Bsi bs en 61109 2008

BS EN 61 1 09:2008

BSI Standards Publication
Insul ators for overhead l i nes —
Composi te suspensi on and
tensi on i nsul ators for a.c. systems
wi th a nomi nal vol tage greater
than 1 000 V — Defi ni ti ons, test
methods and acceptance cri teri a


BS EN 61 1 09:2008

BRITISH STANDARD
National foreword
This British Standard is the UK implementation of EN 61 1 09:2008. It is
identical to IEC 61 1 09:2008.
The UK participation in its preparation was entrusted to Technical Committee
PEL/36, Insulators for power systems.
A list of organizations represented on this committee can be obtained on
request to its secretary.
The attention of users is drawn to the flammability test in Tables 1 and 2 of
BS EN 61 1 09:2008, which references BS EN 6221 7:2005, and is used as an
indicator of power arc ignition and extinction performance. The UK
Committee is of the opinion that work carried out before and after BS EN
6221 7:2005 was published shows that the flammability test is not suitable
for assessing the power arc performance of insulators. The correlation
between performance in different flammability tests, laboratory power arc
tests and behaviour in service is currently under investigation by the
International Council on Large Electric Systems study committee on Materials
and Emerging Technologies (CIGRE SC D1 ). When applying this standard,

users are recommended to consult the power arc tests in ANSI C29.1 8 or IEC
60099-4 surge arrestor specifications in addition to the test in Tables 1 and 2.
The ANSI test also usefully includes an end fitting seal test after power arc
damage.
This publication does not purport to include all the necessary provisions of a
contract. Users are responsible for its correct application.
© BSI 2009
ISBN 978 0 580 67052 7
ICS 29.080.1 0

Compliance with a British Standard cannot confer immunity from
legal obligations.

This British Standard was published under the authority of the Standards
Policy and Strategy Committee on 31 March 2009

Amendments issued since publication
Amd. No.

Date

Text affected


EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM

EN 61 1 09
October 2008

ICS 29.080.1 0

English version

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 and acceptance criteria
(IEC 61 1 09:2008)
Isolateurs pour lignes aériennes Isolateurs composites de suspension
et d'ancrage destinés aux systèmes
à courant alternatif de tension nominale
supérieure à 1 000 V Définitions, méthodes d'essai
et critères d'acceptation
(CEI 61 1 09:2008)

Isolatoren für Freileitungen Verbund-Hänge- und -Abspannisolatoren
für Wechselstromsysteme
mit einer Nennspannung über 1 000 V Begriffe, Prüfverfahren
und Annahmekriterien
(IEC 61 1 09:2008)

This European Standard was approved by CENELEC on 2008-09-01 . CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the

Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1 050 Brussels
© 2008 CENELEC -

All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61 1 09:2008 E


BS EN 61 1 09:200 8
EN 61 1 09: 2008

-2-

Foreword
The text of document 36B/274/FDIS, future edition 2 of IEC 61 1 09, prepared by SC 36B, Insulators for
overhead lines, of IEC TC 36, Insulators, was submitted to the IEC-CENELEC parallel vote and was
approved by CENELEC as EN 61 1 09 on 2008-09-01 .
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement

(dop)

– latest date by which the national standards conflicting
with the EN have to be withdrawn

(dow) 201 1 -09-01

2009-06-01

Annex ZA has been added by CENELEC.

__________

Endorsement notice
The text of the International Standard IEC 61 1 09:2008 was approved by CENELEC as a European
Standard without any modification.

__________


-3-

BS EN 61 1 09:200 8
EN 61 1 09: 2008

Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication
IEC 60383-1

IEC 60383-2

IEC 61 466-1

IEC 6221 7

ISO 3452

Year
- 1)

Title
EN/HD
Insulators for overhead lines with a nominal EN 60383-1
voltage above 1 kV + A1 1
Part 1 : Ceramic or glass insulator units for
a.c. systems - Definitions, test methods and
acceptance criteria
1)
Insulators for overhead lines with a nominal EN 60383-2
voltage above 1 kV Part 2: Insulator strings and insulator sets for
a.c. systems - Definitions, test methods and

acceptance criteria
1)
Composite string insulator units for
EN 61 466-1
overhead lines with a nominal voltage
greater than 1 kV Part 1 : Standard strength classes and end
fittings
2005 Polymeric insulators for indoor and outdoor EN 6221 7
use with a nominal voltage > 1 000 V + corr. December
General definitions, test methods and
acceptance criteria
Series Non-destructive testing - Penetrant
EN ISO 3452
inspection

1)

Un dated reference.

2)

Valid edition at d ate of issue.

Year
1 996 2)
1 999

1 995 2)

1 997 2)

2006
2006
Series


BS EN 61 1 09:200 8
–2–

61 1 09

? I EC: 2008

CON TENTS
I N TRODU CTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 6
1 Scope and obj ect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 N orm ative references. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Term s, definitions and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. 1 Term s and definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. 2 Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
4 I dentification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
5 Environm ental conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
6 Transport, storage and installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
7 H ybrid insulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
8 Tolerances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0
9 Classification of tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
9. 1 Design tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
9. 2 Type tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
9. 3 Sam ple tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1
9. 4 Routine tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

1 0 Design tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
1 0. 1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
1 0. 2 Test specim ens for I EC 6221 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3
1 0. 2. 1 Tests on interfaces and connections of end fittings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3
1 0. 2. 2 Tracking and erosion test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3
1 0. 2. 3 Tests on core m aterial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 3 Product specific pre-stressing for I EC 6221 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 3. 1 Sud den load release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 3. 2 Therm al-m echanical pre-stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 4 Assem bled core load -tim e tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 4. 1 Test specim ens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4
1 0. 4. 2 Mechanical load test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5
1 1 Type tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 1 5
1 1 . 1 Electrical tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5
1 1 . 2 Dam age lim it proof test and test of the tightness of the interface between end
fittings and insulator housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
1 1 . 2. 1 Test specim ens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
1 1 . 2. 2 Perform ance of the test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
1 1 . 2. 3 Evaluation of the test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7
1 2 Sam ple tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7
1 2. 1 General rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7
1 2. 2 Verification of dim ensions (E1 + E2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8
1 2. 3 Verification of the end fittings (E2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8
1 2. 4 Verification of tightness of the interface between end fittings and insulator
housing (E2) and of the specified m echanical load, SML (E1 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 8
1 2. 5 Galvanizing test (E2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
1 2. 6 Re-testing proced ure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
1 3 Routine tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
1 3. 1 M echanical routine test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9

BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

–3–

1 3. 2 Visual exam ination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9
Annex A (inform ative) Principles of the dam age lim it, load coordination and testing for
com posite suspension and tension insulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Annex B (inform ative) Exam ple of two possible devices for sudden release of load . . . . . . . . . . . . . . . 25
Annex C (inform ative) Guidance on non-standard m echanical stresses and dynam ic
m echanical loading of com posite tension/suspension insulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 29
Figure 1 − Therm al-m echanical test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure A. 1 − Load-tim e strength and dam age lim it of a core assem bled with fittings . . . . . . . . . . . . . . 22
Figure A. 2 – Graphical representation of the relationship of the dam age lim it to the
m echanical characteristics and service loads of an insulator with a 1 6 m m d iam eter
core . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 23
Figure A. 3 – Test load s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure B. 1 − Exam ple of possible d evice 1 for sudden release of load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure B. 2 − Exam ple of possible d evice 2 for sudden release of load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table
Table
Table
Table

1
2

3
4

–
–
–
–

Tests to be carried out after design changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
Design tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 3
Mounting arrangem ents for electrical tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
Sam ple sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7


BS EN 61 1 09:200 8
–6–

61 1 09

? I EC: 2008

I N TRODUCTI ON
Com posite insulators consist of an insulating core, bearing the m echanical load protected by a
polym eric housing, the load being transm itted to the core by end fittings. Despite these
com m on features, the m aterials used and the construction details em ployed by different
m anufacturers m ay be quite different.
Som e tests have been grouped together as "Design tests", to be perform ed only once on
insulators which satisfy the sam e design conditions. For all d esign tests of com posite
suspension and tension insulators, the appropriate com m on clauses defined in I EC 6221 7 are
applied. As far as practical, the influence of tim e on the electrical and m echanical properties of

the com ponents (core m aterial, housing, interfaces etc. ) and of the com plete com posite
insulators has been considered in specifying the design tests to ensure a satisfactory life-tim e
under norm ally known stress conditions of transm ission lines. An explanation of the principles
of the dam age lim it, load coordination and testing is presented in Annex A.
I t has not been considered useful to specify a power arc test as a m and atory test. The test
param eters are m anifold and can have very d ifferent values depending on the configurations of
the network and the supports and on the design of arc-protection devices. The heating effect of
power arcs should be considered in the design of m etal fittings. Critical dam age to the m etal
fittings resulting from the m agnitude and d uration of the short-circuit current can be avoided by
properly designed arc-protection d evices. This standard, however, does not exclude the
possibility of a power arc test by agreem ent between the user and m anufacturer.
I EC 61 467 [1 ] 1 gives details of a. c. power arc testing of insulator sets.
Com posite insulators are used in both a. c. and d . c. applications. I n 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. The 1 000 h a. c. tracking and erosion test of I EC 6221 7 is used to
establish a m inim um requirem ent for the tracking resistance of the housing m aterial.
The m echanism of brittle fracture has been investigated by CI GRE B2. 03 2 and conclusions are
published in [2, 3]. Brittle fracture is a result of stress corrosion induced by internal or external
acid attack on the resin bond ed glass fibre core. CI GRE D1 . 1 4 has d eveloped a test procedure
for core m aterials based on tim e-load tests on assem bled cores exposed to acid, along with
chem ical analysis m ethods to verify the resistance against acid attack [4]. I n parallel I EC
TC36WG 1 2 is studying preventive and predictive m easures.
Com posite suspension/tension insulators are not norm ally intended for torsion or other nontensile loads. Guidance on non-standard loads is given in Annex C.
Wherever possible, I EC Guide 1 1 1 [5] has been followed for the drafting of this standard.

___________
1

Fi gu res i n sq uare brackets refer to th e bi bl i ography.

2

I ntern ati on al Cou nci l on Larg e H i gh Vol tag e El ectri c System s: Worki n g Grou p B2. 03.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

–7–
I N S U L AT O RS F O R O VE RH E AD L I N E S –

C O M P O S I T E S U S P E N S I O N AN D T E N S I O N

I N S U L AT O RS

F O R A. C . S YS T E M S WI T H A N O M I N AL VO L T AG E
G RE AT E R T H AN 1

000 V –

D E F I N I T I O N S , T E S T M E T H O D S AN D AC C E P T AN C E C RI T E RI A

1

S co p e an d ob j e ct

This I nternational Standard applies to com posite suspension/tension insulators consisting of a
load-bearing cylindrical insulating solid core consisting of fibres – usually glass – in a resinbased m atrix, a housing (outside the insulating core) m ad e of polym eric m aterial and end

fittings perm anently attached to the insulating core.
Com posite insulators covered by this standard are intend ed for use as suspension/tension line
insulators, but it should be noted that these insulators can occasionally be subj ected to
com pression or bending, for exam ple when used as phase-spacers.
This standard can be applied in part to hybrid com posite insulators where the core is m ade of a
hom ogeneous m aterial (porcelain, resin), see Clause 8.
The obj ect of this stand ard is to
–
–
–

define the term s used,
prescribe test m ethods,
prescribe acceptance criteria.

This standard does not include requirem ents dealing with the choice of insulators for specific
operating conditions.
2

N o rm a t i ve re fe re n c e s

The following referenced docum ents are indispensable for the application of this docum ent. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced docum ent (includ ing any am end m ents) applies.
I EC 60383-1 ,

In sula tors for overh ea d lines with a nomina l volta ge a b ove 1 000 V – Pa rt 1 :

Ce ra mic or gla ss insula tor units for a . c. syste ms – De finitions, te st meth ods a n d a cce pta nce
criteria

I EC 60383-2,
In sula tor

Insula tors for overh ea d lines with a nomina l volta ge a b ove 1 000 V – Pa rt 2:

strings

and

insula tor

se ts

for

a . c.

syste ms

–

Defin ition s,

te st

meth ods

and

a ccepta nce crite ria .

