Siemens SINAMICS G130 Engineering Manual page 123

Units with heat sinks with an integrated stainless steel heat exchanger:
Drinking or urban water of the quality specified below:
•
pH value
•
Chloride ions
•
Sulfate ions
•
 N itrate ions
•
Dissolved solides
•
Total hardness
•
Electrical conductivity
•
Size of entrained particles
If the chloride content cannot be guraranteed, the coolant must be mixed with water with reduced electrical
conductivity.
Inhibitors, anti-freeze, biozides
These additives to the coolant are required under certain conditions.
•
Inhibitors delay corrosive electro-chemical processes. Essentially, they must be used if it is not possible to
fully meet the requirements regarding the materials in the cooling circuit and the requirements regarding the
coolant quality. With SINAMICS S120 Liquid-Cooled units in chassis format, as far as is necessary, Nalco
inhibitor 00GE056 must be used in an amount of 0.2 %.
•
Anti-freeze prevents the freezing of the coolant in minus temperatures and must always be used if the
conditions of use are expected to include frost. Some anti-freeze additives contain inhibitors and have a
biozide effect. With SINAMICS S120 Liquid-Cooled units in chassis format, Antifrogen N should be used as
anti-freeze, when necessary. The amount of Antifrogen N anti-freese must always be between 20 % and
45 %. 45% Antifrogen N anti-freeze provides frost protection up to -30ºC. With lower concentrations than
20 %, Antifrogen N anti-freeze is corrosive and with higher concentrations than 45 % heat dissipation
becomes worst. It must be noted that with the addition of anti-freeze, the kinetic viscosity of the coolant is
changed and the pump must be adapted accordingly.
•
Biozides prevent corrosion as a result of slimy, corrosive or iron-depositing bacteria. These can occur in
both closed cooling circuits with low water hardness and open cooling circuits. Biozides must be selected for
the type of bacteria present. Compatability with inhibitors used together with the biocide must also be
checked.
Protection against condensation
With liquid-cooled units, warm air can condense on the cold surfaces of the pipes and the heat sink. This
condensation depends on the air humidity and the temperature difference between the ambient air and the coolant.
The higher the air humidity, the lower the temperature difference at which the condensation occurs. The water which
is produced as a result of condensation can cause corrosion at the surface of the equipment as well as electrical
damage. As the SINAMICS units cannot prevent condensation by themselves, it must be prevented using external
measures. This can either be an adapted coolant temperature, which ensures that critical temperature differences
cannot occur, or a coolant temperature control dependent on the ambient air temperature.
Closed cooling circuit for SINAMICS S120 Liquid-Cooled units
The diagram on the next page shows an example of a typical closed cooling circuit. This cooling circuit is absolutely
essential for units with aluminium heat sink, through which the coolant directly flows. It is also highly recommended
for units with a heatsink with integrated stainless steel heat exchanger. In the diagram all the important cooling circuit
components are shown.
The closed pressurizer ensures a roughly constant pressure in the cooling circuit, even during great temperature
variations, and must always be installed on the suction side of the pump. At this side a minimum pressure of 0.3 bar
Fundamental Principles and System Description
6.5 to 9.5
< 250 ppm
< 240 ppm
< 50 ppm
< 340 ppm
< 170 ppm
< 2500 μS/cm
< 0.1 mm
Engineering Information
SINAMICS Engineering Manual - May 2008
© Siemens AG
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