SIST EN 62155:2004

SLOVENSKI SIST EN 62155:2004
STANDARD
september 2004
Hollow pressurized and unpressurized ceramic and glass insulators for use in
electrical equipment with rated voltages greater than 1000 V (IEC 62155:2003,
modified)
ICS 29.080.10 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

NORME CEI
INTERNATIONALE IEC
INTERNATIONAL
Première édition
STANDARD
First edition
2003-05
Isolateurs creux avec ou sans pression interne,
en matière céramique ou en verre, pour utilisation
dans des appareillages prévus pour des tensions
nominales supérieures à 1 000 V
Hollow pressurized and unpressurized ceramic
and glass insulators for use in electrical
equipment with rated voltages greater than 1 000 V
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62155 © IEC:2003 – 3 –
CONTENTS
FOREWORD . 7
1 Scope and object . 9
1.1 General . 9
1.2 Hollow insulators or hollow insulator bodies intended for general use . 9
1.3 Ceramic hollow insulators intended for use with permanent gas pressure .11
2 Normative references.11
3 Terms and definitions .13
4 Insulating materials.19
5 General recommendations for design.19
5.1 General recommendations for design of hollow insulators and hollow insulator
bodies intended for general use.19
5.2 Design rules for hollow insulators and hollow insulator bodies for use with
permanent gas pressure .19
6 Classification of the tests, sampling rules and procedures .25
6.1 Classification of the tests.25
6.2 Relevant tests for type, sample and routine tests.27
6.3 Hollow insulator or hollow insulator body selection .29
6.4 Retest procedure for sample tests .31
6.5 Quality assurance.31
7 General test procedures and requirements .33
7.1 Verification of the dimensions and roughness of ground surfaces .33
7.2 Mechanical failing load tests.43
7.3 Temperature cycle test .49
7.4 Porosity test .53
7.5 Galvanizing test.55
8 Type tests.57
8.1 Tests .57
8.2 Pressure test .59
8.3 Bending test .59
9 Sample tests.61
9.1 Tests for hollow insulators or hollow insulator bodies intended for general use .61
9.2 Tests for ceramic hollow insulators or hollow insulator bodies intended for use
with permanent gas pressure.61
10 Routine tests .61
10.1 Tests for hollow insulators or hollow insulator bodies intended for general use .61
10.2 Tests for ceramic hollow insulators or hollow insulator bodies intended for use
with permanent gas pressure.63
10.3 Routine visual inspection .63
10.4 Electrical routine test .65
10.5 Routine mechanical tests for hollow insulators or hollow insulator bodies
intended for general use .67
10.6 Routine mechanical tests for ceramic hollow insulators or hollow insulator bodies
intended for use with permanent gas pressure.69
10.7 Routine thermal shock test .71

62155 © IEC:2003 – 5 –
11 Documentation.71
11.1 Marking .71
11.2 Records.71
Annex A (informative) Methods of testing for tolerances of parallelism, coaxiality,
eccentricity, angular deviation, camber and shed angle of hollow insulators or hollow
insulator bodies.73
Annex B (informative) Methods for bending tests of hollow insulator bodies .85
Annex C (informative) Alternative test method for the temperature-cycle test .91
Annex D (informative) Bending moment equivalent to the design pressure .93
Bibliography.95
Figure 1 – Bending moments.23
Figure 2 – Tolerance of wall thickness .35
Figure 3 – Deviation from roundness of inner or outer core diameter.37
Figure 4 – Effect of camber of the hollow insulator body.39
Figure 5 – Tolerance on height of sanding and porcelain chamfered end flange .41
Figure 6 – Definition of thickness Φ mm for temperature-cycle test .49
Figure A.1 – Measuring of tolerances of form and position .75
Figure A.2 – Measuring of angular deviation of fixing holes.75
Figure A.3 – Method for measuring camber.77
Figure A.4 – Measuring shed angle .79
Figure A.5 – Centring with conical shank screws.79
Figure A.6 – Axial run-out .81
Figure A.7 – Parallelism and perpendicularity.81
Figure A.8 – Coaxiality and concentricity, evenness, alignment of fixing holes
and proper sealing .83
