Condensation Protection; Degrees Of Protection - Siemens SINAMICS S120 Equipment Manual

8.4

Condensation protection

The customer must take measures to protect the units against condensation.
Condensation occurs when the inlet temperature of the coolant is significantly lower than
room temperature (ambient temperature). The permissible temperature difference between
coolant and air varies as a function of the relative humidity φ of the ambient air. The air
temperature at which the aqueous phase drops out is referred to as the "dew point".
The table below shows the dew points (in °C) for an atmospheric pressure of 1 bar
(≈ installation altitude: 0 to 500 m). If the temperature of the coolant is below the specified
value, condensation may occur, i.e. the coolant temperature must always be ≥ the dew point
temperature.
Table 8-8 Dew point temperature as a function of relative air humidity φ and room temperature at an installation altitude
of 0 m.
T room
φ=20% φ=30%
[°C]
10 <0
20 <0
25 0.6
30 4.7
35 8.7
38 11.1
40 12.8
45 16.8
50 20.8
The dew point also depends on the absolute pressure, i.e. the installation altitude.
The dew points for low atmospheric pressure are lower than those at an altitude of 0 m, i.e. it
is always acceptable to calculate the coolant supply temperature for an altitude of 0 m.
8.5

Degrees of protection

SINAMICS S120 Liquid Cooled units have degree of protection IP20 with the exception of
the electrical connections (overall degree of protection IP00).
The temperature ranges specified in Section 3.7.2 also apply to units mounted in a control
cabinet.
No additional measures need to be taken if the modules are mounted in a cabinet with
degree of protection IP21.
However, if they are mounted in a cabinet with a degree of protection higher than IP21, a fan
must be installed above the modules to dissipate any concentrated heat.
The table below specifies the required volumetric flows and the average rates of flow within a
shrouding cover (400 mm high).
If several modules are installed in the same cabinet, then the required volumetric flow
corresponds to the total volumetric flows of the individual components.
In configurations where a number of shrouding covers are interconnected, the total
volumetric flow must also be calculated and a fan selected accordingly.
If a single module is installed in a cabinet with degree of protection IP54, then the fan can be
dispensed with if the required volumetric flow for the module is <0.01 m³/s.
Chassis Power Units Liquid Cooled
SINAMICS S120 Equipment Manual, Edition 12/2007, 6SL3097-2AM00-0BP4
φ=40% φ=50%
<0 <0 0.2
2 6 9.3
6.3 10.5 13.8
10.5 14.9 18.4
14.8 19.3 22.9
17.4 22 25.7
19.1 23.7 27.5
23.3 28.2 32
27.5 32.6 36.6
φ=60% φ=70% φ=80%
2.7 4.8 6.7
12 14.3 16.4
16.7 19.1 21.2
21.3 23.8 26.1
26 28.6 30.9
28.8 31.5 33.8
30.6 33.4 35.8
35.3 38.1 40.6
40 42.9 45.5
Cooling circuit and coolant properties
8.4 Condensation protection
φ=85% φ=90% φ=95%
7.6 8.4 9.2
17.4 18.3 19.1
22.2 23.2 24.1
27.1 28.1 29
32 33 34
34.9 36 36.9
36.9 37.9 38.9
41.8 42.9 43.9
46.6 47.8 48.9
φ=100%
10
20
24.9
29.9
34.9
37.9
39.9
44.9
49.9
8-17