IEC TR 62730:2012

IEC TR 62730 ®
Edition 1.1 2024-06
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
HV polymeric insulators for indoor and outdoor use tracking and erosion testing
by wheel test and 5 000 h test

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IEC TR 62730 ®
Edition 1.1 2024-06
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
HV polymeric insulators for indoor and outdoor use tracking and erosion testing
by wheel test and 5 000 h test
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.10 ISBN 978-2-8322-9239-6
REDLINE VERSION – 2 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope and object . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Background to the tracking and erosion tests . 8
4.1 Difference between the tracking and erosion and accelerated ageing tests on
polymeric insulators . 8
4.2 The wheel test . 8
4.3 The 5 000h multiple stress test . 9
5 Classification of tests . 10
6 General requirements for insulator test specimens . 10
7 The tests . 10
7.1 Wheel test . 10
7.1.1 Test specimens . 10
7.1.2 Procedure . 10
7.1.3 Test conditions . 12
7.1.4 Acceptance criteria . 12
7.2 5 000 hour test (test at multiple stresses) . 12
7.2.1 Test specimen . 12
7.2.2 Procedure . 12
7.2.3 Test conditions . 13
7.2.4 Voltage . 16
7.2.5 Solar simulation . 16
7.2.6 Artificial rain . 16
7.2.7 Dry heat . 17
7.2.8 Humidity . 17
7.2.9 Pollution . 17
7.2.10 Salt fog calibration . 17
7.2.11 Acceptance criteria . 19
Bibliography . 20

Figure 1 – Test arrangement of the tracking wheel test . 11
Figure 2 – Typical layout of the test specimens in the chamber and main dimensions
of the chamber . 13
Figure 3 – Multiple stress cycle . 14
Figure 4 – Typical layout of the rain and salt fog spray systems and the xenon lamp . 15
Figure 5 – Spectrum of xenon arc lamp and solar spectrum . 16
Figure 6 – Reference porcelain insulator .

 IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HV POLYMERIC INSULATORS FOR INDOOR AND OUTDOOR USE
TRACKING AND EROSION TESTING BY WHEEL TEST AND 5 000H TEST

FOREWORD
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This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
IEC 62730 edition 1.1 contains the first edition (2012-03) [documents 36/305/DTR and
36/316A/RVC] and its amendment 1 (2024-06) [documents 36/596/DTR and
36/601/RVDTR].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
REDLINE VERSION – 4 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62730, which is a technical report, has been prepared by IEC technical committee 36:
Insulators.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document and its amendment 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,
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• revised.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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 IEC 2024
INTRODUCTION
IEC 62217 [1] included three different tracking and erosion tests. One, the 1 000 hour salt-
fog test, was included in the main text as a default test and two others, the 5 000 hour test
and the tracking wheel test, were given in annexes as alternative tests.
Following a decision by TC 36 it was decided that it was desirable to have a single
standardised test in IEC 62217; hence a study of the usage and effectiveness of all three
tests was undertaken by Working Group 12 of TC 36. The results of this study indicated that,
while the 5 000h and the tracking wheel tests each had their advantages, only the 1 000 hour
salt fog test was adapted to all insulator types and was more economical to perform.
It was decided by TC 36 to adopt the 1 000 hour salt-fog test as the only standardised test. It
was also decided to draft this Technical Report to reproduce the 5 000 hour and the tracking
wheel test procedures in order to keep the information on the test methods and parameters
available for those wishing to use those tests for research or other purposes.
The tracking and erosion tests given in this technical report are considered as screening tests
intended to reject materials or designs which are inadequate. These tests are not intended to
predict long-term performance for insulator designs under cumulative service stresses.
Composite insulators are used in both a.c. and d.c. applications. In spite of this fact a specific
tracking and erosion test procedure for d.c. applications as a design test has not yet been
defined and accepted.
IEC Guide 111 has been followed during preparation of this technical report wherever
possible.
___________
Numbers in square brackets refer to the Bibliography.

