Parallel Connections - Siemens SINAMICS G130 Engineering Manual

SINAMICS S120 Cabinet Modules
Engineering Information
Line Modules which can be connected in parallel on a Line Connection Module are highlighted in grey in the table.
With these applications, the rectifiers (Line Modules) are positioned on the right and left of the LCM cabinet.
When Line Connection Modules are ordered, the option code L42, L43 or L44 must be added to the order number in
order to indicate whether the LCM will be connected to an Active Line Module (L42), a Basic Line Module (L43) or a
Smart Line Module (L44). This information is required to ensure that the LCM is correctly equipped in the factory.
This applies primarily to the busbar connections at the three-phase side (3AC), to possible precharging circuits and to
the specification of line reactors for Basic Line Modules which can be excluded with option L22.
When Cabinet Modules are selected and combined as defined in the above assignment table, the Line Connection
Modules are equipped and prepared as specified in the factory.
For other combinations of Cabinet Modules which deviate from the standard, please ask your Siemens contact for
further information.
7.2.4.4

Parallel connections

Line Connection Modules can be used to create different types of Line Module parallel connections.
A double parallel connection of two identical Line Modules on a single LCM can be created using LCMs in frame
sizes KL and LL.
Parallel connections consisting of more than two Line Modules can be created by using multiple Line Connection
Modules connected in parallel.
When Line Connection Modules are connected in parallel, they should be arranged symmetrically where ever
possible for achieving symmetrical current distribution and the greatest possible simultaneity of tripping by the line-
side protective devices (circuit breakers or fuses) in the event of a short circuit. In other words, only Line Connection
Modules of identical type should be connected in parallel.
Example:
Implementation of a triple parallel connection of BLMs
In the configuration illustrated above, three identical LCM-BLM combinations have been used, creating an absolutely
symmetrical arrangement.
If a triple parallel connection of Basic Line Modules is implemented using two Line Connection Modules, with two
BLMs connected to an LCM of frame size LL or KL and the third BLM connected to another LCM, the arrangement
will be asymmetrical. This asymmetry can have a negative impact on current distribution and there is a risk that the
various circuit breakers or fuses will not trip simultaneously in response to a short circuit on the DC busbar, making
quick and reliable clearance of the short circuit difficult to achieve. For this reason, it is always preferable to
implement symmetrical parallel connections.
To create a quadruple parallel connection, it is possible to use either two identical LCMs in frame sizes LL or KL or
four single LCMs of identical type. Both methods will produce the optimum symmetrical configuration.
The parallel connection is made up of standard components. Orders for modules for parallel connection are not
subject to any special conditions. Line Connection Modules prepared for parallel connection (displayed on grey
background in the table above) already include two line reactors when used with Basic Line Modules. Smart Line
Modules are generally equipped with line reactors which are integrated in the SLM. Please note the supplementary
physical conditions described in the chapter "Fundamental Principles and System Description".
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Ó Siemens AG