IEC 62772:2023

Composite hollow core station post insulators with a.c. voltage greater than 1 000 V and d.c. voltage greater than 1 500 V - Definitions, test methods and acceptance criteria

IEC 62772:2023 applies to composite hollow core station post insulators consisting of a load-bearing insulating tube (core) made of resin impregnated fibres, insulating filler material (solid, liquid, gaseous – pressurized or unpressurized), a housing (outside the insulating tube) made of polymeric material (for example silicone or ethylene-propylene) and 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 DC. The object of this document is:
- to define the terms used;
- to specify test methods;
- to specify acceptance criteria.

Isolateurs supports composites creux 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

L'IEC 62772:2023 s’applique aux isolateurs supports composites creux qui sont constitués d’un tube (noyau) isolant en fibres imprégnées de résine supportant la charge mécanique, d’un matériau de charge interne (solide, liquide, gaz, sous pression ou pas), d’un revêtement en polymère à l’extérieur du tube isolant (par exemple silicone ou éthylène-propylène) et de dispositifs de fixation à ses extrémités. Les isolateurs supports composites creux, tels que définis dans la présente norme, sont destinés à l’utilisation générale dans les postes, tant en extérieur qu’en intérieur. Ils fonctionnent avec une tension alternative assignée de plus de 1 000 V en courant alternatif et à une fréquence maximale de 100 Hz, ou sont utilisés dans les systèmes à courant continu avec une tension assignée supérieure à 1 500 V en courant continu. Le présent document a pour objet:
- de définir les termes utilisés;
- de spécifier des méthodes d’essai;
- de spécifier les critères d’acceptation.

General Information

• Status: Published
• Publication Date: 14-Nov-2023
• ICS: 29.080.10 - Insulators
• Technical Committee: TC 36 - Insulators
• Drafting Committee: MT 24 - TC 36/MT 24
• Current Stage: PPUB - Publication issued
• Start Date: 15-Nov-2023
• Completion Date: 22-Sep-2023

Relations

• Revises: IEC 62772:2016 - 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
• Effective Date: 05-Sep-2023

Overview

IEC 62772:2023 defines composite hollow core station post insulators for substations operating at AC voltages > 1 000 V (≤ 100 Hz) and DC voltages > 1 500 V. This second edition (Edition 2.0, 2023‑11) is a technical revision that updates terms and definitions, harmonizes required tests, revises selected test procedures and expands annexes (qualification of fillers; load definitions). The standard covers definitions, required test methods, and acceptance criteria for insulators comprising a resin‑impregnated fiber core, insulating filler (solid/liquid/gaseous), polymeric housing (e.g., silicone, EPDM) and end fittings.

Key topics and requirements

IEC 62772:2023 structures its conformity checks and technical content around clearly defined test classes and component evaluations:

• Classification of tests: design tests, type tests, sample tests and routine tests.
• Design and interface tests: verification of interfaces and end‑fitting connections, reference disruptive‑discharge voltage, thermal‑mechanical and water‑immersion pre‑stress.
• Mechanical tests: maximum design cantilever load (MDCL), torsion (MDToL), specified tension/compression and buckling tests, bending and assembled core load tests.
• Electrical tests: dry lightning impulse, switching impulse (dry/wet), dry and wet power‑frequency withstand voltages, internal pressure tests.
• Material and ageing tests: housing hardness, accelerated weathering, tracking and erosion (including 1 000 h salt‑fog AC test), flammability, hydrophobicity transfer.
• Core and filler integrity: porosity/dye‑penetration, water diffusion tests (core alone and core with housing), qualification procedures for fillers, routine seal leak‑rate tests.
• Documentation and marking: identification, transport, storage and installation information, and test reporting requirements.

Practical applications and who uses this standard

IEC 62772:2023 is intended for anyone involved in the design, manufacture, testing, procurement and operation of station post insulators in substations:

• Manufacturers - design validation, type approval and material qualification.
• Test laboratories and certification bodies - reference test procedures and acceptance criteria for certification and type testing.
• Utilities and asset owners - procurement specifications, acceptance testing, and lifecycle assurance.
• Design and installation engineers - guidance on mechanical/electrical load limits, installation, transport and storage conditions.
• Regulatory/compliance teams - harmonized requirements for international projects.

Related standards

• IEC 62217 - general requirements for polymeric insulator materials and interfaces.
• IEC 61462 - composite hollow insulators (pressurized/unpressurized) - definitions and design recommendations.
• IEC 62231 - composite station post insulators for substations.
• IEC TR 62039 - referenced for hydrophobicity transfer and related methods.