Figure B.1 – Test ram for uniform distributed bending moment.85
Figure B.2 – Test ram for non-uniform distributed bending moment.87
Figure B.3 – Test method with bending load applied.89
Figure C.1 – Alternative test arrangement for the temperature-cycle test.91
Figure D.1 – Diameters for determining the equivalent bending moment to
the design pressure.93
Table 1 – Typical examples of load combinations and weighting factors.23
Table 2 – Hollow insulators or hollow insulator bodies intended for general use –
Relevant tests for type, sample and routine tests .27
Table 3 – Ceramic hollow insulators or hollow insulator bodies intended for use with
permanent gas pressure – Relevant tests for type, sample and routine tests.29
Table 4 – Number of samples for sample tests .31
Table 5 – Selection of temperature difference for temperature cycle test.51
Table 6 – Selection of temperature difference for the alternative temperature-cycle test .51
Table 7 – Selection of temperature difference for insulators of annealed glass.53

62155 © IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
HOLLOW PRESSURIZED AND UNPRESSURIZED CERAMIC
AND GLASS INSULATORS FOR USE IN ELECTRICAL EQUIPMENT
WITH RATED VOLTAGES GREATER THAN 1 000 V
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62155 has been prepared by subcommittee 36C: Insulators for
substations, of IEC technical committee 36: Insulators.
This International Standard cancels and replaces the second edition of IEC 60233, published
in 1974, and the second edition of IEC 61264, published in 1998, and constitutes a technical
revision of IEC 60233.
The text of this standard is based on the following documents:
FDIS Report on voting
36C/143/FDIS 36C/145/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until 2007.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
62155 © IEC:2003 – 9 –
HOLLOW PRESSURIZED AND UNPRESSURIZED CERAMIC
AND GLASS INSULATORS FOR USE IN ELECTRICAL EQUIPMENT
WITH RATED VOLTAGES GREATER THAN 1 000 V
1 Scope and object
1.1 General
This standard is applicable to
– ceramic and glass hollow insulators intended for general use in electrical equipment;
– ceramic hollow insulators intended for use with a permanent gas pressure in switchgear
and controlgear.
These insulators are intended for indoor and outdoor use in electrical equipment, operating on
alternating current with a rated voltage greater than 1 000 V and a frequency not greater than
100 Hz or for use in direct-current equipment with a rated voltage of greater than 1 500 V.
The hollow insulators are intended for use in electrical equipment, for example:
– circuit-breakers,
– switch-disconnectors,
– disconnectors,
– earthing switches,
– instrument transformers,
– surge arresters,
– bushings,
– cable sealing ends,
– capacitors.
It is not the object of this standard to prescribe dielectric type tests because the withstand
voltages are not characteristics of the hollow insulator itself but of the apparatus of which it
ultimately forms a part.
1.2 Hollow insulators or hollow insulator bodies intended for general use
Hollow insulators or insulator bodies of ceramic material or glass, intended for use
– without pressure;
– with permanent pressure ≤50 kPa gauge;
– with permanent gas pressure >50 kPa gauge in combination with an internal volume
< 1 l (1 000 cm );
– with permanent hydraulic pressure.

62155 © IEC:2003 – 11 –
The object of this standard is to define
– the terms used;
– the mechanical and dimensional characteristics of hollow insulators and hollow insulator
bodies;
– the electrical soundness of the wall;
– the conditions under which the specified values of these characteristics are verified;
– the methods of test;
– the acceptance criteria.
1.3 Ceramic hollow insulators intended for use with permanent gas pressure
Hollow insulators or hollow insulator bodies with their fixing devices, intended for use with
permanent gas pressure: permanent gas pressure >50 kPa gauge in combination with an
internal volume •1 l (1 000 cm ).
NOTE 1 The gas can be dry air, inert gases, for example, SF or nitrogen or a mixture of such gases.
