IEC 62896:2024

IEC 62896 ®
Edition 1.0 2024-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Hybrid insulators for AC and DC for high-voltage applications greater than
1 000 V AC and 1 500 V DC – Definitions, test methods and acceptance criteria

Isolateurs hybrides pour applications haute tension en courant alternatif et en
courant continu supérieures à 1 000 V en courant alternatif et 1 500 V en courant
continu – Définitions, méthodes d’essai et critères d’acceptation

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IEC 62896 ®
Edition 1.0 2024-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Hybrid insulators for AC and DC for high-voltage applications greater than

1 000 V AC and 1 500 V DC – Definitions, test methods and acceptance criteria

Isolateurs hybrides pour applications haute tension en courant alternatif et en

courant continu supérieures à 1 000 V en courant alternatif et 1 500 V en courant

continu – Définitions, méthodes d’essai et critères d’acceptation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.080.10  ISBN 978-2-8322-8755-2

– 2 – IEC 62896:2024  IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Identification . 11
5 Environmental conditions . 11
6 Tolerances . 11
7 Classification of tests. 11
7.1 Design tests . 11
7.2 Type tests . 12
7.3 Sample tests . 12
7.4 Routine tests. 12
8 Design tests . 15
8.1 General . 15
8.2 Tests on interfaces and connections of end fittings . 15
8.2.1 General . 15
8.2.2 Pre-stressing . 15
8.2.3 Verification tests . 16
8.3 Tests on Shed and Housing Material . 16
8.3.1 Hardness test . 16
8.3.2 Accelerated weathering test . 16
8.3.3 Tracking and erosion test . 17
8.3.4 Flammability test . 17
8.3.5 Hydrophobicity transfer test . 17
8.4 Test on core material . 17
8.4.1 Porosity test . 17
9 Type tests . 17
9.1 General . 17
9.2 Electrical tests . 17
9.3 Mechanical tests . 18
10 Sample tests . 18
11 Routine tests . 18
11.1 General . 18
11.2 Visual examination . 18
Bibliography . 19

Figure 1 – Classification of insulator designs . 8
Figure 2 – Thermal cycle test . 16

Table 1 – Required design and type tests . 13
Table 2 – Design tests . 15

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HYBRID INSULATORS FOR AC AND DC HIGH-VOLTAGE
APPLICATIONS GREATER THAN 1 000 V AC AND 1 500 V DC –
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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
IEC 62896 has been prepared by IEC technical committee 36: Insulators. It is an International
Standard.
This first edition cancels and replaces the IEC TS 62896 published in 2015. 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);
c) harmonization of Table 1 (Tests to be carried out after design and type changes) with other
product standards and IEC 62217.

– 4 – IEC 62896:2024  IEC 2024
The text of this International Standard is based on the following documents:
Draft Report on voting
36/594/FDIS 36/597/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, or
• revised.
INTRODUCTION
Hybrid insulators consist of an insulating core, bearing the mechanical load protected by a
polymeric housing, the load being transmitted to the core by end fittings. Despite these common
features, the materials used and the construction details employed by different manufacturers
may be quite different. The core is made of ceramic or glass material.
Hybrid insulators are applied as overhead line, post or hollow core equipment insulators. In
order to perform the design tests, IEC 62217 is intended to be applied for the polymeric housing
and the interfaces between core and the housing. For the core, the test standards for the
respective ceramic product (IEC 60168, IEC 60383-1 and −2 and IEC 62155) are intended to
be applied.
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 of hybrid 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 hybrid insulators has been considered in specifying the
design tests to ensure a satisfactory life-time under normally known stress conditions in service.
Polymeric housing materials that show the hydrophobicity transfer mechanism (HTM) are
preferred for hybrid insulators. These housing materials are applied as a countermeasure
against severely polluted service conditions.
Pollution tests according to IEC 60507 or IEC 61245 are not included in this document since
they are designed for non-polymeric items. Specific pollution tests for polymeric insulators are
still under consideration.
– 6 – IEC 62896:2024  IEC 2024
HYBRID INSULATORS FOR AC AND DC HIGH-VOLTAGE
APPLICATIONS GREATER THAN 1 000 V AC AND 1 500 V DC –
DEFINITIONS, TEST METHODS AND ACCEPTANCE CRITERIA

