ABB FSO-21, User Manual

Page: 107 / 540

Safety functions 107

SSE with immediate STO
The operation of the SSE with immediate STO function is described in the time
diagrams and tables below. For configuration, see section
How to configure SSE with
immediate STO on page 351 .
Without an encoder
A Time to zero speed (parameter STO.14 ): Time from the STO activation to the moment
when the safety function is completed, the SSE completed indication (parameter
SSE.22 ) goes on and the acknowledgment becomes allowed. You must set this to the
estimated time in which the motor coasts to a stop from the maximum speed.
Step Description
1 The SSE request is received (for example, from the I/O). The FSO activates the drive
STO function and starts a counter for time A. SSE active indication
SSE output
( SSE.21 ) and STO output ( STO.21 ) go on.
2 After time A has elapsed, the FSO module defines the motor as stopped and the SSE
completed indication goes on. The acknowledgement becomes allowed as soon as
the SSE request has been removed (step 3).
3 The SSE request is removed.
4 After the acknowledgement, the SSE and STO functions are deactivated, and the
control is given back to the drive. The indications
SSE output ( SSE.21 ), SSE
completed output ( SSE.22 ), and STO output ( STO.21 ) go off.
Drive STO state
& indication
3
SSE request
Motor speed
Time
A
4 2
SSE completed
indication
1
SSE state &
indication
STO.14