IEC 60099-8:2011

IEC 60099-8


®


Edition 1.0 2011-01



INTERNATIONAL



STANDARD



NORME
INTERNATIONALE
colour
inside
Surge arresters –
Part 8: Metal-oxide surge arresters with external series gap (EGLA) for overhead
transmission and distribution lines of a.c. systems above 1 kV

Parafoudres –
Partie 8: Parafoudres à oxyde métallique avec éclateur extérieur en série (EGLA)
pour lignes aériennes de transmission et de distribution de réseaux à courant
alternatif de plus de 1 kV



IEC 60099-8:2011

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---------------------- Page: 2 ----------------------
IEC 60099-8


®


Edition 1.0 2011-01




INTERNATIONAL



STANDARD



NORME
INTERNATIONALE
colour
inside
Surge arresters –
Part 8: Metal-oxide surge arresters with external series gap (EGLA) for overhead
transmission and distribution lines of a.c. systems above 1 kV

Parafoudres –
Partie 8: Parafoudres à oxyde métallique avec éclateur extérieur en série (EGLA)
pour lignes aériennes de transmission et de distribution de réseaux à courant
alternatif de plus de 1 kV


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 29.240.10 ISBN 978-2-88912-312-4
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – 60099-8  IEC:2011



CONTENTS

FOREWORD . 5


INTRODUCTION . 7

1 Scope . 8

2 Normative references . 8


3 Terms and definitions . 9

4 Identification and classification . 11

4.1 EGLA identification . 11

4.2 EGLA classification . 12
5 Standard ratings and service conditions . 12
5.1 Standard rated voltages . 12
5.2 Standard rated frequencies . 13
5.3 Standard nominal discharge currents . 13
5.4 Service conditions . 13
5.4.1 Normal service conditions . 13
5.4.2 Abnormal service conditions . 13
6 Requirements . 13
6.1 Insulation withstand of the SVU and the complete EGLA . 13
6.1.1 Insulation withstand of the housing of the SVU . 13
6.1.2 Insulation withstand of EGLA with shorted (failed) SVU . 13
6.2 Residual voltages . 14
6.3 High current duty . 14
6.4 Lightning discharge capability . 14
6.5 Short-circuit performance of the SVU . 14
6.6 Mechanical performance . 14
6.7 Weather aging of SVU . 15
6.8 Reference voltage of the SVU . 15
6.9 Internal partial discharges . 15
6.10 Coordination between insulator withstand and EGLA protective level . 15
6.11 Follow current interrupting . 15
6.12 Electromagnetic compatibility . 15
6.13 End of life . 16
7 General testing procedure . 16

7.1 Measuring equipment and accuracy . 16
7.2 Test samples . 16
8 Type tests . 16
8.1 General . 16
8.2 Insulation withstand tests on the SVU housing and on the EGLA with failed
SVU . 17
8.2.1 General . 17
8.2.2 Insulation withstand test on the SVU housing . 17
8.2.3 Insulation withstand tests on EGLA with failed SVU . 18
8.3 Residual voltage tests . 19
8.3.1 General . 19
8.3.2 Procedure for correction and calculation of inductive voltages . 19
8.3.3 Lightning current impulse residual voltage test . 20

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60099-8  IEC:2011 – 3 –


8.3.4 High current impulse residual voltage test . 21

8.4 Standard lightning impulse sparkover test . 21

8.5 High current impulse withstand test . 22

8.5.1 Selection of test samples . 22

8.5.2 Test procedure . 22

8.5.3 Test evaluation . 22

8.6 Lightning discharge capability test . 23

8.6.1 Selection of test samples . 23

8.6.2 Test procedure . 23

8.6.3 Test parameters for the lightning impulse discharge capability test . 23

8.6.4 Measurements during the lightning impulse discharge capability test . 24
8.6.5 Rated lightning impulse discharge capability. 24
8.6.6 List of rated charge values . 24
8.7 Short-circuit tests . 24
8.7.1 General . 24
8.7.2 Preparation of the test samples . 25
8.7.3 Mounting of the test sample . 26
8.7.4 High-current short-circuit tests . 27
8.7.5 Low-current short-circuit test . 29
8.7.6 Evaluation of test results . 29
8.8 Follow current interrupting test . 34
8.8.1 General . 34
8.8.2 "Test method A" . 34
8.8.3 "Test method B" . 36
8.9 Mechanical load tests on the SVU . 38
8.9.1 Bending test . 38
8.9.2 Vibration test . 47
8.10 Weather aging tests . 48
8.10.1 General . 48
8.10.2 Sample preparation . 48
8.10.3 Test procedure . 48
8.10.4 Test evaluation . 48
8.10.5 Additional test procedure for polymer (composite and cast resin)
housed SVUs. 48
9 Routine tests . 49

9.1 General . 49
10 Acceptance tests . 50
10.1 General . 50
10.2 Reference voltage measurement of SVU . 50
10.3 Internal partial discharge test of SVU . 50
10.4 Radio interference voltage (RIV) test . 50
10.5 Test for coordination between insulator withstand and EGLA protective level . 51
10.5.1 General . 51
10.5.2 Front-of-wave impulse sparkover test . 51
10.5.3 Standard lightning impulse sparkover test . 51
10.6 Follow current interrupting test . 52
10.6.1 General . 52
10.6.2 Test procedure . 52
10.6.3 Test sequence . 52

