IEC TR 60099-10:2024
(Main)Surge arresters - Part 10: Rationale for tests specified by IEC 60099-4:2014
Surge arresters - Part 10: Rationale for tests specified by IEC 60099-4:2014
IEC TR 60099-10:2024 is applicable to all tests and arrester types included in IEC 60099-4:2014 and explains the rationale behind each test specified in that document.
This document does not contain requirements and is not intended to replace any clauses of IEC 60099-4:2014.
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IEC TR 60099-10 ®
Edition 1.0 2024-06
TECHNICAL
REPORT
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Surge arresters –
Part 10: Rationale for tests specified by IEC 60099-4:2014
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IEC TR 60099-10 ®
Edition 1.0 2024-06
TECHNICAL
REPORT
colour
inside
Surge arresters –
Part 10: Rationale for tests specified by IEC 60099-4:2014
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.120.50; 29.240.10 ISBN 978-2-8322-8969-3
– 2 – IEC TR 60099-10:2024 © IEC 2024
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 10
4 Structure of the document . 10
4.1 Content of each individual test rationale. 10
4.2 Relation between each test of IEC 60099-4:2014 and this document . 11
5 Insulation withstand tests rationale . 12
5.1 Arrester type for which the tests are applicable . 12
5.2 Purpose of the tests . 12
5.3 Historical notes . 12
5.4 Tests rationale . 12
5.4.1 General . 12
5.4.2 Sample selection rationale . 13
5.4.3 Test procedure rationale . 15
5.4.4 Evaluation rationale . 18
5.4.5 Common misunderstandings . 18
6 Residual voltage tests rationale . 19
6.1 Arrester type for which the tests are applicable . 19
6.2 Purpose of the tests . 19
6.3 Historical notes . 19
6.4 Tests rationale . 19
6.4.1 General . 19
6.4.2 Sample selection rationale . 20
6.4.3 Tests procedures rationale . 20
6.4.4 Evaluation rationale . 23
7 Test to verify long term stability under continuous operating voltage rationale . 23
7.1 Arrester type for which the test is applicable . 23
7.2 Purpose of the test . 23
7.3 Historical notes . 23
7.4 Test rationale . 24
7.4.1 General . 24
7.4.2 Sample selection rationale . 25
7.4.3 Test procedure rationale . 26
7.4.4 Evaluation rationale . 26
8 Test to verify the repetitive charge transfer rating (Q ) rationale . 26
rs
8.1 Arrester type for which the test is applicable . 26
8.2 Purpose of the test . 26
8.3 Historical notes . 26
8.4 Test rationale . 27
8.4.1 General . 27
8.4.2 Sample selection rationale . 27
8.4.3 Test procedure rationale . 27
8.4.4 Evaluation rationale . 28
8.4.5 Common misunderstandings . 28
9 Heat dissipation behavior of test sample rationale . 29
9.1 Arrester type for which the test is applicable . 29
9.2 Purpose of the test . 29
9.3 Historical notes . 29
9.4 Test rationale . 29
9.4.1 General . 29
9.4.2 Sample selection rationale . 30
9.4.3 Test procedure rationale . 30
9.4.4 Evaluation rationale . 30
10 Operating duty test rationale . 31
10.1 Arrester type for which the test is applicable . 31
10.2 Purpose of the test . 31
10.3 Historical notes . 31
10.4 Test rationale . 32
10.4.1 General . 32
10.4.2 Sample selection rationale . 32
10.4.3 Test procedure rationale . 32
10.4.4 Evaluation rationale . 34
10.4.5 Common misunderstandings . 35
11 Power-frequency voltage-versus-time test rationale . 35
11.1 Arrester type for which the test is applicable . 35
11.2 Purpose of the test . 35
11.3 Historical notes . 36
11.4 Test rationale . 36
11.4.1 General . 36
11.4.2 Sample selection rationale . 36
11.4.3 Test procedure rationale . 36
11.4.4 Evaluation rationale . 37
11.4.5 Common misunderstandings . 37
12 Tests of arrester disconnector rationale . 37
12.1 Arrester type for which the tests are applicable . 37
12.2 Purpose of the tests . 37
12.3 Historical notes . 38
12.4 Tests rationale . 38
12.4.1 General . 38
