnsulators

IEC 60060-1, High-voltage test techniques - Part 1: General definitions and test requirements

IEC 60168:1994, Iesfs on indoor and outdoor post insulators of ceramic material or glass forsysfems with nominal voltages greater than 1 000 V

IEC 62217, Polymeric insulators for indoor and outdoor use with a nominal voltage greaterthan 1000 V - General definitions. test methods and acceptance criteria

ISO 1101, Technical drcwings - Geometrical tolerancing - Tolerancing of form, orientation,location and run-out - Generalities, definitions, symbols, indications on drawings

fSO 3452, Non-destructive testing - Penetrant inspection - General principles

62231 @ IEC:2006

3 Terms and definit ions

- ' t7 -

For the purposes of this document, the following terms and definitions apply.

3.1composite station post insulatorpost insulator consist ing of a sol id load bearing cyl indr ical insulat ing core, a housing and endfittings attached to the insulating core

3.2cord (of an insulator)central insulating part of an insulator which provides the mechanical characteristics

NOTE The housing and sheds are not part of the coie.

IEV 471-01-031

3.3housingexternal insulating part of composite insulator providing necessary creepage distance andprotecting core from environment

NOTE An intermediate sheath made of insulat ing material may be part of the housing.

i lEV 471-01-091

3.4housing prof i leshape and dimensions of the housing of the composi tefollowing:- shed overhang(s)- shed thickness at the base and at the tip- shed spacing- shed repetition- shed incl inat ion(s)

3.5

oost insulator which include the

shed (of an insulator)insulating part, projecting from the insulator trunk, intended to increase the creepage distance.The shed can be with or without ribs

!EV 471-01-151

3.6insu lator t runkcentral insulating part of an insulator from which the sheds project

NOTE Also known as shank on smaller insulators.

ltEv 471-01-111

3.7creepage distanceshortest distance or the sum of the shortest distances along the surface on an insulatorbetween two conductive parts which normally have the operating voltage between them

NOTE 1 lhe surface of cement or of any other non-insulat ing joint ing material is not considered as forming part ofthe creepage distance.

62231 @ IEC:2006 - 19 -

NOTE 2 l f a high resistance coating is appl ied to parts of the insulat ing part of an insulator, such parts are

considered to be;ffect ive insulat ing s-urfaces and the distance over them is included in the creepage distance.

i lEV 471-01-041

3.8arcing distanceshortest distance in air external to the insulator between the metallic parts which normallyhave the operating voltage between them

IEV 471-01-011

NOTE The term "dry arcing distance" is also used

3.9interfacessurface between the different materials

NOTE Various interfaces occur in most composite insulators' e.g.

- between housing and f ixing devices,

- between various parts of the housing, e.g. between sheds, or between sheath and sheds,

between core and housing.

ltEc 622171

3.10end fittinginlegral component or formed part of in insulator ihtended to connect it to a supportingstructure, or to a conductor, or to an item of equipment, or to another insulator

NoTE Where the end f i t t ing is metal l ic, the term "metal f i t t ing" is normally used.

EV 471-01-06, modif iedl

3.11connect ion zonezone where the mechanical load is transmitted between the insulating body and the end fitting

llEC 622171

3.12coupl ingpart of the fixing device which transmits load to the hardware external to the insulator

IIEC 622171

3.13trackingorocesJ which forms irreversible degradation by formation of conductive paths (tracks)

starting and developing on the surface of an insulating material

NOTE These oaths are conductive even under dry condit ions.

ltEc 622171

62231 @ IEC:2006

?.14erosionirreversible and non-conducting degradation of the surface of the insulator that occurs by lossof material which can be uniform. localized or tree-shaDed

NOTE Light surface traces, commonly tree-shaped, can occur on composite insulators as on ceramic insulators,after partial f lashover. These traces are not considered to be objectionable as long as they are non-conductive.When they are conductive they are classified as tracking.

IIEC 622171

3.15delamination (of the core)loss of bonding between fibres and matrix

3.16crackany internal fracture or surface fissure of depth greater than 0,1 mm

ltEc 622171

3.'17speci f ied cant i lever loadSCLcantilever load which can be withstood by the insulator when tested under the prescribedcondi t lons

3.18maximum design cant i lever loadMDCLcantilever load level above which damage to the insulator begins lo occur and that should nonfbe exceeded in service

3.19specified torsion loadSToLtorsion load level which can be withstood by the insulator when tested under the prescribedconditions

3.20maximum design torsion loadMDToLtorsion load level above which damage to the insulator begins to occur and that should not beexceeded in service

3.2'lspeci f ied tension loadSTLtension load which can be withstood by the insulator when tested under the prescribedcondi t ions

3.22maximum design tension loadMDTLtension load level above which damaoe to the insulator beoins to occur and that should not beexceeded in service

62231 @ IEC:2006 -23-

3.23speci f ied compression loadSCoLcompression load which can be withstood by the insulator when tested under the prescribedconditions

3.24buckl ing loadcompression load that induces buckling of the insulator core

3.25maximum design compression loadMDCoLload level above which damage to the insulator begins to occur and that should not beexceeded in service

3.26failing load (of a composite station post insulator)maximum load that is reached when tested under the orescribed conditions

NOTE Damage to the core is l ikely to occur at loads lower than the insulator fai l ing load.