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10.6.4 Test evaluation . 52

10.7 Vibration test on the SVU with attached electrode . 52

10.7.1 Test procedure and test condition . 53

10.7.2 Test evaluation . 53

Annex A (informative) Example of a test circuit for the follow current interrupting test . 54

Annex B (normative) Mechanical considerations . 55

Bibliography . 60




Figure 1 – Configuration of an EGLA with insulator and arcing horn . 7

Figure 2 – Examples of SVU units . 32
Figure 3 – Short-circuit test setup . 33
Figure 4 – Example of a test circuit for re-applying pre-failing circuit immediately
before applying the short-circuit test current . 34
Figure 5 – Thermo-mechanical test . 43
Figure 6 – Example of the test arrangement for the thermo-mechanical test and
direction of the cantilever load . 44
Figure 7 – Test sequence of the water immersion test . 45
Figure A.1 – Example of a test circuit for the follow current interrupting test . 54
Figure B.1 – Bending moment – Multi-unit SVU . 55
Figure B.2 – SVU unit . 57
Figure B.3 – SVU dimensions . 58

Table 1 – EGLA classification – “Series X” and “Series Y“ . 12
Table 2 – Steps of rated voltages (r.m.s. values) . 12
Table 3 – Type tests (all tests to be performed without insulator assembly) . 17
Table 4 – Test requirements . 30
Table 5 – Required currents for short-circuit tests . 31
Table 6 – Acceptance tests . 50
Table 7 – Virtual steepness of wave front of front-of-wave lightning impulses . 51

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60099-8  IEC:2011 – 5 –


INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________



SURGE ARRESTERS –



Part 8: Metal-oxide surge arresters with external series gap (EGLA)

for overhead transmission and distribution lines

of a.c. systems above 1 kV





FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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 IEC 60099-8 has been prepared by IEC technical committee 37: Surge
arresters.
The text of this standard is based on the following documents:
FDIS Report on voting
37/370/FDIS 37/377/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.

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– 6 – 60099-8  IEC:2011


A list of all parts of IEC 60098 series, under the general title Surge arresters can be found on

the IEC website.


The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be


• reconfirmed,

• withdrawn,

• replaced by a revised edition, or

• amended.



IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.

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60099-8  IEC:2011 – 7 –


INTRODUCTION


This part of IEC 60099 applies to the externally gapped line arrester (EGLA)


This type of surge arrester is connected directly in parallel with an insulator assembly. It
comprises a series varistor unit (SVU), made up from non-linear metal-oxide resistors

encapsulated in a polymer or porcelain housing, and an external series gap, see Figure 1.


The purpose of an EGLA is to protect the parallel-connected insulator assembly from

lightning-caused overvoltages. The external series gap, therefore, should spark over only due

to fast-front overvoltages. The gap should withstand all power-frequency and slow-front

overvoltages occurring on the system.
In the event of SVU failure, the external series gap should be able to isolate the SVU from the
system.


EGLA
Tower arm
Insulator assembly
S
(insulator assembly,
Series varistor unit V
with/without arcing horns
U or grading elements)

External series gap
(without an insulator
Conductor
in parallel)
IEC  2896/10



Figure 1 – Configuration of an EGLA with insulator and arcing horn

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– 8 – 60099-8  IEC:2011


SURGE ARRESTERS –



Part 8: Metal-oxide surge arresters with external series gap (EGLA)

for overhead transmission and distribution lines

of a.c. systems above 1 kV








1 Scope

This part of IEC 60099 covers metal-oxide surge arresters with external series gap (externally
gapped line arresters (EGLA) that are applied on overhead transmission and distribution lines,
only to protect insulator assemblies from lightning-caused flashovers.
This standard defines surge arresters to protect the insulator assembly from lightning-caused
overvoltages only. Therefore, and since the metal-oxide resistors are not permanently
connected to the line, the following items are not considered for this standard:
• switching impulse sparkover voltage;
• residual voltage at steep current and switching current impulse;
• thermal stability;
• long-duration current impulse withstand duty;
• power-frequency voltage versus time characteristics of an arrester;
• disconnector test;
• aging duties by power-frequency voltage.
Considering the particular design concept and the special application on overhead
transmission and distribution lines, some unique requirements and tests are introduced, such
as the verification test for coordination between insulator withstand and EGLA protective
level, the follow current interrupting test, mechanical load tests, etc.
Designs with the EGLA's external series gap installed in parallel to an insulator are not
covered by this 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 60060-1:1989, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60060-2:1994, High-voltage test techniques – Part 2: Measuring systems
IEC 60068-2-11:1981, Environmental testing – Part 2: Tests. Test kA: Salt mist
IEC 60068-2-14:2009, Environmental testing – Part 2-14: Tests – Test N: Change of
temperature
IEC 60099-4:2009, Surge arresters – Part 4: Metal-oxide surge arresters without gaps for a.c.
systems

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60099-8  IEC:2011 – 9 –


IEC 60270:2000, High-voltage test techniques – Partial discharge measurements


IEC 60507:1991, Artificial pollution tests on high-voltage insulators to be used on a.c.

systems


IEC/TS 60815-1:2008, Selection and dimensioning of high-voltage insulators intended for use

in polluted conditions – Part 1: Definitions, information and general principles


IEC 62217:2005, Polymeric insulators for indoor and outdoor use with a nominal voltage

> 1 000 V – General definitions, test methods and acceptance criteria


ISO 3274, Geometric product specifications (GPS) – Surface texture: Profile method –
Nominal characteristics of contact (stylus) instruments
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
sources
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.
...