1、 International Telecommunication Union ITU-T L.18TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2008) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Sheath closures for terrestrial copper telecommunication cables Recommendation ITU-T L.18 Rec.
2、ITU-T L.18 (05/2008) i Recommendation ITU-T L.18 Sheath closures for terrestrial copper telecommunication cables Summary Recommendation ITU-T L.18 deals with the design, mechanical and environmental characteristics of cable sheath closures for copper cables, applied in telecommunication networks in
3、duct, tunnel, buried, surface troughing and aerial installations. Source Recommendation ITU-T L.18 was approved on 29 May 2008 by ITU-T Study Group 6 (2005-2008) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T L.18 (05/2008) FOREWORD The International Telecommunication Union (ITU) is the Uni
4、ted Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommen
5、dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The app
6、roval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administra
7、tion“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and complianc
8、e with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is re
9、quired of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intell
10、ectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation.
11、However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without th
12、e prior written permission of ITU. Rec. ITU-T L.18 (05/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Characteristics of closures for copper cable . 1 3.1 Design of the closure 1 3.2 Mechanical characteristics 3 3.3 Environmental characteristics 3 Appendix I Environmental classification 5 I.1 B
13、asic environmental classes. 5 I.2 Special conditions. 6 Appendix II Typical performance requirements for sealed non-pressurized copper closures . 7 Appendix III Typical performance requirements for sealed pressurized copper closures 10 Bibliography. 13 iv Rec. ITU-T L.18 (05/2008) Introduction A cop
14、per cable telecommunication network will require, at certain locations, cable interconnections (cable joints) because: a) cables are not necessarily continuous from one terminal point to the other b) cables may need to be branched c) cables may have been damaged. A cable joint consists of spliced co
15、nductors and a closure. The methods for splicing conductors are covered in a separate Recommendation ITU-T L.9: Methods of terminating metallic cable conductors and further information is also found in the ITU-T Handbook, Outside plant technologies for public networks (Part II, Chapter 3 Symmetrical
16、 and coaxial pairs jointing techniques). Basically, a closure is a structure, which is attached at the outer surface of the ends of the sheaths of the cables to be jointed, covering the spliced conductors and thereby restoring the integrity of the cable sheaths at the cable joint. The closure should
17、: Protect the spliced conductors from the environment in the type of plant where it is installed, directly buried, in ducts and tunnels, in surface troughing and as an aerial installation (wall, pole and pole line). Provide mechanical strength across the sheath opening between the cable ends. Provid
18、e electrical bonding and grounding of the metal parts of the sheath where required. The method of achieving this will vary with the type of cable sheath. Further information is given in Recommendations ITU-T K.11 and K.25 and the ITU-T manual: Protection of telecommunication lines against lightning
19、discharges. Rec. ITU-T L.18 (05/2008) 1 Recommendation ITU-T L.18 Sheath closures for terrestrial copper telecommunication cables 1 Scope This Recommendation: Deals with the design of cable sheath closures for copper cables used in telecommunication networks, for all types of outside plant environme
20、nts. Deals with the mechanical and environmental characteristics of sheath closures for copper cable. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publicati
21、on, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the cu
22、rrently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. IEC 60068.x IEC 60068.x-series, Environmental testing. 3 Characteristics of closures for copper cable Closur
23、e design and the required characteristics may be differentiated depending on a number of parameters as listed below. The type of network for which the closure is designed (pressurized, underground, etc.), as well as any limitation in its application domain (for example, compatibility with branch con
24、figurations) should be clearly indicated to the user. Clear and correct installation instructions should be made available, indicating which tools are required, the necessary safety regulations and precautions to be taken and how to select the correct closure size. 3.1 Design of the closure 3.1.1 In
25、stallation environment and sealing level The closure should be mechanically suitable with respect to its application and the environment in which it is to be placed. To prevent corrosion or other electro/chemical damage, the materials should be compatible with other materials normally used in outsid
26、e plant. The level of sealing (water-tightness) must be in accordance with the application environment and pressure in the network. 3.1.1.1 Underground closures Closures for underground networks (for example, ducted, direct buried) should be resistant to permanent water immersion. Closures for use i
27、n pressurized plant should be able to withstand the operating pressure without leaking during their expected lifetime. Air valves are required to reduce the pressure for safe re-entry or as a feeding point to increase the pressure and may be required on the closure for measurement purposes. 2 Rec. I
28、TU-T L.18 (05/2008) 3.1.1.2 Aerial closures For aerial networks, different levels of sealing are applied, depending on the network and local practices. For a sealed network, the closure should not allow air exchange with the environment, and in general it would be suitable for accidental submersion.
29、 For free-breathing networks, the closure design should prevent water penetrating the actual splice due to rain, wind or water running along the cable. Openings should be provided to evacuate water or condensation from the closure. The size of these openings should be limited in order to prevent ent
30、ry of harmful insects. 3.1.2 Direction by which the cables enter the closure Closure designs can also be differentiated by the direction through which the cables enter the closure: butt closures: all cables enter and leave the closure at one end in-line closures: cables enter or leave the closure vi
31、a two opposite ends Y or T-shaped closures: main cables enter the closure via opposite ends (cfr in-line) while one or more (branch) cables leave the closure under an angle (Y) or perpendicular (T) to the main axis of the closure. 3.1.3 Cable characteristics this class may also apply to outdoor wall
32、 mounted products which are close to ground level exposed to contaminants and dust that may occur in the atmosphere in rural, city or industrial areas; the base of the product may be permanently in contact with soil, biological and chemical contaminants that occur at or just below ground or street-l
33、evel, e.g., along roads, pavements and railroads. OS: Outdoor underground (Sub Terrain) outdoor below ground level exposed to soil or water-borne contaminants, including organic and inorganic agents related to the presence of roads and traffic, e.g., in man-holes, hand-holes or direct buried. 6 Rec.
