Condensation Protection - Siemens SINAMICS S120 Equipment Manual

If the measures recommended above are not implemented, the equipment might malfunction
in operation at air temperatures as low as 30 °C. This is because the current transformers
would be overheat!
The coolant connection must be designed to prevent any coolant leakage into the unit. It is
advisable to empty the coolant hoses before connecting them and to plug the heatsink
before removing the coolant hoses.
8.5

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 8-9 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%
[°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.
Chassis Power Units Liquid Cooled
SINAMICS S120 Equipment Manual, Edition 04/2007, 6SL3097-2AM00-0BP2
φ=30% 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
8.5 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
32 33
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 29.9
34 34.9
37.9
39.9
44.9
49.9
8-19