SIEMENS
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Siemens D 21.4 · 2017
Tools and configuration
Configuration notes
System components
13
■
Configuration
(continued)
External 24 V DC supply of components
Power units (Line Modules and Motor Modules) and other
system components must be provided with a 24 V DC voltage
via an electronics power supply made available externally.
SITOP devices, which are available as a modular solution, are
provided as the external 24 V DC electronic power supply.
Connecting the external electronics power supply
The current requirement
I
DC ext
is calculated using the following
formula:
Σ
[Control Unit + built-in options (e.g. TB30 + CBC10) +
system components + Line Module +
Σ
(Motor Modules +
SMCxx + motor brake control)]
The other system components (e.g. line contactor) must also be
taken into account.
The current requirement of individual components can be found
in the relevant technical specifications.
Limit values when configuring the system:
•
The current-carrying capacity of the integrated 24 V DC
busbar (featured only in booksize format) is max. 20 A.
•
In the event of higher current requirements, a number of
24 V DC power supplies must be provided in one drive
line-up. The other infeeds are implemented by means of 24 V
terminal adapters (booksize format only).
•
Cable cross sections of up to 2.5 mm² may be connected to
the Control Units, Terminal Boards, Terminal Modules and
Sensor Modules.
•
Cable cross sections of up to 6 mm² may be connected to the
24 V terminal adapters (booksize format only) for the Line
Modules and Motor Modules.
•
The external 24 V DC power supply should only be used for
the SINAMICS components and the direct loads.
Capacitors in the electronics supply of most components must
be charged when the 24 V DC supply is first switched on. To
charge these capacitors, the power supply must first supply a
current peak which can be a multiple of the current requirement
I
DC ext
calculated above. Allowance must be made for this
current peak when selecting protective elements, e.g. miniature
circuit breakers, for incorporation in the 24 V DC supply system
(types with let-through
I
2
t
values according to characteristic D).
The current peak flows for an interval
t
e
of less than 100 ms. The
crest value is determined by the impedance of the 24 V DC
supply and its electronically limited maximum current.
Typical waveform of the switch-on current of the external 24 V DC supply
=
~
Line
3 AC
Power supply
(3-phase)
24 V DC
Power supply
(single-phase)
24 V DC
Main
contactor
Line
filter
Line
reactor
Line
Module
G_D211_EN_00132
G_D211_EN_00133
I
DC ext
I
t
t
e
© Siemens AG 2017