12.4.2 Sample selection rationale . 38
12.4.3 Tests procedure rationale . 38
12.4.4 Evaluation rationale . 38
13 Short-circuit tests rationale . 39
13.1 Arrester type for which the test is applicable . 39
13.2 Purpose of the test . 39
13.3 Historical notes . 39
13.4 Test rationale . 40
13.4.1 General . 40
13.4.2 Sample selection rationale . 41
13.4.3 Test procedure rationale . 41
13.4.4 Evaluation rationale . 43
13.4.5 Common misunderstandings . 44
– 4 – IEC TR 60099-10:2024 © IEC 2024
14 Test of the bending moment of porcelain-housed arresters rationale . 44
14.1 Arrester type for which the test is applicable . 44
14.2 Purpose of the test . 44
14.3 Historical notes . 44
14.4 Test rationale . 45
14.4.1 General . 45
14.4.2 Sample selection rationale . 46
14.4.3 Test procedure rationale . 46
14.4.4 Evaluation rationale . 46
15 Test of the bending moment of polymer-housed arresters rationale . 47
15.1 Arrester type for which the test is applicable . 47
15.2 Purpose of the test . 47
15.3 Historical notes . 47
15.4 Test rationale . 48
15.4.1 General . 48
15.4.2 Sample selection rationale . 48
15.4.3 Test procedure rationale . 49
15.4.4 Evaluation rationale . 49
16 Environmental tests rationale. 49
16.1 Arrester type for which the tests are applicable . 49
16.2 Purpose of the tests . 49
16.3 Historical notes . 50
16.4 Test rationale . 50
16.4.1 General . 50
16.4.2 Sample selection rationale . 50
16.4.3 Test procedure rationale . 50
16.4.4 Evaluation rationale . 50
17 Seal leak rate test rationale . 51
17.1 Arrester type for which the test is applicable . 51
17.2 Purpose of the test . 51
17.3 Historical notes . 51
17.4 Test rationale . 51
17.4.1 General . 51
17.4.2 Sample selection rationale . 51
17.4.3 Test procedure rationale . 51
17.4.4 Evaluation rationale . 51
18 Radio interference (RIV) test rationale . 51
18.1 Arrester type for which the test is applicable . 51
18.2 Purpose of the test . 52
18.3 Historical notes . 52
18.4 Test rationale . 52
18.4.1 General . 52
18.4.2 Sample selection rationale . 52
18.4.3 Test procedure rationale . 52
18.4.4 Evaluation rationale . 52
19 Test to verify the dielectric withstand of internal components rationale . 52
19.1 Arrester type for which the test is applicable . 52
19.2 Purpose of the test . 52
19.3 Historical notes . 53
19.4 Test rationale . 53
19.4.1 General . 53
19.4.2 Sample selection rationale . 53
19.4.3 Test procedure rationale . 54
19.4.4 Evaluation rationale . 54
20 Tests of internal grading components rationale . 54
20.1 Arrester type for which the tests are applicable . 54
20.2 Purpose of the test . 54
20.3 Historical notes . 54
20.4 Test rationale . 54
20.4.1 General . 54
20.4.2 Sample selection rationale . 55
20.4.3 Test procedure rationale . 55
20.4.4 Evaluation rationale . 55
21 Weather aging tests rationale . 55
21.1 Arrester type for which the tests are applicable . 55
21.2 Purpose of the tests . 56
21.2.1 Salt fog test . 56
21.2.2 UV light test . 56
21.3 Historical notes . 56
21.3.1 Salt fog test . 56
21.3.2 UV light test . 56
21.4 Test rationale . 56
21.4.1 General . 56
21.4.2 Sample selection rationale . 57
21.4.3 Test procedure rationale . 57
21.4.4 Evaluation rationale . 57
22 Routine tests and acceptance tests rationale . 57
22.1 Routine tests. 57
22.2 Acceptance tests . 58
Bibliography . 60
Figure 1 – Possible arcing distances (7 paths to consider for this example) for a multi-
unit arrester (from CIGRÉ 696-2017) . 14
Figure 2 – Withstand voltage versus duration . 16
Figure 3 – Sequence of the test to verify the repetitive charge transfer rating . 27
Figure 4 – Example of cooldown curves of test samples . 31
Figure 5 – Operating duty test sequence . 33
Figure 6 – Examples of TOV curves . 35
Figure 7 – Power-frequency versus time test sequence . 37
Figure 8 – Impact of the connecting leads on arc movement and short-circuit test
severity . 43
