Permissible Dimensions And Topologies Of The Dc Busbar - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information
1.8.2.3

Permissible dimensions and topologies of the DC busbar

The SINAMICS S120 modular drive system is designed to be a central drive system. For this reason, the permissible
dimensions of the DC busbar including the connected Motor Modules are subject to certain limits. Thus all
components linked to the DC busbar (Infeed Modules, Motor Modules, Braking Modules) should ideally be positioned
as close as possible to one another in order to create the most compact possible drive configuration.
Experience has proven that DC busbar dimensions of up to between about 50 m and 75 m can be regarded as
noncritical for Chassis and cabinet units within the power range included in this engineering manual. Boundary
conditions requiring careful examination apply in the case of busbar dimensions ranging between about 75 m and
150 m. In this case technical clarification is generally necessary. DC busbar dimensions in excess of about 150 m as
well as star-shaped topologies in which multiple DC busbar systems are networked across multiple expanses of
100 m, are not permitted. This is because the possibility of undesirable interactions and associated system problems
cannot be ruled out in configurations of this type. Interactions can be minimized most effectively in DC configurations
which are supplied by Active Infeeds and these should be the preferred option in cases where dimensions are at the
borderline.
Examples of permissible arrangements of drive configurations for multi-motor drive systems are shown below. In all
cases, the DC busbar is supplied by an S120 Infeed which can comprise a parallel connection of up to four identical
S120 Line Modules. In these typical configurations, the Motor Modules are arranged along the DC busbar in the
recommended power rating-related sequence.
Example 1 shows a typical linear arrangement of the DC busbar, with the S120 Infeed positioned at the left-hand end
and the Motor Modules positioned to the right of the Infeed in descending order of output power rating.
Example 1: Linear arrangement of a DC busbar with the Infeed at the left-hand end of the configuration
The arrangement illustrated by example 1 is suitable for configurations in the low to medium output power range.
With higher output power ratings, a significant reduction in the load on the DC busbar and thus the required busbar
cross-section can be achieved by positioning the S120 Infeed in the center of the DC busbar and arranging the Motor
Modules in descending order of output power rating to the right and left of the S120 Infeed, as illustrated in
example 2.
Example 2: Linear arrangement of a DC busbar with Infeed in the center of the configuration
With high power outputs in the range of a few MW for which a very long DC busbar might be required, it is better to
divide the configuration into two sub-configurations arranged back-to-back. Furthermore, if the S120 Infeed is
positioned in the center of one sub-configuration and directly connected to the center of the DC busbar of the other
sub-configuration, then very favorable dimensions of busbar cross-section can be achieved. Example 3 shows this
type of arrangement.
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