DIN EN 50174-2 Beiblatt 1:2015-09

The performance of transmission paths defined in DIN EN 50173-1 "Information technology - Generic cabling systems - Part 1: General requirements" with symmetrical copper cables is determined by a number of parameters. The formulas indicated in the standard for the determination of the length of these transmission paths presume an operating temperature of 20 °C. If this temperature is higher corresponding correction factors shall be used which lead to a reduction of the path lengths. The increasing popularity of remote power supply, that is the power supply of end devices via data cables using "Power over Ethernet (PoE)" according to IEEE 802.3at or other methods, leads to significant heating of the cable bundles, in particular because increasingly higher performance is being sought. IEEE is currently investigating the feasibility of PoE with 100 W on the end device. This affects the performance of the transmission paths which are usually not designed for the additional load of electricity to supply end devices. In the worst case, remote power supply can lead to data transmission failure and possibly even thermal problems in the cable laying systems. Therefore, Technical Report CLC/TR 50174-99-1 contains a fundamental examination of the phenomena relevant in practice and a) describes a number of specific implementations that form the basis for a mathematical model for the temperature increase in cable bundles when operated with a remote supply; b) contains a coordinated test protocol which provides data for the mathematical modelling of the temperature increase; c) presents a mathematical model which serves as the basis for the resulting requirements and recommendations. For the first time, CLC/TR 50174-99-1 specifies requirements and recommendations for the limits of the application and operation of a remote power supply using cabling with symmetrical cable components of category 5 or higher according to DIN EN 50173-1. It is intended to take into account the knowledge gained during the revision of both DIN EN 50173-1 and DIN EN 50174-2 (VDE 0800-174-2). The responsible committee is DKE/GUK 715.3 "Informationstechnische Verkabelung von Gebäudekomplexen" ("Customer premises cabling") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.