SIST EN 60674-2:2017

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Specification for plastic films for electrical purposes - Part 2: Methods of test (IEC 60674-2:2016)83.140.10Filmi in folijeFilms and sheets29.035.20PDWHULDOLPlastics and rubber insulating materialsICS:Ta slovenski standard je istoveten z:EN 60674-2:2017SIST EN 60674-2:2017en01-maj-2017SIST EN 60674-2:2017SLOVENSKI
STANDARDSIST EN 60674-2:2002/A1:2004SIST EN 60674-2:20021DGRPHãþD

EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 60674-2
February 2017 ICS 17.220.99; 29.035.20
Supersedes
EN 60674-2:1998
English Version
Specification for plastic films for electrical purposes -
Part 2: Methods of test (IEC 60674-2:2016)
Spécification pour les films en matière plastique à usages électriques - Partie 2: Méthodes d'essai (IEC 60674-2:2016)
Bestimmung für Isolierfolien für elektrotechnische Zwecke - Teil 2: Prüfverfahren (IEC 60674-2:2016) This European Standard was approved by CENELEC on 2016-12-23. 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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17,
B-1000 Brussels © 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60674-2:2017 E SIST EN 60674-2:2017

This document supersedes EN 60674-2:1998. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 60674-2:2016 was approved by CENELEC as a European Standard without any modification. SIST EN 60674-2:2017

Normative references to international publications with their corresponding European publications 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. NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu.
Publication Year Title EN/HD Year IEC 60212 2010
Standard conditions for use prior to and during the testing of solid electrical insulating materials EN 60212 2011
IEC 60216 series
Electrical insulating materials - Thermal endurance properties EN 60216 series
IEC 60243-1 2013
Electric strength of insulating materials - Test methods - Part 1: Tests at power frequencies EN 60243-1 2013
IEC 60243-2 -
Electric strength of insulating materials - Test methods - Part 2: Additional requirements for tests using direct voltage EN 60243-2 -
IEC 60250 1969
Recommended methods for the determination of the permittivity and dielectric dissipation factor of electrical insulating materials at power, audio and radio frequencies including metre wavelengths - -
IEC 60343 -
Recommended test methods for determining the relative resistance of insulating materials to breakdown by surface discharges EN 60343 -
IEC 60394-2 1972
Varnished fabrics for electrical purposes - Part 2: Methods of test - -
IEC 60426 -
Electrical insulating materials - Determination of electrolytic corrosion caused by insulating materials - Test methods EN 60426 -
IEC 60454-2 2007
Pressure-sensitive adhesive tapes for electrical purposes - Part 2: Methods of test EN 60454-2 2007
Methods of test for the determination of ionic impurities in electrical insulating materials by extraction with liquids HD 381 S1 -
IEC/TR 60648 -
Method of test for coefficients of friction of plastic film and sheeting for use as electrical insulation - -
IEC 60674-3 series
Specification for plastic films for electrical purposes - Part 3: Specifications for individual materials EN 60674-3 series
IEC 62631-3-1 -
Dielectric and resistive properties of solid insulating materials - Part 3-1 Determination of resistive properties (DC methods) - Volume resistance and volume resistivity, general method EN 62631-3-1 -
IEC 62631-3-2 -
Dielectric and resistive properties of solid insulating materials - Part 3-2 Determination of resistive properties (DC methods) - Surface resistance and surface resistivity EN 62631-3-2 -
ISO 527-3 1995
Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets EN ISO 527-3 1995
ISO 534 -
Paper and board - Determination of thickness, density and specific volume EN ISO 534 -
ISO 1183-1 -
Plastics - Methods for determining the density of non-cellular plastics - Part 1: Immersion method, liquid pyknometer method and titration method EN ISO 1183-1 -
ISO 4591 1992