1 Scope
This document applies to hybrid insulators for AC and DC applications greater than 1 000 V AC
and 1 500 V DC consisting of a load-bearing insulating solid or hollow core consisting of ceramic
or glass, a housing (defined geometry, outside the insulating core) made of polymeric material
and end fittings permanently attached to the insulating core.
Hybrid insulators covered by this document are intended for use as suspension/tension long
rod and cap and pin type insulators, line post insulators, station post insulators and hollow core
insulators for apparatus.
The object of this document is to:
• define the terms used;
• prescribe test methods;
• prescribe acceptance criteria.
Silicone or other functional coatings (CIGRE Technical Brochure No. 478), booster sheds, shed
extenders and rain deflectors are not within the scope of this document. CIGRE B2.69 published
two Technical Brochures, TB 837 and TB 838, in June 2021 with the scope of practical
applications and collection of experiences for anti-pollution coatings for insulators.
This document does not include requirements dealing with the choice of insulators for specific
operating conditions.
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 60050-471:2007, International Electrotechnical Vocabulary (IEV) – Part 471: Insulators
IEC 60168, Tests on indoor and outdoor post insulators of ceramic material or glass for systems
with nominal voltages greater than 1000 V
IEC 60383-1:2023, Insulators for overhead lines with a nominal voltage above 1000 V – Part 1:
Ceramic or glass insulator units for a.c. systems – Definitions, test methods and acceptance
criteria
IEC 60383-2, Insulators for overhead lines with a nominal voltage above 1000 V – Part 2:
Insulator strings and insulator sets for a.c. systems – Definitions, test methods and acceptance
criteria
IEC 62155, Hollow pressurized and unpressurized ceramic and glass insulators for use in
electrical equipment with rated voltages greater than 1 000 V

IEC 62217, Polymeric HV insulators for indoor and outdoor use – General definitions, test
methods and acceptance criteria
IEC 61211, Insulators of ceramic material or glass for overhead lines with a nominal voltage
greater than 1 000 V – Impulse puncture testing in air
IEC 61325, Insulators for overhead lines with a nominal voltage above 1000 V – Ceramic or
glass insulator units for d.c. systems – Definitions, test methods and acceptance criteria
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-471:2007 and
the following apply (some definitions from IEC 62217 are reproduced here for ease of
reference).
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
high-voltage
HV
voltage over 1 000 V AC or over 1 500 V DC or over 1 500 V peak value
3.2
polymeric insulator
insulator whose insulating body consists of at least one organic based material
Note 1 to entry: Polymeric insulators are also known as non-ceramic insulators.
Note 2 to entry: Coupling devices may be attached to the ends of the insulating body.
[SOURCE: IEC 60050-471:2007, 471-01-13]
3.3
resin insulator
polymeric insulator whose insulating body consists of a solid insulator trunk and sheds
protruding from the insulator trunk made from only one organic based housing material (e.g.
cycloaliphatic epoxy)
3.4
composite insulator
polymeric insulator made of at least two polymeric insulating parts, namely a core and a
housing, equipped with metal fittings
Note 1 to entry: Composite insulators, for example, can consist either of individual sheds mounted on the core, with
or without an intermediate sheath, or alternatively, of a housing directly moulded or cast in one or several pieces on
to the core.
[SOURCE: IEC 60050-471:2007, 471-01-02, modified (addition of "polymeric", replacement of
"end fittings" by "metal fittings"]

– 8 – IEC 62896:2024  IEC 2024
3.5
hybrid insulator
insulator that consists of a ceramic core and a polymeric housing, equipped with one or more
metal fittings
See Figure 1.
Note 1 to entry: According to IEC TS 62896.
Note 2 to entry: The mechanical functions are mainly characterised by the core, the external electrical functions
are mainly characterised by the polymeric housing. The housing may cover the core completely or partly. In the latter
case the exposed portions of the ceramic core are usually covered by glaze.

