IEC 62772:2016

IEC 62772 ®
Edition 1.0 2016-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Composite hollow core station post insulators for substations with a.c. voltage
greater than 1 000 V and d.c. voltage greater than 1 500 V – Definitions, test
methods and acceptance criteria

Isolateurs supports composites creux pour postes présentant une tension
alternative supérieure à 1 000 V et une tension continue supérieure à 1 500 V –
Définitions, méthodes d'essai et critères d'acceptation

All rights reserved. Unless otherwise specified, 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
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, 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'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 15 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: csc@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Catalogue IEC - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
Application autonome pour consulter tous les renseignements
Le premier dictionnaire en ligne de termes électroniques et
bibliographiques sur les Normes internationales,
électriques. Il contient 20 000 termes et définitions en anglais
Spécifications techniques, Rapports techniques et autres
et en français, ainsi que les termes équivalents dans 15
documents de l'IEC. Disponible pour PC, Mac OS, tablettes
langues additionnelles. Egalement appelé Vocabulaire
Android et iPad.
Electrotechnique International (IEV) en ligne.

Recherche de publications IEC - www.iec.ch/searchpub
Glossaire IEC - std.iec.ch/glossary
La recherche avancée permet de trouver des publications IEC 65 000 entrées terminologiques électrotechniques, en anglais
en utilisant différents critères (numéro de référence, texte, et en français, extraites des articles Termes et Définitions des
comité d’études,…). Elle donne aussi des informations sur les publications IEC parues depuis 2002. Plus certaines entrées
projets et les publications remplacées ou retirées. antérieures extraites des publications des CE 37, 77, 86 et

CISPR de l'IEC.
IEC Just Published - webstore.iec.ch/justpublished

Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications IEC. Just
Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur cette
Disponible en ligne et aussi une fois par mois par email. publication ou si vous avez des questions contactez-nous:
csc@iec.ch.
IEC 62772 ®
Edition 1.0 2016-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Composite hollow core station post insulators for substations with a.c. voltage

greater than 1 000 V and d.c. voltage greater than 1 500 V – Definitions, test

methods and acceptance criteria

Isolateurs supports composites creux pour postes présentant une tension

alternative supérieure à 1 000 V et une tension continue supérieure à 1 500 V –

Définitions, méthodes d'essai et critères d'acceptation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.080.10 ISBN 978-2-8322-3601-7

– 2 – IEC 62772:2016 © IEC 2016

CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 8
4 Identification and marking . 12
5 Environmental conditions . 12
6 Information on transport, storage and installation . 12
7 Classification of tests . 12
7.1 General . 12
7.2 Design tests . 13
7.3 Type tests . 13
7.4 Sample tests . 13
7.5 Routine tests . 13
8 Design tests . 14
8.1 General . 14
8.2 Tests on interfaces and connections of end fittings . 15
8.2.1 General . 15
8.2.2 Test specimens . 15
8.2.3 Reference dry power frequency test . 15
8.2.4 Thermal mechanical pre-stressing test . 15
8.2.5 Water immersion pre-stressing test . 15
8.2.6 Verification tests . 15
8.3 Assembled core load tests . 16
8.3.1 Test for the verification of the maximum design cantilever load (MDCL) . 16
8.3.2 Test for the verification of the maximum design torsion load (MDToL) . 16
8.3.3 Verification of the specified tension load (STL) . 17
8.4 Tests on shed and housing material . 18
8.4.1 General . 18
8.4.2 Tracking and erosion test . 18
8.4.3 Flammability test . 18
8.5 Tests on the tube material . 18
8.5.1 General . 18
8.5.2 Dye penetration test . 18
8.5.3 Water diffusion test . 18
9 Type tests . 18
9.1 Internal pressure test . 18
9.2 Bending test . 18
9.3 Specified tension load test, compression and buckling withstand load test . 19
9.4 Electrical tests . 19
9.5 Wet switching impulse withstand voltage . 19
10 Sample tests . 19
11 Routine tests . 19
11.1 General . 19
11.2 Routine seal leak rate test . 19

