1、 IEC/TR 62470 Edition 1.0 2011-10 TECHNICAL REPORT Guidance on techniques for the measurement of the coefficient of friction (COF) between cables and ducts IEC/TR 62470:2011(E) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2011 IEC, Geneva, Switzerland All rights reserved. Unless o
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10、tion 1.0 2011-10 TECHNICAL REPORT Guidance on techniques for the measurement of the coefficient of friction (COF) between cables and ducts INTERNATIONAL ELECTROTECHNICAL COMMISSION N ICS 33.180.10 PRICE CODE ISBN 978-2-88912-744-3 Registered trademark of the International Electrotechnical Commission
11、 colour inside 2 TR 62470 IEC:2011(E) CONTENTS FOREWORD . 3 1 Scope and object 5 2 Reference documents . 5 3 Test procedures . 6 Method A: wheel test . 6 3.1General . 6 3.1.1Sample 6 3.1.2Apparatus 6 3.1.3Procedure 7 3.1.4Calculations. 7 3.1.5Results 8 3.1.6Method B: sloped duct test 8 3.2General .
12、8 3.2.1Sample 9 3.2.2Apparatus 9 3.2.3Procedure 10 3.2.4Calculations. 10 3.2.5Results 10 3.2.6Method C: sloped cable test 11 3.3General . 11 3.3.1Sample 11 3.3.2Apparatus 11 3.3.3Procedure 12 3.3.4Calculations. 12 3.3.5Results 12 3.3.6 Bibliography 14 Figure 1 Sketch of a wheel test 7 Figure 2 Sketc
13、h of the sloped duct test 9 Figure 3 Sketch of the sloped cable test. . 12 TR 62470 IEC:2011(E) 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ GUIDANCE ON TECHNIQUES FOR THE MEASUREMENT OF THE COEFFICIENT OF FRICTION (COF) BETWEEN CABLES AND DUCTS FOREWORD 1) The International Electrotechnical Commis
14、sion (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
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25、ted data of a different kind from that which is normally published as an International Standard, for example “state of the art“. IEC TR 62470, which is a technical report, has been prepared by subcommittee 86A: Fibres and cables, of IEC technical committee 86: Fibre optics. The text of this technica
26、l report is based on the following documents: Enquiry draft Report on voting 86A/1407/DTR 86A/1417/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the
27、ISO/IEC Directives, Part 2. 4 TR 62470 IEC:2011(E) 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
28、 will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the corre
29、ct understanding of its contents. Users should therefore print this document using a colour printer. TR 62470 IEC:2011(E) 5 GUIDANCE ON TECHNIQUES FOR THE MEASUREMENT OF THE COEFFICIENT OF FRICTION (COF) BETWEEN CABLES AND DUCTS 1 Scope and object This technical report describes three techniques to
30、measure the coefficient of friction (COF) between cables and ducts. For a given technique, cable construction, installation method (pulling, pushing, or blowing), and duct size, the relative values of the COF can give some indication as to the relative ease of installation. The techniques can be use
31、d for traditional cables and ducts (see IEC 60794-3-10) as well as for microduct cables and microducts (see IEC 60794-5). A fibre or fibre unit may be evaluated in place of a cable in all techniques. Methods A, B, and C are distinguished by the equipment used for measurements: method A using a wheel
32、 around which the duct is wound, a cable with attached weight being pulled through the latter, while measuring the force needed for this; method B using a device to clamp a duct specimen, a cable specimen placed inside, tilting both while measuring the angle at which the cable specimen starts to sli
33、de, or the angle which sustains sliding; and method C using a device to clamp and straighten a cable specimen, a duct specimen placed around it, tilting both while measuring the angle at which the duct specimen starts to slide, or the angle which sustains sliding. The COF when the cable is not movin
34、g with respect to the duct is the static COF, and will increase until sliding suddenly starts. The COF while the cable is sliding within the duct is the kinetic or dynamic COF. It should be noted that the static COF will generally be a higher value than the kinetic COF. The results from the three me
35、thods can be compared qualitatively, but are not represented as being equivalent. None of the methods are represented as being the Reference Test Method. Method A will yield the kinetic COF; methods B and C will yield both static and kinetic COF. Both the static and kinetic COF may be dramatically a