I EC 61 466-1 ,

Composite

string

insula tor units

for overh ea d

lines

with

a

nomina l

volta ge

a

nomin a l volta ge

grea ter th a n 1 000 V – Pa rt 1 : Sta nda rd stre ngth cla sses a nd end fittings

I EC 6221 7: 2005, Polymeric insula tors for indoor a nd outdoor use
> 1 000 V – Ge nera l definition s, test me th ods a nd a ccepta nce criteria

I SO 3452 (all parts),

Non-destructive testing – Pen etra nt testing

with


BS EN 61 1 09:200 8
–8–

3

61 1 09

? I EC: 2008

Terms, definitions and abbreviations

For the purposes of this d ocum ent, the following term s, definitions and abbreviations apply.
N OTE Certai n term s from I EC 6221 7 are reprod u ced here for ease of reference. Ad d i ti onal d efi ni ti on s appl i cabl e
to i n su l ators can be fou nd i n I EC 60050-471 [6] .

3.1

Terms and definitions

3.1 .1
polymeric insulator

insulator whose insulating body consists of at least one organic based m aterial

N OTE

Pol ym eri c i n su l ators are al so known as n on -ceram i c i nsul ators.

N OTE 2 Coupl i ng d evi ces m ay be attach ed to the end s of the i n su l ati ng bod y.

[I EV 471 -01 -1 3]

3.1 .2
composite insulator

insulator m ade of at least two insulating parts, nam ely a core and a housing equipped with
m etal fittings
N OTE Com posi te i nsu l ators, for exam pl e, can con si st ei ther of i nd i vi d ual shed s m oun ted on th e core, wi th or
wi thou t an i n term ed i ate sh eath , or al ternati vel y, of a h ousi ng d i rectl y m ou l d ed or cast i n on e or several pi eces on to
th e core.

[I EV 471 -01 -02]

3.1 .3
core of a composite insulator

internal insulating part of a com posite insulator which is designed to ensure the m echanical
characteristics
N OTE Th e core usual l y consi sts of ei th er fi bres (e. g . g l ass) whi ch are posi ti on ed i n a resi n-based m atri x or a
hom og en eous i n sul ati n g m ateri al (e. g . porcel ai n or resi n ).

[I EV 471 -01 -03, m odified ]

3.1 .4

insulator trunk

central insulating part of an insulator from which the sheds proj ect
N OTE Al so known as sh ank on sm al l er insul ators.

[I EV 471 -01 -1 1 ]

3.1 .5
housing

external insulating part of a com posite insulator providing the necessary creepage distance and
protecting core from the environm ent
N OTE

An i n term ed i ate sheath m ad e of i n sul ati ng m ateri al m ay be part of the h ou si n g.

[I EV 471 -01 -09]


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

–9–

3.1 .6
shed of an insulator

insulating part, proj ecting from the insulator trunk, intended to increase the creepage distance.

N OTE

The shed can be wi th or wi th out ribs

[I EV 471 -01 -1 5]

3.1 .7
interfaces

surface between the different m aterials
N OTE

Vari ou s i nterfaces occu r i n m ost com posi te i n su l ators, e. g .

–

between housi n g and fi xi n g d evi ces,

–

between vari ou s parts of the housi n g, e. g . between sh ed s, or between sh eath an d shed s,

–

between core and h ou si n g

[Definition 3. 1 0 of I EC 6221 7]

3.1 .8
end fitting

integral com ponent or form ed part of an insulator intend ed to connect it to a supporting
structure, or to a conductor, or to an item of equipm ent, or to another insulator
N OTE Wh ere th e en d fi tti ng is m etal l ic, th e term “m etal fi tti ng ” is norm al l y u sed .

[I EV 471 -01 -06]

3.1 .9
connection zone

zone where the m echanical load is transm itted between the insulating body and the end fitting
[Definition 3. 1 2 of I EC 6221 7]

3.1 .1 0
coupling

part of the end fitting which transm its the load to the accessories external to the insulator

[Definition 3. 1 3 of I EC 6221 7, m odified ]

3.1 .1 1
specified mechanical load
SM L

load, specified by the m anufacturer, which is used for m echanical tests in this standard

3.1 .1 2
routine test load
RTL

load applied to all assem bled com posite insulators during a routine m echanical test

3.1 .1 3
failing load

m axim um load that is reached when the insulator is tested under the prescribed cond itions


BS EN 61 1 09:200 8
– 10 –
3.2

61 1 09

? I EC: 2008

Ab b re v i a t i o n s

The following abbreviations are used in this standard :
E1 , E2

MAV

RTL
SML

4

Sam ple sets for sam ple tests
Average 1 m in failing load of the core assem bled with fittings

Routine test load
Specified m echanical load

I d e n t i fi c a t i o n

I n addition to the requirem ents of I EC 6221 7, each insulator shall be m arked with the SML.
I t is recom m ended that each insulator be m arked or labelled by the m anufacturer to show that
it has passed the routine m echanical test.
5

E n vi ro n m e n t a l c o n d i t i o n s

The norm al environm ental conditions to which insulators are subm itted in service are defined in
I EC 6221 7.
6

Tra n s p o rt ,

s t o ra g e a n d i n s t a l l a t i o n

I n addition to the requirem ents of I EC 6221 7, inform ation on handling of com posite insulators
can be found in CI GRE Technical Brochure 1 84 [7]. During installation, or when used in nonstandard configurations, com posite suspension insulators m ay be subm itted to high torsion,
com pression or bending loads for which they are not d esigned. Annex C gives guid ance on
catering for such loads.
7

