EN 62231:2006

Composite station post insulators for substations with a.c. voltages greater than 1 000 V up to 245 kV - Definitions, test methods and acceptance criteria

This International Standard applies to composite station post insulators consisting of a load bearing cylindrical insulating solid core made of resin impregnated fibres, a housing (outside the insulating solid core) made of elastomer material (e.g. silicone or ethylene-propylene) and end fittings attached to the insulating core. Composite station post insulators covered by this standard are subjected to cantilever, torsion, tension and compression loads. They are intended for substations with a.c. voltages greater than 1 000 V up to 245 kV.

Verbundstützisolatoren für Unterwerke für Wechselspannung größer 1 kV bis 245 kV - Definitionen, Prüfmethoden und Annahmekriterien

Isolateurs supports composites rigides à socle destinés aux postes à courant alternatif de tensions supérieures à 1 000 V jusqu'à 245 kV - Définitions, méthodes d'essai et critères d'acceptation

La présente Norme internationale s'applique aux supports isolants composites rigides à socle constitués d'un noyau isolant plein cylindrique supportant les charges mécaniques réalisé en fibres imprégnées de résine, d'un revêtement (à l'extérieur du noyau plein isolant) réalisée en matériau élastomère (par exemple du silicone ou de l'éthylène-propylène) et des armatures d'extrémité fixées au noyau isolant. Les supports isolants composites rigides à socle relevant de la présente norme sont soumis aux charges de flexion, de torsion, de traction et de compression. Ils sont destinés aux postes à courant alternatif de tensions supérieures à 1 000 V jusqu'à 245 kV.

Postajni kompozitni izolatorji za postaje z izmeničnimi napetostmi, ki so višje od 1 000 V in ne presegajo do 245 kV – Definicije, preskusne metode in sprejemna merila (IEC 62231:2006)

General Information

• Status: Published
• Publication Date: 21-Dec-2006
• Withdrawal Date: 30-Sep-2009
• ICS: 29.080.10 - Insulators
• Technical Committee: CLC/SR 36 - Insulators for substations
• Drafting Committee: IEC/TC 36 - IEC_TC_36
• Parallel Committee: IEC/SC 36C - IEC_SC_36C
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 22-Dec-2006
• Completion Date: 22-Dec-2006
• Ref Project: SIST EN 62231:2007 - Composite station post insulators for substations with a.c. voltages greater than 1 000 V up to 245 kV - Definitions, test methods and acceptance criteria

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Composite station post insulators for substations with a.c. voltages greater than 1 000 V up to 245 kV - Definitions, test methods and acceptance criteria (IEC 62231:2006)Isolateurs supports composites rigides a socle destinés aux postes a courant alternatif de tensions supérieures a 1 000 V jusqu'a 245 kV - Définitions, méthodes d'essai et criteres d'acceptation (IEC 62231:2006)Verbundstützisolatoren für Unterwerke für Wechselspannung größer 1 kV bis 245 kV - Definitionen, Prüfmethoden und Annahmekriterien (IEC 62231:2006)Ta slovenski standard je istoveten z:EN 62231:2006SIST EN 62231:2007en,fr,de29.080.10IzolatorjiInsulatorsICS:SLOVENSKI
STANDARDSIST EN 62231:200701-november-2007

EUROPEAN STANDARD EN 62231 NORME EUROPÉENNE
EUROPÄISCHE NORM December 2006
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2006 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62231:2006 E
ICS 29.080.10
English version
Composite station post insulators for substations
with a.c. voltages greater than 1 000 V up to 245 kV -
Definitions, test methods and acceptance criteria (IEC 62231:2006)
Isolateurs supports composites rigides
à socle destinés aux postes à courant alternatif de tensions supérieures
à 1 000 V jusqu'à 245 kV -
Définitions, méthodes d'essai
et critères d'acceptation (CEI 62231:2006)
Verbundstützisolatoren für Unterwerke
für Wechselspannung größer
1 kV bis 245 kV -
Definitionen, Prüfmethoden
und Annahmekriterien (IEC 62231:2006)
This European Standard was approved by CENELEC on 2006-09-12. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.