REDLINE VERSION – 6 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
HV POLYMERIC INSULATORS FOR INDOOR AND OUTDOOR USE
TRACKING AND EROSION TESTING BY WHEEL TEST AND 5 000H TEST

1 Scope and object
This technical report is applicable to polymeric insulators whose insulating body consists of
one or various organic materials. Polymeric insulators covered by this technical report include
both solid core and hollow insulators. They are intended for use on overhead lines and in
indoor and outdoor equipment with a rated voltage greater than 1 000 V.
The object of this technical report is:
– to define the common terms used;
– to give the background behind the development and use of the 5 000 h multiple stress test
and the tracking wheel test;
– to describe the test methods for the 5 000 h multiple stress test and the tracking wheel
tests on polymeric insulators;
– to describe possible acceptance or failure criteria, if applicable;
These tests, criteria and recommendations are intended to give a common basis for the
5 000h multiple stress test and the tracking wheel test when they are used for research or
required as a supplementary design test. These tests are not mandatory and their use is
subject to prior agreement between the interested parties.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-47:2007, International Electrotechnical Vocabulary – Part 471: Insulators
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test
requirements.
IEC 60507, Artificial pollution tests on high-voltage insulators to be used on a.c systems
IEC 60815-2, Selection and dimensioning of high-voltage insulators intended for use in
polluted conditions – Part 2: Ceramic and glass insulators for a.c. systems
3 Terms and definitions
For the purposes of this document the terms and definitions given in IEC 60050 (471) and the
following apply:
3.1
polymeric insulator
insulator whose insulating body consists of at least one organic based material. Coupling
devices may be attached to the ends of the insulating body
Note 1 to entry: Polymeric insulators are also known as non-ceramic insulators.
[SOURCE: IEC 60050-471:2007, 471-01-13, modified]

 IEC 2024
3.2
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]
3.3
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]
3.4
housing
external insulating part of a composite insulator providing the necessary creepage distance
and protects the core from the 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]
3.5
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]
3.6
creepage distance
shortest distance or the sum of the shortest distances along the surface on an insulator
between two conductive parts which normally have the operating voltage between them
Note 1 to entry: The surface of cement or of any other non-insulating jointing material is not considered as
forming part of the creepage distance.
Note 2 to entry: If a high resistance coating is applied to parts of the insulating part of an insulator, such parts are
considered to be effective insulating surfaces and the distance over them is included in the creepage distance.
[SOURCE: IEC 60050-471:2007, 471-01-04]
3.7
interfaces
surface between the different materials. Various interfaces occur in most composite
insulators, e.g.:
– between housing and fixing devices;
– between various parts of the housing; e.g. between sheds, or between sheath and sheds;
– between core and housing;
3.8
tracking
process which forms irreversible degradation by formation of conductive paths (tracks)
starting and developing on the surface of an insulating material. These paths are conductive
even under dry conditions
REDLINE VERSION – 8 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
3.9
erosion
irreversible and non-conducting degradation of the surface of the insulator that occurs by loss
of material. This can be uniform, localized or tree-shaped.
Note 1 to entry: Light surface traces, commonly tree-shaped, can occur on composite insulators as on ceramic
insulators, after partial flashover. These traces are not considered to be objectionable as long as they are non-
conductive. When they are conductive they are classified as tracking.
3.10
crack
any internal fracture or surface fissure of depth greater than 0,1 mm
3.11
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]
4 Background to the tracking and erosion tests
4.1 Difference between the tracking and erosion and accelerated ageing tests on
polymeric insulators
Although this Technical Report describes tracking and erosion tests which often may be
referred to in the literature as “ageing tests”, it is important to note that they are not
accelerated ageing tests in the sense that these tests do not simulate exactly real life
degradation conditions nor do they accelerate them to give a life-equivalent test in a short
time. Rather they use continuous, cyclic or combined stresses to try to detect potential
weaknesses which could compromise the insulators performance in service.
The tests are better described as screening tests, which can be used to reject materials,
designs, or combinations thereof which are inadequate.
The ageing mechanisms on a polymeric insulator generally do not cause a progressive
reduction of easily measurable ageing-induced properties with time. The transition from “good
condition” to “end of life” is frequently rapid with no forewarning and might be observed by, for
instance, erosion to depths comparable to those obtained in the 1 000 hour salt fog test
defined in IEC 62217 or deep UV-initiated cracks in the surfaces. The time and speed of this
transition depends on multiple parameters, both of the insulator material and design and of
the operating environment. Hence the use of such ageing tests for true "end of life" prediction
is only possible when relevant data on damage and degradation is available for the same or
similar insulators in the same or similar environments.
Therefore these tests are used to give a general indication of the quality of the design and
materials with respect to the stresses arising in relatively harsh but not extreme environments.
For further information, see [2].
4.2 The wheel test
The tracking wheel test was originally developed in Canada and introduced in the Canadian
Electrical Association Light Weight Insulator Working Group CEA LWIWG-01 – Dead-end
suspension composite insulator standard in 1991. It was named Tracking Wheel # 2.
The # 1 version was a spray system rather than a dip system.