3.27overal l Iengthdistance from flange face to flange face of the end fitting

3.28puncture (of an insulator)permanent loss of dielectric strength due to a disruptive discharge passing through the solidinsulat ing mater ial of an insulator

ltEv 471-01-141

3.29residual deflectionthe difference between the initial deflection, if any, of the tip of the insulator measured prior tocantilever load application and the final deflection measured after load release

NOTE The residual deflect ion may depend on the duration of appl icat ion of the load and on the t ime durationbetween the load release and the measurement of the deflect ion.

3.30residual angular displacement .the difference between the initial angular displacement, if any, of one of the insulator endfitting with respect to the other insulalor end fitting measured prior to the application of thetorsion load and the f inal angular displacement measured after torsion load release

NOTE The residual angular displacement may depend on the duration of appl icat ion of the torsion load and onthe t ime duration between the torsion load release and the measurement of the displacement.

4 ldentification

The manufacturer's drawing shall show the relevant dimensions and values necessary foridentifying and testing the insulator in accordance with this standard. The drawing shall alsoshow appl icable manufactur ing to lerances. In addi t ion, the relevant IEC designat ion, whenavai lable, shal l f igure on the drawing.

62231 @ IEC:2006 -25-

Each insulator shall be marked with the name or trademark of the manufacturer and the yearof manufacture. In addition, each insulator shall be marked with ai least the Maximum DesignCant i lever Load (NIDCL) (example: MDCL: 4 kN) or, when avai lable, wi th the relevant IECdesignat ion. These markings shal l be legible and indel ib le.

NOTE At present there is no IEC standard giving designations of composite station post insulators.

5 Environmentalcondit ions

See descriDtion in IEC 62217 .

6 Information on transport, storage and installation

See descr ipt ion in IEC 62217 .

7 Classification of tests

The tests are divided into four groups as follows:

7.'l Design tests

These tests are intended to verify the suitability of the design, materials and manufacturingtechnology (see Annex A for notes on the concept of damage limit).

A composite station post insulator design is defined by

- materials of the core, housing and manufacturing method;

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

- layer thickness of the housing over the core (including a sheaih where used);

- diameter of the core.

When changes in the design occur, re-qualification shall be done according to Table 1.

lF the insulator design changes the.. THEN the fol lowing design tests shal l be repeatedl

8.2 8.3 8.4 8.4 8.4 8.4 8.5 8.5

( !9,^@xi;

;9!9o

<66I

3s

; i :6( !

<;

=.o

EEFo=

,a

E

igHousing materials X X X X X

2 Housing profi le 1) X

3 Core material X X X X4 Core diameter X X X X5 Manufactur ingprocess,Abr 'W X X X X X X X

End fitting material

^/,"(^_

X X7a End f i t t ing connection zone design X,. X7b End f i t t ing coupling design X7c Core-housing-end f i t t ing interface design X8 End f i t t ino method of attachment to core X X1) The fol lowing variat ion of the housing profi le within fol lowing tolerances do not consti tute a changel

Overhang:

Diameter:

!10 %

+15 o/o, -0 o/o

Spacing:

IVIean incl ination:

!10 Vo

t3"

Thickness at base and t ipr i15 % Shed repeti t ionr identical

62231 @ IEC:2006 -27 -

Table 1 - Tests to be carried out after design changes

When a composile station post insulator is submitted to the design tests, it becomes a parentinsulator for a given design and the results shall be considered valid for that design only. Thistested parent insulator defines a particular design of insulators which have all the followingcharacleristics:

a) same materials for the core and housing and same manufacturing method;

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 (including a sheathwhere used) wi th in a to lerance of t15 %;

d) same or smal ler s l ress under mechanical loads;

e) same or greater cross-diameter of the core;

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

62231 @ IEC:2006 _29_

7.2 Type tests

These tests are intended to verify the main characteristics of a composite station postinsulator, which depend mainly on i ts shape and size. Type tests shal l be appl ied tocomposite insulators belonging to an already qualified design. The type tests shall berepeated only when the type of the composite insulator is changed.

Electrically, an insulator type is defined by the

- arcing distance,

- creepage distance,

- housing prof i le.

The electrical type tests shall be performed only once on insulators satisfying the abovedesign criteria for one type and shall be performed with arcing and field grading devices, ifthey are an integral part of the insulator type.

The electrical type tests shall be repeated only when one or more of the above characteristicsis changed.

