Siemens SINAMICS S120 Manual page 172

Cabinet Modules
5.3 Smart Line Modules
Configuration
IGBTs (fundamental frequency-switched) are used as power semiconductors of the Smart
Line Modules. Because this reduces switching losses, high current utilization of the power
units can be achieved.
The current flows in the direction of the infeed via the freewheeling diodes of the IGBTs.
While a diode is conducting, the anti-parallel IGBT is also activated. If the DC link voltage
increases due to regenerative operation of the drives, the IGBTs conduct electricity, thus
feeding the energy back into the supply system.
Smart Line Modules do not require a line-side filter. A line reactor (4% u
standard package. The unit has a built-in pre-charging input circuit for the DC link capacitors.
For this purpose, a main contactor or a motor-operated circuit breaker is included in the Line
Connection Module on the line side.
It should be noted that the capacity of the pre-charging input circuit for charging the DC link
capacitors depends on the unit being used. It is limited to no more than 4 to 7.8 times the
value of the DC link capacitance installed in the device.
Note
Additional information
The configuration examples of the individual Smart Line Modules are used to illustrate the
positioning of the factory-fitted components. They show the maximum possible configuration
of the modules, which contain all options that can be ordered.
Refer to the layout diagrams (AO) on the customer DVD for the precise order-specific
location of the components.
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Cabinet Modules
Manual, 03/2013, A5E03263538A