The object of this standard is to define
– the terms used;
– the mechanical and dimensional characteristics of hollow insulators and hollow insulator
bodies;
– the electrical soundness of the wall;
– the conditions under which the specified values of these characteristics are verified;
– the methods of test;
– the acceptance criteria;
– design rules;
– test procedures and test values.
NOTE 2 Hollow insulators or hollow insulator bodies are usually integrated into electrical equipment which is
electrically type tested as required by the equipment standard.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60672-3:1997, Ceramic and glass insulating materials – Part 3: Specifications for
individual materials
IEC 60694:1996, Common specifications for high-voltage switchgear and controlgear standards
IEC 60865-1:1993, Short-circuit currents – Calculation of effects – Part 1: Definitions and
calculation methods
IEC 61166:1993, High-voltage alternating current circuit-breakers – Guide for seismic
qualification of high-voltage alternating current circuit-breakers
IEC 61463:1996, Bushings – Seismic qualification

62155 © IEC:2003 – 13 –
IEC 62271-100:2001, High-voltage switchgear and controlgear – Part 100: High-voltage
alternating-current circuit-breakers
ISO 1460:1992, Metallic coatings – Hot dip galvanized coatings on ferrous metals –
Gravimetric determination of the mass per unit area
ISO 1461:1999, Hot dip galvanized coatings on fabricated iron and steel articles –
Specifications and test methods
ISO 1463:1982, Metal and oxide coatings – Measurement of coating thickness – Micro-
scopical method
ISO 2064:1996, Metallic and other inorganic coatings – Definitions and conventions concern-
ing the measurement of thickness
ISO 2178:1982, Non-magnetic coatings on magnetic substrates – Measurement of coating
thickness – Magnetic method
ISO 4287:1997, Geometrical Product Specifications (GPS) – Surface texture: Profile method –
Terms, definitions and surface texture parameters
3 Terms and definitions
For the purposes of this document, the following definitions apply.
NOTE Some of the definitions cited below are taken from IEC 60050(471), modified or unmodified.
3.1
hollow insulator body
hollow insulating body, which is open from end to end, with or without sheds, not including the
fixing devices or end fittings
3.2
hollow insulator
hollow insulating part, which is open from end to end, with or without sheds, including
the fixing devices or end fittings
[IEV 471-01-17, modified]
NOTE This is a general term which also covers the definitions 3.4, 3.5 and 3.6.
3.3
fixing device
end fitting
device forming part of a hollow insulator, intended to connect it to a supporting structure or to
an item of equipment, or to another insulator
NOTE Where the fixing device is metallic, the term “metal fitting” is also used.
[IEV 471-01-02, modified]
3.4
hollow post insulator
hollow post insulator, which consists of one hollow post insulator unit or an assembly of more
units and is intended to give support to a live part, which is to be insulated from earth or from
another live part
62155 © IEC:2003 – 15 –
3.5
hollow post insulator unit
hollow post insulator unit, which consists of a permanent assembly of a hollow insulating body
with fixing devices and is intended to give support
3.6
chamber insulator
hollow insulator, which is used as a housing
EXAMPLE Arc extinction chamber of a circuit-breaker.
3.7
bushing
device that enables one or several conductors to pass through a partition such as a wall or
tank and insulates the conductors from it
[IEV 471-02-01, modified]
NOTE The means of attachment (flange or other fixing device) to the partition forms part of the bushing.
3.8
puncture
disruptive discharge passing through the solid insulating material of the insulator which
produces a permanent loss of dielectric strength
[IEV 471-01-11]
3.9
creepage distance
shortest distance along the external surface of an insulator between two conductive parts
[IEV 471-01-08, modified]
NOTE 1 The surface of cement, or of other non-insulating jointing material, is not considered as forming part of
the creepage distance.
NOTE 2 If a high-resistance coating is applied to parts of the surface of an insulator, such parts are considered to
be effective insulating surfaces, and the distance over them is included in the creepage distance.
NOTE 3 The surface resistivity of such high-resistance coatings is usually about 10 Ω but may be as low as
10 Ω.
NOTE 4 If high-resistance coatings are applied to the whole surface of an insulator (the so-called stabilized
insulator), the questions of surface resistivity and creepage distance should be subject to agreement between the
purchaser and the manufacturer.
