Siemens Automation System S7-400 - Manual (Page 44)

Installing the S7-400
2-28
Automation System S7-400 Hardware and Installation
A5E00850741-01
Example of selecting the cabinet type
The example below clarifies the maximum permissible ambient temperature at a
particular power loss for various cabinet types.
Equipment suitable for installation in a cabinet:
1 central rack 150 W
2 expansion racks, 150 Watts each 300 W
1 load current power supply under full load 200 W
Accumulated power loss 650 W
Permissible ambient temperatures at an accumulated power loss as shown in
Figure 2-2:
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
Cabinet dimensions
Vital dimensional design factors for an S7-400 cabinet
• Space requirement of the racks
• Minimum clearance between racks and cabinet walls
• Minimum clearance between racks
• Space requirement of cable ducts or fan subassemblies
• Locations of rails