IEC 60099-6:2019

IEC 60099-6 ®
Edition 2.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Surge arresters –
Part 6: Surge arresters containing both series and parallel gapped structures –
System voltage of 52 kV and less

Parafoudres –
Partie 6: Parafoudres contenant des structures à éclateurs en série et en
parallèle – Tension de réseau inférieure ou égale à 52 kV

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IEC 60099-6 ®
Edition 2.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Surge arresters –
Part 6: Surge arresters containing both series and parallel gapped structures –

System voltage of 52 kV and less

Parafoudres –
Partie 6: Parafoudres contenant des structures à éclateurs en série et en

parallèle – Tension de réseau inférieure ou égale à 52 kV

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.240.10 ISBN 978-2-8322-6919-0

– 2 – IEC 60099-6:2019 © IEC 2019
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 11
4 Identification and classification . 18
4.1 Arrester identification . 18
4.2 Arrester classification . 18
5 Standard ratings and service conditions . 19
5.1 Standard rated voltages . 19
5.2 Standard rated frequencies . 19
5.3 Standard nominal discharge currents . 19
5.4 Service conditions . 19
5.4.1 Normal service conditions . 19
5.4.2 Special environmental conditions . 20
6 Requirements . 20
6.1 Insulation withstand . 20
6.2 Residual voltages . 20
6.3 Impulse protective levels . 20
6.4 Internal partial discharges . 20
6.5 Seal leak rate . 21
6.6 Thermal stability . 21
6.7 Heat dissipation behaviour of test sample . 21
6.8 Repetitive charge transfer withstand . 21
6.9 Operating duty . 21
6.10 Power-frequency voltage versus time characteristics of an arrester . 21
6.11 Short-circuit performance . 22
6.12 Disconnectors . 22
6.12.1 Disconnector withstand . 22
6.12.2 Disconnector operation . 22
6.13 Requirements on internal grading components . 22
6.14 Power-frequency sparkover . 22
6.15 Mechanical loads . 22
6.15.1 General . 22
6.15.2 Bending moment . 22
6.15.3 Resistance against environmental stresses . 23
6.15.4 Insulating base and mounting bracket . 23
6.15.5 Mean value of breaking load (MBL) . 23
6.16 Electromagnetic compatibility . 23
6.17 End of life . 23
7 General testing procedures. 23
7.1 Measuring equipment and accuracy . 23
7.2 Test samples . 23
7.2.1 General . 23
7.2.2 Samples for residual voltage tests . 24
7.2.3 Samples for the test to verify the repetitive charge transfer rating, Q . 24
rs
8 Type tests (design tests) . 24
8.1 General . 24
8.2 Insulation withstand tests . 25
8.2.1 General . 25
8.2.2 Tests on individual unit housing . 26
8.2.3 Ambient air conditions during tests . 26
8.2.4 Wet test procedure . 26
8.2.5 Lightning impulse voltage test. 26
8.2.6 Power- frequency voltage test . 26
8.3 Impulse protective level tests . 27
8.3.1 General . 27
8.3.2 Residual voltage tests . 27
8.3.3 Sparkover tests . 28
8.4 Test to verify the repetitive charge transfer rating, Q . 30
rs
8.4.1 General . 30
8.4.2 MO resistors . 30
8.4.3 Series gaps . 31
8.5 Operating duty tests . 32
8.5.1 General . 32
8.5.2 Test procedure . 33
8.5.3 Rated thermal charge values, Q . 35
th
8.6 Power-frequency voltage-versus-time test . 35
8.6.1 General . 35
8.6.2 Test samples . 36
8.6.3 Initial measurements . 36
8.6.4 Test procedure . 36
8.6.5 Test evaluation . 37
8.7 Tests of arrester disconnectors . 38
8.7.1 General . 38
8.7.2 Operating withstand test . 38
8.7.3 Disconnector operation . 39
8.7.4 Mechanical tests . 40
8.7.5 Temperature cycling and seal pumping test . 40
8.8 Power-frequency voltage sparkover tests . 40
8.9 Short-circuit tests . 41
8.9.1 General . 41
8.9.2 Preparation of the test samples . 41
8.9.3 Mounting of the test sample . 45
8.9.4 High-current short-circuit tests . 46
8.9.5 Low-current short-circuit test . 48
8.9.6 Evaluation of test results . 48
8.10 Test of the bending moment . 49
8.10.1 General . 49
8.10.2 Overview . 49
8.10.3 Sample preparation . 49
8.10.4 Test procedure . 49
8.10.5 Test evaluation . 50
8.10.6 Test on insulating base and mounting bracket . 50

