8.5.3.8
Automatic restart
After the power fails and returns, the drive is automatically switched on again, irrespective of
the length of the power failure. Alarms are acknowledged automatically and the drive is
restarted.
Prerequisites
The following general conditions must be satisfied in order that the drive can be switched on:
● The auxiliary supplies must not fail.
● The power supply for the fans, coolant pumps, and the open-loop/closed-loop controllers
must be maintained.
If the main infeed fails, the pulse block is initiated. The DC link is supported for a short time using
the precharge.
Starting the drive from standstill
This function is suitable for drives with low moments of inertia and load torques that allow the
drive to come to standstill within seconds, e.g. pump drives with a head of water.
Starting the drive with the "flying restart" function
This function can also be activated as follows: The function is suitable for drives with high inertia
loads (e.g. fan drives). This function can be used to switch the drive to the motor that is still
rotating.
Failure of the auxiliary supply
If the main infeed fails, the following possibilities are available:
● The input-side circuit breaker is still closed.
When the medium-voltage supply system has been restored, the DC-link voltage increases.
This increase is detected by the closed-loop and open-loop controllers.
When a threshold value is exceeded, operation is resumed.
● The input-side circuit breaker has tripped.
After a fixed, definable time, the circuit breaker receives a "CLOSE" command.
The system then checks the DC link voltage.
The device is switched off if the DC link voltage continues to decrease.
If the DC-link voltage increases, operation is resumed when a threshold value is exceeded.
Note
Restricted drive operation when operated via the operator panel in the LOCAL mode
The automatic restart function cannot be used in conjunction with the operator panel in the
LOCAL mode.
When operated in the LOCAL mode, the operator panel withdraws the "ON" command to the
circuit breaker if fault OFF1, OFF2 or OFF3 is active.
Operation
8.5 Functions
SINAMICS SM150 6SL3810-7NN38-0AA1
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Operating Instructions Rev.201910281406 EXAMPLE