Figure 9 – Graphic representation of the relationships between tests in the bending
moment tests for porcelain-housed arresters . 45
– 6 – IEC TR 60099-10:2024 © IEC 2024
Figure 10 – Examples of MBL and SSL test results . 46
Figure 11 – Graphic representation of the relationships between tests in the bending
moment tests for polymer-housed arresters . 47
Table 1 – Test rationale clause number for each test in 60099-4:2014 . 11
Table 2 – Calculated minimum life expectancy if MO resistors would perfectly follow
the Arrhenius law . 25
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURGE ARRESTERS –
Part 10: Rationale for tests specified by IEC 60099-4:2014
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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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IEC TR 60099-10 has been prepared by IEC technical committee 37: Surge arresters. It is a
Technical Report.
The text of this Technical Report is based on the following documents:
Draft Report on voting
37/XX/DTR 37/XX/RVDTR
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 Technical Report is English.
– 8 – IEC TR 60099-10:2024 © IEC 2024
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.
A list of all parts in the IEC 60099 series, published under the general title Surge arresters, can
be found on the IEC website.
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.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
INTRODUCTION
This part of IEC 60099, which is a Technical Report, is informative in nature and does not
contain requirements. Its primary purpose is to provide information to users of IEC 60099-4 to
help them understand the underlying rationale for the tests and the specified test parameters.
A secondary purpose is to keep a record of substantive changes in the rationale over the last
few editions of the standard.
This first edition of the Technical Report covers the tests specified in IEC 60099-4:2014. As
tests are added, modified or deleted in future editions of IEC 60099-4, it is planned to amend
this Technical Report to reflect such changes. It is understood that rationale behind
requirements may change significantly over time, for example when a whole new test philosophy
is implemented in a standard.
– 10 – IEC TR 60099-10:2024 © IEC 2024
SURGE ARRESTERS –
Part 10: Rationale for tests specified by IEC 60099-4:2014
1 Scope
This part of IEC 60099, which is a Technical Report, is applicable to all tests and arrester types
included in IEC 60099-4:2014 and explains the rationale behind each test specified in that
document.
This document does not contain requirements and is not intended to replace any clauses of
IEC 60099-4:2014.
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 60099-4:2014, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.
systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60099-4:2014 apply.
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
4 Structure of the document
4.1 Content of each individual test rationale
Each test rationale clause (see Clauses 5 to 21), with the exception of the routine and
acceptance test rationales (see Clause 22), is structured as follows (with X representing the
clause number):
X.1 Arrester types for which the test is applicable
X.2 Purpose of the test
X.3 Historical notes
X.4 Test rationale
X.4.1 General
X.4.2 Sample selection rationale
X.4.3 Test procedure rationale
X.4.4 Evaluation rationale
X.4.5 Common misunderstandings (applicable only to Clauses 5, 8, 10, 11 and 13)
Historical notes provide information with regard to the known first use in IEC 60099-4, initial
references used to develop the test, and major changes over time.
The "Common misunderstandings" subclauses provide general comments with regard to often
misunderstood uses of the characteristics being verified in IEC 60099-4:2014.
