Technical data

PROFIBUS Network Manual
System Manual, Edition 04/2009, C79000-G8976-C124-03
253
Lightning and overvoltage protection of bus cables between
buildings
B
B.1 Why protect your automation system from overvoltage?
Introduction
One of the most common causes of hardware failures is overvoltage, caused by the
following:
● Switching in power networks
● Atmospheric discharge or
● Electrostatic discharge
We will show you how to protect devices attached to a PROFIBUS bus cable from
overvoltages.
Note
This section contains information about protecting hardware components on a PROFIBUS
bus cable from overvoltages.
Comprehensive protection from overvoltage is, however, only assured when the entire
automation system and the entire surrounding building is designed for protection from
overvoltages. In particular, this involves structural measures in the building design phase.
Therefore, for detailed information regarding overvoltage protection, we recommend that you
contact your Siemens representative or a company specializing in lightning protection.
Further references
You will find detailed information on protection of systems automated with SIMATIC S7 from
overvoltage in the relevant system manuals
S7-300 (Page 337) , S7-400 (Page 337) , ET 200 (Page 337).
The solution shown there is based on the lightning protection zone concept described in
IEC 61312-1/DIN VDE 0185 T103.
B.2 Protecting bus cables from lightning
Bus cables within buildings
If you keep to the instructions for installing bus cables located entirely within a building, no
special lightning protection is necessary.