Siemens SIMATIC ET 200S Installation And Operating Manual page 54

General technical specifications
6.3 Electromagnetic Compatibility
Protecting the ET 200S with Fail-Safe Modules from Overvoltage
If your equipment makes protection from overvoltage necessary, we recommend that you
use an external protective circuit (surge filter) between the low voltage power supply and the
low voltage input of the terminal modules to ensure surge immunity for the ET 200S with fail-
safe modules.
Note
Lightning protection measures always require a case-by-case examination of the entire
system. Nearly complete protection from overvoltages, however, can only be achieved if the
entire building surroundings have been designed for overvoltage protection. 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.
The following figure illustrates an example of a configuration with F-modules, standard
modules, and the power modules PM-E DC24..48V/AC24..230V and PM-E F pm DC24V
PROFIsafe. Voltage is supplied over four power supplies.
You can also use fewer power supplies. However, you must ensure that the total current of
the modules fed by one power supply does not exceed the permissible limits.
You can also use PM-E DC24V power modules; the protective circuit corresponds to that of
the PM-E DC24..48V/AC24..230V + miniature circuit breaker (as for PM-E F pm DC24V
PROFIsafe).
For additional information about surge protection for standard modules, see the
Distributed I/O System
6-8
manual.
Hardware Installation and Operating Manual, 07/2005, A5E00103686-04
ET 200S Distributed I/O System - Fail-Safe Modules
ET 200S