Keywords: IEC 62772:2023, composite hollow core station post insulators, test methods, acceptance criteria, substations, AC >1000 V, DC >1500 V, hydrophobicity, water diffusion, end fittings.

Standards Content (Sample)

IEC 62772 ®
Edition 2.0 2023-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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

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IEC 62772 ®
Edition 2.0 2023-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
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
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.10  ISBN 978-2-8322-7899-4
– 2 – IEC 62772:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Identification and marking . 13
5 Environmental conditions . 13
6 Information on transport, storage and installation . 13
7 Classification of tests. 14
7.1 General . 14
7.2 Design tests . 14
7.3 Type tests . 17
7.4 Sample tests . 18
7.5 Routine tests. 18
8 Design tests . 18
8.1 General . 18
8.2 Tests on interfaces and connections of end fittings . 18
8.2.1 General . 18
8.2.2 Test specimens . 19
8.2.3 Reference disruptive- discharge dry power frequency voltage test . 19
8.2.4 Thermal mechanical pre-stressing test . 19
8.2.5 Water immersion pre-stressing test . 19
8.2.6 Verification tests . 19
8.3 Assembled core load tests . 20
8.3.1 Test for the verification of the maximum design cantilever load (MDCL) . 20
8.3.2 Test for the verification of the maximum design torsion load (MDToL) . 20
8.3.3 Verification of the specified tension load (STL) . 21
8.4 Tests on shed and housing material . 22
8.4.1 General Hardness test . 22
8.4.2 Accelerated weathering test . 22
8.4.3 Tracking and erosion test – 1 000 h salt fog AC voltage test . 22
8.4.4 Flammability test . 22
8.4.5 Hydrophobicity transfer test . 22
8.5 Tests on the tube material . 22
8.5.1 General . 22
8.5.2 Porosity test (Dye penetration test) . 22
8.5.3 Water diffusion test . 22
8.6 Water diffusion test on core with housing . 22
9 Type tests . 23
9.1 Internal pressure test . 23
9.2 Bending test . 23
9.3 Specified tension load test, compression and buckling withstand load test . 23
9.4 Electrical tests . 23
9.4.1 General . 23
9.4.2 Mounting arrangements for electrical tests . 23
9.4.3 Dry lightning impulse withstand voltage test. 23

9.4.4 Dry or wet switching impulse withstand voltage test . 24
9.4.5 Dry power-frequency withstand voltage test . 24
9.4.6 Wet power-frequency withstand voltage test . 24
9.5 Wet switching impulse withstand voltage .
10 Sample tests . 24
11 Routine tests . 24
11.1 General . 24
11.2 Routine seal leak rate test . 24
11.2.1 General . 24
11.2.2 Test procedure . 24
11.2.3 Acceptance criteria . 25
12 Documentation . 25
Annexe A (informative) Water diffusion test Qualification of fillers . 26
A.1 General . 26
A.2 Dye penetration test with solid filler . 26
A.3 Water diffusion test with solid filler . 26
A.4 Tests on interfaces and connections of end fittings with filler . 26
Annexe B (informative) Load definitions, relationship of loads . 28
Annexe C (informative) Principle sketch of hollow insulators design assembly . 31
Bibliography . 33

Figure A.1 – Example of sample preparation for water diffusion test . 27
Figure B.1 – Definitions according to IEC 62231 . 28
Figure B.2 – Definitions according to IEC 61462 . 29
Figure B.3 – Comparison of definitions IEC 61462 vs. IEC 62231 . 30
Figure C.1 – Interface description for insulator with housing made by modular
assembly . 31
Figure C.2 – Interface description for insulator with housing made by injection
moulding and ouvermold end fitting . 32

Table 1 – Required design and type tests . 15

– 4 – IEC 62772:2023 RLV © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPOSITE HOLLOW CORE STATION POST
INSULATORS FOR SUBSTATIONS
WITH AC VOLTAGE GREATER THAN
1 000 V AND DC VOLTAGE GREATER THAN 1 500 V –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA

FOREWORD
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This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 62772:2016. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
IEC 62772 has been prepared by IEC technical committee 36: Insulators. It is an International
Standard.
This second edition cancels and replaces the first edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) modifications of terms and definitions;
b) modifications of tests procedures included in IEC TR 62039 and IEC 62217 (Hydrophobicity
transfer test; Water diffusion test on the core with housing);
c) harmonization of Table 1 (Required design and type tests) with other product standards;
d) update of Annex A (Qualification of fillers);
e) addition of a new informative Annex B (Load definitions, relationship of loads).
The text of this International Standard is based on the following documents:
Draft Report on voting
36/569/FDIS 36/587/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
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IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
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– 6 – IEC 62772:2023 RLV © IEC 2023
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 document 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 AC 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 despite the
intended operating voltage limit for substations.
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. For the
time being, the 1 000 h AC tracking and erosion test of IEC 62217 is used to establish a
minimum requirement for the tracking and erosion resistance, for both AC and DC.
Composite hollow core station post insulators are used in both AC and DC applications. Before
the appropriate standard for DC applications will be issued, the majority of tests listed in this
standard can also be applied to DC insulators. In spite of this, a specific tracking and erosion
test procedure for DC applications as a design test is still being considered to be developed.
Some information about the difference of AC and DC material erosion test can be found in the
CIGRE Technical Brochure 611 [8] . For the time being, the 1 000 h AC tracking and erosion
test of IEC 62217 is used to establish a minimum requirement for the tracking and erosion
resistance.
___________
Numbers in square brackets refer to the Bibliography.

COMPOSITE HOLLOW CORE STATION POST
INSULATORS FOR SUBSTATIONS
WITH AC VOLTAGE GREATER THAN
1 000 V AND DC VOLTAGE GREATER THAN 1 500 V –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA

1 Scope
This document, which is an International Standard, applies to composite hollow core station
post insulators consisting of a load-bearing insulating tube (core) made of resin impregnated
fibres, 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 DC.
The object of this document is:
– to define the terms used;
– to prescribe specify test methods;
– to prescribe specify acceptance criteria.
All the tests in this document, apart from the thermal-mechanical test, are performed at normal
ambient temperature. This document does not prescribe specify tests that may be are
characteristic of the apparatus of which the composite hollow core station post insulator
ultimately may form a part (e.g. disconnector switch, reactor support, HVDC valves). 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 1000 V
IEC 61109:2008, Insulators for overhead lines – Composite suspension and tension insulators
for AC systems with a nominal voltage greater than 1 000 V – Definitions, test methods and
acceptance criteria
– 8 – IEC 62772:2023 RLV © IEC 2023
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
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 AC voltages greater
than 1 000 V up to 245 kV – Definitions, test methods and acceptance criteria
IEC TR 62039, Selection guidelines for polymeric materials for outdoor use under HV stress
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
composite hollow core station post insulator
post insulator, consisting of at least three insulating parts, namely a tube, a housing with or
without sheds, and 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.
Note 1 to entry: End fittings are attached to the insulating tube. The housing, with or without sheds, may be omitted
in case of specific environmental conditions (e.g. indoor).
Note 2 to entry: A hollow insulator can be made from one or more permanently assembled insulating elements
3.2
post insulator
insulator intended to give rigid support to a live part which is to be insulated from earth or from
another live part
Note 1 to entry: A post insulator may be an assembly of a number of post insulator units (stack).
Note 2 to entry: Post insulators for substations are also known as station post insulators.
[SOURCE: IEC 60050-471:2007, 471-04-01, modified – addition of "(stack)" in Note 1 to entry]
3.3
tube (core)
central internal insulating part of a composite hollow core station post insulator designed to
ensure which provides 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. The housing, insulating filler material and sheds are not part of the core.
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.

3.4
filler
insulating material filling the entire internal space (e.g. solid, liquid, foam, gaseous –
pressurized or unpressurized) of the hollow core station post insulator which has no load
bearing function
3.5
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, modified – addition of "fixing device" in term]
3.6
coupling
part of the end fitting which transmits the load to the accessories external to the insulator
[SOURCE: IEC 62217:2012, 3.1314]
3.7
connection zone
zone where the mechanical load is transmitted between the insulating body and the end fitting
[SOURCE: IEC 62217:2012, 3.1213]
3.8
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")]
3.9
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]
3.10
insulator trunk
central insulating part of an insulator from which the sheds protrude project
Note 1 to entry: Also known as shank on smaller insulators.
[SOURCE: IEC 60050-471:2007, 471-01-11]
3.11
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

