Siemens SINAMICS S120 Function Manual page 281

The motor is changed over from line supply operation to converter operation in the
inverse sequence: At the start of the operation, contactor K2 is closed and contac-
tor K1 is opened.
S The control bit "bypass command" is deleted (e.g. from the higher-level
automation).
S The bypass function sets the control word bit "synchronizing".
S The pulses are enabled. "Synchronizing" is set before "pulse enable". This
means that the drive converter interprets this as a command to retrieve the
motor from the line supply and resume operation with the motor.
S After the drive converter has synchronized to the line supply frequency, voltage
and phase position, the synchronizing algorithm signals this state.
S The bypass mechanism evaluates this signal and closes contactor K1. The
signal is internally evaluated – BICO wiring is not required.
S After contactor K1 signals back the "closed" state, contactor K2 is opened and
the motor is again fed from the drive converter.
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition
Extended Functions
Bypass (vector)
4-281