11.3 Test procedure . 19
11.4 Acceptance criteria . 19
12 Documentation . 20
Annex A (informative) Water diffusion test . 21
Bibliography . 22

Figure A.1 – Example of sample preparation for water diffusion test . 21

Table 1 – Required design and type tests . 14

– 4 – IEC 62772:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPOSITE HOLLOW CORE STATION POST INSULATORS
FOR SUBSTATIONS WITH A.C. VOLTAGE GREATER THAN
1 000 V AND D.C. VOLTAGE GREATER THAN 1 500 V –
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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 62772 has been prepared by IEC technical committee 36:
Insulators.
The text of this standard is based on the following documents:
FDIS Report on voting
36/386/FDIS 36/389/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
– 6 – IEC 62772:2016 © IEC 2016
INTRODUCTION
Composite hollow core station post insulators consist of an insulating hollow core (tube),
bearing the mechanical load protected by a polymeric housing, the load being transmitted to
the core by end fittings. The hollow core is filled entirely with an insulating material. The core
is made of resin impregnated fibres.
Composite hollow core station post insulators are typically applied as post insulators in
substations. In order to perform the design tests, IEC 62217 is to be applied for materials and
interfaces of the insulator. Some tests have been grouped together as "design tests", to be
performed only once on insulators which satisfy the same design conditions. For all design
tests on composite hollow core station post insulators, the common clauses defined in
IEC 62217 are applied. As far as practical, the influence of time on the electrical and
mechanical properties of the components (core material, housing, interfaces etc.) and of the
complete composite hollow core station post insulator has been considered in specifying the
design tests to ensure a satisfactory life-time under normally known stress conditions in
service.
This standard relates to IEC 61462, Composite hollow insulators – Pressurized and
unpressurized insulators for use in electrical equipment with rated voltage greater than
1 000 V – Definitions, test methods, acceptance criteria and design recommendations, as well
as IEC 62231, 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. Tests and
requirements described in IEC 62231 can be used although this standard has no voltage limit.
The use of polymeric housing materials that show hydrophobicity and hydrophobicity transfer
mechanism (HTM) is preferred for composite hollow core station post insulators. This is due
to the fact that the influence of diameter can be significant for hydrophilic surfaces (see also
IEC 60815-3). For instance silicone rubber is recognized as successful countermeasure
against severe polluted service conditions. The ageing performance of the polymeric housing
can be evaluated by the salt fog test standardized in IEC 62217. For the time being, no test is
defined to quantify the HTM, but CIGRE SC D.1 deals with this subject intensively and
Technical Brochure No. 442 is available for the evaluation of the retention of the
hydrophobicity.
COMPOSITE HOLLOW CORE STATION POST INSULATORS
FOR SUBSTATIONS WITH A.C. VOLTAGE GREATER THAN
1 000 V AND D.C. VOLTAGE GREATER THAN 1 500 V –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA

1 Scope
This International Standard applies to composite hollow core station post insulators consisting
of a load-bearing insulating tube (core) made of resin impregnated fibres an insulating filler
material (e.g. solid, liquid, foam, gaseous – pressurized or unpressurized), a housing (outside
the insulating tube) made of polymeric material (for example silicone or ethylene-propylene)
and metal fixing devices at the ends of the insulating tube. Composite hollow core station post
insulators as defined in this standard are intended for general use in substations in both,
outdoor and indoor environments, operating with a rated AC voltage greater than 1 000 V and
a frequency not greater than 100 Hz or for use in direct current systems with a rated voltage
greater than 1 500 V.
The object of this standard is:
– to define the terms used;
– to prescribe test methods;
– to prescribe acceptance criteria.
All the tests in this standard, apart from the thermal-mechanical test, are performed at normal
ambient temperature. This standard does not prescribe tests that may be characteristic of the
apparatus of which the composite hollow core station post insulator ultimately may form a
part. Further technical input is required in this area.
NOTE 1 "Pressurized" means a permanent gas or liquid pressure greater than 0,05 MPa (0,5 bar) gauge. The gas
can be dry air or inert gases, for example sulphur hexafluoride, nitrogen, or a mixture of such gases.
NOTE 2 "Unpressurized" means a gas or liquid pressure smaller than or equal to 0,05 MPa (0,5 bar) gauge.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60060-1:2010, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60168:2001, Tests on indoor and outdoor post insulators of ceramic material or glass for
systems with nominal voltages greater than 1 000 V
IEC 61109:2008, Insulators for overhead lines – Composite suspension and tension insulators
for a.c. systems with a nominal voltage greater than 1 000 V – Definitions, test methods and
acceptance criteria
IEC 61462:2007, Composite hollow insulators – Pressurized and unpressurized insulators for
use in electrical equipment with rated voltage greater than 1 000 V – Definitions, test
methods, acceptance criteria and design recommendations

– 8 – IEC 62772:2016 © IEC 2016
IEC 62217:2012, Polymeric HV insulators for indoor and outdoor use – General definitions,
test methods and acceptance criteria
IEC 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
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
composite hollow core station post insulator
insulator consisting of at least three insulating parts, namely a tube, an internal filler and a
housing
Note 1 to entry: The housing may consist either of individual sheds mounted on the tube, with or without an
intermediate sheath, or directly applied in one or several pieces onto the tube. A composite hollow core station
post insulator unit is permanently equipped with fixing devices.
3.2
tube (core)
insulating part of a composite hollow core station post insulator designed to ensure the
mechanical characteristics
Note 1 to entry The tube is generally cylindrical or conical, but may have other shapes (for example barrel). The
tube is made of resin impregnated fibres.
Note 2 to entry Resin impregnated fibres are structured in such a manner as to achieve sufficient mechanical
strength. Layers of different fibres may be used to fulfil special requirements.
3.3
filler
insulating material filling the entire space (e.g. solid, liquid, foam, gaseous – pressurized or
unpressurized) of the hollow core station post insulator which has no load bearing function
3.4
fixing device (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 1 to entry: Where the end fitting is metallic, the term “metal fitting” is normally used.
[SOURCE: IEC 60050-471:2007, 471-01-06]
3.5
coupling
part of the end fitting which transmits the load to the accessories external to the insulator
[SOURCE: IEC 62217:2012, definition 3.13]
3.6
connection zone
zone where the mechanical load is transmitted between the insulating body and the end fitting
[SOURCE: IEC 62217:2012, definition 3.12]

3.7
housing
external insulating part of composite hollow core station post insulator providing necessary
creepage distance and protecting the tube from the environment
Note 1 to entry: If an intermediate sheath is used it forms a part of the housing
[SOURCE: IEC 62217:2012, definition 3.7, modified ("composite insulator" replaced by
"composite hollow core station post insulator", "protecting core" replaced by "protecting the
tube")]
3.8
shed
insulating part, projecting from the insulator trunk, intended to increase the creepage distance
Note 1 to entry: The shed can be with or without ribs
[SOURCE: IEC 60050-471:2007, 471-01-15]
3.9
insulator trunk
central insulating part of an insulator from which the sheds protrude
Note 1 to entry: Also known as shank on smaller insulators.
[SOURCE: IEC 60050-471:2007, 471-01-11]
3.10
creepage distance
shortest distance or the sum of the shortest distances along the surface of an insulator
between two conductive parts which normally have the operating voltage between them
Note 1 to entry: The surface of any non-insulating jointing material is not considered as forming part of the
creepage distance.
Note 2 to entry: 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.
[SOURCE: IEC 60050-471:2007, 471-01-04]
3.11
arcing distance
shortest distance in the air external to the insulator between the metallic parts which normally
have the operating voltage between them
[SOURCE: IEC 60050-471:2007, 471-01-01]
3.12
interface
surface between the different materials
Note 1 to entry: Various interfaces occur in most composite insulators, e.g.
– between housing and end fittings,
– between various parts of the housing; e.g. between sheds, or between sheath and sheds,
– between core and housing
– between core and filler.
[SOURCE: IEC 62217:2012, definition 3.11]

