Examples Of Coolant Control - Siemens Sinamics S120 Manual
Liquid-cooled chassis power units
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Also See for Sinamics S120:
- Function manual (1094 pages) ,
- Diagnostic manual (947 pages) ,
- Manual (848 pages)
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Cooling circuit, coolant properties and protection against condensation
9.5 Examples of coolant control
Table 9- 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
<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
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.
9.5
Examples of coolant control
With liquid-cooled devices, warm ambient air can condense on the cold surfaces of heat
sink. The resulting condensate can cause electrical damage such as leakage current bridges
and flashovers. Condensation must be avoided by means of an appropriate temperature of
the coolant by always maintaining the temperature of the heat sink above the dew point of
the ambient air. This can be achieved either by a permanently set and correspondingly high
coolant temperature, or by controlling the temperature of the coolant in accordance with the
ambient air and the relative humidity.
A temperature control of the coolant adds a temperature difference T
... 5 K above the condensation temperature to the ambient temperature T
setpoint T
temperature setpoint with the actual value at the coolant inlet T
via parameter r0037[19]. The coolant temperature control is performed by the three-step
controller with the aid of the servo motor connected to the 3-way valve.
The three-step controller has three switch positions for control of the servo motor:
● +Y1 for forward motion
● 0 for standstill
● –Y1 for backward motion
When the control deviation x exceeds the upper switching hysteresis x
switched on, when the deviation falls below the lower switching hysteresis x
is switched off. When the control deviation falls below the switching hysteresis in the
negative direction, the servo motor runs in the opposite direction until the control deviation
has been cleared and the servo motor is switched off.
340
φ=40%
φ=50%
φ=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
22
25.7
28.8
23.7
27.5
30.6
28.2
32
35.3
32.6
36.6
40
for the coolant temperature, see following figure. The control compares the
set
φ=70%
φ=80%
φ=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
31.5
33.8
34.9
33.4
35.8
36.9
38.1
40.6
41.8
42.9
45.5
46.6
Manual, (GH7), 11/2016, 6SL3097-4AM00-0BP7
φ=90%
φ=95%
φ=100%
8.4
9.2
18.3
19.1
23.2
24.1
28.1
29
33
34
36
36.9
37.9
38.9
42.9
43.9
47.8
48.9
of approximately 3 K
L
and forms the
U
, which can be accessed
act
, the servo motor is
u
, the servo motor
l
Liquid-cooled chassis power units
10
20
24.9
29.9
34.9
37.9
39.9
44.9
49.9
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