In order to comply with the maximum values for the voltage that are specified in VDE 0228, suitable measures are to be taken concerning the earthing of telecommunication cables, both below ground and above ground.
VÖV sheet 04.04.1 / Supplement, edition 01.84, Recommendations for Telecommunication Cables in DC Railway Operations, gives examples of how to apply the earthing principle. The earthing device for type 8971 telecommunication cables is to be set up in accordance with this earthing principle given in the correspondingly quoted VÖV recommendation.
The device has an 800 μF capacitor / DC 700 V and a discharge resistance of 22 kΩ to suppress DC currents via the cable shield.
The terminal strip is to be set up in accordance with VÖV sheet / Detail A with the option to separate or close the corresponding bridges for the measurement. The terminal strip has test sockets for 4 mm plugs.
With the exception of the recommended capacitance of 2700 μF in the above-mentioned VÖV sheet corresponds to the overall earthing device of the above-mentioned sheet. The reduction of earthing capacity was done with regard to economic considerations, since tests up to today have shown that enlarging the capacitor cannot be justified from an economic point of view.
Please refer to the corresponding VDE stipulations and VÖV recommendations concerning the overall planning of telecommunication cables.
Data sheet [PDF]
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