Safety functions 85
Step Description
1 The SS1 request is received (for example, from the I/O).
2 After time B has elapsed, the drive starts to ramp down the motor speed. SAR1
parameter 200.112 defines the deceleration ramp. The FSO starts the SAR1 ramp
monitoring (parameters SARx.21 and SARx.22).
Note: If parameter 200.112 has value 0, the drive (parameter 23.23) defines the ramp.
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 (B), FSO stops the SAR1 monitoring and
activates the drive STO function, and STO active indication parameter STO output
(STO.21) goes on. The SS1 completed output indication (parameter SS1.22) goes on
and the acknowledgement becomes allowed as soon as the SS1 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.
• The SS1 completed indication goes on after the delay defined with parameter
SBC.13 has elapsed from the SBC activation.
Note: You can define an extra delay (parameter SS1.15) before the FSO activates the
drive STO (and SBC, if used) (not shown in the figure).
4 The SS1 request is removed.
5 After the acknowledgement, the STO and SS1 functions are deactivated and the
control is given back to the drive, which is allowed to modulate again. The indications
SS1 output (SS1.21), SS1 completed output (SS1.22), and STO output (STO.21) go
off.
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