- 2 -
Foreword The text of document 36C/159/FDIS, future edition 1 of IEC 62231, prepared by SC 36C, Insulators for substations, of IEC TC 36, Insulators, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62231 on 2006-09-12. This standard is to be used in conjunction with EN 62217:2006, Polymeric insulators for indoor and outdoor use with a nominal voltage > 1 000 V - General definitions, test methods and acceptance criteria. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2007-07-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2009-10-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 62231:2006 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 60865 NOTE
Harmonized in EN 60865 series (not modified). IEC 60507 NOTE
Harmonized as EN 60507:1993 (not modified). IEC 61952 NOTE
Harmonized as EN 61952:2003 (not modified). __________

- 3 - EN 62231:2006 Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
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 edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-471 -1) International Electrotechnical Vocabulary (IEV)
Chapter 471: Insulators - -
IEC 60060-1 -1) High-voltage test techniques Part 1: General definitions and test requirements HD 588.1 S1 19912)
IEC 60168 1994 Tests on indoor and outdoor post insulators
of ceramic material or glass for systems with nominal voltages greater than 1000 V EN 60168 19942)
IEC 62217 -1) Polymeric insulators for indoor and outdoor use with a nominal voltage > 1 000 V - General definitions, test methods and acceptance criteria EN 62217 + corr. December
20062)2006
ISO 1101 -1) Geometrical Product Specifications (GPS) - Geometrical tolerancing - Tolerances of form, orientation, location and run-out EN ISO 1101 20052)
ISO 3452 -1) Non-destructive testing - Penetrant
inspection - General principles - -
1) Undated reference. 2) Valid edition at date of issue.

NORME INTERNATIONALECEIIEC INTERNATIONAL STANDARD 62231Première éditionFirst edition2006-02 Isolateurs supports composites rigides à socle destinés aux postes à courant alternatif de tensions supérieures à 1 000 V jusqu'à 245 kV –Définitions, méthodes d'essai et critères d'acceptation
Composite station post insulators for substations with a.c. voltages greater than 1 000 V up to
245 kV – Definitions, test methods and
acceptance criteria
Pour prix, voir catalogue en vigueur For price, see current catalogue IEC 2006
Droits de reproduction réservés
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Copyright - all rights reserved Aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission,
3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, SwitzerlandTelephone: [phone] Telefax: [phone] E-mail: [e-mail]
Web: www.iec.ch CODE PRIX PRICE CODE
W Commission Electrotechnique InternationaleInternational Electrotechnical Commission

62231  IEC:2006 – 3 – CONTENTS FOREWORD.7 INTRODUCTION.11
1 Scope and object.15 2 Normative references.15 3 Terms and definitions.17 4 Identification.23 5 Environmental conditions.25 6 Information on transport, storage and installation.25 7 Classification of tests.25 7.1 Design tests.25 7.2 Type tests.29 7.3 Sample tests.29 7.4 Routine tests.29 8 Design tests.29 8.1 General.29 8.2 Tests on interfaces and connections of end fittings.31 8.3 Assembled core load tests.31 8.4 Tests on shed and housing material.37 8.5 Tests on the core material.37 9 Type tests.37 9.1 Verification of dimensions.37 9.2 Electrical tests.37 9.3 Mechanical tests.41 10 Sample tests.45 10.1 General rules.45 10.2 Verification of dimensions (E1 + E2).45 10.3 Galvanizing test (E1 + E2).45 10.4 Verification of the specified mechanical loads (E1).47 10.5 Re-testing procedure.47 11 Routine tests.49 11.1 Identification of the station post insulator.49 11.2 Visual examination.49 11.3 Tensile load test.49
Annex A (informative)
Notes on the mechanical loads and tests.53 Annex B (informative)
Determination of the equivalent bending moment caused by
combined cantilever and compression (tension) loads.57 Annex C (informative)
Example of torsion load test arrangement.61 Annex D (normative)
Tolerances of form and position.63 Annex E (informative)
Notes on the compression and buckling test.69
Bibliography.71

62231  IEC:2006 – 5 – Figure 1 – Thermal-mechanical pre-stressing test – Typical cycles.51 Figure B.1 – Combined loads applied to station post insulators.59 Figure D.1 – Parallelism, coaxiality and concentricity.63 Figure D.2 – Angular deviation of fixing holes: Example 1.65 Figure D.3 – Angular deviation of fixing holes: Example 2.65 Figure D.4 – Tolerances according to standard drawing practice.67
Table 1 – Tests to be carried out after design changes.27 Table 2 – Number of samples for sample tests.45