Mechanical ly, an insulator type is def ined by the:

- length (only for the compression and buckl ing wi thstand load test) ,

- core diameter and material

- design and method of attachment of the end fittings.

The mechanical type tests shall be performed only once on insulators satisfying the abovecriteria for each lype.

The mechanical type tests shall be repeated only when one or more of the above character-istics is changed.

7.3 Sample tests

These tests are intended to verify the characteristics of composite station post insulalors,which depend on the quality of manufacture and materials used. They shall be made oninsulators taken at random from lots offered for acceotance.

7.4 Routine tests

These tests are intended to eliminate composite station post insulators with manufacturingdefects. They shall be made on every composite station post insulator to be supplied.

8 Design tests

8.1 General

The design tests shall be performed only once and the results shall be recorded in a testreport. Each lest can be performed independently on new test specimens where appropriate.The composite station post insulator of a particular design shall be deemed qualified onlywhen the insulators or test specimens pass all the design tests.

62231 @ IEG:2006 _ 2,4 _

8.2 Tests on interfaces and connections of end fil

See IEC 622'17. 1 '2

8.2. ' l Test specimens /

see IEC 62217. ( ,L 4

8.2.2 Reference voltage and temperature for veril

see lEc 62217. 7. Z 2

8.2.3 Reference dry power frequency test

See rEC 62217. q,7. ]

\I

--) *\

0'

8.2.4 Therma l-m echa n ica I pre-stressing

The three specimens shall be submitted to a mechanical load in two opposite directions andto temperature cycles as descr ibed in Figure 1. Ihe 24 h temperature cycle shal l be repeatedtwice. Each temperature cycle has two temperature levels with a duration of at least 8 h, oneat +50 "C + 5 K, the other at -35'C * 5 K. The cold period shall be at a temperature at least85 K below the value actually applied in the hot period. The pre-stressing can be conducted inair or any other sui table medium.

The load appl ied to the specimens shal l correspond to the MDCL.

The load shall be applied perpendicularly to the insulator's axis as near as possible to thenormal load application point, either directly at the normal conductor position or at a hardwareattachment point. When the load is not applied at the normal application point, it shall becorrected to oroduce the same bendino momeni at the base of the insulator as the oneexerted by the MDCL.

The direction of the cantilever load applied to the specimens shall be reversed once,general ly at the cool ing passage through ambient temperature as descr ibed in Figure 1. Thecycles may be interrupted for the load direction reversal and for maintenance of the testequipment for a total duration of 2 h. The starting point after any interruption shall be thebeginning of the interrupted cycle.

NOTE The temperatures and loads in this pre-stressing are not intended to represent service condit ions; they aredesigned to produce specific reproducible stresses in the interfaces on the insulator.

8.2.5 Water immersion pre-stressing

See IEC 62217. l rqt-

8.2.6 Ver i f icat iontests

seetEc62217. S'2 '6

8.3 Assembled core load tests

Extreme service temperatures may affect the mechanical behaviour of composite insulators"

62231 @ IEC:2006 -33-

A general rule to define "extreme high or low" insulator temperatures is not available at thistime; for this reason the supplier should always specify service temperature limitations.

NOTE Whenever the insulators are subjected to very high or low temperatures for long periods of t ime, i t isadvisable that customer and supplier agree on a mechanical test at higher or lower temperatures than thatmentioned in this standard.

8.3,1 Test for the ver i f icat ion of the maximum design cant i lever load (MDCL)

8.3.1.1 Test procedure

Three insulators made on the production line using the standard end fittings shall be selected.The overall length of the insulators shall'be at least 8 times the diameter of the cote, unlessthe manufacturer does not have faci l i t ies to make such a length. In th is case, the length ofinsulator shal l be as near as possible to the prescr ibed length range.

The base end-fitting has to be fixed rigidly. The insulators shall be gradually loaded to1,1 t imes the MDCL rat ing at a temperature of 20 "C i 10 K and held for 96 h. The load shal lbe applied to the insulators at the conductor position, perpendicular to the direction of theconductor, and perpendicular to the core of the insulators.

At 24 h, 48 h, 72 h and 96 h, the deflection of the insulators at the point of application of theIoad shall be recorded, as additional information.

After removal of the load, the steps below shall be followed:

- visually inspect the base end fitting for cracks or permanent deformation,

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

- if required, measure the residual deflection.

Cut each insulator 90' 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 longitudinally into two halves in the plane ofthe previously applied cantilever load. The cut surfaces shall be smoothed by means of fineabrasive c loth (grain s ize 180).

- visually inspect the cut halves for cracks and delaminations,

- perform a dye penetration test according to ISO 3452 to the cut surfaces to reveal cracks.