– 10 – IEC 62772:2023 RLV © IEC 2023
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, modified – removal of Note 2 to entry]
3.12
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]
3.13
interface
contact surface between the different materials
Note 1 to entry: Various interfaces occur in most composite insulators (cf. Annex C), e.g.
– between housing and end fittings,
– between various parts of the housing; e.g. between sheds, or between sheath and sheds,
– between core tube and housing
– between core tube and filler.
[SOURCE: IEC 62217:2012, 3.11, modified – addition of "contact"]
3.14
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).
3.15
maximum mechanical load
MML
highest cantilever bending 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 mechanical load
SML
cantilever bending load specified by the manufacturer that is used in the mechanical tests, in
accordance with IEC 61462 and which is verified during a type test at normal ambient
temperature
Note 1 to entry The load is normally applied by bending at normal ambient temperature.
Note 2 1 to entry: The SML forms the basis of the selection of composite hollow station post insulators with regard
to external loads.
3.17
specified cantilever load
SCL
cantilever load which can to be withstood by the insulator when tested under the prescribed
specified conditions in accordance with IEC 62231

3.18
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. For more information to load philosopies and
relationships, see Annex B.
3.19
specified torsion load
SToL
torsion load level which can be withstood by the insulator when tested under the prescribed
specified conditions in accordance with IEC 62231
3.20
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
3.21
specified tension load
STL
tension load which can be withstood by the insulator when tested under the prescribed specified
conditions in accordance with IEC 62231
3.22
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
3.23
specified compression load
SCoL
compression load which can to be withstood by the insulator when tested under the prescribed
specified conditions in accordance with IEC 62231
3.24
buckling load
compression load that induces buckling of the insulator core in accordance with IEC 62231
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 in accordance with IEC 62231 and IEC 61462
3.26
failing load of a composite hollow core station post insulator
load at ultimate failure of the insulator, maximum load that can be reached when the insulator
is tested under the prescribed specified conditions (valid for bending or pressure tests)
Note 1 to entry: Damage to the core and / or the connection zone tube is likely to occur at loads lower than the
insulator failing load.
– 12 – IEC 62772:2023 RLV © IEC 2023
3.27
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.
3.28
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.
3.29
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.
3.30
overpressure
pressure above ambient pressure within a pressurized enclosure
[SOURCE: IEC 60050-426:2020, 426-09-16]
3.31
maximum service pressure
MSP
difference between the maximum absolute internal pressure at maximum operational
temperature and the normal outside pressure
maximum overpressure in service which is specified by the equipment manufacturer
3.32
specified internal pressure
SIP
internal overpressure specified by the manufacturer which is verified during a type test at normal
ambient temperature
Note 1 to entry: The SIP forms the basis of the selection of composite hollow station post insulators with respect to
internal 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).
Note 1 to entry: The SIP is specified as the short-time withstand design limit, under which the insulator structure
stays intact, but damages may already occur. It can be higher than 4 × MSP.
3.33
pressurized insulator
insulator permanently filled with gas or liquid whose maximum service pressure is greater than
0,05 MPa overpressure
3.34
unpressurized insulator
insulator is an insulator permanently filled with gas or liquid whose maximum service pressure
is smaller than or equal to 0,05 MPa overpressure
3.35
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.
3.36
manufacturer
individual or organization producing the composite hollow core station post insulator
3.37
equipment manufacturer
individual or organization producing the electrical equipment utilizing the composite hollow core
station post insulator
3.38
lot
group of insulators offered for acceptance from the same manufacturer, of the same design and
manufactured under similar conditions of production
Note 1 to entry: One or more lots may be offered together for acceptance: the lot(s) offered may consist of the
whole, or part, of the quantity ordered.
[SOURCE: IEC 62155:2003, 3.22, modified – removal of "hollow", removal of "or hollow
insulator bodies"]
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 document. 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.
– 14 – IEC 62772:2023 RLV © IEC 2023
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, formulation 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.
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
X X X X
4 Tube design
c
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
X X X
8 End fitting method of attachment to tube

