Siemens SINAMICS G120 Original Instructions Manual page 310

Setting functions
8.7 Application-specific functions
Changeover operation between line and inverter operation
When switching over to direct online operation, contactor K1 is opened after the inverter
pulses have been inhibited. The system then waits for the de-energization time of the motor
and then contactor K2 is closed so that the motor is connected directly to the line.
When the motor is switched to the line supply, an equalizing current flows that must be taken
into account when the protective equipment is selected and dimensioned.
When changing over to inverter operation, initially contactor K2 must be opened and after
the de-excitation time, contactor K1 is closed. The inverter then captures the rotating motor
and the motor is operated on the inverter.
Bypass function when activating via a control signal (p1267.0 = 1)
The state of the bypass contactors is evaluated when the inverter is switched on. If the
automatic restart function is active (p1210 = 4) and an ON command (r0054.0 = 1) as well as
the bypass signal (p1266 = 1) are still present at power up, then after power up, the inverter
goes into the "ready and bypass" state (r899.0 = 1 and r0046.25 = 1) and the motor
continues to run directly connected to the line supply.
Figure 8-34 Bypass control independent of the speed via a control signal (p1267.0 = 1)
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Inverter with CU230P-2 Control Units
Operating Instructions, 11/2013, FW V4.6.6, A5E02430659B AG