174 Safety functions
Note: For more information on the modoff functionality in a situation where drive
modulation is lost during SLS deceleration ramp, see chapter SLS reaction when
modulation is lost during deceleration ramp, with ramp monitoring on page 147, and
SLS reaction when modulation is lost during deceleration ramp, with time monitoring
on page 157).
5 The Variable SLS request is received again from the safety PLC (for example, 50%).
The FSO sends a request to the drive to ramp down the motor speed to the new speed
limit. The FSO starts a counter for the SLS time delay (B).
Note: The FSO continues to monitor the existing Variable SLS limits until the new
speed limit has been reached.
Note: If variable SLS limits are rescaled before previous limits have been reached,
time monitoring delay SLSx.04 starts from the beginning.
6 After time C has elapsed, the drive starts to ramp down the motor speed. Drive
parameters define the deceleration ramp. The Variable SLS active indication goes off
(see also section How to configure limit hit situations on page 394).
The FSO starts the SLS monitoring when the motor speed is in the middle of the new
SLS limit and the SLS trip limit (see also section How to configure mute time for
monitoring start on page 399).
7 The new motor speed has been reached. The SLS active indication goes on.
8 The FSO starts the SLS monitoring with the new SLS limits at the latest here, that is,
after the SLS time delay (B) has elapsed.
9 The Variable SLS request is received again from the safety PLC (100%). The FSO
sends a request to the drive to accelerate the motor speed to the new speed limit. The
FSO starts to monitor the motor speed according to the new SLS limits.
10 After time C has elapsed and if the motor speed is lower than the new speed limit, the
drive accelerates the motor speed to the requested speed.
11 The Variable SLS request is removed from the safety PLC (acknowledgement method
is manual or from a safety PLC).
Note: If automatic acknowledgement is used, the Variable SLS monitoring is also
ended.
12 The Variable SLS is acknowledged, the FSO stops the SLS monitoring and the drive
continues with the speed reference set by the user. The Variable SLS indication
(parameter SLSx.51) goes off.
Step Description
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