Figure 1 – Classification of insulator designs
3.6
core
central insulating part of an insulator which provides the mechanical characteristics
Note 1 to entry: The housing and sheds are not part of the core.
[SOURCE: IEC 60050-471:2007, 471-01-03]
3.7
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]
3.8
housing
external insulating part of a composite insulator providing the necessary creepage distance and
protecting core from environment
Note 1 to entry: An intermediate sheath made of insulating material may be part of the housing.
[SOURCE: IEC 60050-471:2007, 471-01-09]

3.9
shed (of an insulator)
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
creepage distance
shortest distance or the sum of the shortest distances along the surface on an insulator between
two conductive parts which normally have the operating voltage between them
[SOURCE: IEC 60050-471:2007, 471-01-04]
3.11
arcing distance
shortest distance in 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
sheath
uniform and continuous tubular covering made of insulating material
[SOURCE: IEC 60050-151, 151-12-41, modified (removal of "conductive or")]
3.13
interfaces
surface between the different materials
Note 1 to entry: Various interfaces can be found 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.
3.14
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]
3.15
connection zone
zone where the mechanical load is transmitted between the insulating body and the end fitting
3.16
coupling
part of the end fitting which transmits load to the hardware external to the insulator

– 10 – IEC 62896:2024  IEC 2024
3.17
tracking
progressive degradation of the surface of a solid insulating material by local discharges to form
conducting or partially conducting paths
Note 1 to entry: Tracking paths are conductive even under dry conditions.
3.18
erosion
loss of material due to leakage current or electrical discharge
Note 1 to entry: Light surface traces, commonly tree-shaped, can occur on composite insulators as on ceramic
insulators, after partial discharge. These traces are not considered to be objectionable as long as they are
nonconductive. When they are conductive, they are classified as tracking.
3.19
crack
any internal fracture or surface fissure of depth greater than 0,1 mm
3.20
puncture
permanent loss of dielectric strength due to a disruptive discharge passing through the solid
insulating material of an insulator
[SOURCE: IEC 60050-471:2007, 471-01-14, modified to define puncture as the result of a
discharge, rather than the discharge itself]
3.21
lot
group of insulators or insulator bodies 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.
3.22
hydrophobicity
behaviour of the surface of a solid insulating material to repel to water or aqueous electrolyte
solutions; hydrophobicity of a polymeric insulating material is, in general, a volume property by
means of the chemical composition of a material at its surface
Note 1 to entry: Nonetheless, hydrophobicity is strongly affected by surface effects such as:
– surface structure (i. e. roughness);
– chemical interaction between water and the solid surface (adsorption, absorption, swelling of the solid material
in contact with water);
– an accumulated pollution layer.
Note 2 to entry: Furthermore, the conditions during an evaluation of hydrophobicity (climatic (temperature,
pressure, humidity), method for cleaning or electrostatic charges) may affect the measured degree of hydrophobicity.
3.23
hydrophobicity transfer
hydrophobicity transfer is the phenomenon of a transfer of hydrophobicity from the bulk of the
housing material to pollution layer on its surface

