Siemens CU240B-2 - Flying Restart - Switching on While the Motor Is Running

Advanced commissioning
6.7 Application-specific functions
Converter with the CU240B-2 and CU240E-2 Control Units
298 Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
6.7.5
Flying restart – switching on while the motor is running
If you switch on the motor while it is still rotating, without the "Flying restart" function, there is
a high probability that a fault will occur as a result of overcurrent (F30001 or F07801).
Examples of applications involving an unintentionally rotating motor directly before switching
on:
● The motor rotates after a brief line interruption.
● A flow of air turns the fan impeller.
● A load with a high moment of inertia drives the motor.
Principle of operation
The "Flying restart" function comprises the following steps:
1. After the on command, the inverter impresses the search current in the motor and
increases the output frequency.
2. When the output frequency reaches the actual motor speed, the inverter waits for the
motor excitation build up time.
3. The inverter accelerates the motor to the actual speed setpoint.
Image 6-49 Principle of operation of the "flying restart" function
Setting "flying restart" function
Parameter
Description
p1200
Flying restart operating mode (factory setting: 0)
0
Flying restart is disabled
1 Flying restart is enabled, search for the motor in both directions, start in the direc-
tion of the setpoint
4
Flying restart is enabled, search for the motor only in the direction of the setpoint
No "Flying restart" function for group drives
It is not permissible that you enable the "Flying restart" function if the inverter is
simultaneously driving several motors.