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VELBUS INSTALLATION GUIDE
BUS CABLE
Apart from standard mains electrical cable, a Velbus installation also needs a
bus cable. The bus cable must have four wires: two wires to provide 12...18 V
DC power supply to the Velbus modules, and two other (twisted) wires for bus
communication.
This cable must start at (or at least pass through) the electrical cabinet that
contains your DIN RAIL modules, then pass through each and every point
where some form of control, temperature measurement or Velbus user
interface will be located.
You may want to extend your bus cable to "non-automated" areas to "future
proof" your installation (Keep the loose ends disconnected from the active
installation for as long as they are not in use). The additional cost of a few
metres of cable will greatly outweigh the costs in the future. It is worth
considering using flexible conduit in your installation to protect the cables and
greatly reduce the time necessary to modify or extend the installation in the
future.
Caution: If you use different low voltage power supplies, the grounds must
always be connected to ensure the correct potential difference across all parts
of the installation.
As stated above, the Velbus bus cable must have
four wires (two for power and two for the data).
This can be done with stranded EIB or UTP cable.
The EIB cable is robust and professional; we would
normally recommend this cable for the Velbus
backbone.
Velbus does not impose many demands on the way the bus cable is installed:
branches, loops, parallel connections and tree style installations are all
permissible and can be used together in the same installation. If you install the
bus in a grand loop, users will not suffer a failure even if it were completely
interrupted at any point, for example during expansion or alteration. You can
run a data bus for several hundred meters without problems.
©2015 Velbus
13
www.velbus.eu
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