Safety functions 103
Step Description
1 The SS1 request is received (for example, from the I/O).
2 After time D 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.
3 The motor speed goes below the SBC speed limit (A). The FSO activates the SBC
function.
The FSO starts a counter for time C.
Note: You can define an extra delay (parameter SS1.15, not shown in the figure) before
the FSO activates the SBC function. This affects also the STO activation (step 4).
3b 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.
4 After time C has elapsed, the FSO activates the drive STO function. STO active
indication parameter STO output (STO.21) goes on when STO is activated.
5 The motor speed reaches the zero speed limit (B), the FSO defines the motor as
stopped and stops the SAR1 monitoring. 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 6).
6 The SS1 request is removed.
7 After the acknowledgement, the SS1, STO and SBC 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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