Anti-Condensation Measures - Siemens SINAMICS S120 Manual

Cooling circuit and coolant properties

13.3 Anti-condensation measures

13.3 Anti-condensation measures
The customer must take measures to protect the devices against condensation
Condensation occurs when the inlet temperature of the cooling medium 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 precipitates is referred to as the "dew
point".
The table below shows the dew points (in °C) for an atmospheric pressure of 100 kPa
(≈ 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 13- 3 Dew point temperature as a function of the relative air humidity (Φ) and the room temperature at an installa-
tion altitude of between 0 and 500 m
T Dew point temperature in °C at a relative humidity Φ in %
room
[°C]
20 % 30%
10 < 0 < 0
20 < 0 2
25 0.6 6.3
30 4.7 10.5
35 8.7 14.8
38 11.1 17.4
40 12.8 19.1
45 16.8 23.3
50 20.8 27.5
55 24.9 31.9
The dew point also depends on the absolute pressure (i.e. the installation altitude).
The dew points for lower atmospheric pressures lie below the dew points for a height=0 m.
Therefore, selecting the coolant intake temperature for a height 0 m always sufficient.
Various measures can be taken to prevent condensation:
● Temperature-controlled valves in the supply line.
In the cooling circuit, a temperature-controlled valve must be provided in the supply line.
● Closed-loop water temperature control
The water temperature is controlled depending on the room temperature. This is the
preferred method with high room temperatures, low water temperatures, and high air
humidity.
● Physical dehumidification.
A physical dehumidification is only effective in closed spaces. This method involves
condensing the air humidity in an air-to-water heat exchanger, which is continuously
operated using the cold cooling water.
● Installing a heater with a sufficient power rating in the cabinet.
To prevent condensation, a humidity detector can be used to monitor the air humidity. The
humidity detector is not included in the scope of delivery.
782
40% 50% 60%
< 0 0.2 2.7
6 9.3 12
10.5 13.8 16.7
14.9 18.4 21.3
19.3 22.9 26.1
22 25.7 28.8
23.7 27.5 30.6
28.2 32.1 35.3
32.6 36.6 40.1
37.1 41.2 44.7
70% 80% 85%
4.8 6.7 7.6
14.3 16.4 17.4
19.1 21.2 22.2
23.8 26.1 27.1
28.6 30.9 32.1
31.5 33.8 34.9
33.4 35.8 36.9
38.1 40.6 41.8
42.9 45.5 46.6
47.7 50.4 51.7
Manual, (GH2), 07/2016, 6SL3097-4AC00-0BP8
90% 95% 100 %
8.4 9.2 10
18.3 19.1 20
23.2 24.1 25
28.1 29.1 30
33.1 34.1 35
36.1 36.9 38
37.9 38.9 40
42.9 43.9 45
47.8 48.9 50
52.8 53.9 55
Booksize Power Units