Siemens Automation System S7-400 - Manual (Page 188)

Assembling and Installing Systems
A-20
Automation System S7-400 Hardware and Installation
A5E00850741-01
A.9 Lightning Protection and Overvoltage Protection
Overview
Failures are very often the result of overvoltages caused by:
• Atmospheric discharge or
• Electrostatic discharge.
First of all, we want to introduce you to the lightning protection zone concept, on
which the protection against overvoltage is based.
At the end of this section, you will find rules for the transitions between the
individual lightning protection zones.
Note
This section can only provide information on the protection of a programmable
logic controller against overvoltages.
However, a complete protection against overvoltage is guaranteed only if the
whole surrounding building is designed to provide protection against overvoltages.
This refers especially to constructional measures for the building already in the
planning phase.
If you wish to obtain detailed information on overvoltage protection, we therefore
recommend you to address your Siemens contact or a company specialized in
lightning protection.