4.2 Relation between each test of IEC 60099-4:2014 and this document
All arrester types covered by IEC 60099-4:2014 are covered in this document. A rationale is
provided for each test in IEC 60099-4:2014, including the routine and acceptance tests, with
the following exceptions because these tests are under consideration by IEC Technical
Committee 37 at the moment of publication of this technical report:
• the insulation withstand tests for GIS arresters and separable and dead-front arresters
(IEC 60099-10:2014, 11.8.2 and 12.8.2).
• the short-circuit tests for separable and dead-front and liquid-immersed arresters
(IEC 60099-10:2014, 12.8.10 and 13.8.10).
• the test after erection on site for GIS arresters (IEC 60099-4:2014, 11.10).
• the internal partial discharge test for separable and dead-front arresters (IEC 60099-4:2014,
12.8.17).
Table 1 shows which clause/subclause of this document applies to each test of IEC 60099-
4:2014, for each arrester type.
Table 1 – Test rationale clause/subclause number for each test in 60099-4:2014
Tests in 60099-4:2014 Test rationale clause/subclause number in this document for
each arrester type
Porcelain Polymer Gas Separable Liquid
Clause/subclause Title
a housed housed insulated and dead- immersed
number
metal- front
enclosed
8.2 Insulation withstand tests 5 Not included in this 5
edition
8.3 Residual voltage tests 6
8.4 Test to verify long term 7
stability under continuous
operating voltage
8.5 Test to verify the repetitive 8
charge transfer rating, Q
rs
8.6 Heat dissipation behavior 9
of test sample
8.7 Operating duty test 10
8.8 Power-frequency voltage- 11
versus-time test
8.9 Test of arrester 12 N/A
disconnector
8.10 Short-circuit tests 13 Not included in this
edition
Test of the bending
8.11 14 15 N/A
moment
8.12 Environmental tests 16 N/A
8.13 Seal leak rate test 17 N/A
– 12 – IEC TR 60099-10:2024 © IEC 2024
Tests in 60099-4:2014 Test rationale clause/subclause number in this document for
each arrester type
Porcelain Polymer Gas Separable Liquid
Clause/subclause Title
a housed housed insulated and dead- immersed
number
metal- front
enclosed
8.14 Radio interference (RIV) 18
test
8.15 Test to verify the dielectric 19
withstand of internal
components
8.16 Test of internal grading 20
components
10.8.17 Weather aging test N/A 21 N/A
9 Routine tests and 22
acceptance tests
a
For subclause numbers starting with 8 (ex.: 8.2), equivalent subclauses in Clauses 10, 11, 12 and 13 are also
included (e.g. 10.8.2, 11.8.2, 12.8.2 and 13.8.2 are included in the same line as per 8.2)
5 Insulation withstand tests rationale
5.1 Arrester type for which the tests are applicable
Insulation withstand tests apply to all types of arresters. This clause includes the test rationales
for porcelain-housed arresters, polymer-housed arresters and liquid-immersed arresters only.
Specificities applicable to GIS arresters and separable and dead-front arresters are under
consideration in IEC Technical Committee 37 and are not included yet herein.
However, if an arrester has a dry arc distance longer than the specified levels in
IEC 60099-4:2014, they are exempt from this test. Also, the switching impulse withstand test is
required for arresters applied to systems with U > 245 kV only.
s
5.2 Purpose of the tests
The voltage withstand tests demonstrate the voltage withstand capability of the external
insulation of arrester housings.
5.3 Historical notes
These tests were added for the first time in IEC 60099-4:1991. There was no reference to this
type of test in IEC 60099-1.
Historically, tests on individual housings only were specified irrespective of arrester rating and
tests on complete housing assemblies were "under consideration". This was changed in
IEC 60099-4:2014 to require tests on arresters for systems with U > 245 kV to be performed
s
using complete housing assemblies including the external grading systems. For systems with
U ≤ 245kV, tests are still permitted on individual unit housings.
s
5.4 Tests rationale
5.4.1 General
This test is a procedure to verify that the housing will not experience an external flashover under
anticipated transient conditions that may occur over the life of the arrester. This is not a lightning
impulse withstand (LIWV) test, a switching impulse withstand voltage (SIWV) nor a power
frequency voltage (PFWV) test as applied to other high voltage equipment.