3.10
specified characteristic
– either the numeric value of a voltage, of a mechanical load, or any other characteristic
specified in an IEC standard,
– or the numeric value of any such characteristic agreed between the purchaser and the
manufacturer
3.11
withstand bending moment
withstand bending moment verified in a type test, which is based on load conditions specified
for the hollow insulator
NOTE For a pressurized hollow insulator, it is based on the load conditions specified in 5.2.
3.12
mechanical failing load
maximum load reached when a hollow insulator or hollow insulator body is tested under the
prescribed conditions of test
62155 © IEC:2003 – 17 –
3.13
design pressure
upper limit at least of differential pressure reached between the interior and exterior of the
hollow insulator during operation at the design temperature
3.14
design temperature
highest temperature reached inside the hollow insulator which can occur under service
conditions
NOTE This is generally the upper limit of ambient air temperature increased by the temperature rise due to the
flow of the rated normal current, and to dielectric losses, if any.
3.15
manufacturer
organization that produces the hollow insulators or hollow insulator bodies
3.16
equipment manufacturer
individual or organization which produces the electrical equipment utilizing the hollow
insulators or hollow insulator bodies
3.17
parallelism of the end faces
maximum difference in the height of a hollow insulator measured across the surfaces of the
end fittings or the surfaces of the hollow insulator body
3.18
eccentricity
displacement, perpendicular to the axis of the hollow insulator, between the centres of the
pitch circles of the fixing holes in the top and bottom metal fittings
3.19
axial run-out
relative axial displacement of the end faces of the insulator measured during one revolution
(see Figure A.6)
3.20
angular deviation of the fixing holes
rotational displacement, expressed as an angle, between corresponding fixing holes in the
end fittings at the top and bottom of a hollow insulator
3.21
camber of an insulator
maximum distance between the theoretical axis of an insulator and the curved line being the
locus of the centres of all the transverse cross-sections of the unloaded insulator
[IEV 471-01-19]
3.22
lot
group of hollow insulators or hollow insulator bodies offered for acceptance from the same
manufacturer, of the same design and manufactured under similar conditions of production
NOTE 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.

62155 © IEC:2003 – 19 –
4 Insulating materials
The insulating materials of hollow insulator bodies intended for general use (see 1.2) covered
by this standard are:
– ceramic material, porcelain;
– annealed glass, being glass in which the mechanical stresses have been relaxed by
thermal treatment;
– toughened glass, being glass in which controlled mechanical stresses have been induced
by thermal treatment.
The insulating materials of hollow insulator bodies intended for use with permanent gas
pressure (see 1.3) covered by this standard are:
– ceramic material complying in its characteristics with IEC 60672-3, group C-100 and C-200.
NOTE 1 Further information on the definition and classification of ceramic and glass insulating materials can be
found in other IEC publications (see [4] ).
NOTE 2 The term “ceramic material” is used in this standard to refer to porcelain materials and, contrary to North
American practice, does not include glass.
5 General recommendations for design
5.1 General recommendations for design of hollow insulators and hollow insulator
bodies intended for general use
Specific design rules are not prescribed since the requirements are a function of the equip-
ment application (see 1.2).
5.2 Design rules for hollow insulators and hollow insulator bodies for use with
permanent gas pressure
5.2.1 Purpose
The rules for the design of gas-pressurized hollow insulators for high-voltage equipment
prescribed in this clause take into account that these hollow insulators are subjected to
particular operating conditions which distinguish them from compressed air receivers and
other similar storage vessels (see 1.3).
5.2.2 Rules for design
When designing hollow insulators, the following points shall be taken into consideration.
– Deviations and tolerances of profile: circularity, run-out, camber, parallelism, coaxiality,
evenness, differences in wall thickness, and angular and radial position of fixing holes
shall all take account of the parts to be fitted inside.
– It shall be considered that electrical strength, mechanical strength and technological
problems may influence the real construction, but, due to the complexity of this subject, no
definitive guide can be given.