H yb ri d i n s u l a t o rs

As stated in Clause 1 , this stand ard can be applied in part to hybrid com posite insulators where
the core is m ad e of a hom ogeneous m aterial (porcelain, resin). I n general, the load-tim e

m echanical tests and tests for core m aterial are not applicable to porcelain cores. For such
insulators, the purchaser and the m anufacturer shall agree on the selection of tests to be used
from this standard and from I EC 60383-1 .
8

To l e ra n c e s

U nless otherwise agreed, a tolerance of
± (0, 04 × d + 1 , 5) m m when d ≤ 300 m m ,
± (0, 025 × d + 6 ) m m when d > 300 m m with a m axim um tolerance of ± 50 m m ,

shall be allowed on all dim ensions for which specific tolerances are not requested or given on
the insulator d rawing ( d being the dim ension in m illim etres).
The m easurem ent of creepage distances shall be related to the design dim ensions and
tolerances as determ ined from the insulator drawing, even if this dim ension is greater than the
value originally specified. When a m inim um creepage is specified, the negative tolerance is
also lim ited by this value.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 11 –

I n the case of insulators with creepage d istance exceeding 3 m , it is allowed to m easure a
short section around 1 m long of the insulator and to extrapolate.

9

9.1

Classification of tests
Design tests

These tests are intended to verify the suitability of the design, m aterials and m ethod of
m anufacture (technology). A com posite suspension insulator design is defined by the following
elem ents:
–
–
–
–

m aterials of the core, housing and their m anufacturing m ethod;
m aterial of the end fittings, their design and m ethod of attachm ent (excluding the coupling);
layer thickness of the housing over the core (including a sheath where used);
diam eter of the core.

When changes in the design occur, re-qualification shall be carried out in accordance with
Table 1 .
When a com posite suspension insulator is subm itted to the design tests, it becom es a parent
insulator for a given design and the results shall be considered valid for that design only. This
tested parent insulator defines a particular design of insulators which have all the following
characteristics:
a) sam e m aterials for the core and housing and sam e m anufacturing m ethod;
b) sam e m aterial of the fittings, the sam e connection zone design, and the sam e housing-tofitting interface geom etry;
c) sam e or greater m inim um layer thickness of the housing over the core (including a sheath
where used);
d) sam e or sm aller stress under m echanical loads;
e) sam e or greater d iam eter of the core;

f) equivalent housing profile param eters, see N ote (a) in Table 1 .

9.2

Type tests

The type tests are intended to verify the m ain characteristics of a com posite insulator, which
depend m ainly on its shape and size. They also confirm the m echanical characteristics of the
assem bled core (see Clause A. 4). They are m ade on insulators whose class has satisfied the
design tests, m ore d etails are given in Clause 1 1 .

9.3

Sample tests

The sam ple tests are for the purpose of verifying other characteristics of com posite insulators,
including those which depend on the quality of m anufacture and on the m aterials used. They
are m ade on insulators taken at random from lots offered for acceptance.

9.4

Routine tests

The aim of these tests is to elim inate com posite insulators with m anufacturing d efects. They
are m ad e on every com posite insulator offered for acceptance.


BS EN 61 1 09:200 8
– 12 –

th e fol l owi ng tests sh al l be repeated :

2

H ou si ng profi l e

3

Core m ateri al

a)

b)

c)

Fl am m abi l i ty test

X

6221 7
Tests on h ou si n g
m ateri al
Tracki n g an d erosi on
test

Assem bl ed core l oad –
ti m e tests

X

T yp e t e s t s

Accel erated weath eri n g
test

H ou si n g m ateri al s

61 1 09

te s ts

H ard n ess test

1

6221 7

I n terfaces an d
con n ecti on s of en d
fi tti n g s

Desi g n

X

X

X

X

X

6221 7
Tests on th e
core m ateri al

X

61 1 09

M ech an i cal type tests

TH E N

El ectri cal type tests

th e ch an ge i n i n su l ator d esi gn con cern s:

Water d i ffu si on test

IF

? I EC: 2008

– T e s t s t o b e c a rri e d o u t a ft e r d e s i g n c h a n g e s

Dye pen etrati on test

Tabl e 1

61 1 09

X

X

X

X

X

X

X

X

X

X

X

X

X

X

4

Core d i am eter

5

Core an d en d -fi tti ng m anu facturi n g
process

X

X

6

Core an d en d -fi tti ng assem bl y
process

X

X

7

H ousi ng m anu facturi ng process

8

H ou si ng assem bl y process

9

En d fi tti ng m ateri al

10

En d fi tti ng con necti on zone d esi gn

11

Core/h ou si ng /end fi tti n g i nterface
d esi g n

X

X

X

X

c)

c)

X

X

X

X

X

X

X

X

c)

c)

X

X

X

X

X

X

X

X

c)

X

12
Cou pl i n g type
a) Vari ati on s of the profi l e wi th i n fol l owi ng tol eran ces d o n ot con sti tu te a chang e:
- overhang :
± 10 %
- d i am eter :
+1 5 % , -0 %
- thi ckness at base and ti p : ± 1 5 %
- spaci ng :
± 15 %
- shed i ncl i nati ons :
± 3°
- shed repeti ti on :
i d en ti cal
b) Vari ati ons of the core d i am eter wi th i n ± 1 5 % d o n ot con sti tu te a chang e.

X

c)

X

c) N ot necessary i f i t can be d em onstrated th at the chang e has no i n fl u en ce on th e assem bl ed core stren gth .