62231  IEC:2006 – 7 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ___________
COMPOSITE STATION POST INSULATORS FOR SUBSTATIONS
WITH AC VOLTAGES GREATER THAN 1000 V UP TO 245 kV –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts 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 misinterpretation by any end user. 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 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users 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 individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature 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 references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 62231 has been prepared by subcommittee 36C: Insulators for substations, of IEC technical committee 36: Insulators. This bilingual version (2006-04) replaces the English version. The text of this standard is based on the following documents: FDIS Report on voting 36C/159/FDIS 36C/160/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. The French version of this standard has not been voted upon. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62231  IEC:2006 – 9 – This standard is to be read in conjunction with IEC 62217:2005, Polymeric insulators for indoor and outdoor use with a nominal voltage >1 000 V – General definitions, test methods and acceptance criteria. The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the 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 – 11 – 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 the core by metal fittings. Despite these common features, the materials used and the construction details employed by different manufacturers may be different. 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 manufacturing technologies not suitable for high-voltage applications. The influence of time on the electrical and mechanical properties of 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 satisfactory lifetime under normal service conditions.
The approach for mechanical testing under bending loads used in this Standard is based on IEC 61952. This approach 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 technique to determine the inception of damage.
In some cases, station post insulators can be subjected to a combination of loads. In order to give some guidance, Annex B explains how to calculate the equivalent bending moment in the insulators resulting from the combination of bending, tensile and compression loads.
Pollution tests, as specified in IEC 60507 and IEC 61245, are not included in this document, their applicability to composite station post insulators having not been proven. Such pollution tests performed on composite insulators do not correlate with experience obtained from service. 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 test parameters are manifold and can have very different values depending on the configurations of the network and the supports and on the design of arc-protection devices. The heating effect of power arcs should be considered in the design of metal fittings. Critical damage to the metal fittings, resulting from the magnitude and duration of the short-circuit current 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 user and the manu-facturer. IEC 61467 gives details of a.c. power arc testing of insulator sets. Impulse (mechanical) loads in substation are typically caused by short-circuits. Post insulators are affected by forces due to the interaction of the currents circulating in conductors/busbars supported by insulators.
The impulse load or peak load may be evaluated using guidance found in the IEC 60865 series.

62231  IEC:2006 – 13 – Work is in progress in CIGRE ESCC (Effects of Short-Circuit Currents) task force to review impulse loads caused by short-circuit currents in substations. The aim of this work is to introduce a new concept: the ESL factor (Equivalent Static Load factor) which is frequency dependent. The actual peak load may be replaced, in a first approximation, by the peak load times the ESL factor. This new value may be used as the MDCL in this document for the determination of the cantilever strength. Radio interference and corona tests are not specified in this standard since the radio interference and corona performances are not characteristics of the insulator alone. Composite hollow core station post insulators are currently not dealt with in this standard. IEC 61462 gives details of tests on hollow core composite insulators, many of which can be applied to such station post insulators.

62231  IEC:2006 – 15 – COMPOSITE STATION POST INSULATORS FOR SUBSTATIONS
WITH AC VOLTAGES GREATER THAN 1 000 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 load bearing cylindrical insulating solid core made of resin impregnated fibres, a housing (outside the insulating solid core) made of elastomer material (e.g. silicone or ethylene-propylene) and end fittings attached to the insulating core. Composite station post insulators covered by this standard are subjected to cantilever, torsion, tension and compression loads. They are intended 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 prescribe test methods, – to prescribe acceptance or failure criteria. This standard does not include requirements dealing with the choice of insulators for specific operating conditions. 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 edition of the referenced document (including any amendments) applies. IEC 60050-471, International Electrotechnical Vocabulary (IEV) – Chapter 471: Insulators IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements IEC 60168:1994, Tests on indoor and outdoor post insulators of ceramic material or glass for systems with nominal voltages greater than 1 000 V IEC 62217, Polymeric insulators for indoor and outdoor use with a nominal voltage greater than 1000 V – General definitions, test methods and acceptance criteria
ISO 1101, Technical drawings – Geometrical tolerancing – Tolerancing of form, orientation, location and run-out – Generalities, definitions, symbols, indications on drawings ISO 3452, Non-destructive testing – Penetrant inspection – General principles

