Sls Reaction When Modulation Is Lost During Deceleration Ramp - ABB ACS880 Series Manual

3. The actual motor speed reaches the SLS1 limit positive. The drive limits the motor speed
reference so that the motor speed stays below the SLS1 limit positive. The FSO module
monitors the actual motor speed. If the motor speed goes above the SLS1 trip limit
positive (C), the FSO module activates the SSE function (see section
below the monitored speed (page
(3b) The motor speed goes below the zero speed limit (D). If the motor speed did not
follow the ramp at 2b, the STO acknowledgement is now permitted. The user must reset
the drive if the STO indication parameter (FSOGEN.62 or 31.22) is set so that a fault is
generated.
4. The user or a PLC energizes the applicable digital inputs of the FSO module. This
deactivates the SLS request. The FSO module acknowledges the SLS function
automatically. This is set to be automatic by an FSO parameter (SLSx.02), and no external
acknowledgement input is used. The FSO module stops SLS monitoring and de-energizes
the digital output that indicates the SLS status. The drive returns to normal operation and
starts to follow its ordinary speed reference. The drive accelerates the motor to the desired
speed along its acceleration ramp (drive parameter).
5. Normal operation continues.

SLS reaction when modulation is lost during deceleration ramp

This section describes the functionality of the FSO module when drive modulation is lost
during the SLS deceleration ramp and safe speed estimate is used. Safe speed estimate
is used only when there is an encoder failure and parameter S_ENCGEN.11 is set to Est
switch not active load. For functionality with encoder feedback, see section
loss when encoder feedback is used (page
If the SLS function is activated when motor speed is above the SLS trip limit, FSO causes
the drive to decelerate to the SLS limit. The user can select how the FSO reacts if the drive
stops modulating during this deceleration ramp. The following table lists the possible values
of parameter SLSx.05.
Value of parameter SLSx.05
SLS ramp modoff reaction
Modoff delay time
Monitoring active
Monitoring active and modoff
delay time
Monitoring and modoff delay
time disabled
18)).
30).
FSO reaction if drive modulation is lost during SLS deceleration ramp
STO is activated after the delay defined by parameter SLSx.06. If modulation
returns before SLSx.06 delay has elapsed, monitoring and deceleration to-
wards SLS monitoring limit starts again.
See Example 1: Modoff delay time – modulation returns before modoff
delay (page 24).
SLS ramp or time monitoring remains on. The monitoring limit hits are gener-
ated based on the last valid speed estimate.
See Example 2: SAR1 ramp monitoring active (page 25)
Time monitoring active (page
Modoff delay time and Monitoring active are used: FSO generates the monit-
oring limit hit based on which condition is met first and activates the STO.
See Example 3: SAR1 ramp monitoring and SLS modoff delay time act-
ive (page 26).
Monitoring is stopped and SLS indication is given after STO.14 delay. If
modulation returns during deceleration ramp, monitoring and deceleration
towards SLS monitoring limit start again.
Note: No tripping fault is given due to loss of drive modulation.
See Example 5: Monitoring and modoff delay time disabled (page
Option description 23
27).
SLS with speed
Drive modulation
and Example 4:
28).