SIST IEC 60839-5-4:2002

IEC 60811-508
®

Edition 1.0 2012-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Electric and optical fibre cables – Test methods for non-metallic materials –
Part 508: Mechanical tests – Pressure test at high temperature for insulation
and sheaths

Câbles électriques et à fibres optiques – Méthodes d’essai pour les matériaux
non-métalliques –
Partie 508: Essais mécaniques – Essai de pression à température élevée pour
les enveloppes isolantes et les gaines

IEC 60811-508:2012

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2012 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.


Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les
microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch

About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

Useful links:

IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: csc@iec.ch.


A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.

Liens utiles:

Recherche de publications CEI - www.iec.ch/searchpub Electropedia - www.electropedia.org
La recherche avancée vous permet de trouver des Le premier dictionnaire en ligne au monde de termes
publications CEI en utilisant différents critères (numéro de électroniques et électriques. Il contient plus de 30 000
référence, texte, comité d’études,…). termes et définitions en anglais et en français, ainsi que
Elle donne aussi des informations sur les projets et les les termes équivalents dans les langues additionnelles.
publications remplacées ou retirées. Egalement appelé Vocabulaire Electrotechnique
International (VEI) en ligne.
Just Published CEI - webstore.iec.ch/justpublished
Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications de la CEI.
Just Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur
Disponible en ligne et aussi une fois par mois par email. cette publication ou si vous avez des questions
contactez-nous: csc@iec.ch.

---------------------- Page: 2 ----------------------
IEC 60811-508

®


Edition 1.0 2012-03




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Electric and optical fibre cables – Test methods for non-metallic materials –

Part 508: Mechanical tests – Pressure test at high temperature for insulation

and sheaths




Câbles électriques et à fibres optiques – Méthodes d’essai pour les matériaux

non-métalliques –


Partie 508: Essais mécaniques – Essai de pression à température élevée pour

les enveloppes isolantes et les gaines












INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX R


ICS 29.035.01; 29.060.20 ISBN 978-2-88912-984-3



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 60811-508  IEC:2012
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Test method . 6
4.1 General . 6
4.2 Apparatus . 6
4.2.1 Air oven . 6
4.2.2 Indentation device . 7
4.3 Insulation . 7
4.3.1 Sample and test piece preparation . 7
4.3.2 Procedure . 7
4.4 Sheath . 9
4.4.1 Sample and test piece preparation for sheaths . 9
4.4.2 Procedure . 10
5 Test report. 11
Annex A (normative) Calculation of the compressing force . 15
Annex B (informative) Recommended performance requirement . 17
Bibliography . 18

Figure 1 – Indentation device . 12
Figure 2 – Measurement of indentation . 12
Figure 3 – Measurement of indentation for small test pieces . 13
Figure 4 – Flat cable with a flat smaller side . 13
Figure 5 – Indentation device for flat cables with a flat smaller side . 14

Table A.1 – General value for k . 15

---------------------- Page: 4 ----------------------
60811-508  IEC:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRIC AND OPTICAL FIBRE CABLES –
TEST METHODS FOR NON-METALLIC MATERIALS –

Part 508: Mechanical tests –
Pressure test at high temperature for insulation and sheaths

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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 60811-508 has been prepared by IEC technical committee 20:
Electric cables.
This Part 508 of IEC 60811 cancels and replaces Clause 8 of IEC 60811-3-1:1985, which is
withdrawn. Full details of the replacements are shown in Annex A of IEC 60811-100:2012.
Significant technical changes with respect to the previous edition are as follows:
– re-statement of oven characteristics, especially relating to anti-vibration and to
temperature control;
– enhanced detail as to the preparations and testing of flat cables;
– enhanced detail as to thickness and dimensional measurements.
See also the Foreword to IEC 60811-100:2012.

---------------------- Page: 5 ----------------------
– 4 – 60811-508  IEC:2012
The text of this standard is based on the following documents:
FDIS Report on voting
20/1304/FDIS 20/1353/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.
This part of IEC 60811 shall be used in conjunction with IEC 60811-100.
A list of all the parts in the IEC 60811 series, published under the general title Electric and
optical fibre cables – Test methods for non-metallic materials, 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.