62231  IEC:2006 – 17 – 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 composite station post insulator post insulator consisting of a solid load bearing cylindrical insulating core, a housing and end fittings attached to the insulating core 3.2
core (of an insulator) central insulating part of an insulator which provides the mechanical characteristics NOTE The housing and sheds are not part of the core. [IEV 471-01-03] 3.3
housing external insulating part of composite insulator providing necessary creepage distance and protecting core from environment
NOTE An intermediate sheath made of insulating material may be part of the housing.
[IEV 471-01-09] 3.4
housing profile shape and dimensions of the housing of the composite station post insulator which include the following: – shed overhang(s) – shed thickness at the base and at the tip – shed spacing – shed repetition – shed inclination(s) 3.5
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
[IEV 471-01-15] 3.6
insulator trunk
central insulating part of an insulator from which the sheds project NOTE Also known as shank on smaller insulators.
[IEV 471-01-11] 3.7 creepage distance shortest distance or the sum of the shortest distances along the surface on an insulator between two conductive parts which normally have the operating voltage between them
NOTE 1 The surface of cement or of any other non-insulating jointing material is not considered as forming part of the creepage distance.

62231  IEC:2006 – 19 – NOTE 2 If a high resistance coating is applied to parts of the insulating part of an insulator, such parts are considered to be effective insulating surfaces and the distance over them is included in the creepage distance.
[IEV 471-01-04] 3.8 arcing distance shortest distance in air external to the insulator between the metallic parts which normally have the operating voltage between them
[IEV 471-01-01] NOTE The term “dry arcing distance” is also used. 3.9
interfaces surface between the different materials
NOTE Various interfaces occur in most composite insulators, e.g.
– between housing and fixing devices,
– between various parts of the housing, e.g. between sheds, or between sheath and sheds,
– between core and housing.
[IEC 62217] 3.10 end fitting integral component or formed part of an insulator intended to connect it to a supporting structure, or to a conductor, or to an item of equipment, or to another insulator
NOTE Where the end fitting is metallic, the term “metal fitting” is normally used.
[IEV 471-01-06, modified] 3.11 connection zone zone where the mechanical load is transmitted between the insulating body and the end fitting [IEC 62217] 3.12 coupling part of the fixing device which transmits load to the hardware external to the insulator [IEC 62217] 3.13 tracking process which forms irreversible degradation by formation of conductive paths (tracks) starting and developing on the surface of an insulating material
NOTE These paths are conductive even under dry conditions.
[IEC 62217]
62231  IEC:2006 – 21 – 3.14
erosion irreversible and non-conducting degradation of the surface of the insulator that occurs by loss of material which can be uniform, localized or tree-shaped
NOTE Light surface traces, commonly tree-shaped, can occur on composite insulators as on ceramic insulators, after partial flashover. These traces are not considered to be objectionable as long as they are non-conductive. When they are conductive they are classified as tracking. [IEC 62217]
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
[IEC 62217] 3.17
specified cantilever load
SCL cantilever load which can be withstood by the insulator when tested under the prescribed conditions 3.18
maximum design cantilever load
MDCL
cantilever load level above which damage to the insulator begins to occur and that should not 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 insulator begins to occur and that should not be exceeded in service 3.21
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 damage to the insulator begins to occur and that should not be exceeded in service

62231  IEC:2006 – 23 –
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 compression load that induces buckling of the insulator core 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 composite station post insulator) maximum load that is reached when tested under the prescribed conditions NOTE Damage to the core is likely to occur at loads lower than the insulator failing load. 3.27 overall length distance from flange face to flange face of the end fitting 3.28
puncture (of an insulator) permanent loss of dielectric strength due to a disruptive discharge passing through the solid insulating material of an insulator
[IEV 471-01-14] 3.29
residual deflection the difference between the initial deflection, if any, of the tip of the insulator measured prior to cantilever load application and the final deflection measured after load release NOTE The residual deflection may depend on the duration of application of the load and on the time duration between the load release and the measurement of the deflection. 3.30 residual angular displacement the difference between the initial angular displacement, if any, of one of the insulator end fitting with respect to the other insulator end fitting measured prior to the application of the torsion load and the final angular displacement measured after torsion load release NOTE The residual angular displacement may depend on the duration of application of the torsion load and on the time duration between the torsion load release and the measurement of the displacement. 4 Identification The manufacturer's drawing shall show the relevant dimensions and values necessary for identifying and testing the insulator in accordance with this standard. The drawing shall also show applicable manufacturing tolerances. In addition, the relevant IEC designation, when available, shall figure on the drawing.

