ABB ACS880 Series Manual page 21

3. The actual motor speed reaches the SLS1 limit positive. The drive limits the motor speed
reference so that the motor speed stays at or below the SLS1 limit positive. The FSO
module monitors the actual motor speed. If the motor speed goes above the SLS1 trip
limit positive (D), the FSO module activates the SSE function (see section
speed below the monitored speed (page
(3b) Time (B) has elapsed. The FSO module starts SLS monitoring (if not already started).
Note: If the motor speed is not below the SLS monitoring limit after time B has elapsed,
the FSO module activates the SSE function. Depending on SSE function parameter
settings, the motor either coasts to a stop ("Immediate STO") or ramps down to zero
speed ("Emergency ramp"). For more information, see section
function (page 40)
Note: In this case, the FSO activates the SLS indication when the motor speed goes
below the SLS limit positive (C).
Note: In option +Q978, the SBC function is used to control the main contactor/breaker.
If the drive has this option and a trip limit hit occurs, STO activation causes the main
contactor/breaker to open.
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.
and the FSO module user's manual.
18)).
Option description 21
SLS with
Parameters for the SSE