Siemens SINAMICS S120 Function Manual page 285

A reactor is used to de-couple the drive converter from the line supply - the uk value for the
reactor is 10% +/- 2%.
Figure 5-26
Note
As a result of the overlap, when synchronizing back to the converter, the DC link voltage can
increase; in the worst case scenario this can result in a fault trip. It is possible to activate an
overvoltage protection function, which, when a Vdc max threshold r1242 is reached, the
pulses are inhibited; as a consequence, the DC link voltage stops increasing. When the
pulses are inhibited, the motor coasts down, which is why it must be restarted on-the-fly. As
a consequence, overvoltage protection is only active if the "Flying restart" function was
activated (p1200 = 1).
Activation
The bypass function with synchronization with overlap (p1260 = 1) can only be activated
using a control signal. Activation using a speed threshold is not possible.
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Circuit example: Bypass with synchronization with overlap
Vector control
5.22 Bypass
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