Arresters are unique in that they are self-protecting devices which means that the internal
nonlinear resistors of the arrester will inherently limit the voltage across the terminals. Due to
this self-protecting nature, the arrester housing can have lower withstand voltages than the rest
of the system without any negative impact on the system withstand level.
There are three types of insulation withstand voltages used in this test, intended to represent
the three types of overvoltage stresses that an arrester will experience in its lifetime, namely
lightning, switching and power frequency.
The general rationale for the insulation withstand tests on liquid-immersed arresters is the same
as for porcelain-housed and polymer-housed arresters. Nevertheless, because these arresters
are operated while immersed in liquid, all tests have to be performed in this same liquid and
everything related to other ambient conditions must be ignored: no wet tests, no type test
exceptions because of dry arc to test voltage relation, no correction factor to take into account
density and humidity, etc. The liquid temperature is presumed to have no major impact on its
insulation withstand. So, room temperature is accepted for this test, as it is the case for power
transformers.
5.4.2 Sample selection rationale
5.4.2.1 Rationale applicable to all withstand tests
When individual arrester unit housings are tested, it is expected that the housing design under
test shall be the one that is stressed at its maximum level. The test is thus to be made on the
longest unit and on the most stressed unit (these may be two different units depending on the
arrester design). In determining the most stressed unit, the complete arrester assembly must
be considered, including any type of additional external or internal grading (for example grading
rings or internal capacitors).
For an arrester intended for application on a system where U > 245 kV, the complete arrester
s
housing assembly has to be tested, including internal means to achieve as close as possible
the grading that would be present under high current discharges in the actual arrester.
In all cases, where the standard does not require internal grading, it is acknowledged that the
removal of the active components will affect the results, but this practice has been used for
many years to evaluate arrester housing impulse withstand capability.
5.4.2.2 Rationale specific to the lightning impulse test
The lightning impulse withstand capability of an air gap is a linear function of distance with an
electric field of 500 kV/m. Therefore, a test is not required if the dry arcing distance or the sum
of the partial dry arcing distances in m is larger than the test voltage in kV divided by 500 kV/m.
Figure 1, from CIGRÉ TB 696-2017, presents the combination of different path (dry arcing
distances) to consider from the high voltage side of the arrester to the ground.
– 14 – IEC TR 60099-10:2024 © IEC 2024
Figure 1 – Possible arcing distances (7 paths to consider for this example) for a
multi-unit arrester (from CIGRÉ 696-2017)
5.4.2.3 Rationale specific to the switching impulse test
The test is to be performed on a complete arrester assembly due to the fact that the switching
withstand voltage is a nonlinear function of the dry arc distance and mitigating factors such as
the grading rings make an estimate for multiple sections inaccurate.
For samples intended to be used indoor, it is acceptable to complete this test in dry conditions.
For samples intended to be used outdoor, the arrester must be tested in wet conditions. Both
of these scenarios represent real world applications.
If an arrester has a dry arcing distance or a sum of partial dry arcing distances (see Figure 1)
that exceed the minimum requirement calculated with the following formula, this test is not
required:
(U /1069)
de=2,2×−1
(1)
where:
d is the distance, in m.
U is the test voltage, in kV.
The equation in IEC 60099-4:2014, 8.2.7 gives the limit which comes from IEC 60071-2:1996,
Annex G "Calculation of air gap breakdown strength from experimental data". The equation is
derived from formula G.3 of this latter standard, where U is given as:
Uk=×1080×ln 0,46×+d 1
( ) (2)
where:
k is the gap factor.
d is the distance, in m.
For the purpose of IEC 60099-4:2014, the gap factor k is assumed to be equal to 1,1 and two
standard deviations of 0,05 each are taken into account to achieve the withstand voltage.
5.4.2.4 Rationale specific to power-frequency voltage test
Since this test is only required on arresters applied to systems where U ≤ 245 kV, the testing
s
need only be made on individual unit housings.
For samples intended to be used indoor, it is acceptable to complete this test in dry conditions.
...
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