3.24
hydrophobicity transfer material (HTM)
polymeric material which exhibits hydrophobicity and the capability to transfer hydrophobicity
onto the layer of pollution, which is a combined dynamic behaviour of retention and transfer of
hydrophobicity specific to different insulator materials
[SOURCE: IEC TS 60815-4:2016, 3.1.4, modified – addition of text following "pollution"].
4 Identification
Each insulator shall be marked with the name or trademark of the manufacturer and the year of
manufacture. In addition, each insulator shall be marked with the rated characteristics specified
in the applicable IEC product standards for ceramic or glass insulators. These markings shall
be legible, indelible and their fixings (if any) weather- and corrosion-proof.
5 Environmental conditions
The normal environmental conditions to which insulators are submitted in service are defined
in IEC 62217.
6 Tolerances
Unless otherwise agreed, a tolerance of
• ±(0,04 × d + 1,5) mm when d ≤ 300 mm,
• ±(0,025 × d + 6 ) mm when d > 300 mm with a maximum tolerance of ±50 mm,
shall be allowed on all dimensions for which specific tolerances are not requested or given on
the insulator drawing (d being the dimension in millimetres).
The measurement of creepage distances shall be related to the design dimensions and
tolerances as determined from the insulator drawing, even if this dimension is greater than the
value originally specified. When a minimum creepage is specified, the negative tolerance is
also limited by this value.
7 Classification of tests
7.1 Design tests
These tests are intended to verify the suitability of the design, materials and method of
manufacture (technology). A hybrid insulator design is defined by:
• materials of the core, housing and their manufacturing method;
• material of the end fittings, their design and method of attachment (excluding the coupling);
• layer thickness of the housing over the core (including a sheath where used);
• diameter of the core.
Design tests shall be performed in accordance with Table 1. Sampling, test procedures and
acceptance criteria shall apply as in the standards referenced in Table 1.
When changes in the design occur, re-qualification shall be carried out in accordance with
Table 1.
– 12 – IEC 62896:2024  IEC 2024
When a hybrid insulator is submitted to the design tests, it becomes a parent insulator for a
given design and the results shall be considered valid for that design only. This tested parent
insulator defines a particular design of insulators which have all the following characteristics:
a) same materials for the core and housing and same manufacturing method;
b) same material of the fittings, the same design, and the same method of attachment;
c) same or greater minimum layer thickness of the housing over the core (including a sheath
where used);
d) same or smaller stress under mechanical loads;
e) same or greater cross-diameter of the core;
f) equivalent housing profile parameters, see Note (a) of Table 1.
7.2 Type tests
The type tests are intended to verify the main characteristics of a hybrid insulator, which depend
mainly on its materials, shape and size. Type tests in accordance with Table 1 shall be applied
to hybrid insulators, the class of which has passed the design tests. They shall be repeated
only when the type or material of the hybrid insulator is changed (see Table 1). The type tests
shall be performed, depending on type and application, according to the type tests defined in:
• IEC 60168 for solid core station post insulators,
• IEC 60383-1 and −2 for AC overhead transmission line insulators (cap and pin and long rod
and line post type)
• IEC 61325 for DC overhead transmission line insulators (cap and pin and long rod and line
post type)
• IEC 62155 for hollow core insulators
7.3 Sample tests
The sample tests are for the purpose of verifying other characteristics of hybrid insulators,
including those which depend on the quality of manufacture and on the materials used. They
are made on insulators taken at random from lots offered for delivery. Sample tests shall be
applied in accordance with IEC 60168, IEC 60383-1 or IEC 62155 for the respective kind of
products.
For ceramic cores the porosity test according to IEC 60383-1:2023, Clause 25, shall be
performed.
7.4 Routine tests
The aim of these tests is to eliminate hybrid insulators with manufacturing defects. They are
made on every hybrid insulator offered for acceptance. Routine tests shall be applied in
accordance with IEC 60168, IEC 60383-1 or −2 or IEC 62155 for the respective kind of
products.
Table 1 – Required design and type tests
Then the following tests shall be repeated
Type tests
Design tests
IEC 60168 IEC 60381-1/-2,
IEC 62217
IEC 61325 IEC 60168,
IEC 62217 IEC 62772
Tests on housing material
IF the change in
IEC 62155
insulator design
Interfaces
concerns:
Tracking
and Assembled Accelerated
Mechanical
Hardness and Flammability Hydrophobicity Porosity Electrical
connections core load test, weathering
type tests
test erosion test transfer test test type tests
of end only 8.3.1 test
test
fittings
1 Housing
Materials or
formulation and
1a X X X X X X
manufacturing
process
2 a)e)
1b Assembly process X  X
a)e)
1c Profile   X  X
2 Core
Material or
c) c) b)c)
2a manufacturing X X   X X
process
c) b)c)
2b Design    X
X X
3 End fitting
Material or
f) f)
3a    X
X X
assembly process
End fitting
3b connection zone X     X
design
4 Interface
Primer material
4a and application X
method
– 14 – IEC 62896:2024  IEC 2024