– 4 – IEC 60099-6:2019 © IEC 2019
8.11 Environmental tests . 50
8.11.1 General . 50
8.11.2 Sample preparation . 51
8.11.3 Test procedure . 51
8.11.4 Test evaluation . 51
8.12 Seal leak rate test . 51
8.12.1 General . 51
8.12.2 Sample preparation . 51
8.12.3 Test procedure . 51
8.12.4 Test evaluation . 52
8.13 Test to verify the dielectric withstand of internal components . 52
8.13.1 General . 52
8.13.2 Test procedure . 52
8.13.3 Test evaluation . 52
8.14 Test of internal grading components . 52
8.14.1 Test to verify long term stability under continuous operating voltage . 52
8.14.2 Thermal cyclic test . 53
9 Routine tests and acceptance tests . 54
9.1 Routine tests . 54
9.2 Acceptance tests . 55
9.2.1 Standard acceptance tests . 55
9.2.2 Special thermal stability test . 55
10 Test requirements on polymer-housed surge arresters . 55
10.1 Scope . 55
10.2 Normative references . 56
10.3 Terms and definitions. 56
10.4 Identification and classification . 56
10.5 Standard ratings and service conditions . 56
10.6 Requirements . 56
10.7 General testing procedure . 56
10.8 Type tests (design tests) . 57
10.8.1 General . 57
10.8.2 Insulation withstand tests . 57
10.8.3 Impulse protective level tests . 57
10.8.4 Test to verify the repetitive charge transfer rating, Q . 57
rs
10.8.5 Operating Duty tests . 57
10.8.6 Power frequency voltage-versus-time test . 57
10.8.7 Tests of arrester disconnectors . 58
10.8.8 Power frequency voltage sparkover tests . 58
10.8.9 Short-circuit tests . 58
10.8.10 Test of the bending moment . 63
10.8.11 Environmental tests . 69
10.8.12 Seal leak rate test. 69
10.8.13 Test to verify the dielectric withstand of internal components . 69
10.8.14 Test of internal grading components . 69
10.8.15 Weather ageing test . 69
10.9 Routine tests . 71

Annex A (normative) Special Environmental Conditions . 72
Annex B (normative) Typical information given with enquiries and tenders . 73
B.1 Information given with enquiry . 73
B.1.1 System data . 73
B.1.2 Service conditions . 73
B.1.3 Arrester duty . 73
B.1.4 Characteristics of arrester . 74
B.1.5 Additional equipment and fittings . 74
B.1.6 Any special abnormal conditions . 74
B.2 Information given with tender . 74
Annex C (normative) Mechanical considerations . 76
C.1 Test of bending moment . 76
C.2 Definition of mechanical loads . 77
C.3 Definition of seal leak rate . 77
C.4 Calculation of wind-bending-moment. 78
C.5 Procedures of tests of bending moment for porcelain/cast resin and polymer-
housed arresters . 79

Figure 1 – procedure to verify the repetitive charge transfer rating, Q , for MO
rs
resistors. 30
Figure 2 – Procedure to verify the repetitive charge transfer rating, Q , for series gaps . 32
rs
Figure 3 – Test procedure to verify the thermal charge transfer rating, Q . 33
th
Figure 4 – Test procedure to verify the power frequency versus time characteristic
(TOV test) . 36
Figure 5 – Examples of arrester units. 44
Figure 6 – Examples of fuse wire locations for “Design A“ arresters . 45
Figure 7 – Examples of fuse wire locations for “Design B“ arresters . 45
Figure 8 – Short-circuit test setup for porcelain-housed arresters . 46
Figure 9 – Short-circuit test setup for polymer-housed arresters . 61
Figure 10 – Example of a test circuit for re-applying pre-failing circuit immediately
before applying the short-circuit test current . 63
Figure 11 – Thermomechanical test . 66
Figure 12 – Example of the test arrangement for the thermomechanical test and
direction of the cantilever load . 67
Figure 13 – Water immersion . 68
Figure C.1 – Bending moment – multi-unit surge arrester . 76
Figure C.2 – Definition of mechanical loads . 77
Figure C.3 – Surge arrester unit . 78
Figure C.4 – Surge-arrester dimensions . 79
Figure C.5 – Flow chart of bending moment test procedures . 80