Plastics - Film and sheeting - Determination of average thickness of a sample, and average thickness and yield of a roll, by gravimetric techniques (gravimetric thickness) - -
ISO 4592 -
Plastics - Film and sheeting - Determination of length and width - -
ISO 4593 -
Plastics - Film and sheeting - Determination of thickness by mechanical scanning - -
ISO 6383-1 -
Plastics - Film and sheeting - Determination of tear resistance - Part 1: Trouser tear method EN ISO 6383-1 -
ISO 6383-2 -
Plastics - Film and sheeting - Determination of tear resistance - Part 2: Elmendorf method EN ISO 6383-2 -
ISO 11357-3 2011
Plastics - Differential scanning calorimetry (DSC) - Part 3: Determination of temperature and enthalpy of melting and crystallization EN ISO 11357-3 2013
IEC 60674-2 Edition 2.0 2016-11 INTERNATIONAL STANDARD
Specification for plastic films for electrical purposes –
Part 2: Methods of test
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ICS 17.220.99; 29.035.20
ISBN 978-2-8322-3747-2
– 2 – IEC 60674-2:2016 © IEC 2016 CONTENTS FOREWORD . 6 INTRODUCTION . 8 1 Scope . 9 2 Normative references . 9 3 General notes on tests . 10 4 Thickness . 10 4.1 General . 10 4.2 Determination of thickness by mechanical scanning . 10 4.2.1 General . 10 4.2.2 Measurement by a single sheet . 11 4.3 Determination of thickness by gravimetric method . 11 4.3.1 Measurement by a sample . 11 4.3.2 Measurement by a roll . 11 4.4 Crosswise thickness profile and lengthwise variation in thickness . 11 5 Density . 12 6 Width . 12 7 Windability (bias/camber and sag) . 12 7.1 Principle . 12 7.2 General . 12 7.3 Method A . 12 7.3.1 Principle . 12 7.3.2 Measurement of bias/camber . 12 7.3.3 Measurement of sag . 13 7.4 Method B . 14 7.4.1 Principle . 14 7.4.2 Apparatus . 14 7.4.3 Test specimens . 15 7.4.4 Procedure . 15 7.4.5 Result . 15 8 Surface roughness . 15 9 Space factor . 15 10 Coefficient of friction . 16 11 Wetting tension (polyolefine films) . 16 11.1 Test principle and introductory remarks. 16 11.2 Apparatus . 16 11.3 Reagents . 16 11.4 Test specimens . 17 11.5 Conditioning . 17 11.6 Procedure . 17 11.7 Evaluation . 18 11.8 Report. 18 12 Tensile properties . 18 12.1 General . 18 12.2 Test specimens . 18 12.3 Speed of testing . 18 SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 3 – 12.4 Result . 18 13 Edge tearing resistance . 19 13.1 General . 19 13.2 Principle . 19 14 Tear resistance . 19 15 Stiffness of film . 19 16 Surface resistivity . 19 17 Volume resistivity . 19 17.1 Method 1: Electrode method . 19 17.2 Method 2: Method for wound capacitor dielectric films or films too thin for Method 1. 19 17.2.1 Principle . 19 17.2.2 Test specimens . 20 17.2.3 Procedure . 20 17.2.4 Result . 20 18 Dissipation factor and permittivity . 20 18.1 General . 20 18.2 Method 1. 20 18.2.1 General . 20 18.2.2 Sample and specimen handling . 21 18.2.3 Sample conditioning prior to measurement . 21 18.2.4 Measurements with contacting electrodes . 21 18.2.5 Measurements with non-contacting electrodes . 23 18.2.6 Test procedure . 23 18.2.7 Report . 23 18.3 Method 2. 23 18.3.1 General . 23 18.3.2 Dissipation factor at or above 5 × 10–4 . 24 18.3.3 Dissipation factor below 5 × 10–4 . 24 19 Dissipation factor under impregnated conditions . 24 20 Electric strength . 24 20.1 AC and DC tests of film sheet sandwiched by metal electrodes . 24 20.2 DC test using a wound capacitor . 24 21 Electrical weak spots . 24 21.1 General . 24 21.2 Method A: Testing narrow strips of film in long lengths . 25 21.2.1 Test equipment . 25 21.2.2 Procedure . 25 21.2.3 Results . 25 21.3 Method B: Testing wide strips of film . 25 21.3.1 General . 25 21.3.2 Test equipment . 25 21.3.3 Procedure . 26 21.3.4 Results . 26 21.4 Method C: Testing of film in rolls . 26 21.4.1 General . 26 21.4.2 Unreeling system . 26 21.4.3 Fault counter . 27 SIST EN 60674-2:2017