Then the following tests shall be repeated
Type tests
Design tests
IEC 60168 IEC 60381-1/-2,
IEC 62217
IEC 61325 IEC 60168,
IEC 62217 IEC 62772
Tests on housing material
IF the change in IEC 62155
insulator design
concerns: Interfaces
Tracking
and Assembled Accelerated
Mechanical
Hardness and Flammability Hydrophobicity Porosity Electrical
connections core load test, weathering
type tests
test erosion test transfer test test type tests
of end only 8.3.1 test
test
fittings
Core and end-
4b fitting assembly X X    X
process
Core/housing/end
4c fitting interface X X  X  X
design
d)
5 Type of insulator     X
X
NOTE 1 Housing manufacturing process: General manufacturing method such as injection moulding, modular process etc.
NOTE 2 Housing assembly process: If shed and sheath are mounted separately to the tube, incl. type and method of bonding shed-sheath.
a)
Not necessary if thickness of the housing surrounding the core (including a sheath where used) is equal or greater. The previous edition of this document provided relative
numbers as tolerances, which do not constitute a change of the profile. These have been
– overhang: ±10 %
– thickness at base and tip: ±15 %
– spacing: ±15 %
– shed inclinations: ±3°
– shed repetition: identical.
These relatively small tolerances can 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 9.1 is possible if the equivalence of the profile evaluated in the interface test as well as the tracking and erosion test to the profile in
question can be shown. A possible method is the interpolation of results with different profiles.
b)
Porosity test acc. to IEC 60168 (for ceramic only)
c)
Variations of the core diameter within ±20 % do not constitute a change. However, the type tests shall be performed in case of change of core diameter
d)
Mechanical and electrical type tests shall be carried out according to product test standards for ceramic or glass Insulators. It is permissible to perform the mechanical type
tests without the polymeric housing.
e)
Higher severity design in electric performance can be representative in similar design, if layer thickness of the housing over the core is the same or higher
f)
Not necessary if it can be demonstrated that the change has no influence on "interfaces and connection of end fittings".

8 Design tests
8.1 General
These tests consist of the tests specified in IEC 62217 as listed in Table 2. The design tests
are performed only once, and the results are recorded in a test report. Each part can be
performed independently on new test specimens. The hybrid insulator of a particular design will
be qualified only when all insulators or test specimens pass the design tests.
Table 2 – Design tests
Tests on interfaces and connections of end fittings
thermal-cycle pre-stressing
water immersion pre-stressing
Verification tests:
visual examination
steep-front impulse voltage test
dry power frequency voltage test
Tests on shed and housing material
hardness test
accelerated weathering test
tracking and erosion test – see 8.3.3 for specimens
flammability test
hydrophobicity transfer test
Tests on core material
porosity test
8.2 Tests on interfaces and connections of end fittings
8.2.1 General
One insulator assembled on the production line shall be tested. The insulation length (metal to
metal spacing) shall be not less than 800 mm. Both metal fittings shall be the same as on
standard production insulators. The end fittings shall be assembled so that the insulating part
from the fitting to the closest shed shall be identical to that of the production line insulator.
If the manufacturer only has facilities to produce insulators shorter than 800 mm, the design
tests may be performed on insulators of those lengths available to him, but the results are only
valid for up to the lengths tested.
8.2.2 Pre-stressing
8.2.2.1 Thermal cycle test
The specimen is submitted to temperature cycles under no mechanical load as described in
Figure 2, the 24 h temperature cycle being repeated four times. Each 24 h cycle has two
temperature levels with a duration of at least 8 h, one at +50 °C ± 5 K, the other at –35 °C ± 5 K.
The cold period shall be at a temperature at least 85 K below the value actually applied in the
hot period. The pre-stressing can be conducted in air or any other suitable medium.