– 6 – IEC 60099-6:2019 © IEC 2019
Table 1 – Arrester classification . 19
Table 2 – Steps of rated voltages. 19
Table 3 – Arrester type tests . 25
Table 4 – Requirements for high current impulses . 34
Table 5 – Rated values of thermal charge transfer rating, Q . 35
th
Table 6 – Test requirements for porcelain housed arresters . 43
Table 7 – Required currents for short-circuit tests . 47
Table 8 – Test requirements for polymer-housed arresters . 60

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SURGE ARRESTERS –
Part 6: Surge arresters containing both series and parallel gapped
structures – System voltage of 52 kV and less

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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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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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard lEC 60099-6 has been prepared by lEC technical committee 37: Surge
arresters.
This second edition cancels and replaces the first edition published in 2002. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) A new concept of arrester classification and energy withstand testing was introduced: the
line discharge classification was replaced by a classification based on repetitive charge
transfer rating (Q and thermal charge transfer rating (Q ). The new concept clearly
rs) th
differentiates between impulse and thermal energy handling capability, which is reflected
in the requirements as well as in the related test procedures.

– 8 – IEC 60099-6:2019 © IEC 2019
b) Power-frequency voltage versus time tests – with and without prior duty – were introduced
as type tests.
c) Requirements and tests on disconnectors were added.
d) Definitions for new terms have been added.
e) Clause 10 contains particular requirements for polymer-housed surge arresters. These are
indicated in the form of replacements, additions or amendments to the original clauses or
subclauses concerned.
The text of this International Standard is based on the following documents:
FDIS Report on voting
37/450/FDIS 37/451/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
This part of IEC 60099 presents the minimum criteria for the requirements and testing of
metal-oxide surge arresters containing gapped structures that are applied to AC power
systems with U above 1 kV up to and including 52kV.
s
Arresters covered by this document can be applied to overhead installations in place of the
non-linear type arresters covered in IEC 60099-4.
An accelerated ageing procedure is incorporated in this document to simulate the long-term
effects of voltage and temperature on the arrester. This is necessary since during the
arrester's service life the gaps and resistor elements will have portions of the system power
frequency voltage continuously applied across them.

– 10 – IEC 60099-6:2019 © IEC 2019
SURGE ARRESTERS –
Part 6: Surge arresters containing both series and parallel gapped
structures – System voltage of 52 kV and less

1 Scope
This part of IEC 60099 applies to non-linear metal-oxide resistor type surge arresters with
spark gaps designed to limit voltage surges on AC power circuits with system voltages U
s
above 1 kV up to and including 52 kV. This document basically applies to all metal-oxide
distribution class surge arresters with internal series and/or parallel gaps and housed in either
porcelain or polymeric housings.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60060-2, High-voltage test techniques – Part 2: Measuring systems
IEC 60068-2-11:1981, Basic environmental testing procedures – Part 2-11: Tests – Test Ka:
Salt mist
IEC 60068-2-14, Environmental testing – Part 2-14: Tests – Test N: Change of temperature
IEC 60071-2:2018, Insulation co-ordination – Part 2: Application guidelines
IEC 60270, High-voltage test techniques – Partial discharge measurements
IEC TS 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
IEC 62217, Polymeric HV insulators for indoor and outdoor use – General definitions, test
methods and acceptance criteria
ISO 4287, Geometrical Product Specifications (GPS) – Surface texture: Profile method –
Terms, definitions and surface texture parameters
ISO 4892-1, Plastics – Methods of exposure to laboratory light sources – Part 1: General
guidance
ISO 4892-2, Plastics – Methods of exposure to laboratory light sources – Part 2: Xenon-arc
lamps
ISO 4892-3, Plastics – Methods of exposure to laboratory light sources – Part 3: Fluorescent
UV lamps
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
acceptance test
test made on arresters or representative samples after agreement between manufacturer and
user
3.2
arrester disconnector
device for disconnecting an arrester from the system in the event of arrester failure, to
prevent a persistent fault on the system and to give visible indication of the failed arrester
Note 1 to entry: Clearing of the fault current through the arrester during disconnection generally is not a function
of the device.
3.3
bending moment
force perpendicular to the longitudinal axis of an arrester multiplied by the vertical distance
between the mounting base (lower level of the flange) of the arrester and the point of
application of the force
3.4
breaking load
force perpendicular to the longitudinal axis of a porcelain-housed or cast resin arrester
leading to mechanical failure of the arrester housing
3.5
cast resin housed arrester
arrester using a housing made from only one organic based material (e.g. cycloaliphatic
epoxy) that fractures similarly to a porcelain housing under mechanical overstress
3.6
continuous current of an arrester
current flowing through the arrester when energized at the continuous operating voltage
3.7
continuous operating voltage of an arrester
U
c
designated permissible RMS value of power-frequency voltage that may be applied
continuously between the arrester terminals in accordance with 8.5
3.8
damage limit

lowest value of a force perpendicular to the longitudinal axis of a polymer-housed arrester
leading to mechanical failure of the arrester housing