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

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
– 16 – IEC 62772:2023 RLV © IEC 2023
a)
IF the change in insulator
THEN the following tests shall be repeated:
design concerns:
Design tests Type tests
IEC 6277 IEC 62772
2:-, :-,
IEC 62
IEC 62772:-, 8.4 IEC 627
IEC 62 IEC 62
8.5 8.6 772:-,
72:-,
772:-, 772:-,
Tests on shed and housing
8.2 8.3.1
Tests on Tests on 9.1,
material 9.4
the tube tube with 9.2,
material housing 9.3
1 Housing
Materials, formulation
d) d) d) e) a)
1a or manufacturing
X X X X X X  X
process
c)
1b Assembly process  X
X
b)
1c Profile
X   X
2 Tube
Material, formulation
a)
or manufacturing
2a X X   X X X
X
process
2b Design X   X X  X
3 End fitting
Material or assembly
3a X X     X
process
End fitting connection
3b
X      X
zone design
4 Interface
Primer material and
a)
4a
X     X
application method
Tube and end-fitting
4b
X X     X
assembly process
Tube/housing/end fitting
4c X X  X   X
interface design
Filling material or
X     X
method
Interfaces and
connections of end
fittings
Assembled core load
test
Hardness test
Accelerated
weathering test
Tracking and erosion
test
Flammability test
Hydrophobicity
transfer test
Porosity test (Dye
penetration test)
Water diffusion test
Water Diffusion Test
on Core with
Housing
Electrical type tests
Mechanical type
tests
a)
Explanation
Not necessary if it can be demonstrated that the change has no influence on the property
a) e)
to : considered in the test; material tests could be used to show the equivalence
Additional
b)
Not necessary if thickness of the housing surrounding the core (including a sheath where
information for
used) is equal or greater than that of the parent insulator. Following relative numbers as
which specific
tolerances are provided as reference, which do not constitute a change of the profile:
changes testing
needs to be done
– overhang: ±10 %
– thickness at base and tip: ±15 %
– spacing: ±15 %
– shed inclinations: ±3°
– shed repetition: identical.
These relatively small tolerances serve as reference, however cause a high test demand due
to the variety of today`s profiles. Alternatively, a technical agreement between manufacturer
and user in agreement with chapter 9.1 is possible if the equivalence of the profile evaluated in
the tracking and erosion test to the profile in question can be shown. A possible method is the
interpolation of results with different profiles.
c)
Not necessary if it can be demonstrated that the change has no influence on the property
considered in the test.
d)
Not necessary for change in manufacturing process without material change
e)
Applicable to materials that shall show this property
Explanation
Housing manufacturing process:
1 6
to : Technical General manufacturing method such as injection moulding, modular process etc.
explanation of
Housing assembly process:
hollow core
If shed and sheath are mounted separately to the tube, incl. type and method of bonding
insulator
shed-sheath
components
Tube manufacturing method: Pultrusion, wet filament winding, vacuum impregnation,
including surface preparation
Liner and winding angle
See Annex C for further explanation
See Annex A for further explanation

7.3 Type tests
Type test
...

IEC 62772 ®
Edition 2.0 2023-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Composite hollow core station post insulators 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 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

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IEC 62772 ®
Edition 2.0 2023-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Composite hollow core station post insulators 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 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 978-2-8322-7404-0

– 2 – IEC 62772:2023 © IEC 2023
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 . 13
6 Information on transport, storage and installation . 13
7 Classification of tests. 13
7.1 General . 13
7.2 Design tests . 13
7.3 Type tests . 15
7.4 Sample tests . 16
7.5 Routine tests. 16
8 Design tests . 16
8.1 General . 16
8.2 Tests on interfaces and connections of end fittings . 16
8.2.1 General . 16
8.2.2 Test specimens . 17
8.2.3 Reference disruptive- discharge dry power frequency voltage test . 17
8.2.4 Thermal mechanical pre-stressing test . 17
8.2.5 Water immersion pre-stressing test . 17
8.2.6 Verification tests . 17
8.3 Assembled core load tests . 17
8.3.1 Test for the verification of the maximum design cantilever load (MDCL) . 17
8.3.2 Test for the verification of the maximum design torsion load (MDToL) . 18
8.3.3 Verification of the specified tension load (STL) . 19
8.4 Tests on shed and housing material . 19
8.4.1 Hardness test . 19
8.4.2 Accelerated weathering test . 20
8.4.3 Tracking and erosion – 1 000 h salt fog AC voltage test . 20
8.4.4 Flammability test . 20
8.4.5 Hydrophobicity transfer test . 20
8.5 Tests on the tube material . 20
8.5.1 General . 20
8.5.2 Porosity test (Dye penetration test) . 20
8.5.3 Water diffusion test . 20
8.6 Water diffusion test on core with housing . 20
9 Type tests . 20
9.1 Internal pressure test . 20
9.2 Bending test . 20
9.3 Specified tension load test, compression and buckling withstand load test . 20
9.4 Electrical tests . 21
9.4.1 General . 21
9.4.2 Mounting arrangements for electrical tests . 21
9.4.3 Dry lightning impulse withstand voltage test. 21

