Siemens SINAMICS S120 - Page 456

SINAMICS S120 Cabinet Modules
Engineering Information
SINAMICS Engineering Manual – November 2015
Ó Siemens AG
456/528
Anti-freeze Antifrogen N Antifrogen L Varidos FSK
Manufacturer Clariant Clariant Nalco
Chemical base Monoethylene glycol Propylene glycol Monoethylene glycol
Minimum concentration 20 % 25 % 25 %
Frost protection with
minimum concentration
- 10 °C - 10 °C - 10 °C
Maximum
concentration
45 % 48 % 45 %
Frost protection with
max. concentration
- 30 °C - 30 °C - 30 °C
Inhibitor content Contains nitrite-based
inhibitors
Contains inhibitors which are
amine-, borate- and
phosphate-free
Contains inhibitors which are
amine-, borate- and
phosphate-free
Has biocidal action with
concentration
> 20 % > 30 % > 30 %
Protection against condensation
With liquid-cooled units, warm air can condense on the cold surfaces of heat sinks, pipes and hoses. This
condensation depends on the temperature difference between the ambient air and the coolant, and the humidity of
the ambient air. The temperature at which water vapor contained in the air condenses into water is known as the dew
point. Condensation water can cause corrosion and electrical damage, for example, flashovers in the power unit and,
in the worst-case scenario, can result in irreparable equipment damage. It is therefore absolutely essential to prevent
condensation inside the units.
As the SINAMICS units are incapable of preventing the formation of condensation under certain climatic conditions,
the cooling circuit must be designed and adjusted such as to reliably prevent condensation. In other words, measures
must be taken to ensure that the coolant temperature is always higher than the dew point of the ambient air.
With liquid-cooled S120 Cabinet Modules, this is achieved by regulating the coolant temperature in the inflow line of
the converter-side deionized water circuit. The coolant temperature in the inflow line is regulated to a fixed, adjustable
setpoint by the Heat Exchanger Module which contains an integral control system in combination with a 3-way valve
(bypass valve) for this purpose. The setpoint for the coolant temperature in the inflow line must be determined
according to the maximum predicted ambient temperature T
max
and the maximum predicted relative air humidity Φ
max
.
It is calculated on the basis of the dew point valid for T
max
and Φ
max
plus a safety margin of around 4 °C (see also:
chapter "Fundamental Principles and System Description“, section "Liquid-cooled SINAMICS S120 units", subsection
"Example of coolant temperature control for condensation prevention").
The table below specifies the dew point as a function of ambient temperature T and relative air humidity Φ for an
atmospheric pressure of 100 kPa (1 bar), corresponding to an installation altitude of 0 to approximately 500 m above
sea level. Since the dew point drops as the air pressure decreases, the dew point values at higher installation
altitudes are lower than the specified table values. It is therefore the safest approach to determine the coolant
temperature according to the table values for an installation altitude of zero.
Ambient
temperature
T
Relative air humidity Φ
20 % 30 % 40 % 50 % 60 % 70 % 80 % 85 % 90 % 95 % 100 %
10 °C < 0 °C < 0 °C < 0 °C 0.2 °C 2.7 °C 4.8 °C 6.7 °C 7.6 °C 8.4 °C 9.2 °C 10.0°C
20 °C < 0 °C 2.0 °C 6.0 °C 9.3 °C 12.0°C 14.3°C 16.4°C 17.4°C 18.3°C 19.1°C 20.0°C
25 °C 0.6 °C 6.3 °C 10.5°C 13.8°C 16.7°C 19.1°C 21.2°C 22.2°C 23.2°C 24.1°C 24.9°C
30 °C 4.7 °C 10.5°C 14.9°C 18.4°C 21.3°C 23.8°C 26.1°C 27.1°C 28.1°C 29.0°C 29.9°C
35 °C 8.7 °C 14.8°C 19.3°C 22.9°C 26.0°C 28.6°C 30.9°C 32.0°C 33.0°C 34.0°C 34.9°C
40 °C 12.8°C 19.1°C 23.7°C 27.5°C 30.6°C 33.4°C 35.8°C 36.9°C 37.9°C 38.9°C 39.9°C
45 °C 16.8°C 23.3°C 28.2°C 32.0°C 35.3°C 38.1°C 40.6°C 41.8°C 42.9°C 43.9°C 44.9°C
50 °C 20.8°C 27.5°C 32.6°C 36.6°C 40.0°C 42.9°C 45.5°C 46.6°C 47.8°C 48.9°C 49.9°C
Dew point as a function of ambient temperature T and relative air humidity Φ at installation altitude zero