8,3.1,2 Acceptancecr i ter ia

Observation of any cracks, permanent deformation or delaminations shall constitute failure ofthe test-

8,3,2 Test for the verification of the maximum design torsion load (MDToL)


Three insulalors made on the production line using the standard end fittings shall be selected.The overall length of the insulators shall be at least 8 times the diameter of the core, unlesslhe manufacturer does not have facilities to make such a length. In this case, the length ofinsulators shall be as near as possible to the prescribed length range.

62231 @ IEC:2006 -35-

The torsion load shall be applied to the insulators perpendicularly with the axis of the core ofthe insulator. No bending moment should be appl ied. The insulators shal l be gradual ly loadedto 1,1 t imes the MDToL rat ing at a temperature of 20 'C t 10 K and held for 30 min. Theangular displacement shall be measured at 30 min as additional information. An acceptablevalue of the angular displacement shall be agreed between manufacturer and user.

NOTE In a torsion test, the angular displacement is proport ional to the length of the core between the end l i t t ings.

An example of a test arrangement can be found in Annex C.

After removal of the load, the steps below shall be followed:

- i f required, measure the residual angular displacement,

- visually inspect the end fittings for cracks or permanent deformation,

- 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 inthe middle part of this cut section,

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

- visually inspect the cut surfaces for cracks and delaminations,

- perform a dye penetration test according to ISO 3452 to the cut surfaces to reveal cracksor delaminat ions.

8,3.2,2 Acceptancecr i ter ia

Observation of any cracks, permanent deformation or delaminations shall constitute failure ofthe test.

8.3.3 Verification of the specified tension load (STL)


Three insulators made on the production line using the standard end fittings shall be selected.The overall length of the insulators shall be at least 8 times the diameter of the core, unlessthe manufacturer does not have facilities to make such a length. In this case, the length ofinsulator shall be as near as possible to the prescribed length range.

The tensile load shall be applied to the insulators in line with the axis of the core of theinsulator at a temperalure of 20'C i 10 K. The load shal l be increased rapidly but smoothlyfrom zero to approximately 75 % of the specified tensile load and shall then be graduallyincreased in a time between 30 s and 90 s until the soecified tensile load is reached. lf 100 %of the STL is reached in less than 90 s, the load (100 % of STL) shall be maintained for theremainder of the 90 s.

8.3.3.2 Acceptancecr i ter ia

The test shall be regarded as passed 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 -37 -

8.4 Tests on shed and housing mater ia l

See IEC 62217.

8.5 Tests on the core material

See IEC 62217.

These tesls can be carried out on specimens either wlth or without housing material.

9 Type tests

Insulators made on the product ion l ine using the standard end f i t t ings shal l be selected.

9.1 Ver i f icat ion of d imensions

Unless otherwise agreed, a tolerance of

f (0,04 x d + 1,5) mm when d S 300 mm, or

I (0,025 x d + 6,0) mm when d > 300 mm with a maximum tolerance of O0 mm

shall be allowed on all dimensions for which specific tolerances are not requested (d beingthe dimensions in mi l l imetres).

The measurement of creepage distance shall be related to the design dimensions anotolerances as determined from the insulator drawing, even though this dimension may begreater than the value originally specified by the purchaser. when the creepage distanie rsspecified as a minimum value, the negative tolerance is zero.

Tolerances of parallelism, eccentricity, angular deviation are given in Annex D.

9.2 Electrical tests

Tests in accordance with 9.2-1 and 9.2.2 shall be performed with the insulator in the Dositionin which it will be used in service (vertical or horizontal). lf field-grading devices are used rnservice they shall be used in the tests.

Interpolation of electrical test results may be used for insulators of intermediate length as longas the factor between the arcing distances of the insulators whose results form thelnd pointsof the interpolation range is less than or equal to 1,5. Extrapolation is not allowed.

5.2.1 Dry l ightning impulse vottage test

The post insulator shal l be tested under the condit ions prescr ibed in 4.1,4.2 and 4.4.1 oflEg 99168 The impulse generator sha be adjusted to produce a 1,2tSO imputse (seelEc 60060-1).

lmpulses of both positive and negative polarity shall be used. However, when it is evidentwhich polarity will give the lower flashover voltage, it shall be sufficient to test with thatpolarity.

62231 @ IEC:2006 -39-

Two test procedures are in common use for the lightning impulse test:

- the withstand voltage procedure with 15 impulses;

- the 50 7o flashover voltage procedure.

NOTE The 50 % f lashover voltage procedure gives more jnformation.

The test procedure selected shall be agreed between the purchaser and the manufacturer.

9.2.1.1 Withstand vol tage test using the withstand vol tage procedure

The withstand voltage test shall be performed at the specified voltage corrected for theatmospheric conditions at the time of test (see 4.2.2 of IEC 60168). Fifteen impulses shall beapplied to the post insulator.

The acceotance criteria are as follows:

- the station post insulator passes the test if the number of flashovers does not exceed twofor each ser ies of 15 imoulses.

The station post insulator shall not be damaged by these tests but slight marks on the surfaceof the housing shall be permitted.