---------------------- Page: 6 ----------------------
60811-508  IEC:2012 – 5 –
INTRODUCTION
The IEC 60811 series specifies the test methods to be used for testing non-metallic materials
of all types of cables. These test methods are intended to be referenced in standards for
cable construction and for cable materials.
NOTE 1 Non-metallic materials are typically used for insulating, sheathing, bedding, filling or taping within cables.
NOTE 2 These test methods are accepted as basic and fundamental and have been developed and used over
many years principally for the materials in all energy cables. They have also been widely accepted and used for
other cables, in particular optical fibre cables, communication and control cables and cables for ships and offshore
applications.

---------------------- Page: 7 ----------------------
– 6 – 60811-508  IEC:2012
ELECTRIC AND OPTICAL FIBRE CABLES –
TEST METHODS FOR NON-METALLIC MATERIALS –

Part 508: Mechanical tests –
Pressure test at high temperature for insulation and sheaths



1 Scope
This Part 508 of IEC 60811 gives the procedure for a pressure test at high temperature, which
typically applies to thermoplastic compounds used for insulating and sheathing materials.
NOTE 1 The method is principally intended for thermoplastic materials, but may be used for cross-linked
materials when specifically required by the relevant cable standard.
NOTE 2 The test method is not recommended for thicknesses below 0,7 mm.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60811-100:2012, Electric and optical fibre cables – Test methods for non-metallic
materials –Part 100: General
IEC 60811-201, Electric and optical fibre cables – Test methods for non-metallic materials –

Part 201: General tests – Measurement of insulation thickness
IEC 60811-202, Electric and optical fibre cables – Test methods for non-metallic materials –

Part 202: General tests – Measurement of thickness of non-metallic sheaths
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60811-100 apply.
4 Test method
4.1 General
This part of IEC 60811 shall be used in conjunction with IEC 60811-100.
This standard gives the method for the pressure test at high temperature which applies to
insulation and sheathing compounds.
All the tests shall be carried out not less than 16 h after the extrusion of the insulating or
sheathing compounds.
4.2 Apparatus
4.2.1 Air oven
The test shall be carried out in an oven. The oven shall use natural air circulation.

---------------------- Page: 8 ----------------------
60811-508  IEC:2012 – 7 –
NOTE 1 Forced or continuous air circulation is not required. Ovens fitted with air stirring mechanisms are likely to
cause vibration.
The oven shall not incorporate any equipment likely to cause vibration, nor shall it include
exposed heating elements. The temperature of the air shall be maintained continuously at the
value specified in the relevant cable standard. The oven shall be capable of operating to
within ±2 K of the specified test temperature.
NOTE 2 The need for a temperature control to ±2 K is crucial. This is especially so if the material under test is a
thermoplastic with a sharp melting point (such as some ethylene polymers) as a small temperature rise above that
specified can result in a large increase in indentation.
In operation, the oven shall be located in a position free from vibration.
4.2.2 Indentation device
A device according to Figure 1 shall be used. It shall consist of a rectangular blade with an
edge (0,70 ±0,01) mm wide which can be pressed against the test piece under the influence
of an applied force.
4.3 Insulation
4.3.1 Sample and test piece preparation
For each core to be tested, three adjacent pieces shall be taken from a sample having a
length of 250 mm to 500 mm. The length of each piece shall be 50 mm to 100 mm.
From each core piece taken, any covering – including the semi-conducting layer, if any – shall
be removed mechanically. According to the type of cable, the test piece may have a circular,
flat or sector-shaped cross-section of length (45 ± 5) mm.
The cores of twin- and multiple-grouped-core flat cables without sheath shall not be separated
2
individually, except if the individual conductor cross-section is ≥ 10 mm . If so, a test piece
taken from the insulation of an individual core shall be tested.
The minimum thickness of insulation to be tested shall be 0,7 mm.
NOTE Insulation thickness down to 0,4 mm may be tested under certain circumstances, but it is not
recommended. If tests are made with samples having a thickness below 0,7 mm, it should be recorded as such in
the test report.
4.3.2 Procedure
4.3.2.1 Fixing of test pieces
The final test piece shall consist of a piece of the sample from 4.3.1.
Circular cores shall be mounted in the position shown in Figure 1 (3a).
A flat cable without sheath shall be laid on its flat/major axis side.
Sector-shaped cores shall be mounted on a support of an appropriate type as shown in
Figure 1 (3b and 3c).
All test pieces shall be fixed to the support in such a manner that they do not change position
during the test. Special care shall be taken with test pieces so that they do not curve under
the pressure of the blade.