– A critical selection of materials for cementing and fittings is also necessary. The ceramic
material shall comply in its characteristics with IEC 60672-3, group C-100 and C-200.
___________
Figures in square brackets refer to the bibliography.

62155 © IEC:2003 – 21 –
– An insulating pressurized enclosure may be considered as appropriate for its intended use
only after the electrical equipment of which it is a part has satisfactorily passed the type
tests provided for by the particular standards with which this equipment must comply.
5.2.3 Determination of the design pressure
The design pressure shall be the difference between the maximum absolute pressure, when
the equipment (of which the hollow insulator is a part) is carrying its rated normal current at
maximum ambient temperature and the outside pressure.
The maximum absolute pressure of the gas inside the hollow insulator shall be determined
by the equipment manufacturer.
NOTE In some special cases (for example, circuit-breakers), the pressure rise occurring after a breaking
operation should be taken into account.
5.2.4 Determination of the design temperature
The equipment manufacturer shall determine this value taking account of 3.14.
Solar radiation shall be taken into account.
5.2.5 Determination of the type-test withstand bending moment
The following factors may all contribute to the bending stress that may occur in electrical
equipment: mass, internal pressure, terminal loads, short-circuit loads, ice loads, operating
loads, wind loads, seismic loads (see Table 1).
The following sources shall be used for determining the values necessary for calculating the
relevant loads:
– terminal loads: 6.101.6.1 of IEC 62271-100
– wind loads: 6.101.6.1 of IEC 62271-100 and 2.1.2 of IEC 60694
– ice loads: 6.101.6.1 of IEC 62271-100 and 2.1.2 of IEC 60694
– short-circuit loads: determined from the rated short-circuit level of the
equipment (section 2 of IEC 60865-1)
– seismic loads: 8.1 of IEC 61166 and 10.1 of IEC 61463
– operating loads: values depending on design of equipment
The alternative combinations detailed in Table 1 are typical examples of load combinations
that must be considered in design. Column 1 of Table 1 covers the routinely expected loads
and has been assigned a safety factor of 2,1 for the type-test bending stress.
The three other conditions covering rarely occurring extreme loads have been assigned safety
factors of 1,2 for the type-test bending stress, and for seismic stresses a safety factor of 1,0.
The most onerous of the applicable alternatives shall be used to determine the test withstand
bending stress.
62155 © IEC:2003 – 23 –
From the test withstand bending stress, the test withstand bending moment can be calculated.
Table 1 – Typical examples of load combinations and weighting factors
Stress from rarely occurring extreme loads
Stress from
Loads routinely expected
Alternative 1 Alternative 2 Alternative 3
loads
Short-circuit load Ice load Seismic load
a
Design pressure 100 % 100 % 100 % 100 %
Mass 100 % 100 % 100 % 100 %
Rated terminal load 100 % 50 % 0 % 70 %
Wind pressure 30 % 100 % 0 % 10 %
Short-circuit load 0 % 100 % 0 % 0 %
Ice load 0 % 0 % 100 % 0 %
Seismic load 0 % 0 % 0 % 100 %
Safety factor 2,1 1,2 1,2 1,0
NOTE For details see IEC 62271-100, IEC 60694, IEC 60865-1, IEC 61166 and IEC 61463.
a
See Annex D.
Figure 1 shows the relation between the testing values and the utilization values for the
bending moment of a hollow insulator.
Testing values Utilization values
Type test withstand 100 %
bending moment
= 100 %
1,0
ALT 3     (Table 1)
Rarely occurring extreme loads
= 83,3 %
1,2
ALT 1 or ALT 2 (Table 1)
Rarely occurring extreme loads
Routine test bending 70 %
moment
50 % = 47,6 %
2,1
(Table 1) Routinely
expected loads
IEC  1079/03
Figure 1 – Bending moments
62155 © IEC:2003 – 25 –
6 Classification of the tests, sampling rules and procedures
6.1 Classification of the tests
The tests are divided into three groups as follows.