– 4 – IEC 60674-2:2016 © IEC 2016 21.4.4 Procedure . 27 21.4.5 Results . 27 22 Resistance to breakdown by surface discharges . 28 23 Electrolytic corrosion . 28 24 Melting point . 28 25 Dimensional change . 28 25.1 Test specimens . 28 25.2 Procedure . 28 25.3 Results . 28 26 Dimensional stability under tension with rising temperature . 29 26.1 Test specimens . 29 26.2 Procedure . 29 26.3 Results . 29 27 Dimensional stability under pressure with rising temperature . 29 27.1 Test equipment . 29 27.2 Test specimens . 29 27.3 Procedure . 29 27.4 Results . 30 28 Resistance to penetration at elevated temperature . 30 28.1 General . 30 28.2 Principle . 30 29 Volatile content (loss of mass on heating) . 30 29.1 Test specimens . 30 29.2 Procedure . 30 29.3 Result . 30 30 Thermal endurance . 30 31 Burning characteristics . 31 31.1 Principle . 31 31.2 Apparatus . 31 31.3 Test specimens . 31 31.4 Conditioning . 31 31.5 Procedure . 32 31.6 Interpretation of results . 32 32 Water absorption in a damp atmosphere . 33 32.1 Apparatus . 33 32.2 Test specimens . 33 32.3 Procedure . 33 32.3.1 Water absorption of material as-received . 33 32.3.2 Water absorption of dry material . 33 32.4 Results . 34 33 Absorption of liquid . 34 33.1 Principle . 34 33.2 Apparatus . 34 33.3 Test specimens . 34 33.4 Procedure . 34 33.5 Calculations . 35 33.6 Result . 35 SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 5 – 34 Ionic impurities . 35 35 Effect of insulating varnishes . 35 35.1 Procedure . 35 35.2 Results . 35 36 Effect of polymerisable resinous compounds in a liquid state . 36 36.1 Procedure . 36 36.2 Results . 36
Figure 1 – Windability of film – Measurement of bias/camber – Method A . 36 Figure 2 – Windability of film –
Apparatus for measurement of sag – Method A . 37 Figure 3 – Windability of film – Measurement of sag – Method A. 37 Figure 4 – Three-terminal electrode system for low frequencies (up to 50 kHz) . 38 Figure 5 – Two-electrode system for high frequencies (above 50 kHz) . 38 Figure 6 – Equipment for testing for electrical weak spots by Method A . 39 Figure 7 – Equipment for testing for electrical weak spots by Method B . 40 Figure 8 – Equipment for testing for electrical weak spots by Method C1 . 40 Figure 9 – Equipment for testing for electrical weak spots by Method C2 . 41 10a) Full view on arrangements of rolls, rollers and HV electrode . 41 10b) Schematic diagram with arrangement around the air gap . 41 between HV electrode and earthed roller . 41 Figure 10 – Equipment for testing for electrical weak spots by Method C3 . 41
Table 1 – Concentrations of ethylene-glycol-monoethyl-ether, formamide mixtures
used in measuring wetting tension of polyethylene and polypropylene films . 17 Table 2 – Classification of materials regarding self-extinguishing properties . 33
– 6 – IEC 60674-2:2016 © IEC 2016 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
SPECIFICATION FOR PLASTIC FILMS
FOR ELECTRICAL PURPOSES –
Part 2: Methods of test
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 60674-2 has been prepared by IEC technical committee 15: Solid electrical insulating materials. This second edition cancels and replaces the first edition published in 1988 and Amendment 1 (2001). This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) this document was completely revised editorially and technically and included in the IEC 60674 series of standards; b) the test methods are updated to reflect today’s state of the art; c) a method to obtain DC electric strength is now specified according to IEC 60243-2. SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 7 – The text of this standard is based on the following documents: CDV Report on voting 15/742/CDV 15/760/RVC
Full information on the voting for the approval of this International Standard can be found in the report on voting indicated in the above table. This document has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60674 series, published under the general title Specification for plastic films for electrical purposes, can be found on the IEC website. The committee has decided that the contents of this document will remain unchanged until the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to the specific document. At this date, the document will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended. A bilingual version of this publication may be issued at a later date.