---------------------- Page: 9 ----------------------
– 8 – 60811-508  IEC:2012
4.3.2.2 Application of force
A force calculated according to Annex A shall be applied in a direction perpendicular to the
axis of the core.
The blade shall also be perpendicular to the relevant axis.
4.3.2.3 Protocol in air oven
The loaded blade shall be placed onto the fixed test piece at ambient temperature. The whole
assembly shall then be placed in the air oven which is at the specified test temperature.
The apparatus, with loaded test pieces, shall be placed in a position free from vibration (see
4.2.1).
The temperature of the air shall be maintained continuously at the value specified in the
relevant cable standard. In case of dispute, the temperature shall be checked by means of a
suitable temperature-measuring device, mounted at the same level as the test piece and as
close as possible to one of the test pieces and the temperature shall be continuously
monitored during the test.
NOTE 1 It is critical to ensure that the temperature does not, at any time, exceed the upper limit specified for
testing the particular material. Temperatures below the lower limit specified may be experienced briefly
immediately after starting the test. Such short periods may be ignored.
The assembly shall be kept in the test position for the time specified in the relevant cable
standard, or, if the time is not specified in the cable standard, for the following times:
– 4 h for test pieces having a value of D ≤ 15 mm
– 6 h for test pieces having a value of D > 15 mm.
NOTE 2 Details for the determination of D are found in Annex A.
4.3.2.4 Cooling
At the end of the specified duration, the test piece shall be rapidly cooled under load. This
operation may be carried out inside or outside the air oven by spraying the test piece with
cold water on the spot where the blade is pressing.
The test piece shall be removed from the apparatus when it has cooled to a temperature
where recovery of the insulation no longer occurs; the test piece shall then be cooled further
by immersion in cold water.
4.3.2.5 Measurement
Immediately after cooling, the test piece shall be prepared for determining the depth of
indentation.
The conductor shall be withdrawn, leaving the test piece in the form of a tube.
A narrow strip shall be cut from the test piece in the direction of the axis of the core,
perpendicular to the indentation as shown in Figure 2.
The strip shall be laid flat under a measuring microscope or a measuring projector and the
cross-wire shall be adjusted to the bottom of the indentation and the outside of the test piece
as shown in the same figure.
Small test pieces, up to about 6 mm external diameter, shall be cut transversely at and
adjacent to the indentation, as shown in Figure 3, and the depth of the indentation shall be

---------------------- Page: 10 ----------------------
60811-508  IEC:2012 – 9 –
determined as the difference between the microscope measurements on sectional views 1
and 2 as shown in the same figure.
All measurements shall be made in millimetres to two decimal places.
NOTE Care should be taken when making the measurement, as factors such as thermomechanical forces may
have distorted the upper surface of the sample, giving a false position for the top of indentation, and the true
indentation may differ from that measured directly at the point of indentation. It is therefore essential to use the
thickness value measured before applying the indenter as the baseline figure. If it is evident that distortion has
taken place, or in the case of any uncertainty about the result, a suitable correction to the value of indentation
should be made, thus:
– if the original thickness is δ, but after the test the apparent thickness has becomeδ1 , then for the purposes of
the calculation, the measured indentation (call it M) needs to be corrected by deducting an amount equal to
δ1 – δ ;
– the correct indentation percentage then becomes
M− (δ1−δ )
×100
δ