9.2.1.2 Voltage test using the 50 % f lashover vol tage procedure

The lightning impulse withstand voltage shall be calculated from the 50 % lightning impulsef lashover vol tage, determined by the up-and-down method descr ibed in IEC 60060-1.

The 50 % l ightning impulse vol tage shal l be corrected in accordance wi lh 4.2.2 of IEC 60168.

The acceotance criteria are as follows:

the station post insulator passes the iest if the 50 % lightning impulse flashover voltage is notf ess than (11(1 - 1,3 d )) = 1,040 t imes the speci f ied l ightning impuise withstand vol tage,where o is the standard deviation (assumed equal to 3 %).

The station post insulator shall not be damaged by these tests, but slight marks on thesurface of the housing shall be permitted.

9.2.2 Wet power frequency withstand voltage test


The test circuit shall be in accordance with IEC 60060-1.

The stat ion post insulator shal l be tested under the condit ions prescr ibed in 4.1,4.2,4.3 and4.4.1 of IEC 60168.

The test voltage to be applied to the station post insulator shall be the specified wet powerfrequency withstand voltage corrected for the atmospheric conditions at the time of test (see4.2.2 of IEC 60168). The test vol tage shal l be maintained at th is value for 1 min. As addit ionalinformation, the voltage can be raised until the flashover occurs.

62231 @ IEC:2006 -41 -


The station post insulator passes the test if no flashover or puncture occurs during the test.NoTE lf f lashover occurs on the insulator tested, then a second test on the same unit may be performed, afterveri fying the rain condit ions.

9.2.2,3 Wet power frequency flashover voltage

To provide information, when agreed between the purchaser and the manufacturer, the wetflashover voltage of the station post insulator may be determined by increasing the voltagegradually, from about 75 o/o of lhe wet power-frequency withstand voltige with a iate of rise ofabout 2 96 of this voltage per second. The wet flashover voltage is the irithmetic mean of ftveconsecutive readings, and ihe value, after correction to standard atmospheric conditions (see4.2.2 ol IEC 60168), shatt be recorded.

9.3 Mechanical tests

9.3.1 Cant i lever fai t ing load test

Interpolation of test results may be used for insurators of intermediate rength as rongfactor between lhe moment arm of the insulators whose results from the-end pointiinterpolation range is less than or equal to 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 acomplete station post insulator.

9,3.1.1 Test specimens

Three insulators made on the production line using the standard base fitting shall be selecteo.


It may be necessary to use special bolts to hold securery the base plate to the test jig. Thecanlilever load shall be increased rapidly but smoothly from zero to approximately 7s 6/o-of tnespecified cantilever load (SCL) of the post insulators and then shall be gradually increased ina time between 30 s and 300 s until breakage of either the core or the metal fitting occurs.Precautions shall be taken to keep the direction of application of the load as perpend"icular aspossible to the axis of the unloaded insulator.


The three fai l ing load values shal l be greater than the SCL.

NoTE . The mechanical fai l ing load of a composjte stat ion post insulator is defined as the maximum load thar rsreached dlr ing the test. The fai lure mode is recorded in 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 tensionIoad of a complete station post insurator. short insurators may be used for this test.

as theof the

62231 @ IEC:2006 _43_

9.3,2. ' l Testspecimens

Three insulators made on the product ion l ine using the standard end-f i t t ings shal l be selected.

9.3.2,2 Test procedure

The tension load shall be applied in the direction of the longitudinal axis of the insulator. Theload shall be increased relatively quickly, but smoothly, from 0 kN to approximately 75 % ofthe srl. The load shall then be gradually increased to the srl in a period of no less than30 s but no greater than 90 s. lt 100 % of the STL is reached in less than g0 s, the loao(1O0 o/' ol STL) shall be mainlained for the remainder of the g0 s.


No evidence of partial, or complete, pullout of the core from the end fitting(s).

No evidence of end fitting breakage.

9.3.3 Compression and buckl ing wi thstand load test

This test is only required if compression is a major componenl of the overall servicemechanical loads and shall be performed by agreement between the manufacturer and theuser.

This test shall be performed at 20'c I 1.0 K and is used to determine the withstand load of acomplete station post insulator.

9.3.3.1 Test specimen

one insulator made on the product ion l ine using the standard end f i t t ings shal l be selected.

9.3.3.2 Test procedu re

In service, the coupling of the slation posl insulator belongs to one of the cases 1 to 4 InAnnex E. In the laboratory, the post insulator shall be subjected to a compresslon load alongtheir axis, according to any one of the cases 1 to 4 in Annex E.

The test load is given by SCoL multiplied by the correction facior CF given in Annex E.

The load applied to the insulator shall be increased rapidty but smoothly (within 90 s) fromzero to approximalely 75 o/o of the test load of the post insulators and then shall be graduallyincreased in a time between 30 s and 300 s up to the test load.

