Drive Configurations With Multiple Motor Modules Connected To A Common Dc Busbar; Connection Of Motor Modules To The Dc Busbar, Fuse Protection And Precharging - Siemens SINAMICS G130 Engineering Manual

Fundamental Principles and System Description
Engineering Information
1.8.2

Drive configurations with multiple Motor Modules connected to a common DC busbar

Using components of the SINAMICS S120 modular drive system, it is possible to build drive configurations for multi-
motor drives in which a S120 Infeed (Basic Infeed, Smart Infeed or Active Infeed) comprising one or up to four
parallel-connected Line Modules supplies a DC busbar with several Motor Modules.
When such drive configurations are built various aspects need to be taken into account:
·
Connection of the individual Motor Modules to the DC busbar, fuse protection and precharging.
·
Arrangement of the Motor Modules along the DC busbar.
·
Permissible dimensions and topologies of the DC busbar.
·
Short-circuit currents on the DC busbar.
·
Maximum power output of the drive configuration at the DC busbar.
These aspects are described and explained in more detail below.
1.8.2.1

Connection of Motor Modules to the DC busbar, fuse protection and precharging

The DC busbar is supplied by a SINAMICS S120 Infeed that must be protected on the line side by fuses or circuit
breakers in order to provide line-side protection for the drive configuration.
The DC busbars and the DC cabling must be dimensioned such that the cross-section is sufficiently large for the
current flowing at the relevant point on the busbar. In the simplest case, the DC busbars are dimensioned over their
entire length for the maximum possible DC link current. In certain constellations, however, it is possible to reduce the
cross-section of certain sections of the DC busbar in order to save material and cut costs. When the DC busbar
design is complete, its short-circuit strength must be verified.
The DC busbar itself must be designed to attain the lowest possible inductance. This is achieved by a parallel
arrangement of positive and negative busbars with a minimum possible distance between them (although the bars
must still be separated by the necessary clearances and creepage distances).
Individual SINAMICS S120 Motor Modules can be connected to the DC busbar by three different methods.
Direct connection to the DC busbar
With this connection method, a continuous direct connection between the Motor Modules and the DC busbar is made
without separable contact points using bar conductors, cables or (in some cases) fuses.
Direct connection of a Motor Module to the DC busbar
Each Motor Module must be provided with separate fuse protection.
·
Air-cooled S120 Motor Modules in Chassis format are equipped as standard for this purpose with integrated,
fast semiconductor fuses in both the positive and negative paths. These disconnect the Motor Module
quickly, reliably and completely from the DC busbar in the event of an internal short circuit.
·
S120 Motor Modules in Booksize format have an integrated fuse only in the positive path. For this reason, it
is advisable to provide additional external fuse protection with fast semiconductor fuses in the positive and
negative paths.
·
Liquid-cooled S120 Motor Modules in Chassis format do not feature integrated fuses. They must therefore
be connected to the DC busbar via externally mounted, fast semiconductor fuses. For the recommended
fuse types, please refer to chapter "General Information about Built-in and and Cabinet Units SINAMICS
S120".
Exception: If only a single Motor Module is supplied by a single Infeed with adapted power rating, then the same
conditions apply as with a SINAMICS G130 or G150 converter unit, i.e. the line-side fuses are sufficient to protect
both the Infeed and the Motor Module.
SINAMICS Engineering Manual – November 2015
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Ó Siemens AG