Equipotential Bonding; Coolant Definition; Coolant Properties - Siemens Sinamics S120 Manual

Cooling circuit, coolant properties and protection against condensation

9.2 Coolant definition

9.1.5

Equipotential bonding

All components in the cooling system (SINAMICS units, heat exchanger, piping system,
pump, pressure compensator, etc.) must be connected to an equipotential bonding system.
A copper bar or stranded copper with the appropriate conductor cross-sections must be used
for this purpose to eliminate electrochemical processes.
If the installation comprises several control cabinets, these must be bolted together in a
solid, conductive connection (e.g. bolt cabinet cross-beams together directly at several
points to make conductive connection). This eliminates potential differences and thus the risk
of electrochemical corrosion. A PE bar must be installed in every cabinet (including the
recooling system) and the individual bars then interconnected.
9.2 Coolant definition
9.2.1

Coolant properties

The coolant must fulfill the following requirements over the long term.
The coolant comprises a coolant basis and antifreeze, see "Antifreeze, biocides, inhibitors
(Page 335)".
Table 9- 3 Coolant specifications for aluminum heat sinks
Basis coolant
pH value
Electrical conductivity
Components that can be oxidized
as oxygen content
Residue after vaporization and
drying at 110 °C
Table 9- 4 Coolant specifications for stainless steel heat sinks
Basis coolant
Chloride ions
Sulfate ions
Nitrate ions
pH value
Electrical conductivity
Total hardness
Dissolved solids
Size of entrained particles
332
Distilled, demineralized water (completely desalinated water) or deionized water with
reduced electrical conductivity according to ISO 3696, quality 3
or based on IEC 60993 with the following values:
5.0 ... 8.0
≤ 30 µS/cm (3 mS/m)
< 30 mg/l
< 10 mg/kg
Filtered drinking water with the following quality:
< 200 mg/l
< 240 mg/l
< 50 mg/l
6.5 ... 9.0
< 2000 µS/cm
< 1.7 mmol/l
< 340 mg/l
< 100 µm
Liquid-cooled chassis power units
Manual, (GH7), 11/2016, 6SL3097-4AM00-0BP7