Precaulions shall be taken to keep the direction of the load as close as gossible to the axis oflhe unloaded insulator. lt may be necessary to use special bolts or fixing arrangements lohold securely both end fittings to the test sefup.


The insulator shal l wi thstand the test load withoul v isual damaoe.

62231 @ IEC:2006 -45-

10 Sample tests

10.1 General ru les

For the sample tests, two groups of samples shall be used, E'l and E2. The sizes of thesesamples are indicated in Table 2. lf more than 2 000 insulators are concerned, they shall bedivided into an ootimum number of lols of less than 2 000 insulators. The results of the testsshall be evaluated separately for each lot.

The insulators shall be selected from the lot at random. The purchaser has the right to makethe select ion. The samples shal l be subjected to the appl icable sample tests.

The samole tests are as follows:

- verification of the dimensions (E1 + Ez\l

- galvanizing test (E1 + E2\:

- verification of the specified mechanical loads (E1).

ln the event of a failure of the sample to satisfy a test, the re-testing procedure shall beappl ied as prescr ibed in 10.5.

Table 2 - Number of samples for sample tests

Lot size

w

' . Sample size

E1 E2

Ns100 By agreement By agreement

100<N<300

300<N<2000

2

4

1

3

Insulators of sample E2 only can be used in service only if the galvanising test is performedwith the magnetic method.

10.2 Ver i f icat ion of d imensions (E1 + E2)

On all selected insulators, the dimensions of the composite station post insulator shall complywith the values shown on the drawing, within specified tolerances for geometry, form andposition. Unless otherwise specified, the tolerances given in Annex D and in 9.1 of thisdocument shall be used. The drawing can show points between which the creepage distanceis specified.

The measurement of creepage distance shall be related to the design dimensions asdetermined from the insulator drawing, even though this dimension may be greater than thevalue or ig inal ly speci f ied by the purchaser. When the creepage distance is speci f ied as aminimum value, the negative tolerance is zero.

10.3 Galvaniz ing test (El + E2)

This test shall be performed on all galvanised parts in accordance with IEC 60168.

62231 @ IEC:2006

10,4 ver i f icat ion of the speci f ied mechanical loads (E1)

'10.4.1 Verification of the specified cantilever load (SCL) (El divided by 2)


It may be necessary to use special bolts to hold securely the base plate to the test ji9. Thecantilever load shall be applied to the insulator at the conductor position, perpendicular to thedirection of the conductor, and perpendicular to the core of the insulator.

The load shall be increased rapidly but smoothly from zero to approximately 75% of thespecified cantilever load (SCL) of the post insulator and then shall be gradually increased in atime 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 maintained for the remainder of the 90 s.

'1O.4.1.2 Acceptance criteria

The insulalor shall be regarded as passed if the SCL can be maintained for the required time.

ln order to obtain more information from the test, the load may then be increased until failureof the core or breakage of the metal fitting occurs. The failing load values and the failuremodes 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 longitudinal axis of the insulator. Theload shall be increased relatively quickly, but smoothly, from 0 kN to approximately 75 % ofthe STL. The load shall then be gradually increased to the STL in a period of no less than30 s but no greater than 90 s. lf 1OO o/o of the STL is reached in less than 90 s, the load(100 % of STL) shal l be maintained for the remainder of 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 insulator or metal part fails 10 comply with the sample tests, a new sample equal totwice the quantity originally submitted to the tests shall be subjected to re-testing.

The re-testing shall comprise the test in which failure occurred.

lf two or more insulators or metal parts fail to comply with any of the sample tests, or if anyfailure occurs during the re-testing, the complete lot shall be considered as not complying withthis standard and shall be withdrawn by the manufacturer.

-47 -

62231 @ IEC:2006 -49-

Provided the cause of the failure can be clearly identified, the manufacturer may sort the lot toeliminate all the insulators with this defect. The sorted lot may then be resubmitted for testing.The number then selected shall be three times the first quantity chosen for tests. lf anyinsulator fails during this re-testing, the complete lot shall be considered as not complyingwith this standard"

11 Routine tests

11.1 ldent i f icat ion of the stat ion post insulator

Each insulator shall be marked with the name or trademark of the manufacturer and the yearof manufacture. In addilion, each insulator shall be marked according to Clause 4- Thesemarkings shal l be legible and indel ib le.

11.2 Visual examinat ion

The examination shall be made on each insulator. The mounting of the metal fittings on theinsulating parts shall be in accordance with the drawings. The colour of the insulator shall beapproximately as specified in ihe drawings.

The following imperfections shall be acceptable on the insulator surface:

- superficial defects of area less than 25 mm2 (the total defective area not exceeding 0,2 %of the total insulalor surface) and depth or height less than 1 mm.

11.3 Tensi le load test

Every insulator shall be subjected, at ambient temperature, to a tensile load of at least 50 %of the specified tensile load (STL) for at least 10 s. lf no STL is given for the insulator, an STLof at least 10 kN shal l be assumed.

