Automatic Restart" Function After Power Failure - Siemens SINAMICS G120 Operating Instructions Manual

Note
The higher the search rate (P1203), the longer the search time. A lower search rate shortens
the search time.
The "flying restart" function decelerates the motor slightly. The smaller the drive torque, the
more the drive is decelerated.
The "flying restart" function should not be activated for motors in group drives due to the
different coasting characteristics of the individual motors.
5.10.2.2

"Automatic restart" function after power failure

Restart after a power failure and/or faults within a few seconds.
This automatic restart function is primarily used when the inverter is operated as a stand-
alone device.
The "automatic restart" function is used to restart the drive automatically once the power has
been restored following a power failure. All faults are acknowledged automatically and the
drive is switched on again.
Line undervoltage or power failure
The term "line undervoltage" describes a situation in which the line voltage fails momentarily
and is then restored. The power failure is so short that the 400V power supply of the inverter
is briefly interrupted, but the electronics power supply is still maintained.
The term "power failure" describes a situation in which the power fails for a longer period,
whereby the DC link collapses completely and the Control Unit of the inverter is in a zero-
current state.
Important secondary condition
An ON command prior to the power failure and when the power returns is required for the
"automatic restart" function. The ON command must be connected-up through a digital input.
An ON command from a fieldbus is ignored.
Since the function is not restricted to line supply faults, it can also be used to automatically
acknowledge faults and restart the motor after any tripping. To allow the drive to be switched
to a motor shaft that is still rotating, the "flying restart" function must be activated via P1200.
CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA
Functions
5.10 Technological functions
141