 IEC 2024
The original concept was to energize, at 35 V/mm of creepage, the insulator sample which
had been dipped in a NaCl solution of 1,40 g/l of water and allowed to drip. It was continuous
for the duration of the 30 000 cycles. The original acceptance criteria were: no tracking, no
erosion to the core and no shed or housing puncture. Every unit was then tested with a steep
front impulse and a power frequency voltage test.
The wheel test was not deemed to be an ageing test by the CEA. Although there were
discussions 20 years ago to correlate the aspects of the tested insulators with insulators in
the field and to estimate an aging factor, such correlation was never implied in the standard.
There was also consideration to modify the test parameters to reflect different pollution
severities. This was never introduced.
In the LWIWG-01-1996 version, the description of the test was modified to describe the de-
ionized water and introduce a rest period of 24 hours where the dip tank is empty. It was
observed during the first part of the 1990s that silicone-based housings did not perform well
when the test was uninterrupted. This corresponds to the concept of hydrophobicity recovery
which had gained popularity by that time.
In 2010, the test in the standard was re-affirmed in CSA C411.5 with basically the same
parameters.
In this IEC version, there are no provisions for a rest period, nor impulse and flashover tests
following the 30 000 cycles. There is allocation for test interruptions and a requirement to
change the dip tank solution weekly. The IEC version gives precise guidelines as to the
acceptable erosion depth.
This test is mandatory in the CSA insulator standards. For more than 20 years, this test has
been considered able to detect insulator designs that are not suitable for use on overhead
transmission lines. It is not meant as an ageing test with an estimated acceleration factor.
4.3 The 5 000h multiple stress test
The 5 000h multiple stress test was initially developed by CIGRE WG 22.10 which was set up
in 1978 to establish a technical basis for minimum requirements for composite insulators.
Their work was published in 1983 [3] and included a proposal for a multi-stress 5 000 hour
test combining cycles of humidity, heating, rain, salt fog and solar radiation on energised
insulators. The intention of the test was to reproduce any synergy between the multiple
stresses seen by insulators in service that might not be present in a single stress test. Later
work by EDF in France using the same “CIGRE” cycles reported varying acceleration factors
with respect to different test station environments [4] and classed the test as an accelerated
ageing test.
A similar, but not identical, test cycle was used in Italy as an accelerated ageing test and it
was deemed necessary to “fix” the test parameters by including it in IEC 61109:1992 [5]. At
this point it was given as an alternative to the 1 000h salt-fog test for insulators intended for
extreme conditions. IEC 61109:1992 did not mention any acceleration factors.
When it was decided to group common tests for composite insulators into IEC 62217:2005,
the test was included an alternative tracking and erosion test, not an accelerated ageing test.
The version of the test in 62217:2005 had been revised by IEC TC 36 WG12 on the basis of
work between Sweden and France to improve the reproducibility of the test which had been
shown to be problematic [6]. The main improvement involved calibration of the salt-fog cycle
by using standard dummy insulators at each test position to set up fog distribution and flow
rate.
The procedure included in this Technical Report includes some minor alterations to further
improve reproducibility.
REDLINE VERSION – 10 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
5 Classification of tests
Previously, these tests were alternative or supplementary design tests.
6 General requirements for insulator test specimens
Insulator test specimens for tests of polymeric insulators shall be checked prior to tests:
• for correct assembly, for example by applying the mechanical routine test specified in the
relevant product standard,
• by visual examination according to the relevant product standard;
• for conformance of dimensions with the actual drawing.
For dimensions d without tolerances the following tolerances are acceptable:
• ± (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.
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.
The housing colour of the test specimens shall be approximately as specified in the drawing.
The number of test specimens, their selection and dimensions are specified in the relevant
product standard or agreed upon by the interested parties.
7 The tests
7.1 Wheel test
7.1.1 Test specimens
Two test insulators of identical design with a creepage distance between 500 mm and 800 mm
shall be taken from the production line. If such insulators cannot be taken from the production
line, special test specimens shall be made from other insulators so that the creepage distance
falls between the given values. These special test specimens shall be fitted with standard
production end fittings.
Up to two pairs of test specimens can be tested simultaneously on one wheel. It is
recommended not to mix widely differing materials on the same wheel.
The test samples shall be properly marked so that the pairs can be easily identified at the end
of the test.
7.1.2 Procedure
The test specimens shall be cleaned with de-ionized water before starting the test. The test
specimens are mounted on the wheel as shown in Figure 1. They go through four positions in
one cycle. Each test specimen remains stationary for about 40 s in each of the four positions.
The 90° rotation from one position to the next takes about 8 s. In the first part of the cycle the
insulator is dipped into a saline solution. The second part of the test cycle permits the excess
saline solution to drip off the specimen, ensuring that the light wetting of the surface gives
rise to sparking across dry bands that will form during the third part of the cycle. In that part
the specimen is submitted to a power frequency voltage. In the last part of the cycle the
surface of the specimen that had been heated by the dry band sparking is allowed to cool.

