Interbus
Overvoltage Protection for Remote Bus Lines (Lightning protection) Overvoltage Protection To protect the transmission equipment from coupled voltage spikes (lightning strike), overvoltage protection equipment should be used in the remote bus cables, as soon as it is laid outside of buildings. The nominal discharge current should, in this case, be at least 5kA. The lightning arrestors Type VT RS485 and Type CT B110 from Dehn und Söhne GmbH & Co KG can, for example, be used. For the supplier address and order numbers for protection equipment and accessories, see TSX Momentum, Bus Adapter for INTERBUS, User Manual. To protect an INTERBUS cable, two protection device groups are required in each building. The first group (Type B110) is positioned where the cable enters the building and is used as the lightning conductor. The second group (Type RS485), close to the first node, is the overvoltage protection device. Connection Rules for Protection Devices Before connection of the protection devices please observe the following rules. Install a functional ground (equipotential bonding rail). Assemble the protection devices near the building ground, so that the overload current is diverted along the shortest route. The cable (minimum 6mm2) to the building and functional ground should be as short as possible. A maximum of 10 protection devices connected in series with 4 open land sections, for connecting buildings to each other, are allowed in the INTERBUS cables. Perform a Shield grounding (see page 308) of the INTERBUS lead according to the lightning arrestor used (type CT B110 or type VT RS485).
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