– 10 – IEC 62772:2016 © IEC 2016
3.13
damage limit of the tube under mechanical stress
limit below which mechanical loads can be applied, at normal ambient temperature, without
micro damage to the composite tube
Note 1 to entry: Applying such loads means that the tube is in a reversible elastic phase. If the damage limit of
the tube is exceeded, the tube is in an irreversible plastic phase, which means permanent damage to the tube
which may not be visible at a macroscopic level (for a quantitative definition see Annex C of IEC 61462:1997).
3.14
specified mechanical load
SML
cantilever load specified by the manufacturer that is used in the mechanical tests in
accordance with IEC 61462
Note 1 to entry The load is normally applied by bending at normal ambient temperature.
Note 2 to entry The SML forms the basis of the selection of composite hollow station post insulators with regard
to external loads.
3.15
maximum mechanical load
MML
highest cantilever load which is expected to be applied to the composite hollow core station
post insulators in accordance with IEC 61462
Note 1 to entry: The MML of the composite hollow core station post insulator is specified by the insulator
manufacturer.
3.16
specified cantilever load
SCL
cantilever load which can be withstood by the insulator when tested under the prescribed
conditions in accordance with IEC 62231
3.17
maximum design cantilever load
MDCL
load level above which damage to the insulator begins to occur and that should not be
exceeded in service in accordance with IEC 62231
Note 1 to entry: In the context of this standard (IEC 62772) MDCL is considered to be equal to 1,25 times MML as
determined in IEC 61462:1997, Clause 8 or 0,5 times of SML.
3.18
specified torsion load
SToL
torsion load level which can be withstood by the insulator when tested under the prescribed
conditions in accordance with IEC 62231
3.19
maximum design torsion load
MDToL
load level above which damage to the insulator begins to occur and that should not be
exceeded in service in accordance with IEC 62231
3.20
specified tension load
STL
tension load which can be withstood by the insulator when tested under the prescribed
conditions in accordance with IEC 62231