a) Type tests
b) Sample tests
c) Routine tests
6.1.1 Type tests
The type tests are intended to verify the main characteristics of a hollow insulator and/or a
hollow insulator body, which depend mainly on its design. They are usually carried out on one
hollow insulator and/or hollow insulator body, and only once for a new design or manu-
facturing process, and then subsequently repeated only when the design, material or
manufacturing process is changed; when the change only affects certain characteristics, only
the test(s) relevant to those characteristics need to be repeated. Moreover, it is not necessary
to perform all the type tests on a new design of hollow insulator and/or hollow insulator body if
a test report is available for a hollow insulator and/or hollow insulator body of mechanically
equivalent design. A mechanically equivalent design is the hollow insulator or hollow insulator
body having identical manufacturing and design parameters, and having the following
characteristics:
– the internal and external core diameters are the same;
– the design of the connection between the insulating component and the end fitting is the
same;
– the shape and size of the parts of the end fittings which connect to the insulating com-
ponents are the same;
±
– the nominal height does not differ by more than 20 %.
NOTE 1 Since all factors (materials, manufacturing process, and dimensions) which influence the mechanical
strength of hollow insulators or hollow insulator bodies should be the same for mechanical equivalence, the value
of the bending moment strength, the tensile strength, and the torsional strength will then be the same as those for
hollow insulators or hollow insulator bodies of mechanically equivalent designs, by which they are represented.
NOTE 2 When establishing mechanical equivalence of design, the effect of a significant difference in nominal
external diameter due to change of shed overhang and of shed spacing may need to be considered.
The type tests shall be carried out on hollow insulators and/or hollow insulator bodies which
meet the requirements of all the routine tests. When the insulators for type tests are taken
from a lot offered for acceptance, they shall also serve as sample tests for that lot.
6.1.2 Sample tests
The sample tests are carried out to verify the characteristics of a hollow insulator and/or
hollow insulator body, which can vary with the manufacturing process and the quality of the
component materials of the hollow insulator and/or hollow insulator body. Sample tests are
used as acceptance tests on a sample of hollow insulators and/or hollow insulator bodies,
taken at random from a lot which has met the requirements of the relevant routine tests.
6.1.3 Routine tests
The routine tests are intended to eliminate defective units and are carried out during the
manufacturing process. Routine tests shall be carried out on each hollow insulator and/or
hollow insulator body.
62155 © IEC:2003 – 27 –
6.2 Relevant tests for type, sample and routine tests
All hollow insulators or hollow insulator bodies intended for general use shall be tested
according to tests given in Table 2.
All hollow insulators or hollow insulator bodies intended for use with permanent gas pressure
shall be tested according to tests given in Table 3.
The series of tests to be conducted shall verify the characteristics of the hollow insulator or
hollow insulator body, which are specified on the drawing. In addition, the purchaser and the
manufacturer may agree to make tests other than those specified.
Additional routine tests such as verification of relevant dimensions (7.1) and mechanical tests
(10.5) may be performed after agreement between manufacturer and purchaser.
Table 2 – Hollow insulators or hollow insulator bodies intended for general use –
Relevant tests for type, sample and routine tests
Tests specified Type tests in Sample tests in Routine tests in
Tests
in Subclause Clause 8 Clause 9 Clause 10
Verification of dimensions and
7.1 – x –
roughness of ground surfaces
a a
Mechanical failing load test 7.2 x x –
f
Temperature-cycle test 7.3 x x–
b
Porosity test 7.4 – x –
c
Galvanizing test 7.5 – x –
Visual examination 10.3 – – x
Electrical routine test 10.4 – – x
e
Mechanical routine test 10.5 – – x
d
Routine thermal shock test 10.7 – – x
x Required by this standard.
a
This test is to verify the mechanical performance of the hollow insulator or hollow insulator body when defined
by the relevant drawing. Such tests shall be carried out after the temperature-cycle test.
b
Applicable only to ceramic insulators.
c
Applicable only to hollow insulators assembled with hot dip galvanized metal fittings.
d
Applicable only to toughened glass insulators.
e
Applicable only when specified on the drawing.
f
Applicable only when mechanical failing load test is specified.