 IEC 2024
The test voltage is supplied by a test transformer. When loaded with a resistive current of
250 mA on the high voltage side the test circuit shall exhibit a maximum drop of 5 % in its
output voltage.
The salt solution shall be replaced weekly. Weekly interruptions of the test for inspection
purposes, each of these not exceeding 1 h are permissible. Interruption periods will not be
counted in the test duration. One longer interruption up to 60 h is allowed. An additional
testing time of three times the duration of the interruption period shall be added. The final test
report shall include details of all interruptions.

HV
Rotation in 90° steps
Suspension type insulator
Energized
period
Grounded insulator
support wheel
Cooling
Drip period
period
Salt water
Dip period
IEC  478/12
Figure 1 – Test arrangement of the tracking wheel test

REDLINE VERSION – 12 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
7.1.3 Test conditions
Electrical stress: The power frequency test voltage in kV is determined by
dividing the actual creepage distance in mm by 28,6.
3 3
NaCl content of de-ionised water: 1,40  kg/m ± 0,06  kg/m
Ambient temperature: 20 °C ± 5 K
Test duration: 30 000 cycles
7.1.4 Acceptance criteria
The test specimens of identical design shall be assessed together. Pairs of test specimens of
different design shall be assessed separately. The numbers of flashovers and trip-outs shall
be recorded and noted in the test report. Photographs shall be made to record the test
results. The samples may be washed and lightly brushed in order to remove any loose matter.
The test is regarded as passed, if on both test specimens:
• no tracking occurs, (a Meg Ohm-meter shall be applied along any suspect path, using 1 kV
DC or higher. The probes shall be between 5 mm to 10 mm apart. A resistance of less
than 2 MΩ shall constitute failure);
• For composite insulators: erosion shall not reach the core and in any case the erosion
depth shall be less than 3 mm;
• for resin insulators: erosion depth is less than 3 mm;
• no shed, housing or interface is punctured.
7.2 5 000 hour test (test at multiple stresses)
7.2.1 Test specimen
Two test insulators of identical design with a creepage distance between 500 mm and 800 mm
shall be taken from the production line. If such insulators cannot be taken from the production
line, special test specimens shall be made from other insulators so that the creepage distance
falls between the given values. These special test specimens shall be fitted with standard
production end fittings.
7.2.2 Procedure
The test shall be carried out in a moisture sealed corrosion-proof chamber, the volume of
which shall not exceed 20 m .
An example of a chamber is presented in Figure 2.
An insulated porthole equipped with a wiper and a mobile filter stopping ultraviolet radiation
permits observation of the equipment on test.
NOTE 1 Outside the chamber there are: tanks of salt water and de-ionised water, together with the pumps,
heaters, pipes for water and air, fans, the medium voltage step-up transformer, and its protections, the power
supply to the ultraviolet radiation generator, all the electrical circuits and the devices for control, automatic control,
measurement and regulation.
 IEC 2024
Figure 2 – Typical layout of the test specimens in the chamber
and main dimensions of the chamber
NOTE 2 Chambers with a size larger than 20 m can be used in order to allow testing of full-size objects if the
criteria for calibration and environment (e.g. time to reach temperature during dry heat period) are fulfilled.
7.2.3 Test conditions
The cycle of stresses applied to the insulators and repeated for a period of 5 000 h is shown
in Figure 3. The cycle is designed so that the test specimens are also subjected to the effects
of temperature variation and condensation.
The test specimens are arranged vertically in the chamber as shown in Figure 4. There shall
be a clearance of at least 400 mm between adjacent edges of the sheds of test specimens
and between the test specimens and the roof, the walls and the floor.
The test specimens shall be cleaned with de-ionised water before starting the test.
Up to three pairs of test specimens with comparable creepage distance can be tested
simultaneously.
Weekly interruptions of the test for inspection purposes, each of these not exceeding 1 h are
permissible. Interruption periods shall not be counted in the test duration. Five longer
interruptions up to 60 h each are allowed. An additional testing time of three times the
duration of the interruption period shall be added. The final test report shall include all details
of interruptions.
REDLINE VERSION – 14 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
Humidification
RH = 95 %
Heating
50 °C
Rain
Salt fog
7 kg/m3
Solar radiation
simulation
Voltage
0 2 4 6 8 10 12 14 16 18 20 22 24
Time
(hours)
In service Out of service
IEC  480/12
Figure 3 – Multiple stress cycle