1 0

1 0. 1

D e s i g n te s ts

G e n e ra l

These tests consist of the tests prescribed in I EC 6221 7 as listed in Table 2 below and a
specific assem bled core load-tim e test. The design tests are perform ed only once and the
results are record ed in a test report. Each part can be perform ed independently on new test
specim ens, where appropriate. The com posite insulator of a particular d esign shall be qualified
only when all insulators or test specim ens pass the design tests.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 13 –
T a b l e 2 – D e s i g n te s ts

Te s ts o n

i n t e rfa c e s a n d

co n n e cti o n s o f e n d

fi t t i n g s

Pre-stressi ng – Sud d en l oad rel ease pre-stressi ng
Th erm al -m echani cal pre-stressi n g
(see 1 0. 2. 1 and 1 0. 3 bel ow)
Water i m m ersi on pre-stressi ng
Veri fi cati on tests
Vi su al exam i nati on
Steep-fron t i m pul se vol tag e test
Dry power-frequ en cy vol tag e test
Te s ts o n

sh ed

an d

h ou si n g

m a t e ri a l

H ard ness test
Accel erated weatheri ng test
Tracki n g an d erosi on test – see 1 0. 2. 2 bel ow for speci m ens
Fl am m abi l i ty test
Te s ts o n

t h e c o re m a t e ri a l

– see 1 0. 2. 3 bel ow for speci m en s

Dye penetrati on test
Water d i ffu si on test
As s e m b l e d

c o re l o a d - t i m e t e s t

Determ i nati on of the averag e fail in g l oad of th e core of th e assem bl ed insul ator
Control of the sl ope of the stren gth-ti m e cu rve of th e i nsul ator

1 0. 2

1 0.2.1

T e s t s p e c i m e n s fo r I E C 6 2 2 1 7

T e s t s o n i n t e rfa c e s a n d c o n n e c t i o n s o f e n d fi t t i n g s

Three insulators assem bled on the production line shall be tested. The insulation length (m etal
to m etal spacing) shall be not less than 800 m m . Both end fittings shall be the sam e as on
standard production insulators. The end fittings shall be assem bled so that the insulating part
from the fitting to the closest shed shall be identical to that of the production line insulator. I f
spacers, joining rings or other features are used in the insulator design (notably for longer
insulators), the sam ple shall include any such devices in a typical position.
N OTE I f th e m anu facturer onl y has facil ities to prod uce insul ators sh orter than 800 m m , th e d esig n tests m ay be
perform ed on i n su l ators of th ose l eng th s avai l abl e to hi m , but th e resu l ts are onl y val i d for up to th e l en gths tested .
1 0.2.2

T ra c k i n g a n d e ro s i o n t e s t

I f spacers, j oining rings or other features are used in the insulator design (notably for longer

insulators), the sam ples for this test shall include any such devices in a typical position.
I EC 6221 7 specifies that the creepage distance of the sam ple shall be between 500 m m and
800 m m . I f the inclusion of spacers or j oints, as m entioned above, requires a longer creepage
distance, the design tests m ay be perform ed on insulators of lengths as close to 800 m m as
possible. I f the m anufacturer only has facilities to produce insulators with creepage shorter
than 500 m m , the design tests m ay be perform ed on insulators of those lengths he has
available, but the results are only valid for up to the tested lengths.


BS EN 61 1 09:200 8
– 14 –
1 0.2.3

61 1 09

? I EC: 2008

T e s t s o n c o re m a t e ri a l

The specim ens shall be as specified in I EC 6221 7. H owever, if the housing m aterial is not
bonded to the core, then it shall be rem oved and the rem aining core thoroughly cleaned to
rem ove any traces of sealing m aterial before cutting and testing.
1 0. 3

P ro d u c t s p e c i fi c p re -s t re s s i n g fo r I E C 6 2 2 1 7

The tests shall be carried out on the three specim ens in the sequence as indicated below.
1 0. 3. 1

S u d d e n l o a d re l e a s e

With the insulator at –20 °C to –25 °C, every test specim en is subj ected to five sudd en load
releases from a tensile load am ounting to 30 % of the SML.
N OTE 1

Ann ex B d escribes two exam pl es of possi bl e d evices for su d d en l oad rel ease.

N OTE 2 I n certai n cases, a l ower tem peratu re m ay be sel ected by agreem ent.
1 0. 3. 2

T h e rm a l - m e c h a n i c a l p re - s t re s s

Before com m encing the test, the specim ens shall be loaded at the am bient tem perature by at
least 5 % of the SML for 1 m in, during which the length of the specim ens shall be m easured to
an accuracy of 0, 5 m m . This length shall be considered to be the reference length.
The specim ens are then subm itted to tem perature cycles under a continuous m echanical load
as described in Figure 1 , the 24 h tem perature cycle being perfom ed four tim es. Each 24 h
cycle has two tem perature levels with a duration of at least 8 h, one at (+50 ± 5) °C, the other
at (–35 ± 5) °C. The cold period shall be at a tem perature at least 85 K below the value actually
applied in the hot period . The pre-stressing can be conducted in air or any other suitable
m ed ium .
The applied m echanical load shall be equal to the RTL (at least 50 % of the SML) of the
specim en. The specim en shall be loaded at am bient tem perature before beginning the first
therm al cycle.
N OTE Th e tem peratu res and l oad s i n thi s pre-stressi n g are not i ntend ed to represent servi ce con d i ti on s, they are
d esi gn ed to prod u ce speci fi c reprod uci bl e stresses i n the i nterfaces on the i n su l ator.

The cycles m ay be interrupted for m aintenance of the test equipm ent for a total duration of 2 h.
The starting point after any interruption shall be the beginning of the interrupted cycle.
After the test, the length shall again be m easured in a sim ilar m anner at the sam e load and at

the original specim en tem perature (this is done in order to provide som e additional inform ation
about the relative m ovem ent of the m etal fittings).
1 0.4

1 0 . 4. 1

As s e m b l e d c o re l o a d - t i m e t e s t s

Te s t s p eci m e n s

Six insulators m ade on the production line shall be tested . The insulation length (m etal to m etal
spacing) shall be not less than 800 m m . Both end fittings shall be identical in all aspects to
those used on production line insulators, except that they m ay be m odified beyond the end of
the connection zone in order to avoid failure of the couplings.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 15 –

The six insulators shall be exam ined visually and a check m ade that their dim ensions conform
with the drawing.
N OTE I f th e m anu facturer on l y has facil ities to prod uce insul ators sh orter th an 800 m m , th e d esig n tests m ay be
perform ed on i n su l ators of th ose l eng th s he h as avai l abl e, but the resul ts are onl y val i d for u p to the tested l en gths.

1 0.4.2 Mechanical load test
This test is perform ed in two parts at am bient tem perature.