9.4.4 Dry or wet switching impulse withstand voltage test . 21
9.4.5 Dry power-frequency withstand voltage test . 21
9.4.6 Wet power-frequency withstand voltage test . 21
10 Sample tests . 21
11 Routine tests . 22
11.1 General . 22
11.2 Routine seal leak rate test . 22
11.2.1 General . 22
11.2.2 Test procedure . 22
11.2.3 Acceptance criteria . 22
12 Documentation . 23
Annex A (informative) Qualification of fillers . 24
A.1 General . 24
A.2 Dye penetration test with solid filler . 24
A.3 Water diffusion test with solid filler . 24
A.4 Tests on interfaces and connections of end fittings with filler . 24
Annex B (informative) Load definitions, relationship of loads . 26
Annex C (informative) Principle sketch of hollow insulators design assembly . 29
Bibliography . 31

Figure A.1 – Example of sample preparation for water diffusion test . 25
Figure B.1 – Definitions according to IEC 62231 . 26
Figure B.2 – Definitions according to IEC 61462 . 27
Figure B.3 – Comparison of definitions IEC 61462 vs. IEC 62231 . 28
Figure C.1 – Interface description for insulator with housing made by modular
assembly . 29
Figure C.2 – Interface description for insulator with housing made by injection

moulding and ouvermold end fitting . 30

Table 1 – Required design and type tests . 14

– 4 – IEC 62772:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPOSITE HOLLOW CORE STATION POST
INSULATORS WITH AC VOLTAGE GREATER THAN
1 000 V AND DC 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
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62772 has been prepared by IEC technical committee 36: Insulators. It is an International
Standard.
This second edition cancels and replaces the first edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) modifications of terms and definitions;
b) modifications of tests procedures included in IEC TR 62039 and IEC 62217 (Hydrophobicity
transfer test; Water diffusion test on the core with housing);
c) harmonization of Table 1 (Required design and type tests) with other product standards;
d) update of Annex A (Qualification of fillers);
e) addition of a new informative Annex B (Load definitions, relationship of loads).

The text of this International Standard is based on the following documents:
Draft Report on voting
36/569/FDIS 36/587/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

– 6 – IEC 62772:2023 © IEC 2023
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 document 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 AC 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 despite the intended operating voltage limit
for substations.
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. For the time being, the 1 000 h AC tracking and erosion test
of IEC 62217 is used to establish a minimum requirement for the tracking and erosion
resistance, for both AC and DC.
Composite hollow core station post insulators are used in both AC and DC applications. Before
the appropriate standard for DC applications will be issued, the majority of tests listed in this
standard can also be applied to DC insulators. In spite of this, a specific tracking and erosion
test procedure for DC applications as a design test is still being considered to be developed.
Some information about the difference of AC and DC material erosion test can be found in the
CIGRE Technical Brochure 611 [8] . For the time being, the 1 000 h AC tracking and erosion
test of IEC 62217 is used to establish a minimum requirement for the tracking and erosion
resistance.
___________
Numbers in square brackets refer to the Bibliography.

COMPOSITE HOLLOW CORE STATION POST
INSULATORS WITH AC VOLTAGE GREATER THAN
1 000 V AND DC VOLTAGE GREATER THAN 1 500 V –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA
1 Scope
This document, which is an International Standard, applies to composite hollow core station
post insulators consisting of a load-bearing insulating tube (core) made of resin impregnated
fibres, insulating filler material (solid, liquid, gaseous – pressurized or unpressurized), a
housing (outside the insulating tube) made of polymeric material (for example silicone or
ethylene-propylene) and 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 DC.
The object of this document is:
– to define the terms used;
– to specify test methods;
– to specify acceptance criteria.
All the tests in this document, apart from the thermal-mechanical test, are performed at normal
ambient temperature. This document does not specify tests that are characteristic of the
apparatus of which the composite hollow core station post insulator ultimately may form a part
(e.g. disconnector switch, reactor support, HVDC valves).
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 60168, Tests on indoor and outdoor post insulators of ceramic material or glass for systems
with nominal voltages greater than 1000 V
IEC 61109, Insulators for overhead lines – Composite suspension and tension insulators for AC
systems with a nominal voltage greater than 1 000 V – Definitions, test methods and acceptance
criteria
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
IEC 62217, 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 AC voltages greater
than 1 000 V up to 245 kV – Definitions, test methods and acceptance criteria
IEC TR 62039, Selection guidelines for polymeric materials for outdoor use under HV stress

