Selection And Installation Of Cabinets - Siemens SIMATIC S7-300 Hardware And Installation Manual

Configuring
5.6

Selection and installation of cabinets

You should install your S7-300s in cabinets if ...
• you are planning a large plant,
• you are using your S7-300s in an environment subject to interference or
contamination, and
• in order to meet the UL/CSA requirements, which require installation in
cabinets.
Selecting and dimensioning of cabinets
Note the following criteria when selecting and dimensioning cabinets:
• Ambient conditions at the cabinet's place of installation
• The specified mounting clearance for racks (rails)
• Total power loss of all components in the cabinet
The ambient conditions (temperature, humidity, dust, chemical influence, explosion
hazard) at the cabinet's place of installation determine the degree of protection (IP
xx) required for the cabinet. Further information on degree of protection can be
found in IEC 529 and DIN 40050.
The cabinet's power dissipation
The power dissipation capability of a cabinet depends on its type, ambient
temperature and on the internal arrangement of devices.
Siemens catalogs NV21 and ET1 contain more detailed information about power
dissipation.
Cabinet dimensions
Note the following specifications when you determine the dimensions of a cabinet
suitable for an S7-300 installation:
• Space required for racks (rails)
• Minimum clearance between the racks and cabinet walls
• Minimum clearance between the racks
• Space required for cable ducts or fans
• Position of the stays
5-12
S7-300 Programmable Controller Hardware and Installation
A5E00105492-02