– 12 – IEC 60099-6:2019 © IEC 2019
3.9
designation of an impulse shape
combination of two numbers, the first representing the virtual front time (T ) and the second
the virtual time to half-value on the tail (T )
Note 1 to entry: This is written as T /T , both in microseconds, the sign "/ " having no mathematical meaning.
1 2
3.10
discharge current of an arrester
impulse current which flows through the arrester
3.11
disruptive discharge
phenomenon associated with the failure of insulation under electric stress, which includes a
collapse of voltage and the passage of current
Note 1 to entry: The term applies to electrical breakdowns in solid, liquid and gaseous dielectric, and
combinations of these.
Note 2 to entry: A disruptive discharge in a solid dielectric produces permanent loss of electric strength. In a
liquid or gaseous dielectric the loss may be only temporary.
3.12
distribution class arrester
arrester intended for use on distribution systems, typically of U ≤ 52 kV, to protect
s
components primarily from the effects of lightning
Note 1 to entry: Distribution class arresters may have nominal discharge currents, I , of 2,5 kA; 5 kA or 10 kA.
n
Note 2 to entry: Distribution arresters are classified as “Distribution DH”, “Distribution DM” and “Distribution DL”
(see Table 1).
3.13
electrical unit
portion of an arrester in which each end of the unit is terminated with an electrode which is
exposed to the external environment
3.14
fault indicator
device intended to provide an indication that the arrester is faulty and which does not
disconnect the arrester from the system
3.15
flashover
disruptive discharge over a solid surface
3.16
follow current
current from the connected power source that flows through an arrester during and following
the passage of discharge current
3.17
front of an impulse
part of an impulse which occurs prior to the peak
3.18
high current impulse
peak value of discharge current having a 4/10 impulse shape which is used
to test the stability of the arrester on direct lightning strokes

3.19
housing
external insulating part of an arrester, which provides the necessary creepage distance and
protects the internal parts from the environment
Note 1 to entry: A housing may consist of several parts providing mechanical strength and protection against the
environment.
3.20
impulse
unidirectional wave of voltage or current which, without appreciable oscillations, rises rapidly
to a maximum value and falls, usually less rapidly, to zero with small, if any, excursions of
opposite polarity, with defining parameters being polarity, peak value, front time and time to
half-value
3.21
insulating base
a short insulator (or set of insulators) on which the arrester is mounted to provide a means of
connecting a current monitoring device between the base of the arrester and earth
3.22
internal grading components of an internally gapped arrester
grading impedances, connected in parallel with the internal gap(s), to control the voltage
across the gap section
3.23
internal parts
MO resistor with supporting structure and internal grading system, if equipped
3.24
lightning current impulse
8/20 current impulse with limits on the adjustment of equipment such that the measured
values are from 7 µs to 9 µs for the virtual front time and from 18 µs to 22 µs for the time to
half-value
Note 1 to entry: The time to half-value is not critical and may have any tolerance during the residual voltage type
tests (see 8.3.2.3).
3.25
lightning impulse discharge
an approximately sine half-wave current impulse having a time duration within 200 µs to 230
µs during which the instantaneous value of the impulse current is greater than 5 % of its peak
value
3.26
lightning impulse protection level

LIPL or U
pl
the maximum residual voltage of the arrester for the nominal discharge current
3.27
long-duration current impulse
rectangular current impulse which rises rapidly to maximum value, remains substantially
constant for a specified period and then falls rapidly to zero, with defining parameters being
polarity, peak value, virtual duration of the peak and virtual total duration.
3.28
mean breaking load
MBL
the average breaking load for porcelain or cast resin-housed arresters determined from tests

– 14 – IEC 60099-6:2019 © IEC 2019
3.29
mechanical unit
portion of an arrester in which the MO resistors within the unit are mechanically restrained
from moving in an axial direction
Note 1 to entry: An arrester may contain more than one mechanical units within an electrical unit (see Figure 5).
Note 2 to entry: A mechanical unit may have more than one electrical unit (see Figure 5).
3.30
mounting bracket
means by which a distribution class arrester is physically attached to a pole or other structure
Note 1 to entry: For polymer housed distribution class arresters, the mounting bracket is typically of an insulating
material and is typically attached to the bottom (ground) end of the arrester; for porcelain-housed d
...