Safety functions 117
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), 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.
• The SSE 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 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.
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