 IEC 2024
6 IEC  481/12
Key
1 rain nozzle 4 test specimen
2 salt fog spray nozzle (IEC 60507 type) 5 isolating insulator
3 xenon UV lamp 6 HV power supply
Figure 4 – Typical layout of the rain and salt fog spray systems
and the xenon lamp
REDLINE VERSION – 16 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
7.2.4 Voltage
The power frequency test voltage in kilovolts is adjusted to the actual creepage distance of
the test specimens. It is determined by dividing the creepage distance in millimetres by 34,6
(equal to a specific creepage distance of 20 mm/kV, calculated as phase-to-phase value).
The supply circuit, when loaded with a continuous resistive current of 250 mA (r.m.s.) during
1 s on the high voltage side shall experience a maximum voltage drop of 5 %. The protection
level shall be set at 1 A (r.m.s.).
7.2.5 Solar simulation
The simulated solar irradiation is provided by a xenon arc lamp with a nominal output of
6 500 W and equipped with 2 boron silicate glass filters (see example in Figure 5). The
distance between the xenon lamp and test specimens is approximately 480 mm.
A new lamp and filters shall be used at the beginning of each test. The filters and, if
necessary, the lamp shall be replaced during the test according to the lamp manufacturer’s
recommendations.
Measured radiation
in W/(m × nm)
3,5
2,5
1,5
0,5
250 300 350 400 450 500 550 600 650 700 750
Wavelength  (nm)
IEC  482/12
Key
Spectrum of the xenon arc lamp equipped with two boron silicate filters.
Solar spectrum at midday in June, latitude 42°.
Figure 5 – Spectrum of xenon arc lamp and solar spectrum
7.2.6 Artificial rain
The artificial rain shall be provided by nozzles mounted above the test specimens and outside
their perimeter (see Figure 4). The average precipitation rate shall be in accordance with
IEC 60060-1. Water of a minimum resistivity of 85 Ωm shall be used. Each of the test
specimens is sprayed individually.

 IEC 2024
7.2.7 Dry heat
The chamber is heated up to 50 °C ± 2 °C; the time for the temperature to rise is 15 min as a
maximum.
NOTE It is recommended to heat and insulate the walls of the chamber.
7.2.8 Humidity
Nominal relative humidity: RH = 95 % ± 3 % at 50 °C.
7.2.9 Pollution
The pollution is simulated by a salt fog (salinity: 7  kg/m ± 5 %) sprayed by nozzles of the
IEC 60507 type.
Each of the test specimens is sprayed individually.
Each spray nozzle is mounted below the corresponding test specimen and points upwards
towards the centre of it, within an angle of 40° ± 10° to the horizontal plane.
In case of unused test positions, insulators with comparable dimensions shall be placed at the
unused positions and the corresponding spray nozzles shall be in service.
The spray nozzles are mounted close to the bottom of the chamber and spray upwards
towards the roof of the chamber. The fog should fill up the chamber and not be directly
sprayed on to the test specimen. Salt water prepared from NaCl dissolved in tap water should
be supplied to the spray nozzles. The fog intensity and uniformity should be maintained in the
specimen's exposure zone.
7.2.10 Salt fog calibration
To ensure the test reproducibility and the severity level of the salt fog, the salt fog shall be
adjusted by using the method of calibration described below.
For this purpose a reference insulator is used. Its characteristics are:
• porcelain long rod insulator (hydrophilic material),
• normal shed profile (according to IEC 60815-2),
• Creepage factor = 2,2 ± 10 % (according to IEC 60815-2),
• Shed diameter = 140 mm ± 5 %.