No pullout or slip of the core from the end fitting shall occur.

62231 @ IEC:2006 - 5't -

AKtemperature 'C

501 5

Figure I - Thermal-mechanical pre-stressing test - Typical cycles

62231 @ IEC:2006 -53-

Annex A(informative)

Notes on the mechanical loads and tests

This annex oresents some comments on the various mechanical tests of this standard.

A.1 Design tests

For a fami ly of stat ion post insulators, the maximum design(generally expressed in megapascals, MPal or newton metre€,cantilever loads. The core and the end fittings define a stationfamily may contain insulators of different length.

bending stress or momentN.m, respectively) limits the

post insulator family as each

The maximum design bending stress (resul t ing from MDCL) is the maximum useable bendingstress of the insulator. For each family of station post insulators, a 96 h cdnlilever 'f9ad:testverifiegfthat the core can sustain the maximum design bending stress without damage. Thistest, aS a design lest, needs to be performed only once on a representative length insulatorfor each insulator family.

In applications where torsion loads are the major load component, a 30-min torsion load testverifids that the core can sustain the maximum desion torsion load without damaoe.

In addition, a tensile load test is required to verify the design of the end fittings together withthe method of attachment.

4.2 Type tests

The core diameter, insulator coupling length and method of attachment of the end fittingsmechanical ly def ine a stat ion post insulator type. A maximum design cant i lever load (MDCL),in kN (kilonewtons), is assigned to each station post insulator type usually by interpolationfrom the design MDCL verification test. For each station post insulator type, the assignedMDCL is the allowable ultimate limit for service loads. A test to verify the MDCL for eachstation post insulator type is not included in this standard as such a type test would beuneconomic and t ime consumino.

The cantilever failing load is determined with a short time load type test. This standardrequires that the cantilever failing load shall exceed the specified cantilever load (SCL), whichis the short-time withstand strength of the insulator. The cantilever failing load verifies that therod or base end fitting does not fail at the specified cantilever load, though damage to thecore may occur.

A compression or buckling test may be performed to verify that the insulator can sustain thespecified compression load without visual damage.

62231 @ IEC:2006

A.3 Sample test

A short-time cantilever load test has been included as a sample test to verify the specifiedcantilever load (SCL). A tension load test (STL) verifies that the end fittings are correctlyfastened to the core and that they can sustain the specified load. These tests are performedon production insulators complete with production end fittings. They are simple and relaiivelyqu ick to perform.

A.-4 Routine tensile test

A routine iensile iest is specified instead of a routine bending test. This test provides someverification of the end fitting attachment process during production and is similar to the routinetest performed on composite suspension insulators. This test is used since, unlike porcelain,composite station post insulators are not made with brittle materials, and consequently aroutine bending test at any level below the MDCL would not give any useful information.

By contrast with suspension insulators, this test may be more difficult to perform with somedesigns of end fittings and mounting bases. This difficulty arises since some designs of endf i t t ings impose an unbalanced tensi le load on the insulator. 'Care should be taken to ensurethat the resulting load is applied in line with the axis of the insulator.

62231 A IEC:2006

Annex B(informative)

Determination of the equivalent bending moment caused bycombined canti lever and compression (tension) loads

B.l lntroduct ion

This annex provides guidance for appl icat ions where the compression load is not dominantand will not lead to buckling of the station post insulato.. The torsion load is also deemed tohave no significant influence on the combined loading of the insulator.

This annex does not cover cases where the compression and/or torsion loads are significantcompared to the bending load.

In cases where the bending load on the station post insulator is dominant, the correspondingstress may be significantly modified by the additional stress caused by the simultaneousapplication of a compression (or tension) Ioad. The bending moment corresponding to thecombination of these loads must not exceed the moment which corresDonds to the MDCL.

The following clauses give information on calculating the approximate equivalent bendingmoment when station post insulators are submitted to combined loads.

The following notation is used:

MC

Mr

d

EI

applied compression, tension and cantilever loads (N);

resul t ing moment in the post under compression;

resulting moment in the post under tension;

distance from the point of application of the load to the top edge of the metal basefitting in metres (m):

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

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

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

8.2 Maximum al lowable bending moment, rnmax

The maximum design cantilever load of a composite station post insulator induces themaximum allowable bending moment mr"" = MDCL x d. The maximum stress associated withthis bending moment must not produce any damage to the insulator core.

The maximum combined stress is the maximum stress resulting from the simultaneouslyappl ied cant i lever and compression (or tension) loads. In service, the var ious combinat ions ofloads must not produce a bending moment that is greater than the bending moment inducedbv the MDCL.

L./

62231 @ IEC:2006 -59-

8.3 Gombined loading of stat ion post insulators

The following formulae allow the determination of the moment in the insulator when submittedio single or combined loads. lt should be noted that the accuracy of these formulae dependson the deflection. The more the moment approaches the MDCL, the less accurate theyDecome.

