Parallel Connection Of S120 Smart Line Modules - Siemens SINAMICS G130 Engineering Manual

1.15.4

Parallel connection of S120 Smart Line Modules

Parallel connections of Smart Line Modules can be implemented as either a 6-pulse circuit if the parallel-connected
modules are connected to a two-winding transformer, or as a 12-pulse circuit if the parallel-connected modules are
connected to a three-winding transformer with secondary windings that supply voltages with a phase shift of 30 °.
6-pulse parallel connection of S120 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 controlled by a common Control Unit.
6-pulse parallel connection of S120 Smart Line Modules
As Smart Line Modules have no electronic current sharing control, the current must be balanced by the following
measures:
·
Use of line reactors with a relative short-circuit voltage of v
·
Use of symmetrical power cabling between the transformer and the Smart Line Modules (cables of
identical type with the same cross-section and length)
The current reduction from the rated value for individual Smart Line Modules in a parallel connection is 7.5 %.
12-pulse parallel connection of S120 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 modules, i.e. two or four, must be divided between the two secondary
windings. It is absolutely essential that the Smart Line Modules of both secondary windings are controlled by means
of two Control Units because of the phase displacement of 30º. The use of two Control Units is necessary because,
in contrast to the Basic Line Modules, the gating impulses for the IGBTs in Smart Line Modules are synchronized by
the Control Unit. Thus all Smart Line Modules controlled by one Control Unit must be connected to the same
transformer winding with equal phase position.
Fundamental Principles and System Description
SINAMICS Engineering Manual – November 2015
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