Siemens SIMATIC ET 200SP System Manual page 286

Restrictions of the specified maximum ambient temperature in reference to the installation
altitude
Installation altitude
-1000 m to 2000 m
2000 m to 3000 m
3000 m to 4000 m
4000 m to 5000 m
Base value for application of the derating factor is the maximum permissible ambient temperature in °C for 2000 m.
1)
Note
• Linear interpolation between altitudes is permissible.
• The derating factors compensate for the decreasing cooling effect of air at higher
altitudes due to lower density.
• Note the mounting position of the respective module in the technical specifications. The
basis is the standard IEC 61131-2:2017.
• Make sure that the power supplies you use are rated for altitudes > 2000 m.
Effects on the availability of modules
The higher cosmic radiation present during operation at altitudes above 2000 m will also
start to have an effect on the failure rate of electronic components (the so-called soft error
rate). In rare cases this can result in a transition of modules to the safe state, especially for
fail-safe modules. However, the functional safety of the modules is fully retained.
Note
Fail-safe modules are certified for operation in safety mode up to the maximum altitude listed
in the product data sheet.
All other markings and certifications are currently based on an altitude of up to 2000 m.
Distributed I/O system
System Manual, 09/2019, A5E03576849-AJ
14.5 Mechanical and climatic environmental conditions
Derating factor for ambient temperature
1.0
0.9
0.8
0.7
Technical specifications
1)
285