Current carrying capacity of RADOX ® 125 single core and multi core cables Scope The following tables referring to RADOX connecting leads and multicore cables give easy and fast support for the layout of appa- ratus and components. The following remarks are based on today’s state of the art and practical experience as described in the standard IEC 60216, IEC 60287 and IEC 60364. The application of products will frequently vary from the theoretical values of constant ambient temperature, constant current carrying, homogeneous laying and others. That means, in practice the theoretical current carrying will differ from the real values. For a safe layout of apparatus and components it is recommended to carry out a test with the installed connecting lead or cable under service conditions. Definitions Current load current passed through the cable during operation Continuous operationan operation with constant current whose duration is at least long enough to allow the system to reach thermal equilibrium, but may then go on indefinitely Current rating maximum permissible current under determined operating Permissible operating temperaturemaximum permissible temperature on the condutor in continuous operation Wire insulated single core Cable bundle with jacket with one ore more insulated single cores Conductor temperature temperature of the surface of the core material General remarks The current rating of a cable depends on the conductor cross section, on the cable design, on the characteristics of the insulation materials, on the installation conditions and, for larger cross sections, on the frequency (skin and proximity effects). Also, additional heating effects due to higher ambient temperatures, due to heating elements and due to bunching of cables have to be taken into account. The conductor cross section has to be selected in such a way that the actual current load does not exceed the curent rating, i.e. the conductor temperature does not exceed the permissible operating temperature. The determining factor is the appropriate, most unfavourable operating condition, encountered during operation over the whole length of the cable. Current rating under service conditions I in A I = I N • f 1 • f 2 • f 3 • f 4 • f 5 I in A Current rating for continuous operation under service conditions I N in A Current rating for continuous operation under standard conditions f 1 Reduction factor for increased ambient temperature f 2 Conversion factor for deviated conductor temperature, acc. to. temperature index, IEC 60216 (20 000 h) f 3 Reduction factor for multicore cables f 4 Reduction factor for increased frequency f 5 Reduction factor for bundeled cables Technical information HUBER+SUHNER Wires and cables 89
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