Flying Restart - Siemens SINAMICS G150 Operating Instructions Manual

9.2.6

Flying restart

Description
The "Flying restart" function (enabled via p1200) allows the converter to switch to a motor
that is still rotating. Switching on the converter without the flying restart function would not
allow any flux to build up in the motor while it is rotating. Since the motor cannot generate
any torque without flux, this can cause it to switch off due to overcurrent (F07801).
The flying restart function first determines the speed of the drive with which V/f or vector
control is initialized so that the converter and motor frequency can be synchronized.
During the standard start-up procedure for the converter, the motor must be at a standstill.
The converter then accelerates the motor to the setpoint speed. In many cases, however,
the motor is not at a standstill.
Two different situations are possible here:
1. The drive rotates as a result of external influences, such as water (pump drives) or air
2. The drive rotates as a result of a previous shutdown (e.g. OFF 2 or a power failure). The
In accordance with the setting chosen (p1200), the flying restart function is activated in the
following situations:
● Once power has been restored and the automatic restart function is active
● After a shutdown with the OFF2 command (pulse inhibit) when the automatic restart
● When the ON command is issued.
Note
The flying restart function must be used when the motor may still be running or is being
driven by the load to prevent shutdowns due to overcurrent (F7801).
Note
If the value set for parameter p1203 (search speed factor) is higher, the search curve is
flatter and, as a result, the search time is longer. A lower value has the opposite effect.
In motors with a low moment of inertia, the flying restart function can cause the drive to
accelerate slightly.
In group drives, the flying restart function should not be activated due to the different
coasting properties of the individual motors.
Converter cabinet units
Operating Instructions, 03/2012, A5E03263466A
(fan drives). In this case, the drive can also rotate against the direction of rotation.
drive slowly coasts to a standstill as a result of the kinetic energy stored in the drive train
(example: induced-draft fan with a high moment of inertia and a steeply descending load
characteristic in the lower speed range).
function is active
Functions, Monitoring, and Protective Functions
9.2 Drive Functions
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