Installing the S7-400
2-26
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01
Example for Determining the Type of Cabinet
The following example clarifies the maximum ambient temperature which is
permissible for a particular power dissipation with various types of cabinet.
The following equipment configuration is to be installed in a cabinet:
1 central rack 150 W
2 expansion racks of 150 W power dissipation each 300 W
1 load current power supply under full load 200 W
Total power dissipation 650 W
From Figure 2-2, with a total power dissipation of 650 W, the ambient temperatures
obtained are as follows:
Type of Cabinet Max. Permissible Ambient
Temperature
Closed, with natural convection and forced circulation
(Curve 3)
(no operation possible)
Open, with through-ventilation (Curve 2) approx. 38° C
Closed, with heat exchanger (Curve 1) approx. 45° C
Dimensions of Cabinet
To determine the dimensions of a cabinet suitable for assembling an S7-400, you
must take the following into account:
Space requirement of the racks
Minimum clearances between racks and cabinet walls
Minimum clearances between racks
Space requirement of cable ducts or fan subassemblies
Locations of rails
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