Siemens Sinamics S120 Manual page 318

Cooling circuit, coolant properties and protection against condensation
9.1 Cooling circuits
Water cooling systems with series-connected SINAMICS devices cannot be recommended
for the following reasons:
● The risk of cavitation and abrasion increases as a result of the high total volumetric flow.
● It is not possible to connect SINAMICS S120 in series because the total volumetric flow
inherent to any series connection requires system pressures in the 600 kPa range or
above.
The characteristic curves for the pressure drop across the heat sinks as a function of the
volumetric flow vary depending on the temperature and the antifreeze and water coolant
combination, as can be seen in the following figures.
Coolant mixture comprising Antifrogen N or Dowcal 100 and water
The following diagrams show the pressure drop as a function of the volumetric flow rates for the
different SINAMICS S120 liquid-cooled components when using Antifrogen N or Dowcal 100.
Dowcal 100 has the same flow attribute as Antifrogen N.
Figure 9-5 Pressure drop as a function of volumetric flow for Basic Line Module, frame size FBL
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Liquid-cooled chassis power units
Manual, (GH7), 11/2016, 6SL3097-4AM00-0BP7