REDLINE VERSION – 18 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
An example of a reference insulator is shown in Figure 6.
∅D
∅d
M
M
∅d
∅D
IEC  483/12
Key
Characteristics:
IEC ref: H4-125
Nominal creepage distance: 500 mm
Dry arcing distance: 225 mm
Length H: 210 mm
Shed diameter D: 140 mm
Figure 6 – Reference porcelain insulator
The reference insulator shall be carefully cleaned so that traces of dirt and grease are
removed.
Water, preferably heated to about 50 °C, with the addition of trisodium phosphate or another
detergent, shall be used to wash the surface of the insulator. Subsequently, the insulator is to
be thoroughly rinsed with tap water. The surface of the insulator is deemed to be sufficiently
clean and free from any grease if the surface is completely hydrophilic.
After cleaning, the insulating parts of the insulator should not be touched by hand.
Before every calibration period, the insulator shall be again thoroughly washed with tap water
only, in order to remove all traces of pollution.
The reference insulator shall be installed at each of the different test positions. Insulators with
comparable dimensions shall be placed on the other test positions.
The power frequency test voltage in kilovolts is adjusted to the actual creepage distance of
the reference insulator. It is determined by dividing the creepage distance in millimetres by
34,6 (equal to a specific creepage distance of 20 mm/kV, calculated as phase-to-phase value)
within a tolerance of ±5 %.
6 6
H
 IEC 2024
All the salt fog nozzles shall be in service.
The fog (position of nozzles and flow rate) is adjusted to obtain an average level of the
maximum peak currents (the maximum value recorded every 1 min.) in the range 100 to
200 mA, measured during 4 h. An establishment time of the leakage current of 30 min
maximum is permitted and not included in the calibration.
This is applied to all test locations.
Each test position can be calibrated separately. Alternatively, it is allowed to locate a
reference insulator at each test position and to perform the calibration of all test positions
simultaneously and independently. If the positions are calibrated individually, the calibration
shall be repeated to ensure that the initial fog corrections have not influenced the
neighbouring test positions.
The calibration will be carried out before the start of the test.
2 2
At least two clean collecting receptacles with a collecting area of 8 000 mm ± 2 000 mm and
a maximum height of 100 mm each are placed as close as practical to the position of the ends
of the test object. The receptacles are positioned in such a way that they are not shielded by
the test specimens and to avoid dripping from the construction elements of the chamber or
another source.
They should collect between 1,5 ml and 2,0 ml of precipitation per hour (corrected to 8
000 mm collecting area) averaged over a minimum period of 16 h.
NOTE The flow rate necessary to obtain such precipitation (typically of the order of 0,3 l/m h based on a chamber
not larger than 15 m ) should be noted. (The water flow rate is defined in litres per hour and per cubic meter of the
test chamber volume.) Subsequently during the test, the flow rate should be checked at least every 100 h and
should remain within ± 25 % of the initial value.
It is not permitted to re-circulate the water.
7.2.11 Acceptance criteria
The test specimens of identical design shall be assessed together. The numbers of flashovers
and trip-outs shall be recorded and noted in the test report. Photographs shall be made to
record the test results. The samples may be washed and lightly brushed in order to remove
any loose matter.
The test is regarded as passed if on both test specimens:
• no tracking occurs (a Meg Ohm-meter shall be applied along a suspect path, using 1 kV
DC or higher. The probes shall be between 5 mm to 10 mm apart. A resistance of less
than 2 MΩ shall constitute failure);
• for composite insulators: erosion depth is less than 3 mm and does not reach the core, if
applicable;
• for resin insulators: erosion depth is less than 3 mm;
• no shed, housing or interface is punctured.

REDLINE VERSION – 20 – IEC TR 62730:2012+AMD1:2024 CSV
 IEC 2024
Bibliography
[1] IEC 62217, Polymeric insulators for indoor and outdoor use with a nominal voltage
> 1000 V – General definitions, test methods and acceptance criteria
[2] CIGRE technical Brochure No. 142: “Natural and artificial ageing and pollution testing of
polymeric insulators”, June 1999
[3] “Technical basis for minimal requirements for composite insulators” CIGRE WG22-10,
ELECTRA N°88, May 1983, pp 89-114
[4] Accelerated ageing test for non-ceramic insulators EDF’s experience”, G. Riquel - SEE
Workshop: Non-ceramic outdoor insulation, Paris 15-16 April 1993
[5] IEC 61109, Insulators for overhead lines – Composite suspension and tension insulators
for a.c. systems with a nominal voltage greater than 1 000 V – Definitions, test methods
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