– 8 – IEC 62772:2023 © IEC 2023
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
composite hollow core station post insulator
post insulator, consisting of at least three insulating parts, namely a tube, a housing with or
without sheds, and an internal filler
Note 1 to entry: End fittings are attached to the insulating tube. The housing, with or without sheds, may be omitted
in case of specific environmental conditions (e.g. indoor).
Note 2 to entry: A hollow insulator can be made from one or more permanently assembled insulating elements
3.2
post insulator
insulator intended to give rigid support to a live part which is to be insulated from earth or from
another live part
Note 1 to entry: A post insulator may be an assembly of a number of post insulator units (stack).
Note 2 to entry: Post insulators for substations are also known as station post insulators.
[SOURCE: IEC 60050-471:2007, 471-04-01, modified – addition of "(stack)" in Note 1 to entry]
3.3
tube (core)
central internal insulating part of a composite hollow core station post insulator which provides
the mechanical characteristics
Note 1 to entry: The housing, insulating filler material and sheds are not part of the core.
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.
3.4
filler
insulating material filling the entire internal space (solid, liquid, gaseous – pressurized or
unpressurized) of the hollow core station post insulator
3.5
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, modified – addition of "fixing device" in term]
3.6
coupling
part of the end fitting which transmits the load to the accessories external to the insulator
[SOURCE: IEC 62217:2012, 3.14]

3.7
connection zone
zone where the mechanical load is transmitted between the insulating body and the end fitting
[SOURCE: IEC 62217:2012, 3.13]
3.8
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, 3.7]
3.9
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]
3.10
insulator trunk
central insulating part of an insulator from which the sheds project
Note 1 to entry: Also known as shank on smaller insulators.
[SOURCE: IEC 60050-471:2007, 471-01-11]
3.11
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.
[SOURCE: IEC 60050-471:2007, 471-01-04, modified – removal of Note 2 to entry]
3.12
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]
3.13
interface
contact surface between the different materials
Note 1 to entry: Various interfaces occur in most composite insulators (cf. Annex C), e.g.
– between housing and end fittings,
– between various parts of the housing; e.g. between sheds, or between sheath and sheds,
– between tube and housing
– between tube and filler.
[SOURCE: IEC 62217:2012, 3.11, modified – addition of "contact"]

– 10 – IEC 62772:2023 © IEC 2023
3.14
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).
3.15
maximum mechanical load
MML
highest cantilever bending 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 mechanical load
SML
cantilever bending load specified by the manufacturer that is used in the mechanical tests, and
which is verified during a type test at normal ambient temperature
Note 1 to entry: The SML forms the basis of the selection of composite hollow station post insulators with regard
to external loads.
3.17
specified cantilever load
SCL
cantilever load to be withstood by the insulator when tested under the specified conditions in
accordance with IEC 62231
3.18
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: For more information to load philosopies and relationships, see Annex B.
3.19
specified torsion load
SToL
torsion load level which can be withstood by the insulator when tested under the specified
conditions in accordance with IEC 62231
3.20
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
3.21
specified tension load
STL
tension load which can be withstood by the insulator when tested under the specified conditions
in accordance with IEC 62231
3.22
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
3.23
specified compression load
SCoL
compression load to be withstood by the insulator when tested under the specified conditions
in accordance with IEC 62231
3.24
buckling load
compression load that induces buckling of the insulator core in accordance with IEC 62231
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 in accordance with IEC 62231
3.26
failing load of a composite hollow core station post insulator
load at ultimate failure of the insulator, maximum load that can be reached when the insulator
is tested under the specified conditions (valid for bending or pressure tests)
Note 1 to entry: Damage to the tube is likely to occur at loads lower than the insulator failing load.
3.27
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.
3.28
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
3.29
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.
3.30
overpressure
pressure above ambient pressure within a pressurized enclosure
[SOURCE: IEC 60050-426:2020, 426-09-16]
3.31
maximum service pressure
MSP
maximum overpressure in service which is specified by the equipment manufacturer