62155 © IEC:2003 – 29 –
Table 3 – Ceramic hollow insulators or hollow insulator bodies intended for use with
permanent gas pressure – Relevant tests for type, sample and routine tests
Tests specified Type tests in Sample tests in Routine tests in
Tests
in Subclause Clause 8 Clause 9 Clause 10
Verification of dimensions and
7.1 – x –
roughness of ground surfaces
a a
Mechanical failing load test 7.2 x x –
Temperature-cycle test 7.3 x x –
Porosity test 7.4 – x –
b
Galvanizing test 7.5 – x –
Visual examination 10.3 – – x
Electrical routine test 10.4 – – x
Mechanical routine test 10.6.1; 10.6.2 – – x
c
Other mechanical tests 10.6.3 – – x
x Required by this standard.
a
This test is to verify the mechanical performance of the hollow insulator or hollow insulator body as defined in 7.2
and by the relevant drawing. Such tests shall be carried out after the temperature cycle test. The pressure and
bending tests are compulsory.
b
Applicable only to hollow insulators assembled with hot dip galvanized metal fittings.
c
Applicable only when specified on the drawing.
6.3 Hollow insulator or hollow insulator body selection
6.3.1 Hollow insulator or hollow insulator body selection for type tests
One hollow insulator or hollow insulator body shall be subjected to each test. The test shall be
carried out on an insulator which has passed all the requirements for the routine and sample
tests, except the sample mechanical test. Insulators which have been submitted to type tests
which may affect their mechanical characteristics shall not be used in service.
Normally the manufacturer selects the hollow insulator or hollow insulator body used for the
type test. If type and sample tests (see 6.1.1 and 6.1.2) are carried out consecutively, the
purchaser may make the selection.
6.3.2 Hollow insulator or hollow insulator body selection for sample tests
The number of hollow insulators or hollow insulator bodies selected for test shall be in
accordance with Table 4. The purchaser may make the selection from a lot which meets the
requirements of the routine tests.
Insulators which have been submitted to sample tests which may affect their mechanical
characteristics shall not be used in service.

62155 © IEC:2003 – 31 –
Table 4 – Number of samples for sample tests
Number of insulators in the lot, n Number of samples
1 or by agreement
n ≤ 100
a
100 < n ≤ 500 1 %
n
a
4 + 1,5 ×
500 < n
1 000
a
If the percentage or calculation does not give a whole number, then the next whole number above shall
be chosen.
6.4 Retest procedure for sample tests
If only one hollow insulator or hollow insulator body or metal fitting fails to comply with any of
the sample tests, a new sample, equal to twice the quantity originally submitted to that test,
shall be subjected to retesting. The retesting shall comprise the test in which failure occurred,
preceded by those tests which may be considered as having influenced the results of the
original test.
If two or more hollow insulators or hollow insulator bodies or metal fittings fail to comply with
any of the sample tests or if any failure occurs during the retesting, the complete lot is
considered as not complying with this standard and shall be withdrawn by the manufacturer.
Provided the cause of the failure can be clearly identified, the manufacturer may sort the lot to
eliminate all the hollow insulators or hollow insulator bodies with that defect. The sorted lot, or
part thereof, may then be re-submitted for testing.
The number then selected shall be three times the first quantity chosen for the tests. The
retesting shall comprise the test in which failure occurred, preceded by those tests which may
be considered as having influenced the results of the original test. If any hollow insulator or
hollow insulator body fails during this retesting, the complete lot is considered as not
complying with this standard.
NOTE 1 Where failure in the galvanizing test is due to a mechanical load in a previous test in excess of the
routine test load, the retest may be carried out, either on unassembled metal fittings, or on other hollow insulators
in the lot.
NOTE 2 If, during the sample testing, one or more hollow insulators or hollow insulator bodies fail to comply with
the tolerances as specified in 7.1 or on the relevant drawing, then, by agreement between the purchaser and the
manufacturer, the tolerances of each hollow insulator or hollow insulator body may be checked.
6.5 Quality assurance
A quality assurance programme, taking into account the requirements of this standard, can be
used, after agreement between the purchaser and the manufacturer.