3.21
maximum design tension load
MDTL
load level above which damage to the insulator begins to occur and that should not be
exceeded in service in accordance with IEC 62231
3.22
specified compression load
SCoL
compression load which can be withstood by the insulator when tested under the prescribed
conditions in accordance with IEC 62231
3.23
buckling load
compression load that induces buckling of the insulator core in accordance with IEC 62231
3.24
maximum design compression load
MDCoL
load level above which damage to the insulator begins to occur and that should not be
exceeded in service in accordance with IEC 62231 and IEC 61462
3.25
failing load of a composite hollow core station post insulator
maximum load that can be reached when the insulator is tested under the prescribed
conditions (valid for bending or pressure tests)
Note 1 to entry: Damage to the core and / or the connection zone is likely to occur at loads lower than the
insulator failing load.
3.26
deflection under cantilever load
displacement of a point on an insulator, measured perpendicularly to its axis, under the effect
of a load applied perpendicularly to this axis
Note 1 to entry: Deflection/load relationships are determined by the manufacturer.
3.27
residual deflection
difference between the initial deflection of a composite hollow core station post insulator prior
to bending load application, and the final deflection after release of the load
Note 1 to entry: The measurement of residual deflection serves for qualitative comparison with strain gauge
measurements.
3.28
residual angular displacement
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 1 to entry: 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.
3.29
specified internal pressure
SIP
internal pressure specified by the manufacturer which is verified during a type test at normal
ambient temperature
– 12 – IEC 62772:2016 © IEC 2016
Note 1 to entry: The SIP forms the basis of the selection of composite hollow station post insulators with respect
to internal pressure.
3.30
maximum service pressure
MSP
difference between the maximum absolute internal pressure at maximum operational
temperature and the normal outside pressure
Note 1 to entry The MSP of the composite hollow core station post insulator is specified by the insulator
manufacturer.
Note 2 to entry The MSP is equivalent to "design pressure" as used for ceramic hollow insulators (see
IEC 62155).
3.31
specified temperatures
highest and lowest temperature permissible for the composite hollow core station post
insulator
Note 1 to entry: The specified temperatures are specified by the manufacturer.
3.32
manufacturer
individual or organization producing the composite hollow core station post insulator
3.33
equipment manufacturer
individual or organization producing the electrical equipment utilizing the composite hollow
core station post insulator
4 Identification and marking
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 be stated on the drawing.
Each composite hollow core station post insulator shall be marked with the name or trade
mark of the manufacturer and the year of manufacture. In addition, each hollow core station
post composite insulator shall be marked with the type reference and serial numbers in order
to allow identification. In addition, each insulator shall be marked with at least the maximum
design mechanical load, for example: MDCL: 4 kN. This marking shall be legible and indelible.
5 Environmental conditions
See description in IEC 62217.
6 Information on transport, storage and installation
See description in IEC 62217.
7 Classification of tests
7.1 General
The tests are divided into groups as follows:

7.2 Design tests
These tests are intended to verify the suitability of the design, materials and manufacturing
technology.
A composite hollow core station post insulators design is defined by:
• materials and design of the tube, housing, filler and manufacturing method,
• material of the end fittings, their design and method of attachment,
• layer thickness of the housing over the tube (including a sheath where used).
For new designs and when changes in the design occur, re-qualification shall be done
according to Table 1.
7.3 Type tests
Type tests are intended to verify the main characteristics of a composite hollow core station
post insulator, which depend mainly on its shape and size. Type tests in accordance with
Table 1 shall be applied to composite hollow core station post insulators, the class of which
has passed the design tests. They shall be repeated only when the type or material of the
composite hollow core station post insulator is changed (see Table 1). The type tests shall be
performed, according to the type tests defined in IEC 62231.
Electrically, a composite hollow core station post insulator type is defined by the
• arcing distance,
• creepage distance,
• housing profile,
• internal filler.
Mechanically, a composite hollow core station post insulator type is defined by the
• length (only for the compression and buckling withstand load test),
• tube‘s diameter, wall thickness, design and material,
• design and method of attachment of the end fittings.
7.4 Sample tests
These tests are for the purpose of verifying the characteristics of composite hollow core
station post insulators which depend on the manufacturing quality and the material used. They
shall be made on insulators taken at random from batches offered for acceptance.
7.5 Routine tests
These tests are for the purpose of eliminating composite hollow core station post insulators
with manufacturing defects. They shall be made on each composite hollow core station post
insulator.
– 14 – IEC 62772:2016 © IEC 2016
Table 1 – Required design and type tests
THEN the following tests shall be repeated:
Design Tests Type Tests
If a new design is made or if the change in
insulator design concerns:
1 Housing materials X X X X X

a
2 Housing profile  X X
3 Tube material X X X X X
b
4 Tube design  X X X X
c
5 Manufacturing process of housing   X X X X

d
6 Manufacturing process of tube  X X X X X

7 End fitting material X X X
e
8 End fitting method of attachment to tube  X X X

9 Tube-housing-end fitting interface design X X X

10 Filling material and / or method X X X X

a
The following variation of the housing profile within following tolerances do not constitute a change:
Overhang of sheds: ±10 %; Spacing: ±10 %; Mean inclination of sheds: ±3°; Thickness at root and tip of
sheds: ±15 %; Shed repetition: identical.
b
Liner, winding angle
c
Curing and moulding method (e.g. extrusion, injection, single shed assembly…)
d
Pultrusion, wet filament winding, vacuum impregnation, including surface preparation
e
Applications: bending, pressure, combined pressure-bending
f
one sample smallest OD and smallest wall thickness, and one sample largest OD and smallest wall thickness

