ABB FSO-21, User Manual

Page: 73 / 540

Safety functions 73
C Restart delay after STO (parameter STO.13 ): Time from the STO activation to the
moment when the acknowledgment becomes allowed. With this parameter, you can
allow a restart of the drive before the motor has stopped (fly-start). You can use this
feature only in certain applications. This parameter is relevant only when an external
request activates the STO function.
Step Description
1 The STO request is received (for example, from the I/O). The FSO activates the drive
STO function and starts counters for times B and C. STO active indication parameter
STO output (
STO.21 ) goes on.
2 After time C has elapsed, the acknowledgement becomes allowed as soon as the STO
request has been removed (step 5).
3 After time B has elapsed, the FSO activates the SBC function (brake).
Note : If zero speed limit A is reached before time B has elapsed, the FSO activates the
SBC function immediately when the motor has stopped.
4 The motor speed reaches the zero speed limit (A), the FSO module defines the motor
as stopped and the STO completed indication goes on.
5 The STO request is removed.
6 After the acknowledgement, the STO and SBC are deactivated, and the control is given
back to the drive, which controls the brake from now on. The indications STO output
(
STO.21 ) and STO completed output ( STO.22 ) go off.