62231  IEC:2006 – 25 – Each insulator shall be marked with the name or trademark of the manufacturer and the year of manufacture. In addition, each insulator shall be marked with at least the Maximum Design Cantilever Load (MDCL) (example: MDCL: 4 kN) or, when available, with the relevant IEC designation. These markings shall be legible and indelible. NOTE At present there is no IEC standard giving designations of composite station post insulators. 5 Environmental conditions See description in IEC 62217. 6 Information on transport, storage and installation See description in IEC 62217. 7 Classification of tests The tests are divided into four groups as follows: 7.1 Design tests These tests are intended to verify the suitability of the design, materials and manufacturing technology (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 sheath where used); – diameter of the core.
When changes in the design occur, re-qualification shall be done according to Table 1.

62231  IEC:2006 – 27 – Table 1 – Tests to be carried out after design changes IF the insulator design changes the. THEN the following design tests shall be repeated:
8.2 8.3 8.4 8.4 8.4 8.4 8.5 8.5
Interfaces and connections of end fittings Assembled core load tests Hardness test Accelerated weathering Tracking and erosion test Flammability test Dye penetra-tion test Water diffusion test 1 Housing materials X
X X X X
2 Housing profile 1)
X
3 Core material X X
X X 4 Core diameter
X X
X X 5 Manufacturing process X X X X X
X X 6 End fitting material X X
7a End fitting connection zone design X X
7b End fitting coupling design
X
7c Core-housing-end fitting interface design X
8 End fitting method of attachment to core X X
1)
The following variation of the housing profile within following tolerances do not constitute a change: Overhang:
±10 % Spacing:
±10 % Diameter:
+15 %, –0 % Mean inclination:
±3 ° Thickness at base and tip: ±15 % Shed repetition:
identical
When a composite station post insulator is submitted to the design tests, it becomes a parent insulator for a given design and the results shall be considered valid for that design only. This tested parent insulator defines a particular design of insulators which have all the following characteristics: 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 sheath where used) within a tolerance of ±15 %;
d) same or smaller stress 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 post insulator, which depend mainly on its shape and size. Type tests shall be applied to composite insulators belonging to an already qualified design. The type tests shall be repeated only when the type of the composite insulator is changed. Electrically, an insulator type is defined by the – arcing distance, – creepage distance, – housing profile. 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 insulator type.
The electrical type tests shall be repeated only when one or more of the above characteristics is changed.
Mechanically, an insulator type is defined by the: – length (only for the compression and buckling withstand 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 above criteria for each type.
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 insulators, which depend on the quality of manufacture and materials used. They shall be made on insulators taken at random from lots offered for acceptance. 7.4 Routine tests These tests are intended to eliminate composite station post insulators with manufacturing defects. 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 test report. Each test can be performed independently on new test specimens where appropriate. The composite station post insulator of a particular design shall be deemed qualified only when the insulators or test specimens pass all the design tests.