8 Design tests
8.1 General
These tests are described in IEC 62217. The design tests shall be performed only once and
the results are recorded in a test report. Each part can be performed independently on new
test specimens where appropriate. A composite hollow core station post insulator of a
particular design shall be deemed accepted only when all insulators or test specimens pass
the design tests in the given sequence.
All the design tests, apart from the thermal-mechanical test, are performed at normal ambient
temperature.
A summary of the tests is shown in Table 1.
Extreme service temperatures may affect the mechanical behaviour of composite insulators. 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.
Whenever the insulators are subjected to very high or low temperatures for long periods of
Assembled core load test,
f
only 8.3.1
Interfaces and connections
of end fittings
Hardness test
Accelerated weathering test
Tracking and erosion test
Flammability test
Dye penetration test
Water diffusion test
Mechanical type tests
Electrical type tests
time, it is advisable that both manufacturer and user agree on a mechanical test at higher or
lower temperatures than mentioned in this standard.
8.2 Tests on interfaces and connections of end fittings
8.2.1 General
See IEC 62217.
These tests shall be performed in the given sequence on the same specimen.
8.2.2 Test specimens
One composite hollow core station post insulator assembled on the production line shall be
tested. The tube's internal diameter shall be at least 100 mm and the wall thickness at least 3
mm. The insulation length (metal-to-metal spacing) shall be at least three times the tube's
internal diameter but not less than 800 mm. Both end fittings shall have the same method of
attachment and sealing as on standard production insulators. The composite hollow core
station post insulator shall be submitted to the routine tests
Caution should be taken in case of pressurized designs which may have hazardous failure
mode
The manufacturer shall define the SML value for the test specimen.
8.2.3 Reference dry power frequency test
See IEC 62217.
8.2.4 Thermal mechanical pre-stressing test
See IEC 61462.
8.2.5 Water immersion pre-stressing test
See IEC 62217.
8.2.6 Verification tests
8.2.6.1 General
See IEC 62217.
8.2.6.2 Visual examination
See IEC 62217.
8.2.6.3 Steep-front impulse high voltage test
See IEC 62217.
8.2.6.4 Dry power frequency voltage test
See IEC 62217.
8.2.6.5 Internal pressure test
See IEC 61462.
– 16 – IEC 62772:2016 © IEC 2016
This test is not applicable for composite hollow core station post insulators with solid material
fillers and foam. For unpressurized types with non-solid fillers only a gas leakage test must be
performed in accordance with Subclause 11.2.
8.3 Assembled core load tests
8.3.1 Test for the verification of the maximum design cantilever load (MDCL)
NOTE MDCL is considered to be equal with 1,25 times MML as determined by the type test as determined in
IEC 61462:2007, Clause 8.
8.3.1.1 Test procedure
The test can be performed without a filler or the filler may be removed after the test and
before the dye penetration test.
One insulator with the smallest outer tube diameter and the smallest wall thickness and one
insulator with the largest outer tube diameter and the smallest wall thickness 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 outer diameter of the tube, 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 junction of the tube to
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 to the cut surfaces to reveal cracks.
Some housing and filler materials may be penetrated by the penetrant. In such cases,
evidence shall be provided to validate the interpretation of the results (see IEC 61109:2008,
11.2.2 and 11.2.3).
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
The test can be performed without a filler or the filler may be removed after the test and
before the dye penetration test.

One insulator with the smallest outer tube diameter and the smallest wall thickness and one
insulator with the largest outer tube diameter and the smallest wall thickness 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. 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
...