34、 ITU-T L.18 (05/2008) I.2 Special conditions Extreme any environment for which at least one of the environmental parameters exceeds the boundaries of the five basic environmental classes as specified above, e.g., more extreme temperature excursions exact test settings are to be agreed between the su
35、pplier and the customer. Additional requirements In specific cases, extra constraints may be required on top of the conditions of one of the basic environmental classes (e.g., bullet resistance, accidental flooding, etc.). This is not included under the term “extreme“ conditions: For these occasions
36、, additional requirements or tests can be added on top of the test program of the basic environmental class; see also Appendix III for information on potential additional requirements. Table I.1 Summary of typical parameters for the basic environmental classes Indoor Outdoor IC IN OA OG OS Exposure
37、Temp controlled Temp non controlled Above ground Ground level Underground Temp Min (C) +5 10 40 40 30 Temp Max (C) +40 +60 +65 +65 +60 Solar Radiation No Yes Yes No Relative Humidity (max) (%) 93% (decreasing once above 30C) 100% (occasional/permanent exposure to water possible) Precipitation No Rai
38、n, Snow,. Rain, Snow,. N.A. Submersion No b)No No b)Yes Vibration (m/s) 10-55 Hz 1 m/s (0.1g) (whole system) 5 m/s (0.5g) (components) 5-500 Hz 10 m/s (1g) (due to, e.g., traffic, wind, etc.) Chemical Negligible a)Atmospheric Atmospheric + Soil (base only) Soil/waterborne Biological Negligible Atmos
39、pheric Atmospheric + Soil (base only) Soil/waterborne a)In areas where corrosive atmospheres can be expected (marine and coastal areas, industrial areas, urban pollution), increased corrosion protection may be requested as an additional requirement. b)If accidental flooding may occur, e.g., in vault
40、s or basements, this is to be added as a conditional requirement. This will also correspond to a higher IP rating according to b-IEC 60529. Rec. ITU-T L.18 (05/2008) 7 Appendix II Typical performance requirements for sealed non-pressurized copper closures (This appendix does not form an integral par
41、t of this Recommendation) Performance criteria Method and conditions Intern. Norm/ref Requirements Performance criteria references Appearance Examination with the unaided naked eye No defects which will adversely affect product performance Tightness1)Test temperature: Internal pressure: Test time: (
42、23 3)C (40 2) kPa 15 min IEC 60068-2-17 Test Qc No continuous emission of air bubbles Installation tests Closure installability Assembly between: (10 and 45) 2C Tightness Prior to subsequent product testing Mechanical tests Axial tension2)Test temp. range: Test pressure: Load:3)Test time: (5 to +45)
43、 2C (40 2) kPa regulated D/45 1000 N, max. 1000 Nor D/45 500 N, max. 500 N 8 hrs each cable Tightness Bending2)Test temp. range: Test pressure: Bend: Force: Clamp at: Duration: (5 to +45) 2C (40 2) kPa regulated 30 or max. 300 mm displacement max. 500 N 10 D (min. 250 mm) 2 cycles/cable Tightness Im
44、pact2)Test temp. range: Test pressure: Impact tool: Weight: Drop height: Site of impact: No. of impacts: (5 2)C (40 2) kPa regulated Steel ball (1000 10) g 2 m in the centre 1 Tightness Static load2)Test temp. range: Test pressure: Time: Load: Area: No. of applications: (5 to +45) 2C (40 2) kPa regu
45、lated 5 min (1000 10) N 25 cm 10% 2 Tightness 8 Rec. ITU-T L.18 (05/2008) Performance criteria Method and conditions Intern. Norm/ref Requirements Torsion2)Test temp. range: Test pressure: Torque: Clamp at: Duration: No. of cycles: (5 to +45) 2C (40 2) kPa regulated Max. 50 Nm or 90 rotation 10 D (m
46、in. 250 mm) 5 min 2 cycles/cable Tightness Vibration Test temp. range: Test pressure: Vibration: Amplitude: Clamping distance: Test time: (+10 to +45) 2C (40 2) kPa regulated 10 Hz, sinusoidal 3 mm (6 mm peak-to-peak) 10 D (min: 250 mm) 10 days IEC 60068-2-6 Test Fc Tightness Environmental tests Res
47、istance to aggressive Media A Test temperature: Test pressure: Test media: Test time: (23 3)C (40 2) kPa regulated pH 2, pH 12 30 days Tightness Resistance to aggressive Media B4)Test temperature: Test pressure: Test media: Test time: (23 3)C (40 2) kPa regulated Diesel for cars Petroleum jelly 7 da
48、ys EN 590 Tightness Resistance to residual stress cracking Test temperature: Test pressure: Test medium: Test time: (50 2)C (40 2) kPa regulated 10% Igepal 7 days Tightness No visible cracking Temperature cycling High temperature: Low temperature: Dwell/Transition time: Cycle duration: Internal pres
49、sure: No. of cycles: (60 2)C (30 2)C 4 hrs/2 hrs 12 hrs (40 2) kPa regulated 10 IEC 60068-2-14 Test Nb Tightness Salt fog Test temperature: Spray solution: Test time: (35 2)C 5% NaCl 30 days IEC 60068-2-11 Test Ka No visible degradation Rec. ITU-T L.18 (05/2008) 9 Performance criteria Method and conditions Intern. Norm/ref Requirements Waterhead5)Test temperature: Depth: Test time: (23 3)C 5 m 30 days IEC 60068-2-17 Test Qf No wa