1 0.4.2.1

Determination of the average failing load of the core of the assembled
insulator MAV

Three of the specim ens shall be subj ected to a tensile load. The tensile load shall be increased
rapidly but sm oothly from zero to approxim ately 75 % of the expected m echanical failing load
and shall then be gradually increased in a tim e between 30 s and 90 s until breakage of the
core or com plete pull-out occurs. The average of the three failing loads MAV shall be
calculated.

1 0.4.2.2

Verification of the 96 h withstand load

Three specim ens shall be subjected to a tensile load. The tensile load shall be increased
rapidly but sm oothly from zero up to 60 % of MAV , as calculated in 1 0. 4. 2. 1 and then
m aintained at this value for 96 h without failure (breakage or com plete pull-out). I f for any
reason the load application is interrupted , then the test shall be restarted on a new specim en.

1 1 Type tests
An insulator type is electrically d efined by the arcing distance, creepage d istance, shed
inclination, shed d iam eter and shed spacing.
The electrical type tests shall be perform ed only once on insulators satisfying the cond itions
above and shall be perform ed with arcing or field control devices (which are generally
necessary on com posite insulators at transm ission voltages) if they are an integral part of the
insulator type.
Furtherm ore, Table 1 outlines the insulator design characteristics that, when changed, also
require a repeat of the electrical type tests.

An insulator type is mechanically defined principally by a m axim um SML for the given core
diam eter, m ethod of attachm ent and coupling design.
The m echanical type tests shall be perform ed only once on insulators satisfying the criteria for
each type.
Furtherm ore, Table 1 indicates additional insulator d esign characteristics that, when changed,
require a repeat of the m echanical type tests.

1 1 .1 Electrical tests
The electrical tests in Table 3 shall be perform ed according to I EC 60383-2 to confirm the
specified values. I nterpolation of electrical test results m ay be used for insulators of
interm ediate length, provided that the factor between the arcing distances of the insulators
whose results form the end points of the interpolation range is less than or equal to 1 , 5.
Extrapolation is not allowed.


BS EN 61 1 09:200 8
– 16 –

61 1 09

? I EC: 2008

Table 3 – M ounting arrangements for electrical tests
Test

M ounting arrangem ent

Dry l i ghtni n g i m pu l se withstand vol tage test

Stan d ard m ou nti ng arrang em en t of an i nsul ator stri ng or

i nsu l ator set wh en swi tchi n g i m pul se tests are not
requ i red

Wet power-freq uen cy test

Stan d ard m ou nti ng arrang em en t of an i nsul ator stri ng or
i nsu l ator set wh en swi tchi n g i m pul se tests are not
requ i red

Wet swi tch i ng i m pul se wi thstand vol tag e test for
i nsul ators i nten d ed for system s wi th Um ≥ 300 kV

Stand ard m oun ti ng arrangem ent of an i nsu l ator stri n g or
i n sul ator set when swi tchi n g i m pul se tests are requ i red

1 1 .2 Damage limit proof test and test of the tightness of the interface between end
fittings and insulator housing
1 1 .2.1

Test specimens

Four insulators taken from the production line shall be tested. I n the case of long insulators,
specim ens m ay be m anufactured , assem bled on the production line, with an insulation length
(m etal to m etal spacing) not less than 800 m m . Both end fittings shall be the sam e as on
standard production insulators. The fittings shall be assem bled such that the insulating part
from the fitting to the closest shed is identical to that of the production line insulator. The
insulators shall be exam ined visually and checked to see that the d im ensions conform with the
drawing; they shall then be subj ected to the m echanical routine test accord ing to 1 3. 1 .
N OTE I f th e m anu facturer on l y has facil ities to prod uce insul ators sh orter th an 800 m m , th e d esig n tests m ay be
perform ed on i n su l ators of th ose l eng th s avai l abl e to hi m , but th e resu l ts are onl y val i d for up to th e l en gths tested .

1 1 .2.2

Performance of the test

a) The four specim ens are subj ected to a tensile load applied between the couplings at
am bient tem perature. The tensile load shall be increased rapidly but sm oothly from zero up
to 70 % of the SM L and then m aintained at this value for 96 h.
b) Both ends of one of the four specim ens shall, at the end of the 96 h test, be subj ected to
crack indication by d ye penetration, in accordance with I SO 3452, on the housing in the
zone em bracing the com plete length of the interface between the housing and m etal fitting
and including an additional area, sufficiently extended, beyond the end of the m etal part.
The indication shall be perform ed in the following way:
– the surface shall be properly pre-cleaned with the cleaner;
– the penetrant shall be applied on the cleaned surface and left to act for 20 m in;
– the surface shall be cleaned of the excess penetrant and dried;
– the developer shall be applied, if necessary;
– the surface shall be inspected.
Som e housing m aterials m ay be penetrated by the penetrant. I n such cases, evidence shall
be provid ed to validate the interpretation of the results.
After the penetration test the specim en shall be inspected . I f any cracks are visible, the
housing and, if necessary, the m etal fittings and the core shall be cut perpendicular to the
crack in the m iddle of the widest of the indicated cracks, into two halves. The surface of the
two halves shall then be investigated to m easure the depth of the cracks.
c) The three rem aining specim ens are then again subj ected to a tensile load applied between
the couplings at am bient tem perature. The tensile load shall be increased rapidly but
sm oothly from zero to approxim ately 75 % of the SMS and then gradually increased in a
tim e between 30 s to 90 s to the SMS. I f 1 00 % of the SML is reached in less than 90 s, the

BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 17 –

load (1 00 % of SML) shall be m aintained for the rem ainder of the 90 s (this test is
considered to be equivalent to a 1 m in 1 00 % withstand test at SML).
I n order to obtain m ore inform ation from the test, unless special reasons apply (for instance
the m axim um tensile load of the test m achine), the load m ay be increased until the failing
load is reached and its value recorded.

