ABB FSO-21, User Manual

Page: 123 / 540

Safety functions 123
Step Description
1 The SSE request is received (for example, from the I/O). SSE active indication SSE
output ( SSE.21 ) goes on.
2 After time B has elapsed, the drive starts to ramp down the motor speed. SAR0
parameter
200.102 defines the deceleration ramp. The FSO starts the SAR0 ramp
monitoring (parameters SARx.11 and SARx.12 ).
2b If the motor speed hits a ramp monitoring limit, 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.
3 The motor speed reaches the zero speed limit (A), the FSO stops the SAR0 monitoring
and 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 (and SBC, if used) (not shown in the figure).
4 The SSE request is removed.
5 After the acknowledgement, the STO and SSE functions are deactivated and the
control is given back to the drive, which is allowed to modulate again. The indications
SSE output ( SSE.21 ), SSE completed output ( SSE.22 ), and STO output ( STO.21 ) go
off.