– 12 – IEC 62772:2023 © IEC 2023
3.32
specified internal pressure
SIP
internal overpressure specified by the manufacturer which is verified during a type test at normal
ambient temperature
Note 1 to entry: The SIP is specified as the short-time withstand design limit, under which the insulator structure
stays intact, but damages may already occur. It can be higher than 4 × MSP.
3.33
pressurized insulator
insulator permanently filled with gas or liquid whose maximum service pressure is greater than
0,05 MPa overpressure
3.34
unpressurized insulator
insulator is an insulator permanently filled with gas or liquid whose maximum service pressure
is smaller than or equal to 0,05 MPa overpressure
3.35
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.
3.36
manufacturer
individual or organization producing the composite hollow core station post insulator
3.37
equipment manufacturer
individual or organization producing the electrical equipment utilizing the composite hollow core
station post insulator
3.38
lot
group of insulators offered for acceptance from the same manufacturer, of the same design and
manufactured under similar conditions of production
Note 1 to entry: One or more lots may be offered together for acceptance: the lot(s) offered may consist of the
whole, or part, of the quantity ordered.
[SOURCE: IEC 62155:2003, 3.22, modified – removal of "hollow", removal of "or hollow
insulator bodies"]
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 document. 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, formulation 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.
– 14 – IEC 62772:2023 © IEC 2023
Table 1 – Required design and type tests
a)
IF the change in insulator
THEN the following tests shall be repeated:
design concerns:
Design tests Type tests
IEC 6277 IEC 62772
2:-, :-,
IEC 62
IEC 62772:-, 8.4 IEC 627
IEC 62 IEC 62
8.5 8.6 772:-,
72:-,
772:-, 772:-,
Tests on shed and housing
8.2 8.3.1
Tests on Tests on 9.1,
material 9.4
the tube tube with 9.2,
material housing 9.3
1 Housing
Materials, formulation
d) d) d) e) a)
or manufacturing
1a X X
X X X X X
process
2 c)
1b
Assembly process X  X
b)
1c Profile     X
X
2 Tube
Material, formulation
a)
or manufacturing
2a X X   X X X X
process
2b X   X X  X
Design
3 End fitting
Material or assembly
3a X X     X
process
End fitting connection
3b X      X
zone design
4 Interface
Primer material and
a)
4a X
X
application method
Tube and end-fitting
4b X X     X
assembly process
Tube/housing/end fitting
4c
X X  X   X
interface design
Filling material or
5 X     X
method
Interfaces and
connections of end
fittings
Assembled core load
test
Hardness test
Accelerated
weathering test
Tracking and erosion
test
Flammability test
Hydrophobicity
transfer test
Porosity test (Dye
penetration test)
Water diffusion test
Water Diffusion Test
on Core with
Housing
Electrical type tests
Mechanical type
tests
a)
Explanation
Not necessary if it can be demonstrated that the change has no influence on the property
a) e)
to : considered in the test; material tests could be used to show the equivalence
Additional
b)
Not necessary if thickness of the housing surrounding the core (including a sheath where
information for
used) is equal or greater than that of the parent insulator. Following relative numbers as
which specific
tolerances are provided as reference, which do not constitute a change of the profile:
changes testing
needs to be done
– overhang: ±10 %
– thickness at base and tip: ±15 %
– spacing: ±15 %
– shed inclinations: ±3°
– shed repetition: identical.
These relatively small tolerances serve as reference, however cause a high test demand due
to the variety of today`s profiles. Alternatively, a technical agreement between manufacturer
and user in agreement with chapter 9.1 is possible if the equivalence of the profile evaluated in
the tracking and erosion test to the profile in question can be shown. A possible method is the
interpolation of results with different profiles.
c)
Not necessary if it can be demonstrated that the change has no influence on the property
considered in the test.
d)
Not necessary for change in manufacturing process without material change
e)
Applicable to materials that shall show this property
Explanation
Housing manufacturing process:
1 6
to : Technical General manufacturing method such as injection moulding, modular process etc.
explanation of
Housing assembly process:
hollow core
If shed and sheath are mounted separately to the tube, incl. type and method of bonding
insulator
shed-sheath
components
Tube manufacturing method: Pultrusion, wet filament winding, vacuum impregnation,
including surface preparation
Liner and winding angle
See Annex C for further explanation
See Annex A for further explanation

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 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,
– arcing and field grading devices, if equipped.
Mechanically, a composite hollow core station post insulator type is defined by:
– the length (only for the compression and buckling withstand load test),
– the tube inner diameters,
– the wall thicknesses of the tube,
– the tube lamination parameters,
– the method of attachment,
– 16 – IEC 62772:2023 © IEC 2023
– the material of insulator,
– the material of the metal end fittings,
– the manufacturing process.
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 lots 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.
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 po
...