1 1 .2.3

Evaluation of the test

The test is passed if
–
–
–

no failure (breakage or com plete pull-out of the core, or fracture of the m etal fitting) occurs
either during the 96 h test at 70 % of the SML (1 1 . 2. 2 a)) or during the 1 m in 1 00 %
withstand test at SML (1 1 . 2. 2 c)),
no cracks are ind icated by the d ye penetration m ethod described in 1 1 . 2. 2. 2 b),
the investigation of the halves described in 1 1 . 2. 2. 2 b) shows clearly that the cracks do not
reach the core.

1 2 Sample tests

1 2.1

General rules

For the sam ple tests, two sam ples are used, E1 and E2. The sizes of these sam ples are
indicated in Table 4 below. I f m ore than 1 0 000 insulators are concerned, they shall be divided
into an optim um num ber of lots com prising between 2 000 and 1 0 000 insulators. The results of
the tests shall be evaluated separately for each lot.
The insulators shall be selected from the lot at random . The purchaser has the right to m ake
the selection. The sam ples shall be subj ected to the applicable sam pling tests.
The sam pling tests are as follows:
a)

verification of dim ensions … … … … … … … … … … … … … … … … … … .

(E1 + E2)

b)

verification of the locking system … … … … … … … … … … … … … … …

(E2)

c)

verification of the tightness of the interface between
end fittings and insulator housing … … … … … … … … … … … … … … . .

(E2)

d)

verification of the specified m echanical load, SML … … … … … … …

(E1 )

e)

galvanizing test … … … … … … … … … … … … … … … … … … … … … … …

(E2)

I n the event of a failure of the sam ple to satisfy a test, the re-testing procedure shall be applied
as prescribed in 1 2. 6.
I nsulators of sam ple E2 only can be used in service and only if the galvanizing test is
perform ed with the m agnetic m ethod.

Table 4 – Sample sizes
Sample size

Lot size
N

E1

E2
Su bject to ag reem ent

N ≤ 300
300 < N ≤ 2 000

4

3

2 000 < N ≤ 5 000

8

4

5 000 < N ≤ 1 0 000

12

6


BS EN 61 1 09:200 8
– 18 –

61 1 09

? I EC: 2008

1 2.2 Verification of dimensions (E1 + E2)
The dim ensions given in the drawings shall be verified. The tolerances given in the drawings
are valid. I f no tolerances are given in the drawings the values m entioned in Clause 8 shall be
used .

1 2.3 Verification of the end fittings (E2)
The dim ensions and gauges for end fittings are given in I EC 61 466-1 . The appropriate
verification shall be m ade for the types of fitting used including, if applicable, verification of the
locking system in accordance with I EC 60383-1 .

1 2.4 Verification of tightness of the interface between end fittings and insulator
housing (E2) and of the specified mechanical load, SM L (E1 )
a) One insulator, selected rand om ly from the sam ple E2, shall be subj ected to crack indication
by dye penetration, in accordance with I SO 3452, on the housing in the zone em bracing the
com plete length of the interface between the housing and m etal fitting and including an
ad ditional area, sufficiently extended , beyond the end of the m etal part.
The indication shall be perform ed in the following way:
– the surface shall be properly pre-cleaned with the cleaner;
– the penetrant, which shall act during 20 m in, shall be applied on the cleaned surface;
– within 5 m in after the application of the penetrant, the insulator shall be subjected, at
the am bient tem perature, to a tensile load of 70 % of the SML, applied between the
m etal fittings; the tensile load shall be increased rapidly but sm oothly from zero up to
70 % of the SML, and then m aintained at this value for 1 m in;
– the surface shall be cleaned with the excess penetrant rem oved , and dried;
– the developer shall be applied, if necessary;
– the surface shall be inspected.
Som e housing m aterials m ay be penetrated by the penetrant. I n such cases, evidence shall
be provided to validate the interpretation of the results.
After the 1 m in test at 70 % of the SML, if any cracks occur, the housing and, if necessary,
the m etal fittings and the core shall be cut perpendicular to the crack in the m iddle of the
widest of the indicated cracks, into two halves. The surface of the two halves shall then be
investigated to m easure the depth of the cracks.
b) The insulators of the sam ple E1 shall be subjected at am bient tem perature to a tensile
load, applied between the couplings. The tensile load shall be increased rapidly but
sm oothly from zero to approxim ately 75 % of the SML and then gradually increased to the

SML in a tim e between 30 s to 90 s.
I f 1 00 % of the SML is reached in less than 90 s, the load (1 00 % of the SML) shall be
m aintained for the rem ainder of the 90 s (this test is considered to be equivalent to a 1 m in
withstand test at the SML).
I n order to obtain m ore inform ation from the test, unless special reasons apply (for instance
the m axim um tensile load of the test m achine), the load m ay be increased until the failing
load is reached, and its value recorded.
The insulators have passed this test if
–
–
–

no failure (breakage or com plete pull-out of the core, or fracture of the m etal fitting) occurs
either during the 1 m in 70 % withstand test (a)) or d uring the 1 m in 1 00 % withstand
test (b)),
no cracks are ind icated after the d ye penetration m ethod described in 1 2. 4 a),
the investigation of the halves described in 1 2. 4 a) shows clearly that the cracks do not
reach the core.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 19 –

1 2.5 Galvanizing test (E2)
This test shall be perform ed on all galvanized parts in accordance with I EC 60383-1 .

1 2.6 Re-testing procedure
I f only one insulator or end fitting fails to com ply with the sam pling tests, re-testing shall be
perform ed using a new sam ple size equal to twice the quantity originally subm itted to the tests.
The re-testing shall com prise the test in which failure occurred.
I f two or m ore insulators or m etal parts fail to com ply with any of the sam pling tests, or if any
failure occurs during the re-testing, the com plete lot is considered as not com plying with this
standard and shall be withdrawn by the m anufacturer.
Provid ed the cause of the failure can be clearly identified, the m anufacturer m ay sort the lot to
elim inate all the insulators with this defect. The sorted lot m ay then be re-subm itted for testing.
The num ber then selected shall be three tim es the first quantity chosen for tests. I f any
insulator fails during this re-testing, the com plete lot is consid ered as not com plying with this
standard and shall be withdrawn by the m anufacturer.