– 8 – IEC 60674-2:2016 © IEC 2016 INTRODUCTION This document is one of a series which deals with plastic films for electrical purposes. The series consists of three parts: Part 1:
Definitions and general requirements (IEC 60674-1) Part 2:
Methods of test (IEC 60674-2) Part 3:
Specifications for individual materials (IEC 60674-3 (all parts)) SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 9 – SPECIFICATION FOR PLASTIC FILMS
FOR ELECTRICAL PURPOSES –
Part 2: Methods of test
1 Scope This part of IEC 60674 is applicable to plastic films used for electrical purposes. This part of IEC 60674 gives methods of test. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60212:2010, Standard conditions for use prior to and during the testing of solid electrical insulating materials IEC 60216 (all parts), Electrical insulating materials – Thermal endurance properties IEC 60243-1:2013, Electric strength of insulating materials – Test methods – Part 1: Tests at power frequencies IEC 60243-2, Electric strength of insulating materials – Test methods – Part 2: Additional requirements for tests using direct voltage IEC 60250:1969, Recommended methods for the determination of the permittivity and dielectric dissipation factor of electrical insulating materials at power, audio and radio frequencies including metre wavelengths IEC 60343, Recommended test methods for determining the relative resistance of insulating materials to breakdown by surface discharges IEC 60394-2:1972, Varnished fabrics for electrical purposes – Part 2: Methods of test IEC 60426, Electrical insulating materials – Determination of electrolytic corrosion caused by insulating materials – Test methods IEC 60454-2:2007, Pressure-sensitive adhesive tapes for electrical purposes – Part 2: Methods of test IEC 60589, Methods of test for the determination of ionic impurities in electrical insulating materials by extraction with liquids IEC TR 60648, Method of test for coefficients of friction of plastic film and sheeting for use as electrical insulation IEC 60674-3 (all parts), Specification for plastic films for electrical purposes – Part 3: Specifications for individual materials SIST EN 60674-2:2017

– 10 – IEC 60674-2:2016 © IEC 2016 IEC 62631-3-1, Dielectric and resistive properties of solid insulating materials – Part 3-1: Determination of resistive properties (DC methods) – Volume resistance and volume resistivity – General method IEC 62631-3-2, Dielectric and resistive properties of solid insulating materials – Part 3-2: Determination of resistive properties (DC methods) – Surface resistance and surface resistivity ISO 527-3:1995, Plastics – Determination of tensile properties – Part 3: Test conditions for films and sheets ISO 534, Paper and board – Determination of thickness, density and specific volume ISO 1183, Plastics – Methods for determining the density of non-cellular plastics – Part 1: Immersion method, liquid pyknometer method and titration method ISO 4591:1992, Plastics – Film and sheeting – Determination of average thickness of a sample, and average thickness and yield of a roll, by gravimetric techniques (gravimetric thickness) ISO 4592, Plastics – Film and sheeting – Determination of length and width ISO 4593, Plastics – Film and sheeting – Determination of thickness by mechanical scanning ISO 6383-1, Plastics – Film and sheeting – Determination of tear resistance – Part 1: Trouser tear method ISO 6383-2, Plastics – Film and sheeting – Determination of tear resistance – Part 2: Elmendorf method ISO 11357-3:2011, Plastics – Differential scanning calorimetry (DSC) – Part 3: Determination of temperature and enthalpy of melting and crystallization 3 General notes on tests 3.1 Discard at least the first three layers of film from the roll to be tested before removing test specimens. 3.2 Sample rolls shall be exposed for at least 24 h to the standard atmosphere 23 °C ± 2 K and 50 % ± 5 % RH before test specimens are removed for test. Unless otherwise specified, all individual test specimens shall be conditioned for 1 h and tested in the same standard atmosphere. 4 Thickness 4.1 General Thickness shall be measured by any one or more of the methods given below as required by IEC 60674-3 (all parts). 4.2 Determination of thickness by mechanical scanning 4.2.1 General Two methods, the first using a single sheet and the second using a stack of sheets, are given individually as follows. SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 11 – 4.2.2 Measurement by a single sheet 4.2.2.1 Principle The method is based on ISO 4593 using a precision micrometre to measure the thickness of a single sheet test specimen. 4.2.2.2 Test specimens and measuring points Cut three strips about 100 mm wide across the width of the sample. The test strips shall not contain creases or other defects. Determine the thickness of the test strips in accordance with the requirements of ISO 4593 using a micrometre having plane or radiused measuring surfaces. Measurements shall be made at nine points at approximately equally spaced intervals along the length of the test strips. In the case of samples less than 300 mm wide make the measurements every 50 mm along the length of the test strips. In the case of untrimmed rolls, readings shall not be taken within 50 mm of the edges. 4.2.2.3 Result The thickness is the central value of all the measurements, the highest and lowest values on each strip being reported. 4.2.2.4 Measurement by a multi-layer of sheets Bulking (micrometric) thickness shall be measured according to ISO 534, except that the method for obtaining sample pieces is different. Before taking samples, some outer layers of the roll should be removed to obtain undamaged film surface. The four test pieces are initially made up of 12 film layers, the layers being cut together using a suitable template (preferably 250 mm × 200 mm, the 200 mm dimension being in the machine direction) from a stack of film pieces. Discard the first and last layer of each pack or test piece just prior to placing the pack between the pressure faces of the micrometre. 