Sinamics S120 Liquid-Cooled Units In Chassis Format; General; Design Of The Sinamics S120 Liquid-Cooled Units - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information
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SINAMICS S120 Liquid-Cooled units in chassis format

General

The units of the modular SINAMICS S120 drive system in chassis format are available in both air-cooled and liquid-
cooled variants.
Liquid cooling allows much more efficient heat dissipation than air cooling. Therefore, liquid-cooled units are more
compact than comparable air-cooled units with the same output power rating. Due to the fact that the power losses in
the units are almost entirely absorbed by the coolant, no fans or only very small fans are required for the cooling of
the electronic boards. Consequently, the units are very quiet. Due to their compactness and their almost neglectable
cooling air requirement, the use of liquid-cooled units is recommened where very little space is available and/or harsh
ambient conditions exist. Hermetically-sealed cabinet units with degree of protection IP54 or higher can be built easily
using liquid-cooled systems.

Design of the SINAMICS S120 Liquid-Cooled units

SINAMICS S120 Liquid-Cooled units in chassis format are characterized by a high power density and a footprint-
optimised design. They come with degree of protection IP00. The electrical power connections for the supply and the
DC link are located at the top of the units and the motor connections at the bottom. The connections for the coolant
(inflow and return flow) are also located at the bottom of the units.
SINAMICS S120 Liquid-Cooled chassis units: Examples of a Basic Line Module and a Motor Module
SINAMICS S120 Liquid-Cooled chassis units in the higher output power range (Basic Line Modules in frame sizes
FBL and GBL and Motor Modules in frame sizes HXL and JXL) have an aluminium heat sink, through which the
coolant directly flows. So the best heat transfer between heat sink and coolant is achieved. However, the aluminium
heat sink places high demands on the cooling circuit and the properties of the coolant.
SINAMICS S120 Liquid-Cooled chassis units in the lower output power range (AC/AC Power Modules in frame sizes
FL and GL and Motor Modules in frame sizes FXL and GXL) have a heat sink with an integrated stainless steel heat
exchanger. These units place low demands on the cooling circuit and the properties of the coolant.
The heat sink of the most liquid-cooled units is equipped with power unit components on both sides. These include
the power semi-conductors of the rectifier and the inverter, the DC link capacitors and the symmetrizing resistors of
the DC link. Consequently, the power losses of all the main components are absorbed by the coolant. Only the very
small power losses of the electronic boards and the busbars are dissipated into the air. The Control Unit CU320,
which is required for the operation of the unit, is not a part of the Power Module.
The functionality of the liquid-cooled units corresponds to that of the corresponding air-cooled units. This includes
overload capacity, factory-set pulse frequency, current derating factors for increased pulse frequencies, possibility of
parallel connection of up to four identical power units and derating factors for the parallel configuration.
All system components of the air-cooled units are also available for the liquid-cooled variants. These include both,
power components such as line and motor-side reactors and filters (with the exception of the line filter according to
category C2 and Braking Modules which, due to their cooling principle can only be used in air-cooled units) and the
electronic components, such as Communication Boards, Terminal Modules and Sensor Modules.
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