Siemens SINAMICS G130 Engineering Manual page 116

Fundamental Principles and System Description
Engineering Information
b) Supply from different medium-voltage supply systems:
- The master Infeed is supplied via isolation transformer 1, whereby the secondary winding can be either
grounded (TN supply system) or non-grounded (IT supply system). With respect to voltage loads on
the DC link and on the motor windings to ground, however, operation with a non-grounded IT supply
system is preferable.
- The slave Infeed(s) must be supplied by its/their own isolation transformer, whereby all secondary
windings must be non-grounded.
·
If it is acceptable to operate the DC link at reduced power if an Active Infeed fails, each Active Infeed can be
dimensioned for the respective proportion of the full infeed current, taking into account a current derating of
5% with respect to the rated current. If the full infeed power is required if an Active Infeed fails, each of the
Active Infeeds and associated transformers must be overdimensioned accordingly.
·
The Active Line Modules that remain in operation if a fault occurs must, in conjunction with the Active
Interface Modules, be able to precharge the complete common DC link capacitance.
SINAMICS Engineering Manual – November 2015
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Ó Siemens AG