3.7.3
Removal of Power
Dissipation from Cabinets
T
he power dissipation that can be removed from a cabinet is governed
by the cabinet design, its ambient temperature and the arrangement of
equipment in the cabinet.
S
hown in the following figure is a diagram with guide values for the
permissible ambient temperature of a cabinet measuring 600 x 600 x
2200 mm, as a function of power dissipation. These values only apply
to the arrangement of equipment in the cabinet as given in
Section 3.6.2. Further details can be found in Catalogs NV21 and ET1.
Note
When fitting the subracks of the S5-135U/155U series, the
maximum power dissipation which can be removed by the fans
must not be exceeded. The maximum removable power
dissipation per unit with a supply air temperature of 55
o
C is
250 W. This value is increased by 20 W for each reduction in
supply air temperature by 1
o
C.
20
30
40
50
55
200
400
600
800
1000
1200
1400 W
Power Dissipation
Ambient Temperature
in
o
C
1
2
3
1
Closed cabinet with heat exchanger of size 11/6 (920 x 460 x 111 mm)
2
Cabinet with through ventilation by natural convection
3
Closed cabinet with natural convection and forced circulation using fan
Figure 3-16
Maximum Cabinet Ambient Temperature as a Function of Power Dissipation
3
Selection and Installation of Cabinets with SIMATIC S5
System Manual
C79000-B8576-C199-03
3 - 39