36、ffected by lubrication of the cable and/or duct. While not specifically addressed herein, the intent of these methods may be used with lubricated cable/duct samples. These methods do not constitute a routine test used in the general evaluation of the installation performance of cables in ducts. This
37、 parameter is not generally specified within a detail specification. 2 Reference documents 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 doc
38、uments (including any amendments) applies. IEC 60794-1-1:2001, Optical fibre cables Part 1-1: Generic specification General IEC 60794-3-10: Optical fibre cables Part 3-10: Outdoor cables Family specification for duct, directly buried and lashed aerial optical telecommunication cables IEC 60794-5: Op
39、tical fibre cables Part 5: Sectional specification Microduct cabling for installation by blowing 6 TR 62470 IEC:2011(E) 3 Test procedures Method A: wheel test 3.1General 3.1.1 This subclause describes a technique for the measurement of the COF between a cable specimen and a duct specimen, an importa
40、nt parameter for the installation performance (pushing, pulling, blowing, etc.) of the cable in the duct; see IEC 60794-1-1:2001, Annex C (to be IEC/TR 62691). This method particularly evaluates the friction seen when a cable travels around a curve in a duct. In this method, a cable specimen with at
41、tached weight is pulled through a duct specimen wound around the wheel and the pulling force is measured. Several variants of wheel tests are used with different weights, diameters, and angles over which the duct is pulled over the wheel. Sometimes a pulley is also used to direct the cable in line w
42、ith the pulling/force-measuring device. One variant is given here as an example. Sample 3.1.2 The test sample comprises a duct specimen and a cable specimen of the type under consideration. A new, clean, grease-free specimen of each is required for each test to avoid the effects of wear and contamin
43、ation. Sometimes a dummy cable, with the same weight but a lower stiffness than the cable to be tested, is used to minimise stiffness effects at the ends of the ducts. The duct specimen is of sufficient length to wrap around the wheel or segment (see 3.1.3) the number of times required by the detail
44、 specification, with an additional length for an entrance and exit end (see Figure 1 and 3.1.4). Typically, 1 wrap around the wheel is used. The cable specimen shall be long enough to fit within the duct specimen, with additional length to accommodate attachments at each end (see 3.1.3 and 3.1.4) an
45、d gauge length(s) for all test runs (see 3.1.4). Apparatus 3.1.3 A wheel with radius R per the detail specification (50 2 cm is the suggested standard value) is placed before a tensile test machine, see Figure 1. A mass, M, is attached to the tail end of the cable specimen to provide the specimen wi
46、th a counter-weight, W (see Figure 1). The weight serves to simulate the upstream functional force, as friction from a long length of cable. The arrangement allows the pulling force to be measured where a cable specimen is pulled through a duct specimen wound around the wheel. In the case of install
47、ation by blowing the attached weight in the wheel test must be small in order to simulate the friction in blowing practice as closely as possible. In this case its mass M should be approximately equal to the mass of a length of 2 m of the cable specimen. The low forces involved in said case do not a
48、llow the use of (relatively small diameter) pulleys, where bending the cable, thus dissipating energy, results in extra forces that cannot be ignored. TR 62470 IEC:2011(E) 7 l Tensile test machine M R IEC 2410/11 Figure 1 Sketch of a wheel test Procedure 3.1.4 The procedure follows the intent of the
49、 following steps, with variations as necessary for the specific test: Wind the duct specimen firmly around the wheel over the arc for the number of turns specified in the detail specification (360, 1 wrap, is a common value). At each end of the duct specimen, a free angle, , of about 10 is provided (see Figure 1). This minimises the effect of bending a cable with stiffness from straight to curved. Insert the cable specimen into the duct by pushing or pu
