Siemens SIMATIC NET PROFIBUS Owner's Manual page 257

Lightning and Surge Voltage Protection for LAN Cables Between Buildings
LAN Cables between Buildings
Since LAN cables between buildings are subject to higher overvoltage risks (the
effects of lightning), the nodes included in the attached bus segment must be
protected from the effects of overvoltage.
Lightning protection facilities for LAN cables are implemented in two different
components, coarse protection and fine protection.
Coarse Protection
While coarse protection prevents the progress of high-energy lightning currents at
the point of entry to the building, the fine protection installed in the vicinity of the
DTE provides finer limitation of overvoltage for the bus node.
S The lightning protection devices described below represent a protection concept
developed in conjunction with the company of Dehn & Söhne for SIMATIC NET
PROFIBUS and that can be used for all transmission rates (9.6 Kbps to 12
Mbps). The devices can be ordered directly from the firm of Dehn & Söhne;
ordering data are listed below.
S When configuring a network make sure that the coarse and fine protection
together must be considered as a node (reduction of the number of nodes in
segments with lightning protection modules).
S If a PROFIBUS segment runs through several buildings (several lightning
components used in series), a repeater should be installed in each building to
refresh the signal.
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
B-3