4.3.2.6 Expression of the results
The indentation values, measured on the three test pieces taken from each core or strip, shall
be calculated as a percentage of the insulation thickness (as measured in accordance with
Annex A). The median of the three values shall be recorded. If there are changes in thickness
due to the test, the formula in the NOTE in 4.3.2.5 should be used.
For flat cables, the median indentation value is the mean value of the indentation values from
all the cores of the same size in the sample.
NOTE In the absence of any requirement in the relevant cable standard, a recommendation is given in Annex B.
4.4 Sheath
4.4.1 Sample and test piece preparation for sheaths
For each sheath to be tested, three adjacent pieces shall be taken from a sample having a
length of 250 mm to 500 mm from which the covering (if any) and all the internal parts (cores,
fillers, inner covering, armour etc. if any) have been removed.
The length of each piece of sheathing shall be 50 mm to 100 mm.
From each piece of sheathing, a strip of width equal to about one-third of the perimeter, but
not more than 20 mm, shall be cut parallel to the direction of the axis of the cable if the
sheath does not have ridges.
If the sheath shows ridges caused by five or fewer cores, the strip shall be cut in the direction
of the ridges so that it contains at least one groove which lies approximately in the middle of
the strip throughout its length.
If the sheath has ridges caused by more than five cores, the strip shall be cut in the same
manner and these ridges shall be removed by grinding.
NOTE 1 A machine of the type specified in Annex A of IEC 60811-501:2012 has been found suitable for grinding
or cutting the ridges.
If the sheath is directly applied on a concentric conductor, an armour or on a metallic screen,
and therefore has ridges which cannot be ground or cut away (unless the diameter is large),
the sheath shall not be removed, and the whole cable piece shall be used as a test piece.

---------------------- Page: 11 ----------------------
– 10 – 60811-508  IEC:2012
If the smaller sides of a flat cable are fully rounded in shape, this test shall be carried out on
one of the smaller sides. To calculate the compressing force (see Annex A), D is the minor
dimension of the cable and δ is the mean sheath thickness e as shown in Figure 4.
3
If the smaller sides are flat, or nearly flat, as depicted in Figure 4, a test piece shall be
prepared by cutting a strip from the wide side of the cable in the direction of the axis of the
cable. On the inner side, only the ridges shall be removed by grinding or cutting. The width of
the strip to be tested shall be at least 10 mm but not more than 20 mm. The thickness of the
strip shall be measured at the place where the compressing force, F, is applied.
NOTE 2 Insulation thickness down to 0,4 mm may be tested under certain circumstances, but it is not
recommended. If tests are made with samples having a thickness below 0,7 mm, it should be recorded as such in
the test report.
4.4.2 Procedure
4.4.2.1 Fixing of test pieces
The strips shall be supported by a metal mandrel, which may be halved in the direction of its
axis to make a more stable support.
NOTE A metal pin or a metal tube is suitable as a mandrel.
The radius of the mandrel shall be approximately equal to half the inner diameter of the test
piece.
The apparatus, the strip and the supporting mandrel shall be arranged so that the mandrel
supports the strip and the blade is pressed against the outer surface of the test piece.
Test pieces of flat cable sheaths shall be placed on a support as shown in Figure 5 when the
smaller sides of the cable are flat.
The force shall be applied in a direction perpendicular to the axis of the mandrel (or of the
cable when a whole cable piece is used) and the blade shall also be perpendicular to the axis
of the mandrel, or of the cable when a whole cable is used.
If the smaller sides of a flat cable are flat, or nearly flat, as depicted in Figure 4, the test piece
(strip) shall be bent around a mandrel having a diameter approximately equal to the diameter
of the core of the cable; the longitudinal axis of the strip shall be perpendicular to the axis of
the mandrel. Provision shall be made so that the inner surface of the strip shall be in contact
over at least 120° of the circumference of the mandrel (see Figure 5). The metal blade of the
test apparatus shall be placed on the middle of the test piece.
For flat cables where the smaller sides are flat, or nearly flat δ (in mm) is the thickness of the
strip at the place where the force is applied. D (in mm) is the diameter of the mandrel plus
twice the value of δ and as shown in Figure 5.
4.4.2.2 Application of force
A force calculated according to Annex A shall be applied in a direction perpendicular to the
axis of the mandrel (or of the cable when a whole cable piece is used).
The blade shall also be perpendicular to the relevant axis.
4.4.2.3 Protocol in air oven
See 4.3.2.3.

---------------------- Page: 12 ----------------------
60811-508  IEC:2012 – 11 –
4.4.2.4 Cooling
See 4.3.2.4.
4.4.2.5 Measurement
The indentation shall be measured on a narrow strip cut from the test piece, as described in
4.3.2.5 and shown in Figure 2.
For flat cables where the smaller sides are flat, or nearly flat, the depth of indentation shall be
related to the original value, δ, as described in 4.4.2.1 and as shown in Figure 5.
NOTE Care should be taken when making the measurement, as factors such as thermomechanical forces may
have distorted the upper surface of the sample giving a false
...