IEC 60794-4:2018 pdf download – Optical fibre cables – Part 4: Sectional specification – Aerial optical cables along electrical power lines.
3 Terms, definitions, symbols and abbreviated terms For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in IEC 60794-1 -1 apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 4 Optical fibre 4.1 General Single-mode optical fibre which meets the requirements of IEC 60793-2 shall be used. Fibres other than those specified above can be used, if mutually agreed between the user and the supplier. 4.2 Attenuation 4.2.1 Attenuation coefficient The typical maximum cable attenuation coefficient shall conform to IEC 60794-1 -1 . Particular values may be agreed between the customer and supplier. The attenuation coefficient shall be measured in accordance with IEC 60793-1 -40. 4.2.2 Attenuation uniformity-attenuation discontinuities Point discontinuities shall be measured in accordance with IEC 60793-1 -40, method C, and conform to IEC 60794-1 -1 . 4.3 Cut-off wavelength of cabled fibre For single mode fibre, the cabled fibre cut-off wavelength, λ cc , shall be less than the operational wavelength, when measured in accordance with IEC 60793-1 -44, and conform to IEC 60794-1 -1 . 4.4 Fibre colouring If the primary coated fibres are coloured for identification, the coloured coating shall be readily identifiable throughout the lifetime of the cable and shall be a reasonable match to IEC 60304.
4.5 Polarization mode dispersion (PMD) Cabled single-mode fibre PMD shall be measured in accordance with IEC 60793-1 -48 and conform to IEC 60794-1 -1 . 5 Cable element 5.1 General Generally, optical cables comprise several elements or individual constituents, depending on the cable design, which take into account the cable application, operating environment and manufacturing processes, as well as the need to protect the fibre during handling and cabling.
The material(s) used for a cable element shall be selected to be compatible with the other elements in contact with it. An appropriate compatibility test method shall be defined in the family or detail specification. When the fibres are in contact with a filling compound, the compatibility of the filling compound with the fibre coating shall be demonstrated by testing coating stripping force stability after accelerated ageing in accordance with IEC 60794-1 -21 , method E5. Alternative ageing conditions and tests may be agreed between the customer and supplier. Optical elements are cable elements containing optical fibres and are designed to be a primary functional unit of the cable core. They may comprise any of the cable elements described below. Optical elements and each fibre within a cable element shall be uniquely identified, for example, by colours, a positional scheme, markings, tapes, threads or specified in the detail specification. Tests may be performed on cable elements either in uncabled form or in finished cable. Unless otherwise specified, testing shall be performed on cable elements in a finished cable. This means that testing shall be performed only on a finished cable if the cable element manufacturing operation is done by the same manufacturer as the cabling operation. Testing shall be performed on cable elements only if the cable element is supplied by a third party; this does not exclude testing of the finished cable. Different types of optical elements are described below.
5.2 Slotted core The slotted core is obtained by extruding a suitable material (for example polyethylene or polypropylene) with a defined number of slots, providing helical or SZ configuration along the core. One or more primary coated fibres or optical element is located in each slot which may be filled. The slotted core usually contains a central element which may be either metallic or non- metallic. In this case, there shall be adequate adhesion between the central element and the extruded core in order to obtain the required temperature stability and tensile behaviour for the slotted core element. The profile of the slot shall be uniform and shall ensure the optical and mechanical performance required for the optical cable.