NOTE Detailed information on the use of quality assurance is given in ISO standards (see [1], [2] and [3]).
ISO 9001 is recommended as a guide for a quality system for manufacturing of insulators, considering 1.2
of ISO 9001.
62155 © IEC:2003 – 33 –
7 General test procedures and requirements
The hollow insulator or hollow insulator body shall be subjected to the tests specified in
Tables 2 or 3.
7.1 Verification of the dimensions and roughness of ground surfaces
The dimensions of all hollow insulators or hollow insulator bodies shall meet the values,
including the permissible tolerances specified on the drawing. If not specified or unless
otherwise agreed between the purchaser and the manufacturer, the following tolerances shall
be applied.
7.1.1 General dimensional tolerances
Unless otherwise specified, the tolerance on each dimension shall be
± (0,04 × L + 1,5) mm when L ”300;
d d
± (0,025 × L + 6) mm when L > 300,
d d
where L is the checked dimension in millimetres (mm).
d
NOTE In many equipment designs the inner diameter, d , is of importance. An example of such a tolerance
±(0,025 × d + 1,5) mm is suggested.
7.1.2 Creepage distance tolerance
The measurement of creepage distance shall be related to the design dimensions as specified
on the insulator drawing, even though this dimension may be greater than originally specified
by the purchaser.
The creepage distance shall be subject to the following tolerances:
– when the creepage distance is specified as a nominal value, the following negative
tolerance will apply:
(0,04 × L + 1,5) mm, where L is the nominal creepage distance;
c c
– when the creepage distance is specified as a minimum value, it shall be considered as the
minimum value obtained in measurements on the insulators.
NOTE The value of the creepage distance can affect the behaviour of the insulators in the electrical type tests.
Therefore, the measured value of the creepage distance of the insulators submitted to the type tests should not
exceed a maximum value of 1,04 × L .
c
62155 © IEC:2003 – 35 –
7.1.3 Tolerance of wall thickness
t
d ± x
d ± y
IEC  1080/03
Nominal wall Tolerance on
thickness t wall thickness
mm mm
t < 10 +a / –1,5
10 ≤ t < 15 +a / –2,0
≤ +a / –3,0
15 t < 20
+a / –3,5
20 ≤ t < 25
25 ≤ t < 30 +a / –4,0
+a / –4,5
30 ≤ t < 40
+a / –5,0
40 ≤ t < 55
+a / –6,0
55 ≤ t < 70
NOTE 1 These tolerances are not applicable to ground wall.
x + y
NOTE 2 Tolerance a is determined by the following equation:
a =
x and y are tolerances on diameter d and d .
1 2
d − d
2 1
NOTE 3 Nominal wall thickness
t =
Figure 2 – Tolerance of wall thickness

62155 © IEC:2003 – 37 –
7.1.4 Deviation from roundness of inner or outer core diameter
Maximum deviation from roundness
The deviation from roundness is included
in the tolerance of the diameter.
Lower limit
Nominal diameter
Tolerances see 7.1.1
Upper limit
IEC  1081/03
Figure 3 – Deviation from roundness of inner or outer core diameter
7.1.5 Camber
The camber δ of a hollow insulator body shall not be greater than
h
– (0,006 × h + 1) mm when ” 8
d
h
– 0,008 × h mm when > 8
d
where
h is the height of the hollow insulator in millimetres (mm);
d is the greatest inner core diameter of the hollow insulator in millimetres (mm).
NOTE A suitable indirect method for measuring camber is indicated in Clause A.4 (Figure A.3).

62155 © IEC:2003 – 39 –
Reference plane
h
X
H
min.
D
δ
A A
d
90°
θ
H
max.
IEC  1082/03
Figure 4 – Effect of camber of the hollow insulator body
7.1.6 Position of end shed
Due to the camber of the hollow insulator body there may be a shed inclination at the ends of
h h
the porcelain. The maximum camber of 0,6 % ≤ 8 or 0,8 % > 8 of insulator length will
d d
1 1
h
give an angle θ
...