1 3 Routine tests
1 3.1 Mechanical routine test
Every insulator shall withstand , at am bient tem perature, a tensile load at RTL corresponding to
0, 5 × SML (

+1 0
)
0

% for at least 1 0 s.

1 3.2 Visual examination
Each insulator shall be exam ined. The m ounting of the end fittings on the insulating parts shall
be in accordance with the drawings. The colour of the insulator shall be approxim ately as
specified in the drawings. The m arkings shall be in conform ance with the requirem ents of this
standard (see Clause 4).
The following defects are not perm itted:

a)
b)
c)
d)
e)

superficial defects of an area greater than 25 m m 2 (the total d efective area not to exceed
0, 2 % of the total insulator surface) or of depth greater than 1 m m ;
cracks at the root of the shed, notably next to the m etal fittings;
separation or lack of bond ing at the housing to m etal fitting joint (if applicable);
separation or bonding d efects at the shed to sheath interface,
m oulding flashes protruding m ore than 1 m m above the housing surface.


BS EN 61 1 09:200 8
– 20 –

61 1 09

? I EC: 2008

88

96 Time h

Load RTL
(≥0,5 SML)

8

16

24

32

40

48

56

64

72

80

Air
temperature °C
+50 ± 5

4

8 1 2 1 6 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 Time h

–35 ± 5
Thermal cycles
IEC

Figure 1 − Thermal-mechanical test

807/08


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 21 –
An n e x A

(informative)
P ri n c i p l e s o f th e d a m a g e l i m i t , l o a d c o o rd i n a ti o n a n d t e s t i n g
fo r c o m p o s i t e s u s p e n s i o n a n d te n s i o n i n s u l a t o rs

A. 1

I n t ro d u c t o ry re m a rk

This annex is intended to explain the long-term behaviour of com posite suspension and tension
insulators under m echanical load, to show typical coordination between SML and service load s
and to explain the m echanical testing philosophy.
A. 2

L o a d -t i m e b e h a vi o u r a n d t h e d a m a g e l i m i t

An essential part of the m echanical behaviour of resin bonded fibre cores, typically used for
com posite insulators, is their load-tim e behaviour, which deserves som e explanation.

The vast experience gained with com posite insulators load ed with tension load s, both in the
laboratory and confirm ed in service, has shown that the load-tim e curve is indeed a curve, and
not a straight line as was presented in the first version of I EC 61 1 09. This straight line had
often been m isinterpreted , leading to the d eduction that a com posite insulator would only
retain a sm all fraction of its original m echanical strength after a period of 50 years, whatever
the applied load.
I t is now known that the tim e to failure of com posite insulators under static tensile loads follows
a curve such as that presented in Figure A. 1 . To take into account the dispersion in the tensile
characteristic of the insulator, the withstand curve is positioned, as shown in Figure A. 1 , below
the failure curve. Being asym ptotic, it shows that for a given insulator, there is a load below
which the insulator will not fail no m atter how long the load is applied since there is no d am age
to the core. This load level is known as the dam age lim it. Typically the dam age lim it lays
around 60 % to 70 % of the ultim ate strength of the core when assem bled with fittings.
The d am age lim it depends on the kind of core m aterial, on the type of end fitting and on the
design of the connection zone. The dam age lim it represents the load value which causes
inception of m icroscopic m echanical dam age within the core m aterial.


BS EN 61 1 09:200 8
– 22 –

61 1 09

? I EC: 2008

Load
Average failing load curve

Withstand load curve

Damage limit of
the assembled core

Log(time)
IEC

808/08

Figure A.1 − Load-time strength and damage limit
of a core assembled with fittings

A.3

Service load coordination

For both short- and long-term m echanical loading of the entire com posite insulator, the
m echanical properties of the individ ual end fitting types also have to be considered. The
m axim um adm issible working load value for the m etal end fittings is lim ited by the elastic lim it
of the m etal m aterial and the design (m echanically stressed cross-section) of the weakest end
fitting part. The m axim um adm issible load for the entire insulator is therefore given either by
the elastic lim it of the end fittings or by the dam age lim it of the assem bled core (und er norm al
environm ental conditions as given in I EC 6221 7).
Figure A. 2 shows a graphical representation of the typical relationship of the dam age lim it to
the m echanical characteristics of an insulator with a 1 6 m m d iam eter core for typical service
loads.


BS EN 61 1 09:200 8
61 1 09

? I EC: 2008

– 23 –

% SML

I n s u l ator

Core

kN
1 70

1 30 %

1 00 %
80 %
70 %
60 %
50 %
40 %
20 %

SML

P l asti c p h ase

1 33
Dam ag e l i m i t

Elastic limit of fittings
Typical EML*
RTL

80
E l asti c p h ase

Ran g e of typi cal
e veryd a y l oad s

0

0%
* EML

Extraordinary mechanical working load (1 week/50 years)
IEC

809/08

F i g u re A. 2 – G ra p h i c a l re p re s e n t a t i o n o f t h e re l a t i o n s h i p o f t h e d a m a g e l i m i t t o t h e
m e c h a n i c a l c h a ra c t e ri s t i c s a n d s e rv i c e l o a d s o f a n i n s u l a t o r w i t h a 1 6 m m d i a m e t e r c o re

I n all cases, the m axim um working load (static and d ynam ic) shall be below the dam age lim it of
the insulator. I t is norm al practice to adopt a safety factor of at least 2 between the SML and
the m axim um working load; this generally ensures that there is also a sufficient m argin
between the dam age lim it of the insulator and all service loads. I EC 60826 [8] gives guidance
for calculation of loads and application of proper safety factors.
A. 4

Ve ri fi c a t i o n t e s t s

Two tests are prescribed in this standard to check m echanical strength and dam age:
–
–

a design test “96 h withstand load test” (load/tim e pairs D1 and D2 in Figure A. 3) to check
the position of the strength/tim e curve of the insulator (see 1 0. 4. 2);
a type test ”dam age lim it proof test” (load/tim e pairs T1 and T2 in Figure A. 3) to check the
dam age lim it after loading with a constant load of 0, 7 SML for 96 h (see 1 1 . 2).