It should also be noted that the applied loads can induce damaging stress levels in the endfittings or accessories even when the moment in the insulator is at an acceptable level.

tEc o22n6

Figure 8.1 - Gombined loads appl ied to stat ion post insulators

A - Comoression case

The cantilever (C) component of the load applies a cantilever moment to the insulator; thecompression load (Co) is taken as being applied to the head of the insulator toward its base.The moment resulting from the application of these two forces is given by

u "o

= lc2 Eil coll t2 tan la (cotet)t tzl

In service, Mco should not exceed mmax.

B - Tension case

The cantilever (C) component of the load applies a cantilever moment to the insulator; thetension load (IJ is taken as being applied to the head of the insulaior away from its base. Themoment resulting from the application of these two forces is given by

M, = lcz E r l1t2 1, ,nh ld (r tEt)1t21

In service, Mr should not exceed mmax.

fil l '

62231 @ IEC:2006 - 61 -

Annex C(informative)

Example of torsion load test arrangement

Disdlacement sensor

Tensile system

Embedded area

lEc 02w6

One example of the mounting arrangement for the torsion load test could be as follows:

Torsion moment Mt: Mt = F xD.lz .Linear disolacement d

Angular displacement a

a = 2d/Dz

where a is in radians

Top View

62231 @ IEC:2006 -63-

Annex D(normative )

Tolerances of form and posit ion

The following Figures D.1 to D.3 give tolerances of form and position for composite stationpost 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 showtwo examples of methods of measuring.the angular deviation of the fixing holes; Figure D.4summarizes the appl icable to lerances according to standard drawing pract ice ( lSO 1101).

Guidel ines on the methods of measurement can be found in IEC 60168.

Legend

Parallelism of the end faces:

forh<1m, p<0,5mmforh>'1 m, p < 0,5 h mm with h in m

The tolerances of the parallelism are relatedto a diameter of 250 mm.

Coaxi'ality and concentricity: C = 2 y. e

Eccentricity: e < 2 (1 + h) mm with h in m

Figure D.1 - Paral le l ism, coaxial i ty and concentr ic i ty

Reference diameter

62231 @ IEC:2006

a = Ian-l

Precision lev€l for direct readingof angular position a

Pr€cision level inhorizontal position

-65-

Centred pins

Tolerance of the deviation: a< * i'

Figure D.2 - Angular deviation of fixing holes: Example 1

Centred pins

where f* is the distance between the centres of two opposite pins

Tolerance of the deviation: u< * 1'

Figure D.3 - Angular deviat ion of f ix ing holes: Example 2

f a")r.il

62231 @ IEC:2006 -67 -

Figure D.4 - Tolerances according to gtandard drawing practice

Paral lel ism: the upper plane face is paral lel to the lower reference plane C within the indicatedtolerances.

Coaxial i ty and concentr ici ty: the axes of the top f i t t ing f ixing holes have to be within a cyl inder witha diameter as indicated bv the numerical value.

raf Evenness: the numerical value indicates the maximum admissibie unevenness of the face.

Alignment of the f ixing holesr the l ine between two opposite,axes of holes of the top f i t t ing have tobe in I ine with the corresponding l ine of the bottom f i t t ing with two paral lels of specif ied distance

62231 A IEC:2006 - 69 -

Annex E(informative )

Notes on the compression and buckling test

The result of the compression and buckling test is influenced by:

- rod diameter,

- length between end fittings,

- coupling arrangement of the end fitting (top and bottom).

Depending on the coupling at the top and bottom of the station post insulator the buckling testhas 4 Ioad condi t ions (elast ic Euler-buckl ing).

Lj, k = 0,7

The correction factor CF is given by:

gP = (L/ Ly)z where j corresponds to the service coupling arrangement, and k Gorresponds tothe laboratory arrangement.

As an example, if service coupling arrangement corresponds to case 1, and the laboratoryset-up corresponds to case 4, then the correction factor CF= (2lO,flz = 16.

1

l.TI

I+

FB

L/

62231 @ IEC:2006

Bibliography

IEC 60865 (alf parts), Short-citcuit currents - Calculation of effects

IEC 61245, Artificial pollution tests on high-voltage insulators to be used on d.c. sysferns

IEC 61462, Composite insulators - Hollow insulators for use in outdoor and indoor electricalequipment - Detinitions, test methods, acceptance criteria and design recommendations

IEC 61467, lnsulatorc for overhead lines with a nominal voltage above 1 000 V - AC powerarc fesls on insulator sets

fEC 60507, Artificial pollution fesfs on high-voftage insulators to be used on a.c. sysfems

IEC 61952, Insulators for overhead /ines - Composite line post insulators for alternativecurrent with a nominal voltage > 1 000 V

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cei iec 62231 edition 1.0 (2006-02)

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