Function description
Switching from converter operation to line operation
1. The converter switches the motor OFF.
2. The converter opens the K1 converter contactor via a digital output.
3. The converter waits for the unlocking time of the motor.
4. The converter waits for the feedback that the K1 converter contactor is open.
5. The converter closes the K2 line contactor via a digital output.
The motor is now operated directly on the line supply.
Note
Current surge when switching from converter operation to line operation
When switching from converter operation to line operation, a current > 10 × rated motor current
can flow temporarily. The current depends on the random phase shift between the converter
voltage and the line voltage.
Switching from line operation to converter operation
1. The converter opens the K2 line contactor via a digital output.
2. The converter waits for the unlocking time of the motor.
3. The converter waits for the feedback that the K2 line contactor is open.
4. The converter closes the K1 converter contactor via a digital output.
5. The converter switches the motor on.
6. The converter adjusts with the "Flying restart" function its output frequency to the speed of
the motor.
The motor is now operated on the converter.
Advanced commissioning
6.10 Energy saving
SINAMICS G120X converter
440
Operating Instructions, 06/2019, FW V1.01, A5E44751209B AC