ABB FSO-21, User Manual

Page: 119 / 540

Safety functions 119
Step Description
1 The SSE request is received (for example, from the I/O). The FSO starts a counter for
time A. SSE active indication
SSE output ( SSE.21 ) goes on.
2 After time C has elapsed, the drive starts to ramp down the motor speed. SAR0
parameter
200.102 defines the deceleration ramp.
3 The motor speed reaches the zero speed limit (B), the FSO activates the drive STO
function and STO active indication parameter
STO output ( STO.21 ) goes on. The SSE
completed indication goes on and the acknowledgement becomes allowed as soon as
the SSE request has been removed (step 4).
Note : If the SBC is configured in the STO function (see section Safe torque off (STO) on
page 67 ), also the SBC is activated (not shown in the figure).
• If the STO SBC delay (parameter SBC.12 ) is negative, the SBC is activated here and
the drive STO after this delay.
• If the STO SBC delay is positive or zero, the SBC and drive STO functions are
activated at the same time.
Note : You can define an extra delay (parameter SSE.16 ) before the FSO activates the
drive STO (and SBC, if used) (not shown in the figure).
3b If the drive has not ramped down fast enough when time A has elapsed, the FSO
activates the STO function. See section
Safe torque off (STO) on page 67 for more
information on how to configure the STO function.
4 The SSE request is removed.
5 After the acknowledgement, the STO and SSE functions are deactivated. The
indications
SSE output ( SSE.21 ), SSE completed output ( SSE.22 ), and STO output
( STO.21 ) go off.