4.3 Determination of thickness by gravimetric method 4.3.1 Measurement by a sample Principle: calculation of the thickness of a sample from measurements of mass, area and density in accordance with Clause 3 of ISO 4591:1992. 4.3.2 Measurement by a roll Principle: calculation of the average thickness from measurements of the length, average width and net mass of the roll and the density of the film in accordance with Clause 4 of ISO 4591:1992. 4.4 Crosswise thickness profile and lengthwise variation in thickness The non-contacting measurement methods, for example using radiation or laser light, are commonly used. The apparatus may be installed in the production line by the manufacturer if the profile and the variation in a roll are required. The minimum resolution for the measurement, its accuracy and testing surface area (width and length) are the subjects specified in IEC 60674-3 (all parts). SIST EN 60674-2:2017

– 12 – IEC 60674-2:2016 © IEC 2016 5 Density Density shall be determined in accordance with ISO 1183. The particular method is specified in IEC 60674-3 (all parts). 6 Width The width is to be determined in accordance with ISO 4592, except that a 5 m sample length is used. Determine the width five times along the length at equal intervals after the film has relaxed for 1 h. Record each width measured and report the central value as the width of the roll. 7 Windability (bias/camber and sag) 7.1 Principle An assessment is made of the distortion of the film as supplied in the roll. Two forms of distortion may be apparent in the film which can impair its subsequent winding characteristics. These distortions are: 1) the film may exhibit bias or camber and therefore its edges may not be straight (see Figure 1); 2) the film may sag below its general level in areas where it has been stretched (see Figures 2 and 3). 7.2 General Two methods are given. Method A is appropriate for narrow (i.e. less than 150 mm) films where distortion is apparent mainly as bias/camber and also for the measurement of sag for very thick films where the tension required for extension by Method B is excessive. Method B is appropriate for wider (i.e. greater than 150 mm) films where distortion is apparent, mainly as sag. 7.3 Method A 7.3.1 Principle To assess bias/camber, a length of film is unwound and laid on a flat surface and the deviation of each of its edges from a straight line is measured (see Figure 1). To assess sag, a length of film is unwound and laid orthogonally over two parallel bars under defined conditions and the deviation from a uniform catenary is measured (see Figure 2). It may sometimes be convenient to make this measurement using the rollers of a winding machine, but in cases of dispute the dimensions and distances shall be as given below. 7.3.2 Measurement of bias/camber 7.3.2.1 Apparatus A flat, horizontal table of any suitable material having a satin finish (not polished) of sufficient width to accommodate the maximum width of film to be tested and of length 1 500 mm ± 15 mm with ends parallel to within 0,1° (or 1,8 mm per 1 metre of table width). Alternatively, the table may be longer than the above length but shall then have two reference lines clearly marked on its surface 1 500 mm ± 15 mm apart and parallel to the same accuracy. SIST EN 60674-2:2017

IEC 60674-2:2016 © IEC 2016 – 13 – • A soft brush suitable for smoothing the film specimen on the table surface. • A long (in excess of 1 525 mm) steel straight-edge. • A 150 mm steel rule with 1 mm graduations. 7.3.2.2 Test specimens The first three layers of film from the roll are discarded. For each specimen a fresh length of approximately 2 m is taken, being drawn from the roll with the lightest tension necessary to unwind it slowly (at about 300 mm/s). 7.3.2.3 Procedure The specimen length of film is placed lengthwise over the table as shown in Figure 1. Starting from one end, the soft brush is used to lightly press the film into intimate contact with the table surface, expelling any trapped air as far as possible. The steel straight-edge is then placed along one edge of the film so that any deviation of the film edge from a straight line can be readily observed. The straight-edge is adjusted to coincide with the film edge at the two table ends (or at the reference marks if these are used) and the distance between these points shall be 1 500 mm ± 15 mm. The distance between the straight edge and the film edge is measured to the nearest 1 mm at approximately mid-span by means of the steel rule. The deviation of the second film edge is then measured using the same procedure. The sum of the distances in millimetres of the two edges of the film from the steel straight-edge at the mid-span is the bias/camber value for that test specimen. The above procedure is repeated for two further test specimens. 7.3.2.4 Results The bias/camber is the central value of the three determinations, the other two values being reported. 7.3.3 Measurement of sag 7.3.3.1 Apparatus A rigid framework supporting two parallel, freely rotatable metal rollers, each roller 100 mm ± 10 mm in diameter and of sufficient length to accommodate the maximum width of film are to be tested. The axes of the rollers shall be in the same horizontal plane and set mutually parallel to within 0,1° (i.e. within 1,8 mm per 1 m length of roller) with a separation of 1 500 mm ± 15 mm. The roller surfaces shall be accurately cylindrical to within 0,1 mm with any suitable satin finish (not polished) (see Figure 2). The framework shall be f
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