1.14 Twisted-Pair-cables Overview On the following pages we keep repeating the aspects described herein. – Please pay attention in particular on the notes shielding, transmission quality and fire protection. – You will find the corresponding buttons and logos, placed again at the various products. „Twisted pair“ is the English name for network cable with twisted or stranded wire pairs. Twisted pair cables provide a better protection against external alternating magnetic fields and electrostatic interference. Likewise, the crosstalk between adjacent pairs is reduced within the cable. The copper wires of installing cables are made of solid wires while patch cables are made of stranded wires, usually produced with 7 individual wires. – The diameter of the wires are defined in AWG. Solid wires typically have a thickness of 22 to 24 AWG, stranded wires AWG 24-27th – The insulation of the wires as well as the sheath of the cable as a whole are often made of PVC, but now often made of a halogen-free low-smoke plastic mixture. More on this in the section fire safety. There are different approaches whether and how twisted-pair cables are being protect. In this case, significant differences in the quality of the cable are related to the intended use. Especially at higher transmission rates and for greater lengths shielded cables have a significantly better transmission quality. – It is important that the decision is made consistently in terms of shielding for an installation. – The following shielding types are within our product portfolio: U / UTP (unscreened / unshielded twisted pair) or shortUTP: – These cables have neither a common shield, nor an individual shield for each separate twisted pair. – They have the lowest protection against electromagnetic influences. F / UTP (Foiled / Unshielded Twisted Pair) or short FTP: – The pairs are unshielded, the cable has a full shield aluminium-laminated foil that wraps all the pairs together. – A version thereof is S / UTP (Screened / Unshielded Twisted Pair): – The pairs are also unshielded, the overall shield consists of a tinned copper braid. The quality of this cable is much higher than for U / UTP cables. SF / UTP (Foiled / Unshielded Twisted Pair) or simply S / FTP: – The pairs are unshielded, there is an overall shield made of aluminium-laminated foil and also a tinned copper braid. – The protective effect of this combination is again higher than with a simple shielding. S / FTP (screened / shielded twisted pair) or simply S / FTP: – All wire pairs are shielded with aluminium laminated foil, and there is an overall shielding of a tinned copper braid. – The paired shielding attenuates the disruption of the pairs („crosstalk“) considerably. The combination of foil and braid also has the highest possible protection against electromagnetic influences from outside. (Green: laminated aluminum foil / Red: tinned copper braid) Twisted pair cable – as well as the associated components (e.g., junction boxes) – are classified according to transmission quality into classes or categories. Each class or category covers various requirements and quality standards. The concept of category (abbreviated „Cat.“) is mainly extracted from the American standardization (EIA / TIA), the class of the international (ISO / IEC) or from the European (EN). – There is a distinction between data for individual parts or components (patch cables, connectors, installation cables, patch panels, etc.) and information for so-called links. Links can be used as a permanent link (Patch Panel + Installation + cable junction box) and as a channel (s. Figure above), which includes the patch cable. – The class C to EA (corresponding categories 3 to 6A) are defined and valid. Class F (equivalent to Category 7) is defined, but the standardization is not further pursued. The FA class is currently in the process of standardization. Two comments on it: 1. The Class EA (equivalent to Category 6A) was specified so that 10 Gigabit Ethernet can be transmitted. 2. For classes from F (equivalent categories as of 7) the current state of RJ-45 due to the close contact assembly cannot meet the required specifications. – If patch cables are still designated „Cat.7“, it is just because the cable (material) meets the requirements of Cat.7 – even the highest quality RJ-45 maximum fulfills Cat.6A. – In order to achieve optimal performance from your network, all components (patch cables, connectors, installation cables, patch panels, etc.) of a link must support the same category or class. – The component with the lowest performance determines the transmission class (Link Class) of the entire system. When using e.g. a Cat 5e cable with Cat. 6 connector components, the entire link still only fulfils Class D (Cat.5e). Shielding Quality General Information Diameter Cross section AWG (inch) (mm) (mm2) 22 0.0253 0.644 0.326 23 0.0226 0.573 0.258 24 0.0201 0.511 0.205 25 0.0179 0.455 0.162 26 0.0159 0.405 0.129 27 0.0142 0.361 0.102 Category Class Max. Frequency Application 3 C 16 MHz Fast Ethernet 5e D 100 MHz Gigabit Ethernet 6 E 250 MHz Gigabit Ethernet 6A EA 500 MHz 10 Gigabit Ethernet 7 F 600 MHz 10 Gigabit Ethernet 8 G 2 GHz 40 Gigabit Ethernet
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