Bypass Without Synchronization (P1260 = 3) - Siemens SINAMICS S120 Function Manual

4.22.3

Bypass without synchronization (p1260 = 3)

Description
When the motor is transferred to the line supply, contactor K1 is opened (after the drive
converter pulses have been inhibited); the system then waits for the motor de-excitation time
and then contactor K2 is closed so that the motor is directly connected to the line supply.
When the motor is switched on in a non-synchronized manner, an equalizing current flows
that must be taken into account when the protective equipment is designed.
When the converter retrieves the motor from the line supply, initially contactor K2 is opened,
and after the excitation time has expired, contactor K1 is closed. The drive converter then
connects to the rotating motor and the motor is fed from the drive converter.
In this case, contactor K2 must be designed/selected to be able to switch inductive loads.
Contactors K1 and K2 must be interlocked so that they cannot simultaneously close.
The "flying restart" function must be activated (p1200).
Figure 4-31
Activating
The bypass without synchronization (p1260 = 3) can be triggered by the following signals
(p1267):
● Bypass by means of control signal (p1267.0 = 1):
● Bypass at speed threshold (p1267.1 = 1):
Drive functions
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Circuit example, bypass without synchronization
The bypass can be activated by means of a digital signal (p1266) (e.g. from a higher-level
automation system). If the digital signal is withdrawn again after the debypass delay time
has expired (p1263), then a changeover is made to drive converter operation.
Once a certain speed is reached, the system switches to bypass (i.e. the converter is
used as a start-up converter). The bypass cannot be connected until the speed setpoint is
greater than the bypass speed threshold (p1265).
Vector control
4.22 Bypass
179