62231  IEC:2006 – 31 – 8.2 Tests on interfaces and connections of end fittings
See IEC 62217. 8.2.1 Test specimens See IEC 62217. 8.2.2 Reference voltage and temperature for verification tests See IEC 62217. 8.2.3 Reference dry power frequency test See IEC 62217. 8.2.4 Thermal-mechanical pre-stressing The three specimens shall be submitted to a mechanical load in two opposite directions and to temperature cycles as described in Figure 1. The 24 h temperature cycle shall be repeated twice. Each temperature cycle has two temperature levels 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 temperature at least 85 K below the value actually applied in the hot period. The pre-stressing can be conducted in air or any other suitable medium. The load applied to the specimens shall correspond to the MDCL. The load shall be applied perpendicularly to the insulator's axis as near as possible to the normal load application point, 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 produce the same bending moment 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, generally at the cooling passage through ambient temperature as described in 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 beginning of the interrupted cycle. NOTE The temperatures and loads in this pre-stressing are not intended to represent service conditions; they are designed to produce specific reproducible stresses in the interfaces on the insulator. 8.2.5 Water immersion pre-stressing See IEC 62217. 8.2.6 Verification tests See IEC 62217. 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 this time; 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 time, it is advisable that customer and supplier agree on a mechanical test at higher or lower temperatures than that mentioned in this standard. 8.3.1 Test for the verification of the maximum design cantilever 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 core, unless the manufacturer does not have facilities to make such a length. In this case, the length of insulator shall be as near as possible to the prescribed length range. The base end-fitting has to be fixed rigidly. The insulators shall be gradually loaded to 1,1 times the MDCL rating at a temperature of 20 °C ± 10 K and held for 96 h. The load shall be applied to the insulators at the conductor position, perpendicular to the direction of the conductor, 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 the load 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 of the previously applied cantilever load. The cut surfaces shall be smoothed by means of fine abrasive cloth (grain size 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 Acceptance criteria Observation of any cracks, permanent deformation or delaminations shall constitute failure of the test. 8.3.2 Test for the verification of the maximum design torsion load (MDToL)
8.3.2.1 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 core, unless the manufacturer does not have facilities to make such a length. In this case, the length of insulators 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 of the insulator. No bending moment should be applied. The insulators shall be gradually loaded to 1,1 times the MDToL rating at a temperature of 20 °C ± 10 K and held for 30 min. The angular displacement shall be measured at 30 min as additional information. An acceptable value of the angular displacement shall be agreed between manufacturer and user. NOTE In a torsion test, the angular displacement is proportional to the length of the core between the end fittings. An example of a test arrangement can be found in Annex C. After removal of the load, the steps below shall be followed: – if 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 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 surfaces for cracks and delaminations, – perform a dye penetration test according to ISO 3452 to the cut surfaces to reveal cracks or delaminations. 8.3.2.2 Acceptance criteria Observation of any cracks, permanent deformation or delaminations shall constitute failure of the test. 8.3.3 Verification of the specified tension load (STL) 8.3.3.1 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 core, unless the manufacturer does not have facilities to make such a length. In this case, the length of insulator 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 the insulator at a temperature of 20 °C ± 10 K. The load shall be increased rapidly but 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 specified tensile load is reached. If 100 % of the STL is reached in less than 90 s, the load (100 % of STL) shall be maintained for the remainder of the 90 s. 8.3.3.2 Acceptance criteria 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 material
See IEC 62217. 8.5 Tests on the core material
See IEC 62217. These tests can be carried out on specimens either with or without housing material. 9 Type tests Insulators made on the production line using the standard end fittings shall be selected. 9.1 Verification of dimensions
Unless otherwise agreed, a tolerance of ± (0,04 x d + 1,5) mm
when d < 300 mm, or ± (0,025 x d + 6,0) mm when d > 300 mm with a maximum tolerance of 50 mm
shall be allowed on all dimensions for which specific tolerances are not requested (d being the dimensions in millimetres). The measurement of creepage distance shall be related to the design dimensions and 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 distance is specified 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 position in which it will be used in service (vertical or horizontal). If field-grading devices are used in service they shall be used in the tests.
Interpolation of electrical test results may be used for insulators of intermediate length as long as the factor between the arcing distances of the insulators whose results form the end points of the interpolation range is less than or equal to 1,5. Extrapolation is not allowed. 9.2.1 Dry lightning impulse voltage test The post insulator shall be tested under the conditions prescribed in 4.1, 4.2 and 4.4.1 of IEC 60168. The impulse generator shall be adjusted to produce a 1,2/50 impulse (see IEC 60060-1). Impulses 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.

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 % flashover voltage procedure. NOTE The 50 % flashover voltage procedure gives more information. The test procedure selected shall be agreed between the purchaser and the manufacturer. 9.2.1.1 Withstand voltage test using the withstand voltage procedure The withstand voltage test shall be performed at the specified voltage corrected for the atmospheric conditions at the time of test (see 4.2.2 of IEC 60168). Fifteen impulses shall be applied to the post insulator. The acceptance criteria are as follows: – the station post insulator passes the test if the number of flashovers does not exceed two for each series of 15 impulses. The station post insulator shall not be damaged by t
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