Siemens SINAMICS S120 Function Manual page 511

The following rules must be observed when connecting Smart Line Modules in parallel:
● Up to four identical Smart Line Modules can be connected in parallel.
● A common Control Unit must always be used to implement the parallel connection.
● A 4% reactor is always required upstream of each Smart Line Module for the purpose of
● Special Line Connection Modules are available for the parallel connection.
● With multiple infeeds, power must be supplied to the systems from a common infeed
● A derating factor of 7.5% must be taken into consideration, regardless of the number of
6-pulse parallel connection of Smart Line Modules
With the 6-pulse parallel connection, up to four Smart line modules are supplied by a
common two-winding transformer on the line side and synchronously controlled by a
common Control Unit.
As Smart Line Modules have no current compensation control, the current must be balanced
by the following measures:
● Use of suitable line reactors for the Smart Line Modules.
● Use of symmetrical power cabling between the transformer and the parallel-connected
● The current reduction (derating) from the rated value for individual Smart Line Modules in
12-pulse parallel connection of Smart Line Modules
With 12-pulse parallel connections, up to four Smart Line Modules are supplied by a three-
winding transformer on the line side. In this case, an even number of Smart Line Modules,
i.e. two or four, must be divided between the two secondary windings. In contrast to Basic
Line Modules, the Smart Line Modules of both subsystems have to be controlled by two
Control Units due to the 30° phase displacement in the input voltages.
Drive functions
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
current balancing.
point (i.e. the modules cannot be operated on different line supplies).
modules connected in parallel.
Smart Line Modules (cables of identical type with the same cross-section and length).
a parallel connection is 7.5%.
Function modules
7.10 Parallel connection of power units
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