– 16 – IEC 62896:2024  IEC 2024

Figure 2 – Thermal cycle test
The cycles may be interrupted for maintenance of the test equipment for a total duration of 2 h.
The starting point after any interruption shall be the beginning of the interrupted cycle.
8.2.2.2 Water immersion pre-stressing
Shall be performed according to IEC 62217.
8.2.3 Verification tests
8.2.3.1 General
Shall be performed according to IEC 62217.
8.2.3.2 Visual examination
Shall be performed according to IEC 62217.
8.2.3.3 Steep-front impulse voltage test
Shall be performed according to IEC 62217.
If necessary for insulators with a nominal length < 500 mm, the test arrangement only of
IEC 61211 may be used.
8.2.3.4 Dry power frequency voltage test
Shall be performed according to IEC 62217.
8.3 Tests on Shed and Housing Material
8.3.1 Hardness test
Shall be performed according to IEC 62217.
8.3.2 Accelerated weathering test
Shall be performed according to IEC 62217.

8.3.3 Tracking and erosion test
Shall be performed according to IEC 62217.
IEC 62217 specifies that the creepage distance shall be between 500 mm and 800 mm. If the
manufacturer only has facilities to produce insulators with creepage shorter than 500 mm, the
design tests may be performed on insulators of those lengths he has available, but the results
are only valid for up to the tested lengths.
If the insulator design does not allow samples with this creepage distance requirement, (e.g.
insulators with one shed) then the original insulator shall be used as test sample and the
line-to-earth voltage as specified by the manufacturer shall be applied as test voltage.
The acceptance criteria for composite insulators defined in IEC 62217 apply.
NOTE Tracking and erosion has no significant impact on the mechanical performance for hybrid insulators.
8.3.4 Flammability test
Shall be performed according to IEC 62217.
8.3.5 Hydrophobicity transfer test
Shall be performed according to IEC 62217.
8.4 Test on core material
8.4.1 Porosity test
Shall be performed according to IEC 60168.
9 Type tests
9.1 General
An insulator type is electrically defined by the arcing distance, creepage distance, shed
inclination, shed diameter and shed spacing. The electrical type tests shall be performed only
once on insulators satisfying the above criteria for one type and shall be performed with arcing
and/or corona devices, if they are an integral part of the insulator type.
An insulator type is mechanically defined by the core diameter and the method of attachment
of the metal fittings. The mechanical type tests shall be performed only once on insulators
satisfying the above criteria for each type.
The electrical and/or mechanical type tests shall be repeated only when one or more of the
above-mentioned characteristics are changed.
9.2 Electrical tests
The electrical tests for line insulators shall be performed according to IEC 60383-1 and
IEC 60383-2 to confirm the specified values. Electrical tests for station post insulators shall be
performed according to IEC 60168. No electrical type tests are required for hollow core
insulators.
Interpolation of electrical test results may be used for insulators of intermediate length, provided
that the factor between the arcing distances of the insulators whose results form the end points
of the interpolation range is less than or equal to 1,5. Extrapolation is not allowed.

– 18 – IEC 62896:2024  IEC 2024
9.3 Mechanical tests
The mechanical type tests shall be performed according to the respective product standard for
the kind of ceramic or glass insulator (e.g. IEC 60383-1, IEC 60168, IEC 62155 etc.).
10 Sample tests
The sample tests shall be performed according to the respective product standard for the kind
of insulator (e.g. IEC 60383-1, IEC 60168, IEC 62155 etc.).
For the verification of dimensions, in the case of repetitive shed profile and uniform diameter,
it is permissible to measure a short section (approximately 1 m in length) of the insulator and
then to extrapolate.
11 Routine tests
11.1 General
The general routine tests shall be performed according to the respective product standard for
the kind of insulator (e.g., IEC 60383-1, IEC 60168, IEC 62155 etc.).
11.2 Visual examination
Each insulator shall be examined. The mounting of metallic parts on the insulator assembly
shall be in accordance with the drawings. The colour of the insulator shall approximately be as
specified in the drawing.
The following defects are not permitted:
– on the housing, superficial defects of an area greater than 25 mm (the total defective area
shall not exceed 0,2 % of the total insulator surface) or depth or height greater than 1 mm;
– crack at the roo
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