1、ITU-T RECMN+L.Lb 93 e 48625911 0583947 634 II INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANTS L.16 (03/93) CONDUCTIVE PLASTIC MATERIAL (CPM) AS PROTECTIVE COVERING FOR
2、 METAL CABLE SHEATHS ITU-T Recommendation L.16 (Previously CCIlT Recommendation”) ITU-T RECMN*L=Lb 93 W 4Bb2591 0583948 570 W FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying t
3、echnical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups w
4、hich, in their turn, produce Recommendations on these topics. ITU-T Recommendation L. 16 was prepared by the ITU-T Study Group VI (1988- 1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU
5、), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication
6、of this Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure
7、. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic
8、 or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*L.Lb 93 .I q8bZ591i 0583949 407 CONTENTS Page 1 Introduction. . 1 2 Scope 1 3 Benefits of CPM for protective coverings 1 4 Types of cables . 1 5 Properties of CPM coverings . 1 6 Performance
9、s of CPM cables in field . 1 7 Economic criteria suggested for application of CPM cables in areas exposed to lightning discharges . 2 Recommendation L.16 (03/93) i ITU-T RECMN*L-Lb 73 4862573 0583750 329 Recommendation L.16 CONDUCTIVE PLASTIC MATERIAL (CPM) AS PROTECTIVE COVERING FOR METAL CABLE SHE
10、ATHS (Helsinki, 1993) 1 Introduction With reference to Recommendation K.29 “Coordinated protection schemes for telecommunication cables below ground”, in which conductive plastic coverings (CPMs) are considered, the present Recommendation is based on the experience made available by several Administ
11、rations as far as CPM protective coverings are concerned. 2 Scope This Recommendation: - refers to conductive plastic material as protective covering for metal cable sheaths as actually used by administrations and operating agencies; details physico-chemical properties of CPM coverings and main fiel
12、d performances of cables; advises on economic criteria for the applications of CPM coverings. - - 3 The most important benefits of CPM cables are: Benefits of CPM for protective coverings - - - simplification of protection projects. Also service quality improvement shall be taken into account. coord
13、inated protection against corrosion, lightning, effects of electric power and traction lines; maintenance cost reduction especially for earthing; 4 Types of cables CPM are used in directly buried, underground copper conductor cables either local or junction types. Moreover applications in cables wit
14、h an improved reduction factor are reported. Also optical cables could be taken into account. 5 Properties of CPM coverings Polyethylene polymers or PE copolymers with conductive carbon black are used with values for main physical and chemical properties that are equivalent or more severe than the v
15、alues reported in Recommendation K.29. In the appendix there are several values adopted by some Administrations. 6 The main electrical performances of CPM cables in field and relative values, are the following: Performances of CPM cables in field - transversal resistivity (ohm . m): 10 - 100; resist
16、ance to earth (ohm): 1 - 5 for cable length 2 2 km. - Recommendation L.16 (03/93) 1 ITU-T RECNN*L.Lb i3 m 4862593 0583953 Ob5 7 Economic criteria suggested for application of CPM cables in areas exposed to lightning discharges For estimating the risk of damages due to lightning strokes the manual “T
17、he protection of telecommunication lines and equipment against lightning discharges” should be consulted. Defining economic criteria for the application of CPM cables in cases of unacceptable high risk requires further studies. Appendix I (This appendice does not form an integral part of this Recomm
18、endation) Up to now CPM coverings have been used by several Administrations either experimentally or regularly; some Administrations are going on in the application. The values of the main physical and chemical properties of CPM coverings used by some Administrations are reported in the following ta
19、ble: CPM properties Polymer Carbon black (%) Density (g/cm3) Cold bend test at -15 “C Melt flow Index (g/10 min) Volume resistivity (ohm . m) Tensile strength at break (MPa) (%I Per cent elongation at break (%) Var.per cent elongation after ageing (%) Environm. stress cracking res. (h) Water absorpt
20、ion -24 h; 100 c (%) Var.tens.srength after ageing France Italy Norway Czech. PE 10 0.924 - 0.94 No vis. crack I 0.6 0.9 - 6.6 12 400 4.500 0.28 Test method IEC 81 1-4.1 IEC 811-1.3 IEC 811-1.4 IEC 811-4.1 IEC 93 IEC 811-1.1 IEC 811-1.1 IEC 811-1.1 IEC 811-1.1 IEC 811-4.1 IEC 811-1.3 2 Recommendation L.16 (03/93)
