Lust CDA3000 - Calculation of Filter Fans

7-4
Engineering Guide CDA3000
7 System installation
Radiated power of a switch cabinet surface
If the effective switch cabinet surface A and the heat transfer coefficient k
are known, the radiated power Q
S
at maximum cabinet interior tempera-
ture T
i
and maximum outside temperature T
u
can be calculated as
follows:
(1)
There are also diagrams from which the radiated power can be read
directly, without calculation (See Figure 7.2).
Figure 7.2 Radiated power of a switch cabinet surface
7.1.3 Calculation of
filter fans
The necessary volumetric flow of a filter fan depends on the power loss of
the components installed in the switch cabinet and on the difference
between the maximum permissible interior and exterior temperatures:
Necessary volumetric flow
(2)
Q
S
kA T
i
T
u
–()⋅⋅=
2000
1500
1000
900
800
700
600
500
400
300
200
150
100
1
1,5
2
3
456
7
8910
5
7,5
10
15
20
30
Switch cabinet surface A [m²]
to VDE 0660 Part 500
Radiated power Q
s
[W]
Temperature difference D T [K]
Vf
Q
v
T
i
T
u
–
---------------
⋅=