Siemens SINAMICS S120 Function Manual page 240

Vector control
5.17 Flying restart
Application example
After a power failure, a fan drive can be quickly reconnected to the running fan motor by
means of the "flying restart" function.
Figure 5-23
Figure 5-24
240
Flying restart, example of induction motor without encoder
Flying restart, example of induction motor with encoder
Function Manual, (FH1), 04/2014, 6SL3097-4AB00-0BP4
Drive functions